xref: /petsc/src/dm/impls/forest/p4est/pforest.h (revision 4dfa11a44d5adf2389f1d3acbc8f3c1116dc6c3a)

#include <petscds.h>
#include <petsc/private/dmimpl.h>
#include <petsc/private/dmforestimpl.h>
#include <petsc/private/dmpleximpl.h>
#include <petsc/private/dmlabelimpl.h>
#include <petsc/private/viewerimpl.h>
#include <../src/sys/classes/viewer/impls/vtk/vtkvimpl.h>
#include "petsc_p4est_package.h"

#if defined(PETSC_HAVE_P4EST)

#if !defined(P4_TO_P8)
#include <p4est.h>
#include <p4est_extended.h>
#include <p4est_geometry.h>
#include <p4est_ghost.h>
#include <p4est_lnodes.h>
#include <p4est_vtk.h>
#include <p4est_plex.h>
#include <p4est_bits.h>
#include <p4est_algorithms.h>
#else
#include <p8est.h>
#include <p8est_extended.h>
#include <p8est_geometry.h>
#include <p8est_ghost.h>
#include <p8est_lnodes.h>
#include <p8est_vtk.h>
#include <p8est_plex.h>
#include <p8est_bits.h>
#include <p8est_algorithms.h>
#endif

typedef enum {
  PATTERN_HASH,
  PATTERN_FRACTAL,
  PATTERN_CORNER,
  PATTERN_CENTER,
  PATTERN_COUNT
} DMRefinePattern;
static const char *DMRefinePatternName[PATTERN_COUNT] = {"hash", "fractal", "corner", "center"};

typedef struct _DMRefinePatternCtx {
  PetscInt       corner;
  PetscBool      fractal[P4EST_CHILDREN];
  PetscReal      hashLikelihood;
  PetscInt       maxLevel;
  p4est_refine_t refine_fn;
} DMRefinePatternCtx;

static int DMRefinePattern_Corner(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrant) {
  p4est_quadrant_t    root, rootcorner;
  DMRefinePatternCtx *ctx;

  ctx = (DMRefinePatternCtx *)p4est->user_pointer;
  if (quadrant->level >= ctx->maxLevel) return 0;

  root.x = root.y = 0;
#if defined(P4_TO_P8)
  root.z = 0;
#endif
  root.level = 0;
  p4est_quadrant_corner_descendant(&root, &rootcorner, ctx->corner, quadrant->level);
  if (p4est_quadrant_is_equal(quadrant, &rootcorner)) return 1;
  return 0;
}

static int DMRefinePattern_Center(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrant) {
  int                 cid;
  p4est_quadrant_t    ancestor, ancestorcorner;
  DMRefinePatternCtx *ctx;

  ctx = (DMRefinePatternCtx *)p4est->user_pointer;
  if (quadrant->level >= ctx->maxLevel) return 0;
  if (quadrant->level <= 1) return 1;

  p4est_quadrant_ancestor(quadrant, 1, &ancestor);
  cid = p4est_quadrant_child_id(&ancestor);
  p4est_quadrant_corner_descendant(&ancestor, &ancestorcorner, P4EST_CHILDREN - 1 - cid, quadrant->level);
  if (p4est_quadrant_is_equal(quadrant, &ancestorcorner)) return 1;
  return 0;
}

static int DMRefinePattern_Fractal(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrant) {
  int                 cid;
  DMRefinePatternCtx *ctx;

  ctx = (DMRefinePatternCtx *)p4est->user_pointer;
  if (quadrant->level >= ctx->maxLevel) return 0;
  if (!quadrant->level) return 1;
  cid = p4est_quadrant_child_id(quadrant);
  if (ctx->fractal[cid ^ ((int)(quadrant->level % P4EST_CHILDREN))]) return 1;
  return 0;
}

/* simplified from MurmurHash3 by Austin Appleby */
#define DMPROT32(x, y) ((x << y) | (x >> (32 - y)))
static uint32_t DMPforestHash(const uint32_t *blocks, uint32_t nblocks) {
  uint32_t c1   = 0xcc9e2d51;
  uint32_t c2   = 0x1b873593;
  uint32_t r1   = 15;
  uint32_t r2   = 13;
  uint32_t m    = 5;
  uint32_t n    = 0xe6546b64;
  uint32_t hash = 0;
  int      len  = nblocks * 4;
  uint32_t i;

  for (i = 0; i < nblocks; i++) {
    uint32_t k;

    k = blocks[i];
    k *= c1;
    k = DMPROT32(k, r1);
    k *= c2;

    hash ^= k;
    hash = DMPROT32(hash, r2) * m + n;
  }

  hash ^= len;
  hash ^= (hash >> 16);
  hash *= 0x85ebca6b;
  hash ^= (hash >> 13);
  hash *= 0xc2b2ae35;
  hash ^= (hash >> 16);

  return hash;
}

#if defined(UINT32_MAX)
#define DMP4EST_HASH_MAX UINT32_MAX
#else
#define DMP4EST_HASH_MAX ((uint32_t)0xffffffff)
#endif

static int DMRefinePattern_Hash(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrant) {
  uint32_t            data[5];
  uint32_t            result;
  DMRefinePatternCtx *ctx;

  ctx = (DMRefinePatternCtx *)p4est->user_pointer;
  if (quadrant->level >= ctx->maxLevel) return 0;
  data[0] = ((uint32_t)quadrant->level) << 24;
  data[1] = (uint32_t)which_tree;
  data[2] = (uint32_t)quadrant->x;
  data[3] = (uint32_t)quadrant->y;
#if defined(P4_TO_P8)
  data[4] = (uint32_t)quadrant->z;
#endif

  result = DMPforestHash(data, 2 + P4EST_DIM);
  if (((double)result / (double)DMP4EST_HASH_MAX) < ctx->hashLikelihood) return 1;
  return 0;
}

#define DMConvert_pforest_plex _infix_pforest(DMConvert, _plex)
static PetscErrorCode DMConvert_pforest_plex(DM, DMType, DM *);

#define DMFTopology_pforest _append_pforest(DMFTopology)
typedef struct {
  PetscInt              refct;
  p4est_connectivity_t *conn;
  p4est_geometry_t     *geom;
  PetscInt             *tree_face_to_uniq; /* p4est does not explicitly enumerate facets, but we must to keep track of labels */
} DMFTopology_pforest;

#define DM_Forest_pforest _append_pforest(DM_Forest)
typedef struct {
  DMFTopology_pforest *topo;
  p4est_t             *forest;
  p4est_ghost_t       *ghost;
  p4est_lnodes_t      *lnodes;
  PetscBool            partition_for_coarsening;
  PetscBool            coarsen_hierarchy;
  PetscBool            labelsFinalized;
  PetscBool            adaptivitySuccess;
  PetscInt             cLocalStart;
  PetscInt             cLocalEnd;
  DM                   plex;
  char                *ghostName;
  PetscSF              pointAdaptToSelfSF;
  PetscSF              pointSelfToAdaptSF;
  PetscInt            *pointAdaptToSelfCids;
  PetscInt            *pointSelfToAdaptCids;
} DM_Forest_pforest;

#define DM_Forest_geometry_pforest _append_pforest(DM_Forest_geometry)
typedef struct {
  DM base;
  PetscErrorCode (*map)(DM, PetscInt, PetscInt, const PetscReal[], PetscReal[], void *);
  void             *mapCtx;
  PetscInt          coordDim;
  p4est_geometry_t *inner;
} DM_Forest_geometry_pforest;

#define GeometryMapping_pforest _append_pforest(GeometryMapping)
static void GeometryMapping_pforest(p4est_geometry_t *geom, p4est_topidx_t which_tree, const double abc[3], double xyz[3]) {
  DM_Forest_geometry_pforest *geom_pforest = (DM_Forest_geometry_pforest *)geom->user;
  PetscReal                   PetscABC[3]  = {0.};
  PetscReal                   PetscXYZ[3]  = {0.};
  PetscInt                    i, d = PetscMin(3, geom_pforest->coordDim);
  double                      ABC[3];
  PetscErrorCode              ierr;

  (geom_pforest->inner->X)(geom_pforest->inner, which_tree, abc, ABC);

  for (i = 0; i < d; i++) PetscABC[i] = ABC[i];
  ierr = (geom_pforest->map)(geom_pforest->base, (PetscInt)which_tree, geom_pforest->coordDim, PetscABC, PetscXYZ, geom_pforest->mapCtx);
  PETSC_P4EST_ASSERT(!ierr);
  for (i = 0; i < d; i++) xyz[i] = PetscXYZ[i];
}

#define GeometryDestroy_pforest _append_pforest(GeometryDestroy)
static void GeometryDestroy_pforest(p4est_geometry_t *geom) {
  DM_Forest_geometry_pforest *geom_pforest = (DM_Forest_geometry_pforest *)geom->user;
  PetscErrorCode              ierr;

  p4est_geometry_destroy(geom_pforest->inner);
  ierr = PetscFree(geom->user);
  PETSC_P4EST_ASSERT(!ierr);
  ierr = PetscFree(geom);
  PETSC_P4EST_ASSERT(!ierr);
}

#define DMFTopologyDestroy_pforest _append_pforest(DMFTopologyDestroy)
static PetscErrorCode DMFTopologyDestroy_pforest(DMFTopology_pforest **topo) {
  PetscFunctionBegin;
  if (!(*topo)) PetscFunctionReturn(0);
  if (--((*topo)->refct) > 0) {
    *topo = NULL;
    PetscFunctionReturn(0);
  }
  if ((*topo)->geom) PetscCallP4est(p4est_geometry_destroy, ((*topo)->geom));
  PetscCallP4est(p4est_connectivity_destroy, ((*topo)->conn));
  PetscCall(PetscFree((*topo)->tree_face_to_uniq));
  PetscCall(PetscFree(*topo));
  *topo = NULL;
  PetscFunctionReturn(0);
}

static PetscErrorCode PforestConnectivityEnumerateFacets(p4est_connectivity_t *, PetscInt **);

#define DMFTopologyCreateBrick_pforest _append_pforest(DMFTopologyCreateBrick)
static PetscErrorCode DMFTopologyCreateBrick_pforest(DM dm, PetscInt N[], PetscInt P[], PetscReal B[], DMFTopology_pforest **topo, PetscBool useMorton) {
  double  *vertices;
  PetscInt i, numVerts;

  PetscFunctionBegin;
  PetscCheck(useMorton, PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Lexicographic ordering not implemented yet");
  PetscCall(PetscNew(topo));

  (*topo)->refct = 1;
#if !defined(P4_TO_P8)
  PetscCallP4estReturn((*topo)->conn, p4est_connectivity_new_brick, ((int)N[0], (int)N[1], (P[0] == DM_BOUNDARY_NONE) ? 0 : 1, (P[1] == DM_BOUNDARY_NONE) ? 0 : 1));
#else
  PetscCallP4estReturn((*topo)->conn, p8est_connectivity_new_brick, ((int)N[0], (int)N[1], (int)N[2], (P[0] == DM_BOUNDARY_NONE) ? 0 : 1, (P[1] == DM_BOUNDARY_NONE) ? 0 : 1, (P[2] == DM_BOUNDARY_NONE) ? 0 : 1));
#endif
  numVerts = (*topo)->conn->num_vertices;
  vertices = (*topo)->conn->vertices;
  for (i = 0; i < 3 * numVerts; i++) {
    PetscInt j = i % 3;

    vertices[i] = B[2 * j] + (vertices[i] / N[j]) * (B[2 * j + 1] - B[2 * j]);
  }
  (*topo)->geom = NULL;
  PetscCall(PforestConnectivityEnumerateFacets((*topo)->conn, &(*topo)->tree_face_to_uniq));
  PetscFunctionReturn(0);
}

#define DMFTopologyCreate_pforest _append_pforest(DMFTopologyCreate)
static PetscErrorCode DMFTopologyCreate_pforest(DM dm, DMForestTopology topologyName, DMFTopology_pforest **topo) {
  const char *name = (const char *)topologyName;
  const char *prefix;
  PetscBool   isBrick, isShell, isSphere, isMoebius;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscValidCharPointer(name, 2);
  PetscValidPointer(topo, 3);
  PetscCall(PetscStrcmp(name, "brick", &isBrick));
  PetscCall(PetscStrcmp(name, "shell", &isShell));
  PetscCall(PetscStrcmp(name, "sphere", &isSphere));
  PetscCall(PetscStrcmp(name, "moebius", &isMoebius));
  PetscCall(PetscObjectGetOptionsPrefix((PetscObject)dm, &prefix));
  if (isBrick) {
    PetscBool flgN, flgP, flgM, flgB, useMorton = PETSC_TRUE, periodic = PETSC_FALSE;
    PetscInt  N[3] = {2, 2, 2}, P[3] = {0, 0, 0}, nretN = P4EST_DIM, nretP = P4EST_DIM, nretB = 2 * P4EST_DIM, i;
    PetscReal B[6] = {0.0, 1.0, 0.0, 1.0, 0.0, 1.0}, Lstart[3] = {0., 0., 0.}, L[3] = {-1.0, -1.0, -1.0}, maxCell[3] = {-1.0, -1.0, -1.0};

    if (dm->setfromoptionscalled) {
      PetscCall(PetscOptionsGetIntArray(((PetscObject)dm)->options, prefix, "-dm_p4est_brick_size", N, &nretN, &flgN));
      PetscCall(PetscOptionsGetIntArray(((PetscObject)dm)->options, prefix, "-dm_p4est_brick_periodicity", P, &nretP, &flgP));
      PetscCall(PetscOptionsGetRealArray(((PetscObject)dm)->options, prefix, "-dm_p4est_brick_bounds", B, &nretB, &flgB));
      PetscCall(PetscOptionsGetBool(((PetscObject)dm)->options, prefix, "-dm_p4est_brick_use_morton_curve", &useMorton, &flgM));
      PetscCheck(!flgN || nretN == P4EST_DIM, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_SIZ, "Need to give %d sizes in -dm_p4est_brick_size, gave %" PetscInt_FMT, P4EST_DIM, nretN);
      PetscCheck(!flgP || nretP == P4EST_DIM, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_SIZ, "Need to give %d periodicities in -dm_p4est_brick_periodicity, gave %" PetscInt_FMT, P4EST_DIM, nretP);
      PetscCheck(!flgB || nretB == 2 * P4EST_DIM, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_SIZ, "Need to give %d bounds in -dm_p4est_brick_bounds, gave %" PetscInt_FMT, P4EST_DIM, nretP);
    }
    for (i = 0; i < P4EST_DIM; i++) {
      P[i]     = (P[i] ? DM_BOUNDARY_PERIODIC : DM_BOUNDARY_NONE);
      periodic = (PetscBool)(P[i] || periodic);
      if (!flgB) B[2 * i + 1] = N[i];
      if (P[i]) {
        Lstart[i]  = B[2 * i + 0];
        L[i]       = B[2 * i + 1] - B[2 * i + 0];
        maxCell[i] = 1.1 * (L[i] / N[i]);
      }
    }
    PetscCall(DMFTopologyCreateBrick_pforest(dm, N, P, B, topo, useMorton));
    if (periodic) PetscCall(DMSetPeriodicity(dm, maxCell, Lstart, L));
  } else {
    PetscCall(PetscNew(topo));

    (*topo)->refct = 1;
    PetscCallP4estReturn((*topo)->conn, p4est_connectivity_new_byname, (name));
    (*topo)->geom = NULL;
    if (isMoebius) PetscCall(DMSetCoordinateDim(dm, 3));
#if defined(P4_TO_P8)
    if (isShell) {
      PetscReal R2 = 1., R1 = .55;

      if (dm->setfromoptionscalled) {
        PetscCall(PetscOptionsGetReal(((PetscObject)dm)->options, prefix, "-dm_p4est_shell_outer_radius", &R2, NULL));
        PetscCall(PetscOptionsGetReal(((PetscObject)dm)->options, prefix, "-dm_p4est_shell_inner_radius", &R1, NULL));
      }
      PetscCallP4estReturn((*topo)->geom, p8est_geometry_new_shell, ((*topo)->conn, R2, R1));
    } else if (isSphere) {
      PetscReal R2 = 1., R1 = 0.191728, R0 = 0.039856;

      if (dm->setfromoptionscalled) {
        PetscCall(PetscOptionsGetReal(((PetscObject)dm)->options, prefix, "-dm_p4est_sphere_outer_radius", &R2, NULL));
        PetscCall(PetscOptionsGetReal(((PetscObject)dm)->options, prefix, "-dm_p4est_sphere_inner_radius", &R1, NULL));
        PetscCall(PetscOptionsGetReal(((PetscObject)dm)->options, prefix, "-dm_p4est_sphere_core_radius", &R0, NULL));
      }
      PetscCallP4estReturn((*topo)->geom, p8est_geometry_new_sphere, ((*topo)->conn, R2, R1, R0));
    }
#endif
    PetscCall(PforestConnectivityEnumerateFacets((*topo)->conn, &(*topo)->tree_face_to_uniq));
  }
  PetscFunctionReturn(0);
}

#define DMConvert_plex_pforest _append_pforest(DMConvert_plex)
static PetscErrorCode DMConvert_plex_pforest(DM dm, DMType newtype, DM *pforest) {
  MPI_Comm  comm;
  PetscBool isPlex;
  PetscInt  dim;
  void     *ctx;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  comm = PetscObjectComm((PetscObject)dm);
  PetscCall(PetscObjectTypeCompare((PetscObject)dm, DMPLEX, &isPlex));
  PetscCheck(isPlex, comm, PETSC_ERR_ARG_WRONG, "Expected DM type %s, got %s", DMPLEX, ((PetscObject)dm)->type_name);
  PetscCall(DMGetDimension(dm, &dim));
  PetscCheck(dim == P4EST_DIM, comm, PETSC_ERR_ARG_WRONG, "Expected DM dimension %d, got %" PetscInt_FMT, P4EST_DIM, dim);
  PetscCall(DMCreate(comm, pforest));
  PetscCall(DMSetType(*pforest, DMPFOREST));
  PetscCall(DMForestSetBaseDM(*pforest, dm));
  PetscCall(DMGetApplicationContext(dm, &ctx));
  PetscCall(DMSetApplicationContext(*pforest, ctx));
  PetscCall(DMCopyDisc(dm, *pforest));
  PetscFunctionReturn(0);
}

#define DMForestDestroy_pforest _append_pforest(DMForestDestroy)
static PetscErrorCode DMForestDestroy_pforest(DM dm) {
  DM_Forest         *forest  = (DM_Forest *)dm->data;
  DM_Forest_pforest *pforest = (DM_Forest_pforest *)forest->data;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  if (pforest->lnodes) PetscCallP4est(p4est_lnodes_destroy, (pforest->lnodes));
  pforest->lnodes = NULL;
  if (pforest->ghost) PetscCallP4est(p4est_ghost_destroy, (pforest->ghost));
  pforest->ghost = NULL;
  if (pforest->forest) PetscCallP4est(p4est_destroy, (pforest->forest));
  pforest->forest = NULL;
  PetscCall(DMFTopologyDestroy_pforest(&pforest->topo));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, PetscStringize(DMConvert_plex_pforest) "_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, PetscStringize(DMConvert_pforest_plex) "_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, "DMSetUpGLVisViewer_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, "DMCreateNeumannOverlap_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, "DMPlexGetOverlap_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, "MatComputeNeumannOverlap_C", NULL));
  PetscCall(PetscFree(pforest->ghostName));
  PetscCall(DMDestroy(&pforest->plex));
  PetscCall(PetscSFDestroy(&pforest->pointAdaptToSelfSF));
  PetscCall(PetscSFDestroy(&pforest->pointSelfToAdaptSF));
  PetscCall(PetscFree(pforest->pointAdaptToSelfCids));
  PetscCall(PetscFree(pforest->pointSelfToAdaptCids));
  PetscCall(PetscFree(forest->data));
  PetscFunctionReturn(0);
}

#define DMForestTemplate_pforest _append_pforest(DMForestTemplate)
static PetscErrorCode DMForestTemplate_pforest(DM dm, DM tdm) {
  DM_Forest_pforest *pforest  = (DM_Forest_pforest *)((DM_Forest *)dm->data)->data;
  DM_Forest_pforest *tpforest = (DM_Forest_pforest *)((DM_Forest *)tdm->data)->data;

  PetscFunctionBegin;
  if (pforest->topo) pforest->topo->refct++;
  PetscCall(DMFTopologyDestroy_pforest(&(tpforest->topo)));
  tpforest->topo = pforest->topo;
  PetscFunctionReturn(0);
}

#define DMPlexCreateConnectivity_pforest _append_pforest(DMPlexCreateConnectivity)
static PetscErrorCode DMPlexCreateConnectivity_pforest(DM, p4est_connectivity_t **, PetscInt **);

typedef struct _PforestAdaptCtx {
  PetscInt  maxLevel;
  PetscInt  minLevel;
  PetscInt  currLevel;
  PetscBool anyChange;
} PforestAdaptCtx;

static int pforest_coarsen_currlevel(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrants[]) {
  PforestAdaptCtx *ctx       = (PforestAdaptCtx *)p4est->user_pointer;
  PetscInt         minLevel  = ctx->minLevel;
  PetscInt         currLevel = ctx->currLevel;

  if (quadrants[0]->level <= minLevel) return 0;
  return (int)((PetscInt)quadrants[0]->level == currLevel);
}

static int pforest_coarsen_uniform(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrants[]) {
  PforestAdaptCtx *ctx      = (PforestAdaptCtx *)p4est->user_pointer;
  PetscInt         minLevel = ctx->minLevel;

  return (int)((PetscInt)quadrants[0]->level > minLevel);
}

static int pforest_coarsen_flag_any(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrants[]) {
  PetscInt         i;
  PetscBool        any      = PETSC_FALSE;
  PforestAdaptCtx *ctx      = (PforestAdaptCtx *)p4est->user_pointer;
  PetscInt         minLevel = ctx->minLevel;

  if (quadrants[0]->level <= minLevel) return 0;
  for (i = 0; i < P4EST_CHILDREN; i++) {
    if (quadrants[i]->p.user_int == DM_ADAPT_KEEP) {
      any = PETSC_FALSE;
      break;
    }
    if (quadrants[i]->p.user_int == DM_ADAPT_COARSEN) {
      any = PETSC_TRUE;
      break;
    }
  }
  return any ? 1 : 0;
}

static int pforest_coarsen_flag_all(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrants[]) {
  PetscInt         i;
  PetscBool        all      = PETSC_TRUE;
  PforestAdaptCtx *ctx      = (PforestAdaptCtx *)p4est->user_pointer;
  PetscInt         minLevel = ctx->minLevel;

  if (quadrants[0]->level <= minLevel) return 0;
  for (i = 0; i < P4EST_CHILDREN; i++) {
    if (quadrants[i]->p.user_int != DM_ADAPT_COARSEN) {
      all = PETSC_FALSE;
      break;
    }
  }
  return all ? 1 : 0;
}

static void pforest_init_determine(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrant) {
  quadrant->p.user_int = DM_ADAPT_DETERMINE;
}

static int pforest_refine_uniform(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrant) {
  PforestAdaptCtx *ctx      = (PforestAdaptCtx *)p4est->user_pointer;
  PetscInt         maxLevel = ctx->maxLevel;

  return ((PetscInt)quadrant->level < maxLevel);
}

static int pforest_refine_flag(p4est_t *p4est, p4est_topidx_t which_tree, p4est_quadrant_t *quadrant) {
  PforestAdaptCtx *ctx      = (PforestAdaptCtx *)p4est->user_pointer;
  PetscInt         maxLevel = ctx->maxLevel;

  if ((PetscInt)quadrant->level >= maxLevel) return 0;

  return (quadrant->p.user_int == DM_ADAPT_REFINE);
}

static PetscErrorCode DMPforestComputeLocalCellTransferSF_loop(p4est_t *p4estFrom, PetscInt FromOffset, p4est_t *p4estTo, PetscInt ToOffset, p4est_topidx_t flt, p4est_topidx_t llt, PetscInt *toFineLeavesCount, PetscInt *toLeaves, PetscSFNode *fromRoots, PetscInt *fromFineLeavesCount, PetscInt *fromLeaves, PetscSFNode *toRoots) {
  PetscMPIInt    rank = p4estFrom->mpirank;
  p4est_topidx_t t;
  PetscInt       toFineLeaves = 0, fromFineLeaves = 0;

  PetscFunctionBegin;
  for (t = flt; t <= llt; t++) { /* count roots and leaves */
    p4est_tree_t     *treeFrom  = &(((p4est_tree_t *)p4estFrom->trees->array)[t]);
    p4est_tree_t     *treeTo    = &(((p4est_tree_t *)p4estTo->trees->array)[t]);
    p4est_quadrant_t *firstFrom = &treeFrom->first_desc;
    p4est_quadrant_t *firstTo   = &treeTo->first_desc;
    PetscInt          numFrom   = (PetscInt)treeFrom->quadrants.elem_count;
    PetscInt          numTo     = (PetscInt)treeTo->quadrants.elem_count;
    p4est_quadrant_t *quadsFrom = (p4est_quadrant_t *)treeFrom->quadrants.array;
    p4est_quadrant_t *quadsTo   = (p4est_quadrant_t *)treeTo->quadrants.array;
    PetscInt          currentFrom, currentTo;
    PetscInt          treeOffsetFrom = (PetscInt)treeFrom->quadrants_offset;
    PetscInt          treeOffsetTo   = (PetscInt)treeTo->quadrants_offset;
    int               comp;

    PetscCallP4estReturn(comp, p4est_quadrant_is_equal, (firstFrom, firstTo));
    PetscCheck(comp, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "non-matching partitions");

    for (currentFrom = 0, currentTo = 0; currentFrom < numFrom && currentTo < numTo;) {
      p4est_quadrant_t *quadFrom = &quadsFrom[currentFrom];
      p4est_quadrant_t *quadTo   = &quadsTo[currentTo];

      if (quadFrom->level == quadTo->level) {
        if (toLeaves) {
          toLeaves[toFineLeaves]        = currentTo + treeOffsetTo + ToOffset;
          fromRoots[toFineLeaves].rank  = rank;
          fromRoots[toFineLeaves].index = currentFrom + treeOffsetFrom + FromOffset;
        }
        toFineLeaves++;
        currentFrom++;
        currentTo++;
      } else {
        int fromIsAncestor;

        PetscCallP4estReturn(fromIsAncestor, p4est_quadrant_is_ancestor, (quadFrom, quadTo));
        if (fromIsAncestor) {
          p4est_quadrant_t lastDesc;

          if (toLeaves) {
            toLeaves[toFineLeaves]        = currentTo + treeOffsetTo + ToOffset;
            fromRoots[toFineLeaves].rank  = rank;
            fromRoots[toFineLeaves].index = currentFrom + treeOffsetFrom + FromOffset;
          }
          toFineLeaves++;
          currentTo++;
          PetscCallP4est(p4est_quadrant_last_descendant, (quadFrom, &lastDesc, quadTo->level));
          PetscCallP4estReturn(comp, p4est_quadrant_is_equal, (quadTo, &lastDesc));
          if (comp) currentFrom++;
        } else {
          p4est_quadrant_t lastDesc;

          if (fromLeaves) {
            fromLeaves[fromFineLeaves]    = currentFrom + treeOffsetFrom + FromOffset;
            toRoots[fromFineLeaves].rank  = rank;
            toRoots[fromFineLeaves].index = currentTo + treeOffsetTo + ToOffset;
          }
          fromFineLeaves++;
          currentFrom++;
          PetscCallP4est(p4est_quadrant_last_descendant, (quadTo, &lastDesc, quadFrom->level));
          PetscCallP4estReturn(comp, p4est_quadrant_is_equal, (quadFrom, &lastDesc));
          if (comp) currentTo++;
        }
      }
    }
  }
  *toFineLeavesCount   = toFineLeaves;
  *fromFineLeavesCount = fromFineLeaves;
  PetscFunctionReturn(0);
}

/* Compute the maximum level across all the trees */
static PetscErrorCode DMPforestGetRefinementLevel(DM dm, PetscInt *lev) {
  p4est_topidx_t     t, flt, llt;
  DM_Forest         *forest      = (DM_Forest *)dm->data;
  DM_Forest_pforest *pforest     = (DM_Forest_pforest *)forest->data;
  PetscInt           maxlevelloc = 0;
  p4est_t           *p4est;

  PetscFunctionBegin;
  PetscCheck(pforest, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Missing DM_Forest_pforest");
  PetscCheck(pforest->forest, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Missing p4est_t");
  p4est = pforest->forest;
  flt   = p4est->first_local_tree;
  llt   = p4est->last_local_tree;
  for (t = flt; t <= llt; t++) {
    p4est_tree_t *tree = &(((p4est_tree_t *)p4est->trees->array)[t]);
    maxlevelloc        = PetscMax((PetscInt)tree->maxlevel, maxlevelloc);
  }
  PetscCall(MPIU_Allreduce(&maxlevelloc, lev, 1, MPIU_INT, MPI_MAX, PetscObjectComm((PetscObject)dm)));
  PetscFunctionReturn(0);
}

/* Puts identity in coarseToFine */
/* assumes a matching partition */
static PetscErrorCode DMPforestComputeLocalCellTransferSF(MPI_Comm comm, p4est_t *p4estFrom, PetscInt FromOffset, p4est_t *p4estTo, PetscInt ToOffset, PetscSF *fromCoarseToFine, PetscSF *toCoarseFromFine) {
  p4est_topidx_t flt, llt;
  PetscSF        fromCoarse, toCoarse;
  PetscInt       numRootsFrom, numRootsTo, numLeavesFrom, numLeavesTo;
  PetscInt      *fromLeaves = NULL, *toLeaves = NULL;
  PetscSFNode   *fromRoots = NULL, *toRoots = NULL;

  PetscFunctionBegin;
  flt = p4estFrom->first_local_tree;
  llt = p4estFrom->last_local_tree;
  PetscCall(PetscSFCreate(comm, &fromCoarse));
  if (toCoarseFromFine) PetscCall(PetscSFCreate(comm, &toCoarse));
  numRootsFrom = p4estFrom->local_num_quadrants + FromOffset;
  numRootsTo   = p4estTo->local_num_quadrants + ToOffset;
  PetscCall(DMPforestComputeLocalCellTransferSF_loop(p4estFrom, FromOffset, p4estTo, ToOffset, flt, llt, &numLeavesTo, NULL, NULL, &numLeavesFrom, NULL, NULL));
  PetscCall(PetscMalloc1(numLeavesTo, &toLeaves));
  PetscCall(PetscMalloc1(numLeavesTo, &fromRoots));
  if (toCoarseFromFine) {
    PetscCall(PetscMalloc1(numLeavesFrom, &fromLeaves));
    PetscCall(PetscMalloc1(numLeavesFrom, &fromRoots));
  }
  PetscCall(DMPforestComputeLocalCellTransferSF_loop(p4estFrom, FromOffset, p4estTo, ToOffset, flt, llt, &numLeavesTo, toLeaves, fromRoots, &numLeavesFrom, fromLeaves, toRoots));
  if (!ToOffset && (numLeavesTo == numRootsTo)) { /* compress */
    PetscCall(PetscFree(toLeaves));
    PetscCall(PetscSFSetGraph(fromCoarse, numRootsFrom, numLeavesTo, NULL, PETSC_OWN_POINTER, fromRoots, PETSC_OWN_POINTER));
  } else PetscCall(PetscSFSetGraph(fromCoarse, numRootsFrom, numLeavesTo, toLeaves, PETSC_OWN_POINTER, fromRoots, PETSC_OWN_POINTER));
  *fromCoarseToFine = fromCoarse;
  if (toCoarseFromFine) {
    PetscCall(PetscSFSetGraph(toCoarse, numRootsTo, numLeavesFrom, fromLeaves, PETSC_OWN_POINTER, toRoots, PETSC_OWN_POINTER));
    *toCoarseFromFine = toCoarse;
  }
  PetscFunctionReturn(0);
}

/* range of processes whose B sections overlap this ranks A section */
static PetscErrorCode DMPforestComputeOverlappingRanks(PetscMPIInt size, PetscMPIInt rank, p4est_t *p4estA, p4est_t *p4estB, PetscInt *startB, PetscInt *endB) {
  p4est_quadrant_t *myCoarseStart = &(p4estA->global_first_position[rank]);
  p4est_quadrant_t *myCoarseEnd   = &(p4estA->global_first_position[rank + 1]);
  p4est_quadrant_t *globalFirstB  = p4estB->global_first_position;

  PetscFunctionBegin;
  *startB = -1;
  *endB   = -1;
  if (p4estA->local_num_quadrants) {
    PetscInt lo, hi, guess;
    /* binary search to find interval containing myCoarseStart */
    lo    = 0;
    hi    = size;
    guess = rank;
    while (1) {
      int startCompMy, myCompEnd;

      PetscCallP4estReturn(startCompMy, p4est_quadrant_compare_piggy, (&globalFirstB[guess], myCoarseStart));
      PetscCallP4estReturn(myCompEnd, p4est_quadrant_compare_piggy, (myCoarseStart, &globalFirstB[guess + 1]));
      if (startCompMy <= 0 && myCompEnd < 0) {
        *startB = guess;
        break;
      } else if (startCompMy > 0) { /* guess is to high */
        hi = guess;
      } else { /* guess is to low */
        lo = guess + 1;
      }
      guess = lo + (hi - lo) / 2;
    }
    /* reset bounds, but not guess */
    lo = 0;
    hi = size;
    while (1) {
      int startCompMy, myCompEnd;

      PetscCallP4estReturn(startCompMy, p4est_quadrant_compare_piggy, (&globalFirstB[guess], myCoarseEnd));
      PetscCallP4estReturn(myCompEnd, p4est_quadrant_compare_piggy, (myCoarseEnd, &globalFirstB[guess + 1]));
      if (startCompMy < 0 && myCompEnd <= 0) { /* notice that the comparison operators are different from above */
        *endB = guess + 1;
        break;
      } else if (startCompMy >= 0) { /* guess is to high */
        hi = guess;
      } else { /* guess is to low */
        lo = guess + 1;
      }
      guess = lo + (hi - lo) / 2;
    }
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestGetPlex(DM, DM *);

#define DMSetUp_pforest _append_pforest(DMSetUp)
static PetscErrorCode DMSetUp_pforest(DM dm) {
  DM_Forest         *forest  = (DM_Forest *)dm->data;
  DM_Forest_pforest *pforest = (DM_Forest_pforest *)forest->data;
  DM                 base, adaptFrom;
  DMForestTopology   topoName;
  PetscSF            preCoarseToFine = NULL, coarseToPreFine = NULL;
  PforestAdaptCtx    ctx;

  PetscFunctionBegin;
  ctx.minLevel  = PETSC_MAX_INT;
  ctx.maxLevel  = 0;
  ctx.currLevel = 0;
  ctx.anyChange = PETSC_FALSE;
  /* sanity check */
  PetscCall(DMForestGetAdaptivityForest(dm, &adaptFrom));
  PetscCall(DMForestGetBaseDM(dm, &base));
  PetscCall(DMForestGetTopology(dm, &topoName));
  PetscCheck(adaptFrom || base || topoName, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONGSTATE, "A forest needs a topology, a base DM, or a DM to adapt from");

  /* === Step 1: DMFTopology === */
  if (adaptFrom) { /* reference already created topology */
    PetscBool          ispforest;
    DM_Forest         *aforest  = (DM_Forest *)adaptFrom->data;
    DM_Forest_pforest *apforest = (DM_Forest_pforest *)aforest->data;

    PetscCall(PetscObjectTypeCompare((PetscObject)adaptFrom, DMPFOREST, &ispforest));
    PetscCheck(ispforest, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_NOTSAMETYPE, "Trying to adapt from %s, which is not %s", ((PetscObject)adaptFrom)->type_name, DMPFOREST);
    PetscCheck(apforest->topo, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONGSTATE, "The pre-adaptation forest must have a topology");
    PetscCall(DMSetUp(adaptFrom));
    PetscCall(DMForestGetBaseDM(dm, &base));
    PetscCall(DMForestGetTopology(dm, &topoName));
  } else if (base) { /* construct a connectivity from base */
    PetscBool isPlex, isDA;

    PetscCall(PetscObjectGetName((PetscObject)base, &topoName));
    PetscCall(DMForestSetTopology(dm, topoName));
    PetscCall(PetscObjectTypeCompare((PetscObject)base, DMPLEX, &isPlex));
    PetscCall(PetscObjectTypeCompare((PetscObject)base, DMDA, &isDA));
    if (isPlex) {
      MPI_Comm              comm = PetscObjectComm((PetscObject)dm);
      PetscInt              depth;
      PetscMPIInt           size;
      p4est_connectivity_t *conn = NULL;
      DMFTopology_pforest  *topo;
      PetscInt             *tree_face_to_uniq = NULL;

      PetscCall(DMPlexGetDepth(base, &depth));
      if (depth == 1) {
        DM connDM;

        PetscCall(DMPlexInterpolate(base, &connDM));
        base = connDM;
        PetscCall(DMForestSetBaseDM(dm, base));
        PetscCall(DMDestroy(&connDM));
      } else PetscCheck(depth == P4EST_DIM, comm, PETSC_ERR_ARG_WRONG, "Base plex is neither interpolated nor uninterpolated? depth %" PetscInt_FMT ", expected 2 or %d", depth, P4EST_DIM + 1);
      PetscCallMPI(MPI_Comm_size(comm, &size));
      if (size > 1) {
        DM      dmRedundant;
        PetscSF sf;

        PetscCall(DMPlexGetRedundantDM(base, &sf, &dmRedundant));
        PetscCheck(dmRedundant, comm, PETSC_ERR_PLIB, "Could not create redundant DM");
        PetscCall(PetscObjectCompose((PetscObject)dmRedundant, "_base_migration_sf", (PetscObject)sf));
        PetscCall(PetscSFDestroy(&sf));
        base = dmRedundant;
        PetscCall(DMForestSetBaseDM(dm, base));
        PetscCall(DMDestroy(&dmRedundant));
      }
      PetscCall(DMViewFromOptions(base, NULL, "-dm_p4est_base_view"));
      PetscCall(DMPlexCreateConnectivity_pforest(base, &conn, &tree_face_to_uniq));
      PetscCall(PetscNew(&topo));
      topo->refct = 1;
      topo->conn  = conn;
      topo->geom  = NULL;
      {
        PetscErrorCode (*map)(DM, PetscInt, PetscInt, const PetscReal[], PetscReal[], void *);
        void *mapCtx;

        PetscCall(DMForestGetBaseCoordinateMapping(dm, &map, &mapCtx));
        if (map) {
          DM_Forest_geometry_pforest *geom_pforest;
          p4est_geometry_t           *geom;

          PetscCall(PetscNew(&geom_pforest));
          PetscCall(DMGetCoordinateDim(dm, &geom_pforest->coordDim));
          geom_pforest->map    = map;
          geom_pforest->mapCtx = mapCtx;
          PetscCallP4estReturn(geom_pforest->inner, p4est_geometry_new_connectivity, (conn));
          PetscCall(PetscNew(&geom));
          geom->name    = topoName;
          geom->user    = geom_pforest;
          geom->X       = GeometryMapping_pforest;
          geom->destroy = GeometryDestroy_pforest;
          topo->geom    = geom;
        }
      }
      topo->tree_face_to_uniq = tree_face_to_uniq;
      pforest->topo           = topo;
    } else PetscCheck(!isDA, PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Not implemented yet");
#if 0
      PetscInt N[3], P[3];

      /* get the sizes, periodicities */
      /* ... */
                                                                  /* don't use Morton order */
      PetscCall(DMFTopologyCreateBrick_pforest(dm,N,P,&pforest->topo,PETSC_FALSE));
#endif
    {
      PetscInt numLabels, l;

      PetscCall(DMGetNumLabels(base, &numLabels));
      for (l = 0; l < numLabels; l++) {
        PetscBool   isDepth, isGhost, isVTK, isDim, isCellType;
        DMLabel     label, labelNew;
        PetscInt    defVal;
        const char *name;

        PetscCall(DMGetLabelName(base, l, &name));
        PetscCall(DMGetLabelByNum(base, l, &label));
        PetscCall(PetscStrcmp(name, "depth", &isDepth));
        if (isDepth) continue;
        PetscCall(PetscStrcmp(name, "dim", &isDim));
        if (isDim) continue;
        PetscCall(PetscStrcmp(name, "celltype", &isCellType));
        if (isCellType) continue;
        PetscCall(PetscStrcmp(name, "ghost", &isGhost));
        if (isGhost) continue;
        PetscCall(PetscStrcmp(name, "vtk", &isVTK));
        if (isVTK) continue;
        PetscCall(DMCreateLabel(dm, name));
        PetscCall(DMGetLabel(dm, name, &labelNew));
        PetscCall(DMLabelGetDefaultValue(label, &defVal));
        PetscCall(DMLabelSetDefaultValue(labelNew, defVal));
      }
      /* map dm points (internal plex) to base
         we currently create the subpoint_map for the entire hierarchy, starting from the finest forest
         and propagating back to the coarsest
         This is not an optimal approach, since we need the map only on the coarsest level
         during DMForestTransferVecFromBase */
      PetscCall(DMForestGetMinimumRefinement(dm, &l));
      if (!l) PetscCall(DMCreateLabel(dm, "_forest_base_subpoint_map"));
    }
  } else { /* construct from topology name */
    DMFTopology_pforest *topo;

    PetscCall(DMFTopologyCreate_pforest(dm, topoName, &topo));
    pforest->topo = topo;
    /* TODO: construct base? */
  }

  /* === Step 2: get the leaves of the forest === */
  if (adaptFrom) { /* start with the old forest */
    DMLabel            adaptLabel;
    PetscInt           defaultValue;
    PetscInt           numValues, numValuesGlobal, cLocalStart, count;
    DM_Forest         *aforest  = (DM_Forest *)adaptFrom->data;
    DM_Forest_pforest *apforest = (DM_Forest_pforest *)aforest->data;
    PetscBool          computeAdaptSF;
    p4est_topidx_t     flt, llt, t;

    flt         = apforest->forest->first_local_tree;
    llt         = apforest->forest->last_local_tree;
    cLocalStart = apforest->cLocalStart;
    PetscCall(DMForestGetComputeAdaptivitySF(dm, &computeAdaptSF));
    PetscCallP4estReturn(pforest->forest, p4est_copy, (apforest->forest, 0)); /* 0 indicates no data copying */
    PetscCall(DMForestGetAdaptivityLabel(dm, &adaptLabel));
    if (adaptLabel) {
      /* apply the refinement/coarsening by flags, plus minimum/maximum refinement */
      PetscCall(DMLabelGetNumValues(adaptLabel, &numValues));
      PetscCallMPI(MPI_Allreduce(&numValues, &numValuesGlobal, 1, MPIU_INT, MPI_MAX, PetscObjectComm((PetscObject)adaptFrom)));
      PetscCall(DMLabelGetDefaultValue(adaptLabel, &defaultValue));
      if (!numValuesGlobal && defaultValue == DM_ADAPT_COARSEN_LAST) { /* uniform coarsen of the last level only (equivalent to DM_ADAPT_COARSEN for conforming grids)  */
        PetscCall(DMForestGetMinimumRefinement(dm, &ctx.minLevel));
        PetscCall(DMPforestGetRefinementLevel(dm, &ctx.currLevel));
        pforest->forest->user_pointer = (void *)&ctx;
        PetscCallP4est(p4est_coarsen, (pforest->forest, 0, pforest_coarsen_currlevel, NULL));
        pforest->forest->user_pointer = (void *)dm;
        PetscCallP4est(p4est_balance, (pforest->forest, P4EST_CONNECT_FULL, NULL));
        /* we will have to change the offset after we compute the overlap */
        if (computeAdaptSF) PetscCall(DMPforestComputeLocalCellTransferSF(PetscObjectComm((PetscObject)dm), pforest->forest, 0, apforest->forest, apforest->cLocalStart, &coarseToPreFine, NULL));
      } else if (!numValuesGlobal && defaultValue == DM_ADAPT_COARSEN) { /* uniform coarsen */
        PetscCall(DMForestGetMinimumRefinement(dm, &ctx.minLevel));
        pforest->forest->user_pointer = (void *)&ctx;
        PetscCallP4est(p4est_coarsen, (pforest->forest, 0, pforest_coarsen_uniform, NULL));
        pforest->forest->user_pointer = (void *)dm;
        PetscCallP4est(p4est_balance, (pforest->forest, P4EST_CONNECT_FULL, NULL));
        /* we will have to change the offset after we compute the overlap */
        if (computeAdaptSF) PetscCall(DMPforestComputeLocalCellTransferSF(PetscObjectComm((PetscObject)dm), pforest->forest, 0, apforest->forest, apforest->cLocalStart, &coarseToPreFine, NULL));
      } else if (!numValuesGlobal && defaultValue == DM_ADAPT_REFINE) { /* uniform refine */
        PetscCall(DMForestGetMaximumRefinement(dm, &ctx.maxLevel));
        pforest->forest->user_pointer = (void *)&ctx;
        PetscCallP4est(p4est_refine, (pforest->forest, 0, pforest_refine_uniform, NULL));
        pforest->forest->user_pointer = (void *)dm;
        PetscCallP4est(p4est_balance, (pforest->forest, P4EST_CONNECT_FULL, NULL));
        /* we will have to change the offset after we compute the overlap */
        if (computeAdaptSF) PetscCall(DMPforestComputeLocalCellTransferSF(PetscObjectComm((PetscObject)dm), apforest->forest, apforest->cLocalStart, pforest->forest, 0, &preCoarseToFine, NULL));
      } else if (numValuesGlobal) {
        p4est_t                   *p4est = pforest->forest;
        PetscInt                  *cellFlags;
        DMForestAdaptivityStrategy strategy;
        PetscSF                    cellSF;
        PetscInt                   c, cStart, cEnd;
        PetscBool                  adaptAny;

        PetscCall(DMForestGetMaximumRefinement(dm, &ctx.maxLevel));
        PetscCall(DMForestGetMinimumRefinement(dm, &ctx.minLevel));
        PetscCall(DMForestGetAdaptivityStrategy(dm, &strategy));
        PetscCall(PetscStrncmp(strategy, "any", 3, &adaptAny));
        PetscCall(DMForestGetCellChart(adaptFrom, &cStart, &cEnd));
        PetscCall(DMForestGetCellSF(adaptFrom, &cellSF));
        PetscCall(PetscMalloc1(cEnd - cStart, &cellFlags));
        for (c = cStart; c < cEnd; c++) PetscCall(DMLabelGetValue(adaptLabel, c, &cellFlags[c - cStart]));
        if (cellSF) {
          if (adaptAny) {
            PetscCall(PetscSFReduceBegin(cellSF, MPIU_INT, cellFlags, cellFlags, MPI_MAX));
            PetscCall(PetscSFReduceEnd(cellSF, MPIU_INT, cellFlags, cellFlags, MPI_MAX));
          } else {
            PetscCall(PetscSFReduceBegin(cellSF, MPIU_INT, cellFlags, cellFlags, MPI_MIN));
            PetscCall(PetscSFReduceEnd(cellSF, MPIU_INT, cellFlags, cellFlags, MPI_MIN));
          }
        }
        for (t = flt, count = cLocalStart; t <= llt; t++) {
          p4est_tree_t     *tree     = &(((p4est_tree_t *)p4est->trees->array)[t]);
          PetscInt          numQuads = (PetscInt)tree->quadrants.elem_count, i;
          p4est_quadrant_t *quads    = (p4est_quadrant_t *)tree->quadrants.array;

          for (i = 0; i < numQuads; i++) {
            p4est_quadrant_t *q = &quads[i];
            q->p.user_int       = cellFlags[count++];
          }
        }
        PetscCall(PetscFree(cellFlags));

        pforest->forest->user_pointer = (void *)&ctx;
        if (adaptAny) PetscCallP4est(p4est_coarsen, (pforest->forest, 0, pforest_coarsen_flag_any, pforest_init_determine));
        else PetscCallP4est(p4est_coarsen, (pforest->forest, 0, pforest_coarsen_flag_all, pforest_init_determine));
        PetscCallP4est(p4est_refine, (pforest->forest, 0, pforest_refine_flag, NULL));
        pforest->forest->user_pointer = (void *)dm;
        PetscCallP4est(p4est_balance, (pforest->forest, P4EST_CONNECT_FULL, NULL));
        if (computeAdaptSF) PetscCall(DMPforestComputeLocalCellTransferSF(PetscObjectComm((PetscObject)dm), apforest->forest, apforest->cLocalStart, pforest->forest, 0, &preCoarseToFine, &coarseToPreFine));
      }
      for (t = flt, count = cLocalStart; t <= llt; t++) {
        p4est_tree_t     *atree     = &(((p4est_tree_t *)apforest->forest->trees->array)[t]);
        p4est_tree_t     *tree      = &(((p4est_tree_t *)pforest->forest->trees->array)[t]);
        PetscInt          anumQuads = (PetscInt)atree->quadrants.elem_count, i;
        PetscInt          numQuads  = (PetscInt)tree->quadrants.elem_count;
        p4est_quadrant_t *aquads    = (p4est_quadrant_t *)atree->quadrants.array;
        p4est_quadrant_t *quads     = (p4est_quadrant_t *)tree->quadrants.array;

        if (anumQuads != numQuads) {
          ctx.anyChange = PETSC_TRUE;
        } else {
          for (i = 0; i < numQuads; i++) {
            p4est_quadrant_t *aq = &aquads[i];
            p4est_quadrant_t *q  = &quads[i];

            if (aq->level != q->level) {
              ctx.anyChange = PETSC_TRUE;
              break;
            }
          }
        }
        if (ctx.anyChange) break;
      }
    }
    {
      PetscInt numLabels, l;

      PetscCall(DMGetNumLabels(adaptFrom, &numLabels));
      for (l = 0; l < numLabels; l++) {
        PetscBool   isDepth, isCellType, isGhost, isVTK;
        DMLabel     label, labelNew;
        PetscInt    defVal;
        const char *name;

        PetscCall(DMGetLabelName(adaptFrom, l, &name));
        PetscCall(DMGetLabelByNum(adaptFrom, l, &label));
        PetscCall(PetscStrcmp(name, "depth", &isDepth));
        if (isDepth) continue;
        PetscCall(PetscStrcmp(name, "celltype", &isCellType));
        if (isCellType) continue;
        PetscCall(PetscStrcmp(name, "ghost", &isGhost));
        if (isGhost) continue;
        PetscCall(PetscStrcmp(name, "vtk", &isVTK));
        if (isVTK) continue;
        PetscCall(DMCreateLabel(dm, name));
        PetscCall(DMGetLabel(dm, name, &labelNew));
        PetscCall(DMLabelGetDefaultValue(label, &defVal));
        PetscCall(DMLabelSetDefaultValue(labelNew, defVal));
      }
    }
  } else { /* initial */
    PetscInt initLevel, minLevel;
#if defined(PETSC_HAVE_MPIUNI)
    sc_MPI_Comm comm = sc_MPI_COMM_WORLD;
#else
    MPI_Comm comm = PetscObjectComm((PetscObject)dm);
#endif

    PetscCall(DMForestGetInitialRefinement(dm, &initLevel));
    PetscCall(DMForestGetMinimumRefinement(dm, &minLevel));
    PetscCallP4estReturn(pforest->forest, p4est_new_ext,
                         (comm, pforest->topo->conn, 0, /* minimum number of quadrants per processor */
                          initLevel,                    /* level of refinement */
                          1,                            /* uniform refinement */
                          0,                            /* we don't allocate any per quadrant data */
                          NULL,                         /* there is no special quadrant initialization */
                          (void *)dm));                 /* this dm is the user context */

    if (initLevel > minLevel) pforest->coarsen_hierarchy = PETSC_TRUE;
    if (dm->setfromoptionscalled) {
      PetscBool   flgPattern, flgFractal;
      PetscInt    corner = 0;
      PetscInt    corners[P4EST_CHILDREN], ncorner = P4EST_CHILDREN;
      PetscReal   likelihood = 1. / P4EST_DIM;
      PetscInt    pattern;
      const char *prefix;

      PetscCall(PetscObjectGetOptionsPrefix((PetscObject)dm, &prefix));
      PetscCall(PetscOptionsGetEList(((PetscObject)dm)->options, prefix, "-dm_p4est_refine_pattern", DMRefinePatternName, PATTERN_COUNT, &pattern, &flgPattern));
      PetscCall(PetscOptionsGetInt(((PetscObject)dm)->options, prefix, "-dm_p4est_refine_corner", &corner, NULL));
      PetscCall(PetscOptionsGetIntArray(((PetscObject)dm)->options, prefix, "-dm_p4est_refine_fractal_corners", corners, &ncorner, &flgFractal));
      PetscCall(PetscOptionsGetReal(((PetscObject)dm)->options, prefix, "-dm_p4est_refine_hash_likelihood", &likelihood, NULL));

      if (flgPattern) {
        DMRefinePatternCtx *ctx;
        PetscInt            maxLevel;

        PetscCall(DMForestGetMaximumRefinement(dm, &maxLevel));
        PetscCall(PetscNew(&ctx));
        ctx->maxLevel = PetscMin(maxLevel, P4EST_QMAXLEVEL);
        if (initLevel + ctx->maxLevel > minLevel) pforest->coarsen_hierarchy = PETSC_TRUE;
        switch (pattern) {
        case PATTERN_HASH:
          ctx->refine_fn      = DMRefinePattern_Hash;
          ctx->hashLikelihood = likelihood;
          break;
        case PATTERN_CORNER:
          ctx->corner    = corner;
          ctx->refine_fn = DMRefinePattern_Corner;
          break;
        case PATTERN_CENTER: ctx->refine_fn = DMRefinePattern_Center; break;
        case PATTERN_FRACTAL:
          if (flgFractal) {
            PetscInt i;

            for (i = 0; i < ncorner; i++) ctx->fractal[corners[i]] = PETSC_TRUE;
          } else {
#if !defined(P4_TO_P8)
            ctx->fractal[0] = ctx->fractal[1] = ctx->fractal[2] = PETSC_TRUE;
#else
            ctx->fractal[0] = ctx->fractal[3] = ctx->fractal[5] = ctx->fractal[6] = PETSC_TRUE;
#endif
          }
          ctx->refine_fn = DMRefinePattern_Fractal;
          break;
        default: SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "Not a valid refinement pattern");
        }

        pforest->forest->user_pointer = (void *)ctx;
        PetscCallP4est(p4est_refine, (pforest->forest, 1, ctx->refine_fn, NULL));
        PetscCallP4est(p4est_balance, (pforest->forest, P4EST_CONNECT_FULL, NULL));
        PetscCall(PetscFree(ctx));
        pforest->forest->user_pointer = (void *)dm;
      }
    }
  }
  if (pforest->coarsen_hierarchy) {
    PetscInt initLevel, currLevel, minLevel;

    PetscCall(DMPforestGetRefinementLevel(dm, &currLevel));
    PetscCall(DMForestGetInitialRefinement(dm, &initLevel));
    PetscCall(DMForestGetMinimumRefinement(dm, &minLevel));
    if (currLevel > minLevel) {
      DM_Forest_pforest *coarse_pforest;
      DMLabel            coarsen;
      DM                 coarseDM;

      PetscCall(DMForestTemplate(dm, MPI_COMM_NULL, &coarseDM));
      PetscCall(DMForestSetAdaptivityPurpose(coarseDM, DM_ADAPT_COARSEN));
      PetscCall(DMLabelCreate(PETSC_COMM_SELF, "coarsen", &coarsen));
      PetscCall(DMLabelSetDefaultValue(coarsen, DM_ADAPT_COARSEN));
      PetscCall(DMForestSetAdaptivityLabel(coarseDM, coarsen));
      PetscCall(DMLabelDestroy(&coarsen));
      PetscCall(DMSetCoarseDM(dm, coarseDM));
      PetscCall(PetscObjectDereference((PetscObject)coarseDM));
      initLevel = currLevel == initLevel ? initLevel - 1 : initLevel;
      PetscCall(DMForestSetInitialRefinement(coarseDM, initLevel));
      PetscCall(DMForestSetMinimumRefinement(coarseDM, minLevel));
      coarse_pforest                    = (DM_Forest_pforest *)((DM_Forest *)coarseDM->data)->data;
      coarse_pforest->coarsen_hierarchy = PETSC_TRUE;
    }
  }

  { /* repartitioning and overlap */
    PetscMPIInt size, rank;

    PetscCallMPI(MPI_Comm_size(PetscObjectComm((PetscObject)dm), &size));
    PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)dm), &rank));
    if ((size > 1) && (pforest->partition_for_coarsening || forest->cellWeights || forest->weightCapacity != 1. || forest->weightsFactor != 1.)) {
      PetscBool      copyForest  = PETSC_FALSE;
      p4est_t       *forest_copy = NULL;
      p4est_gloidx_t shipped     = 0;

      if (preCoarseToFine || coarseToPreFine) copyForest = PETSC_TRUE;
      if (copyForest) PetscCallP4estReturn(forest_copy, p4est_copy, (pforest->forest, 0));

      if (!forest->cellWeights && forest->weightCapacity == 1. && forest->weightsFactor == 1.) {
        PetscCallP4estReturn(shipped, p4est_partition_ext, (pforest->forest, (int)pforest->partition_for_coarsening, NULL));
      } else SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_PLIB, "Non-uniform partition cases not implemented yet");
      if (shipped) ctx.anyChange = PETSC_TRUE;
      if (forest_copy) {
        if (preCoarseToFine || coarseToPreFine) {
          PetscSF        repartSF; /* repartSF has roots in the old partition */
          PetscInt       pStart = -1, pEnd = -1, p;
          PetscInt       numRoots, numLeaves;
          PetscSFNode   *repartRoots;
          p4est_gloidx_t postStart  = pforest->forest->global_first_quadrant[rank];
          p4est_gloidx_t postEnd    = pforest->forest->global_first_quadrant[rank + 1];
          p4est_gloidx_t partOffset = postStart;

          numRoots  = (PetscInt)(forest_copy->global_first_quadrant[rank + 1] - forest_copy->global_first_quadrant[rank]);
          numLeaves = (PetscInt)(postEnd - postStart);
          PetscCall(DMPforestComputeOverlappingRanks(size, rank, pforest->forest, forest_copy, &pStart, &pEnd));
          PetscCall(PetscMalloc1((PetscInt)pforest->forest->local_num_quadrants, &repartRoots));
          for (p = pStart; p < pEnd; p++) {
            p4est_gloidx_t preStart = forest_copy->global_first_quadrant[p];
            p4est_gloidx_t preEnd   = forest_copy->global_first_quadrant[p + 1];
            PetscInt       q;

            if (preEnd == preStart) continue;
            PetscCheck(preStart <= postStart, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Bad partition overlap computation");
            preEnd = preEnd > postEnd ? postEnd : preEnd;
            for (q = partOffset; q < preEnd; q++) {
              repartRoots[q - postStart].rank  = p;
              repartRoots[q - postStart].index = partOffset - preStart;
            }
            partOffset = preEnd;
          }
          PetscCall(PetscSFCreate(PetscObjectComm((PetscObject)dm), &repartSF));
          PetscCall(PetscSFSetGraph(repartSF, numRoots, numLeaves, NULL, PETSC_OWN_POINTER, repartRoots, PETSC_OWN_POINTER));
          PetscCall(PetscSFSetUp(repartSF));
          if (preCoarseToFine) {
            PetscSF         repartSFembed, preCoarseToFineNew;
            PetscInt        nleaves;
            const PetscInt *leaves;

            PetscCall(PetscSFSetUp(preCoarseToFine));
            PetscCall(PetscSFGetGraph(preCoarseToFine, NULL, &nleaves, &leaves, NULL));
            if (leaves) {
              PetscCall(PetscSFCreateEmbeddedRootSF(repartSF, nleaves, leaves, &repartSFembed));
            } else {
              repartSFembed = repartSF;
              PetscCall(PetscObjectReference((PetscObject)repartSFembed));
            }
            PetscCall(PetscSFCompose(preCoarseToFine, repartSFembed, &preCoarseToFineNew));
            PetscCall(PetscSFDestroy(&preCoarseToFine));
            PetscCall(PetscSFDestroy(&repartSFembed));
            preCoarseToFine = preCoarseToFineNew;
          }
          if (coarseToPreFine) {
            PetscSF repartSFinv, coarseToPreFineNew;

            PetscCall(PetscSFCreateInverseSF(repartSF, &repartSFinv));
            PetscCall(PetscSFCompose(repartSFinv, coarseToPreFine, &coarseToPreFineNew));
            PetscCall(PetscSFDestroy(&coarseToPreFine));
            PetscCall(PetscSFDestroy(&repartSFinv));
            coarseToPreFine = coarseToPreFineNew;
          }
          PetscCall(PetscSFDestroy(&repartSF));
        }
        PetscCallP4est(p4est_destroy, (forest_copy));
      }
    }
    if (size > 1) {
      PetscInt overlap;

      PetscCall(DMForestGetPartitionOverlap(dm, &overlap));

      if (adaptFrom) {
        PetscInt aoverlap;

        PetscCall(DMForestGetPartitionOverlap(adaptFrom, &aoverlap));
        if (aoverlap != overlap) ctx.anyChange = PETSC_TRUE;
      }

      if (overlap > 0) {
        PetscInt i, cLocalStart;
        PetscInt cEnd;
        PetscSF  preCellSF = NULL, cellSF = NULL;

        PetscCallP4estReturn(pforest->ghost, p4est_ghost_new, (pforest->forest, P4EST_CONNECT_FULL));
        PetscCallP4estReturn(pforest->lnodes, p4est_lnodes_new, (pforest->forest, pforest->ghost, -P4EST_DIM));
        PetscCallP4est(p4est_ghost_support_lnodes, (pforest->forest, pforest->lnodes, pforest->ghost));
        for (i = 1; i < overlap; i++) PetscCallP4est(p4est_ghost_expand_by_lnodes, (pforest->forest, pforest->lnodes, pforest->ghost));

        cLocalStart = pforest->cLocalStart = pforest->ghost->proc_offsets[rank];
        cEnd                               = pforest->forest->local_num_quadrants + pforest->ghost->proc_offsets[size];

        /* shift sfs by cLocalStart, expand by cell SFs */
        if (preCoarseToFine || coarseToPreFine) {
          if (adaptFrom) PetscCall(DMForestGetCellSF(adaptFrom, &preCellSF));
          dm->setupcalled = PETSC_TRUE;
          PetscCall(DMForestGetCellSF(dm, &cellSF));
        }
        if (preCoarseToFine) {
          PetscSF            preCoarseToFineNew;
          PetscInt           nleaves, nroots, *leavesNew, i, nleavesNew;
          const PetscInt    *leaves;
          const PetscSFNode *remotes;
          PetscSFNode       *remotesAll;

          PetscCall(PetscSFSetUp(preCoarseToFine));
          PetscCall(PetscSFGetGraph(preCoarseToFine, &nroots, &nleaves, &leaves, &remotes));
          PetscCall(PetscMalloc1(cEnd, &remotesAll));
          for (i = 0; i < cEnd; i++) {
            remotesAll[i].rank  = -1;
            remotesAll[i].index = -1;
          }
          for (i = 0; i < nleaves; i++) remotesAll[(leaves ? leaves[i] : i) + cLocalStart] = remotes[i];
          PetscCall(PetscSFSetUp(cellSF));
          PetscCall(PetscSFBcastBegin(cellSF, MPIU_2INT, remotesAll, remotesAll, MPI_REPLACE));
          PetscCall(PetscSFBcastEnd(cellSF, MPIU_2INT, remotesAll, remotesAll, MPI_REPLACE));
          nleavesNew = 0;
          for (i = 0; i < nleaves; i++) {
            if (remotesAll[i].rank >= 0) nleavesNew++;
          }
          PetscCall(PetscMalloc1(nleavesNew, &leavesNew));
          nleavesNew = 0;
          for (i = 0; i < nleaves; i++) {
            if (remotesAll[i].rank >= 0) {
              leavesNew[nleavesNew] = i;
              if (i > nleavesNew) remotesAll[nleavesNew] = remotesAll[i];
              nleavesNew++;
            }
          }
          PetscCall(PetscSFCreate(PetscObjectComm((PetscObject)dm), &preCoarseToFineNew));
          if (nleavesNew < cEnd) {
            PetscCall(PetscSFSetGraph(preCoarseToFineNew, nroots, nleavesNew, leavesNew, PETSC_OWN_POINTER, remotesAll, PETSC_COPY_VALUES));
          } else { /* all cells are leaves */
            PetscCall(PetscFree(leavesNew));
            PetscCall(PetscSFSetGraph(preCoarseToFineNew, nroots, nleavesNew, NULL, PETSC_OWN_POINTER, remotesAll, PETSC_COPY_VALUES));
          }
          PetscCall(PetscFree(remotesAll));
          PetscCall(PetscSFDestroy(&preCoarseToFine));
          preCoarseToFine = preCoarseToFineNew;
          preCoarseToFine = preCoarseToFineNew;
        }
        if (coarseToPreFine) {
          PetscSF            coarseToPreFineNew;
          PetscInt           nleaves, nroots, i, nleavesCellSF, nleavesExpanded, *leavesNew;
          const PetscInt    *leaves;
          const PetscSFNode *remotes;
          PetscSFNode       *remotesNew, *remotesNewRoot, *remotesExpanded;

          PetscCall(PetscSFSetUp(coarseToPreFine));
          PetscCall(PetscSFGetGraph(coarseToPreFine, &nroots, &nleaves, &leaves, &remotes));
          PetscCall(PetscSFGetGraph(preCellSF, NULL, &nleavesCellSF, NULL, NULL));
          PetscCall(PetscMalloc1(nroots, &remotesNewRoot));
          PetscCall(PetscMalloc1(nleaves, &remotesNew));
          for (i = 0; i < nroots; i++) {
            remotesNewRoot[i].rank  = rank;
            remotesNewRoot[i].index = i + cLocalStart;
          }
          PetscCall(PetscSFBcastBegin(coarseToPreFine, MPIU_2INT, remotesNewRoot, remotesNew, MPI_REPLACE));
          PetscCall(PetscSFBcastEnd(coarseToPreFine, MPIU_2INT, remotesNewRoot, remotesNew, MPI_REPLACE));
          PetscCall(PetscFree(remotesNewRoot));
          PetscCall(PetscMalloc1(nleavesCellSF, &remotesExpanded));
          for (i = 0; i < nleavesCellSF; i++) {
            remotesExpanded[i].rank  = -1;
            remotesExpanded[i].index = -1;
          }
          for (i = 0; i < nleaves; i++) remotesExpanded[leaves ? leaves[i] : i] = remotesNew[i];
          PetscCall(PetscFree(remotesNew));
          PetscCall(PetscSFBcastBegin(preCellSF, MPIU_2INT, remotesExpanded, remotesExpanded, MPI_REPLACE));
          PetscCall(PetscSFBcastEnd(preCellSF, MPIU_2INT, remotesExpanded, remotesExpanded, MPI_REPLACE));

          nleavesExpanded = 0;
          for (i = 0; i < nleavesCellSF; i++) {
            if (remotesExpanded[i].rank >= 0) nleavesExpanded++;
          }
          PetscCall(PetscMalloc1(nleavesExpanded, &leavesNew));
          nleavesExpanded = 0;
          for (i = 0; i < nleavesCellSF; i++) {
            if (remotesExpanded[i].rank >= 0) {
              leavesNew[nleavesExpanded] = i;
              if (i > nleavesExpanded) remotesExpanded[nleavesExpanded] = remotes[i];
              nleavesExpanded++;
            }
          }
          PetscCall(PetscSFCreate(PetscObjectComm((PetscObject)dm), &coarseToPreFineNew));
          if (nleavesExpanded < nleavesCellSF) {
            PetscCall(PetscSFSetGraph(coarseToPreFineNew, cEnd, nleavesExpanded, leavesNew, PETSC_OWN_POINTER, remotesExpanded, PETSC_COPY_VALUES));
          } else {
            PetscCall(PetscFree(leavesNew));
            PetscCall(PetscSFSetGraph(coarseToPreFineNew, cEnd, nleavesExpanded, NULL, PETSC_OWN_POINTER, remotesExpanded, PETSC_COPY_VALUES));
          }
          PetscCall(PetscFree(remotesExpanded));
          PetscCall(PetscSFDestroy(&coarseToPreFine));
          coarseToPreFine = coarseToPreFineNew;
        }
      }
    }
  }
  forest->preCoarseToFine = preCoarseToFine;
  forest->coarseToPreFine = coarseToPreFine;
  dm->setupcalled         = PETSC_TRUE;
  PetscCallMPI(MPI_Allreduce(&ctx.anyChange, &(pforest->adaptivitySuccess), 1, MPIU_BOOL, MPI_LOR, PetscObjectComm((PetscObject)dm)));
  PetscCall(DMPforestGetPlex(dm, NULL));
  PetscFunctionReturn(0);
}

#define DMForestGetAdaptivitySuccess_pforest _append_pforest(DMForestGetAdaptivitySuccess)
static PetscErrorCode DMForestGetAdaptivitySuccess_pforest(DM dm, PetscBool *success) {
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;

  PetscFunctionBegin;
  forest   = (DM_Forest *)dm->data;
  pforest  = (DM_Forest_pforest *)forest->data;
  *success = pforest->adaptivitySuccess;
  PetscFunctionReturn(0);
}

#define DMView_ASCII_pforest _append_pforest(DMView_ASCII)
static PetscErrorCode DMView_ASCII_pforest(PetscObject odm, PetscViewer viewer) {
  DM dm = (DM)odm;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 2);
  PetscCall(DMSetUp(dm));
  switch (viewer->format) {
  case PETSC_VIEWER_DEFAULT:
  case PETSC_VIEWER_ASCII_INFO: {
    PetscInt    dim;
    const char *name;

    PetscCall(PetscObjectGetName((PetscObject)dm, &name));
    PetscCall(DMGetDimension(dm, &dim));
    if (name) PetscCall(PetscViewerASCIIPrintf(viewer, "Forest %s in %" PetscInt_FMT " dimensions:\n", name, dim));
    else PetscCall(PetscViewerASCIIPrintf(viewer, "Forest in %" PetscInt_FMT " dimensions:\n", dim));
  }
  case PETSC_VIEWER_ASCII_INFO_DETAIL:
  case PETSC_VIEWER_LOAD_BALANCE: {
    DM plex;

    PetscCall(DMPforestGetPlex(dm, &plex));
    PetscCall(DMView(plex, viewer));
  } break;
  default: SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "No support for format '%s'", PetscViewerFormats[viewer->format]);
  }
  PetscFunctionReturn(0);
}

#define DMView_VTK_pforest _append_pforest(DMView_VTK)
static PetscErrorCode DMView_VTK_pforest(PetscObject odm, PetscViewer viewer) {
  DM                 dm      = (DM)odm;
  DM_Forest         *forest  = (DM_Forest *)dm->data;
  DM_Forest_pforest *pforest = (DM_Forest_pforest *)forest->data;
  PetscBool          isvtk;
  PetscReal          vtkScale = 1. - PETSC_MACHINE_EPSILON;
  PetscViewer_VTK   *vtk      = (PetscViewer_VTK *)viewer->data;
  const char        *name;
  char              *filenameStrip = NULL;
  PetscBool          hasExt;
  size_t             len;
  p4est_geometry_t  *geom;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 2);
  PetscCall(DMSetUp(dm));
  geom = pforest->topo->geom;
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERVTK, &isvtk));
  PetscCheck(isvtk, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_INCOMP, "Cannot use viewer type %s", ((PetscObject)viewer)->type_name);
  switch (viewer->format) {
  case PETSC_VIEWER_VTK_VTU:
    PetscCheck(pforest->forest, PetscObjectComm(odm), PETSC_ERR_ARG_WRONG, "DM has not been setup with a valid forest");
    name = vtk->filename;
    PetscCall(PetscStrlen(name, &len));
    PetscCall(PetscStrcasecmp(name + len - 4, ".vtu", &hasExt));
    if (hasExt) {
      PetscCall(PetscStrallocpy(name, &filenameStrip));
      filenameStrip[len - 4] = '\0';
      name                   = filenameStrip;
    }
    if (!pforest->topo->geom) PetscCallP4estReturn(geom, p4est_geometry_new_connectivity, (pforest->topo->conn));
    {
      p4est_vtk_context_t *pvtk;
      int                  footerr;

      PetscCallP4estReturn(pvtk, p4est_vtk_context_new, (pforest->forest, name));
      PetscCallP4est(p4est_vtk_context_set_geom, (pvtk, geom));
      PetscCallP4est(p4est_vtk_context_set_scale, (pvtk, (double)vtkScale));
      PetscCallP4estReturn(pvtk, p4est_vtk_write_header, (pvtk));
      PetscCheck(pvtk, PetscObjectComm((PetscObject)odm), PETSC_ERR_LIB, P4EST_STRING "_vtk_write_header() failed");
      PetscCallP4estReturn(pvtk, p4est_vtk_write_cell_dataf,
                           (pvtk, 1, /* write tree */
                            1,       /* write level */
                            1,       /* write rank */
                            0,       /* do not wrap rank */
                            0,       /* no scalar fields */
                            0,       /* no vector fields */
                            pvtk));
      PetscCheck(pvtk, PetscObjectComm((PetscObject)odm), PETSC_ERR_LIB, P4EST_STRING "_vtk_write_cell_dataf() failed");
      PetscCallP4estReturn(footerr, p4est_vtk_write_footer, (pvtk));
      PetscCheck(!footerr, PetscObjectComm((PetscObject)odm), PETSC_ERR_LIB, P4EST_STRING "_vtk_write_footer() failed");
    }
    if (!pforest->topo->geom) PetscCallP4est(p4est_geometry_destroy, (geom));
    PetscCall(PetscFree(filenameStrip));
    break;
  default: SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "No support for format '%s'", PetscViewerFormats[viewer->format]);
  }
  PetscFunctionReturn(0);
}

#define DMView_HDF5_pforest _append_pforest(DMView_HDF5)
static PetscErrorCode DMView_HDF5_pforest(DM dm, PetscViewer viewer) {
  DM plex;

  PetscFunctionBegin;
  PetscCall(DMSetUp(dm));
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMView(plex, viewer));
  PetscFunctionReturn(0);
}

#define DMView_GLVis_pforest _append_pforest(DMView_GLVis)
static PetscErrorCode DMView_GLVis_pforest(DM dm, PetscViewer viewer) {
  DM plex;

  PetscFunctionBegin;
  PetscCall(DMSetUp(dm));
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMView(plex, viewer));
  PetscFunctionReturn(0);
}

#define DMView_pforest _append_pforest(DMView)
static PetscErrorCode DMView_pforest(DM dm, PetscViewer viewer) {
  PetscBool isascii, isvtk, ishdf5, isglvis;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 2);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &isascii));
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERVTK, &isvtk));
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERHDF5, &ishdf5));
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERGLVIS, &isglvis));
  if (isascii) {
    PetscCall(DMView_ASCII_pforest((PetscObject)dm, viewer));
  } else if (isvtk) {
    PetscCall(DMView_VTK_pforest((PetscObject)dm, viewer));
  } else if (ishdf5) {
    PetscCall(DMView_HDF5_pforest(dm, viewer));
  } else if (isglvis) {
    PetscCall(DMView_GLVis_pforest(dm, viewer));
  } else SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Viewer not supported (not VTK, HDF5, or GLVis)");
  PetscFunctionReturn(0);
}

static PetscErrorCode PforestConnectivityEnumerateFacets(p4est_connectivity_t *conn, PetscInt **tree_face_to_uniq) {
  PetscInt *ttf, f, t, g, count;
  PetscInt  numFacets;

  PetscFunctionBegin;
  numFacets = conn->num_trees * P4EST_FACES;
  PetscCall(PetscMalloc1(numFacets, &ttf));
  for (f = 0; f < numFacets; f++) ttf[f] = -1;
  for (g = 0, count = 0, t = 0; t < conn->num_trees; t++) {
    for (f = 0; f < P4EST_FACES; f++, g++) {
      if (ttf[g] == -1) {
        PetscInt ng;

        ttf[g]  = count++;
        ng      = conn->tree_to_tree[g] * P4EST_FACES + (conn->tree_to_face[g] % P4EST_FACES);
        ttf[ng] = ttf[g];
      }
    }
  }
  *tree_face_to_uniq = ttf;
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPlexCreateConnectivity_pforest(DM dm, p4est_connectivity_t **connOut, PetscInt **tree_face_to_uniq) {
  p4est_topidx_t numTrees, numVerts, numCorns, numCtt;
  PetscSection   ctt;
#if defined(P4_TO_P8)
  p4est_topidx_t numEdges, numEtt;
  PetscSection   ett;
  PetscInt       eStart, eEnd, e, ettSize;
  PetscInt       vertOff = 1 + P4EST_FACES + P8EST_EDGES;
  PetscInt       edgeOff = 1 + P4EST_FACES;
#else
  PetscInt vertOff = 1 + P4EST_FACES;
#endif
  p4est_connectivity_t *conn;
  PetscInt              cStart, cEnd, c, vStart, vEnd, v, fStart, fEnd, f;
  PetscInt             *star = NULL, *closure = NULL, closureSize, starSize, cttSize;
  PetscInt             *ttf;

  PetscFunctionBegin;
  /* 1: count objects, allocate */
  PetscCall(DMPlexGetSimplexOrBoxCells(dm, 0, &cStart, &cEnd));
  PetscCall(P4estTopidxCast(cEnd - cStart, &numTrees));
  numVerts = P4EST_CHILDREN * numTrees;
  PetscCall(DMPlexGetDepthStratum(dm, 0, &vStart, &vEnd));
  PetscCall(P4estTopidxCast(vEnd - vStart, &numCorns));
  PetscCall(PetscSectionCreate(PETSC_COMM_SELF, &ctt));
  PetscCall(PetscSectionSetChart(ctt, vStart, vEnd));
  for (v = vStart; v < vEnd; v++) {
    PetscInt s;

    PetscCall(DMPlexGetTransitiveClosure(dm, v, PETSC_FALSE, &starSize, &star));
    for (s = 0; s < starSize; s++) {
      PetscInt p = star[2 * s];

      if (p >= cStart && p < cEnd) {
        /* we want to count every time cell p references v, so we see how many times it comes up in the closure.  This
         * only protects against periodicity problems */
        PetscCall(DMPlexGetTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
        PetscCheck(closureSize == P4EST_INSUL, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Cell %" PetscInt_FMT " with wrong closure size %" PetscInt_FMT " != %d", p, closureSize, P4EST_INSUL);
        for (c = 0; c < P4EST_CHILDREN; c++) {
          PetscInt cellVert = closure[2 * (c + vertOff)];

          PetscCheck(cellVert >= vStart && cellVert < vEnd, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Non-standard closure: vertices");
          if (cellVert == v) PetscCall(PetscSectionAddDof(ctt, v, 1));
        }
        PetscCall(DMPlexRestoreTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
      }
    }
    PetscCall(DMPlexRestoreTransitiveClosure(dm, v, PETSC_FALSE, &starSize, &star));
  }
  PetscCall(PetscSectionSetUp(ctt));
  PetscCall(PetscSectionGetStorageSize(ctt, &cttSize));
  PetscCall(P4estTopidxCast(cttSize, &numCtt));
#if defined(P4_TO_P8)
  PetscCall(DMPlexGetSimplexOrBoxCells(dm, P4EST_DIM - 1, &eStart, &eEnd));
  PetscCall(P4estTopidxCast(eEnd - eStart, &numEdges));
  PetscCall(PetscSectionCreate(PETSC_COMM_SELF, &ett));
  PetscCall(PetscSectionSetChart(ett, eStart, eEnd));
  for (e = eStart; e < eEnd; e++) {
    PetscInt s;

    PetscCall(DMPlexGetTransitiveClosure(dm, e, PETSC_FALSE, &starSize, &star));
    for (s = 0; s < starSize; s++) {
      PetscInt p = star[2 * s];

      if (p >= cStart && p < cEnd) {
        /* we want to count every time cell p references e, so we see how many times it comes up in the closure.  This
         * only protects against periodicity problems */
        PetscCall(DMPlexGetTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
        PetscCheck(closureSize == P4EST_INSUL, PETSC_COMM_SELF, PETSC_ERR_ARG_INCOMP, "Cell with wrong closure size");
        for (c = 0; c < P8EST_EDGES; c++) {
          PetscInt cellEdge = closure[2 * (c + edgeOff)];

          PetscCheck(cellEdge >= eStart && cellEdge < eEnd, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Non-standard closure: edges");
          if (cellEdge == e) PetscCall(PetscSectionAddDof(ett, e, 1));
        }
        PetscCall(DMPlexRestoreTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
      }
    }
    PetscCall(DMPlexRestoreTransitiveClosure(dm, e, PETSC_FALSE, &starSize, &star));
  }
  PetscCall(PetscSectionSetUp(ett));
  PetscCall(PetscSectionGetStorageSize(ett, &ettSize));
  PetscCall(P4estTopidxCast(ettSize, &numEtt));

  /* This routine allocates space for the arrays, which we fill below */
  PetscCallP4estReturn(conn, p8est_connectivity_new, (numVerts, numTrees, numEdges, numEtt, numCorns, numCtt));
#else
  PetscCallP4estReturn(conn, p4est_connectivity_new, (numVerts, numTrees, numCorns, numCtt));
#endif

  /* 2: visit every face, determine neighboring cells(trees) */
  PetscCall(DMPlexGetSimplexOrBoxCells(dm, 1, &fStart, &fEnd));
  PetscCall(PetscMalloc1((cEnd - cStart) * P4EST_FACES, &ttf));
  for (f = fStart; f < fEnd; f++) {
    PetscInt        numSupp, s;
    PetscInt        myFace[2] = {-1, -1};
    PetscInt        myOrnt[2] = {PETSC_MIN_INT, PETSC_MIN_INT};
    const PetscInt *supp;

    PetscCall(DMPlexGetSupportSize(dm, f, &numSupp));
    PetscCheck(numSupp == 1 || numSupp == 2, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "point %" PetscInt_FMT " has facet with %" PetscInt_FMT " sides: must be 1 or 2 (boundary or conformal)", f, numSupp);
    PetscCall(DMPlexGetSupport(dm, f, &supp));

    for (s = 0; s < numSupp; s++) {
      PetscInt p = supp[s];

      if (p >= cEnd) {
        numSupp--;
        if (s) supp = &supp[1 - s];
        break;
      }
    }
    for (s = 0; s < numSupp; s++) {
      PetscInt        p = supp[s], i;
      PetscInt        numCone;
      DMPolytopeType  ct;
      const PetscInt *cone;
      const PetscInt *ornt;
      PetscInt        orient = PETSC_MIN_INT;

      PetscCall(DMPlexGetConeSize(dm, p, &numCone));
      PetscCheck(numCone == P4EST_FACES, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "cell %" PetscInt_FMT " has %" PetscInt_FMT " facets, expect %d", p, numCone, P4EST_FACES);
      PetscCall(DMPlexGetCone(dm, p, &cone));
      PetscCall(DMPlexGetCellType(dm, cone[0], &ct));
      PetscCall(DMPlexGetConeOrientation(dm, p, &ornt));
      for (i = 0; i < P4EST_FACES; i++) {
        if (cone[i] == f) {
          orient = DMPolytopeConvertNewOrientation_Internal(ct, ornt[i]);
          break;
        }
      }
      PetscCheck(i < P4EST_FACES, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "cell %" PetscInt_FMT " faced %" PetscInt_FMT " mismatch", p, f);
      if (p < cStart || p >= cEnd) {
        DMPolytopeType ct;
        PetscCall(DMPlexGetCellType(dm, p, &ct));
        SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "cell %" PetscInt_FMT " (%s) should be in [%" PetscInt_FMT ", %" PetscInt_FMT ")", p, DMPolytopeTypes[ct], cStart, cEnd);
      }
      ttf[P4EST_FACES * (p - cStart) + PetscFaceToP4estFace[i]] = f - fStart;
      if (numSupp == 1) {
        /* boundary faces indicated by self reference */
        conn->tree_to_tree[P4EST_FACES * (p - cStart) + PetscFaceToP4estFace[i]] = p - cStart;
        conn->tree_to_face[P4EST_FACES * (p - cStart) + PetscFaceToP4estFace[i]] = (int8_t)PetscFaceToP4estFace[i];
      } else {
        const PetscInt N = P4EST_CHILDREN / 2;

        conn->tree_to_tree[P4EST_FACES * (p - cStart) + PetscFaceToP4estFace[i]] = supp[1 - s] - cStart;
        myFace[s]                                                                = PetscFaceToP4estFace[i];
        /* get the orientation of cell p in p4est-type closure to facet f, by composing the p4est-closure to
         * petsc-closure permutation and the petsc-closure to facet orientation */
        myOrnt[s]                                                                = DihedralCompose(N, orient, DMPolytopeConvertNewOrientation_Internal(ct, P4estFaceToPetscOrnt[myFace[s]]));
      }
    }
    if (numSupp == 2) {
      for (s = 0; s < numSupp; s++) {
        PetscInt       p = supp[s];
        PetscInt       orntAtoB;
        PetscInt       p4estOrient;
        const PetscInt N = P4EST_CHILDREN / 2;

        /* composing the forward permutation with the other cell's inverse permutation gives the self-to-neighbor
         * permutation of this cell-facet's cone */
        orntAtoB = DihedralCompose(N, DihedralInvert(N, myOrnt[1 - s]), myOrnt[s]);

        /* convert cone-description permutation (i.e., edges around facet) to cap-description permutation (i.e.,
         * vertices around facet) */
#if !defined(P4_TO_P8)
        p4estOrient = orntAtoB < 0 ? -(orntAtoB + 1) : orntAtoB;
#else
        {
          PetscInt firstVert      = orntAtoB < 0 ? ((-orntAtoB) % N) : orntAtoB;
          PetscInt p4estFirstVert = firstVert < 2 ? firstVert : (firstVert ^ 1);

          /* swap bits */
          p4estOrient = ((myFace[s] <= myFace[1 - s]) || (orntAtoB < 0)) ? p4estFirstVert : ((p4estFirstVert >> 1) | ((p4estFirstVert & 1) << 1));
        }
#endif
        /* encode neighbor face and orientation in tree_to_face per p4est_connectivity standard (see
         * p4est_connectivity.h, p8est_connectivity.h) */
        conn->tree_to_face[P4EST_FACES * (p - cStart) + myFace[s]] = (int8_t)myFace[1 - s] + p4estOrient * P4EST_FACES;
      }
    }
  }

#if defined(P4_TO_P8)
  /* 3: visit every edge */
  conn->ett_offset[0] = 0;
  for (e = eStart; e < eEnd; e++) {
    PetscInt off, s;

    PetscCall(PetscSectionGetOffset(ett, e, &off));
    conn->ett_offset[e - eStart] = (p4est_topidx_t)off;
    PetscCall(DMPlexGetTransitiveClosure(dm, e, PETSC_FALSE, &starSize, &star));
    for (s = 0; s < starSize; s++) {
      PetscInt p = star[2 * s];

      if (p >= cStart && p < cEnd) {
        PetscCall(DMPlexGetTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
        PetscCheck(closureSize == P4EST_INSUL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Non-standard closure");
        for (c = 0; c < P8EST_EDGES; c++) {
          PetscInt       cellEdge = closure[2 * (c + edgeOff)];
          PetscInt       cellOrnt = closure[2 * (c + edgeOff) + 1];
          DMPolytopeType ct;

          PetscCall(DMPlexGetCellType(dm, cellEdge, &ct));
          cellOrnt = DMPolytopeConvertNewOrientation_Internal(ct, cellOrnt);
          if (cellEdge == e) {
            PetscInt p4estEdge = PetscEdgeToP4estEdge[c];
            PetscInt totalOrient;

            /* compose p4est-closure to petsc-closure permutation and petsc-closure to edge orientation */
            totalOrient                                                = DihedralCompose(2, cellOrnt, DMPolytopeConvertNewOrientation_Internal(DM_POLYTOPE_SEGMENT, P4estEdgeToPetscOrnt[p4estEdge]));
            /* p4est orientations are positive: -2 => 1, -1 => 0 */
            totalOrient                                                = (totalOrient < 0) ? -(totalOrient + 1) : totalOrient;
            conn->edge_to_tree[off]                                    = (p4est_locidx_t)(p - cStart);
            /* encode cell-edge and orientation in edge_to_edge per p8est_connectivity standart (see
             * p8est_connectivity.h) */
            conn->edge_to_edge[off++]                                  = (int8_t)p4estEdge + P8EST_EDGES * totalOrient;
            conn->tree_to_edge[P8EST_EDGES * (p - cStart) + p4estEdge] = e - eStart;
          }
        }
        PetscCall(DMPlexRestoreTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
      }
    }
    PetscCall(DMPlexRestoreTransitiveClosure(dm, e, PETSC_FALSE, &starSize, &star));
  }
  PetscCall(PetscSectionDestroy(&ett));
#endif

  /* 4: visit every vertex */
  conn->ctt_offset[0] = 0;
  for (v = vStart; v < vEnd; v++) {
    PetscInt off, s;

    PetscCall(PetscSectionGetOffset(ctt, v, &off));
    conn->ctt_offset[v - vStart] = (p4est_topidx_t)off;
    PetscCall(DMPlexGetTransitiveClosure(dm, v, PETSC_FALSE, &starSize, &star));
    for (s = 0; s < starSize; s++) {
      PetscInt p = star[2 * s];

      if (p >= cStart && p < cEnd) {
        PetscCall(DMPlexGetTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
        PetscCheck(closureSize == P4EST_INSUL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Non-standard closure");
        for (c = 0; c < P4EST_CHILDREN; c++) {
          PetscInt cellVert = closure[2 * (c + vertOff)];

          if (cellVert == v) {
            PetscInt p4estVert = PetscVertToP4estVert[c];

            conn->corner_to_tree[off]                                       = (p4est_locidx_t)(p - cStart);
            conn->corner_to_corner[off++]                                   = (int8_t)p4estVert;
            conn->tree_to_corner[P4EST_CHILDREN * (p - cStart) + p4estVert] = v - vStart;
          }
        }
        PetscCall(DMPlexRestoreTransitiveClosure(dm, p, PETSC_TRUE, &closureSize, &closure));
      }
    }
    PetscCall(DMPlexRestoreTransitiveClosure(dm, v, PETSC_FALSE, &starSize, &star));
  }
  PetscCall(PetscSectionDestroy(&ctt));

  /* 5: Compute the coordinates */
  {
    PetscInt coordDim;

    PetscCall(DMGetCoordinateDim(dm, &coordDim));
    PetscCall(DMGetCoordinatesLocalSetUp(dm));
    for (c = cStart; c < cEnd; c++) {
      PetscInt           dof;
      PetscBool          isDG;
      PetscScalar       *cellCoords = NULL;
      const PetscScalar *array;

      PetscCall(DMPlexGetCellCoordinates(dm, c, &isDG, &dof, &array, &cellCoords));
      PetscCheck(dof == P4EST_CHILDREN * coordDim, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Need coordinates at the corners: (dof) %" PetscInt_FMT " != %d * %" PetscInt_FMT " (sdim)", dof, P4EST_CHILDREN, coordDim);
      for (v = 0; v < P4EST_CHILDREN; v++) {
        PetscInt i, lim = PetscMin(3, coordDim);
        PetscInt p4estVert = PetscVertToP4estVert[v];

        conn->tree_to_vertex[P4EST_CHILDREN * (c - cStart) + v] = P4EST_CHILDREN * (c - cStart) + v;
        /* p4est vertices are always embedded in R^3 */
        for (i = 0; i < 3; i++) conn->vertices[3 * (P4EST_CHILDREN * (c - cStart) + p4estVert) + i] = 0.;
        for (i = 0; i < lim; i++) conn->vertices[3 * (P4EST_CHILDREN * (c - cStart) + p4estVert) + i] = PetscRealPart(cellCoords[v * coordDim + i]);
      }
      PetscCall(DMPlexRestoreCellCoordinates(dm, c, &isDG, &dof, &array, &cellCoords));
    }
  }

#if defined(P4EST_ENABLE_DEBUG)
  PetscCheck(p4est_connectivity_is_valid(conn), PETSC_COMM_SELF, PETSC_ERR_PLIB, "Plex to p4est conversion failed");
#endif

  *connOut = conn;

  *tree_face_to_uniq = ttf;

  PetscFunctionReturn(0);
}

static PetscErrorCode locidx_to_PetscInt(sc_array_t *array) {
  sc_array_t *newarray;
  size_t      zz, count = array->elem_count;

  PetscFunctionBegin;
  PetscCheck(array->elem_size == sizeof(p4est_locidx_t), PETSC_COMM_SELF, PETSC_ERR_PLIB, "Wrong locidx size");

  if (sizeof(p4est_locidx_t) == sizeof(PetscInt)) PetscFunctionReturn(0);

  newarray = sc_array_new_size(sizeof(PetscInt), array->elem_count);
  for (zz = 0; zz < count; zz++) {
    p4est_locidx_t il = *((p4est_locidx_t *)sc_array_index(array, zz));
    PetscInt      *ip = (PetscInt *)sc_array_index(newarray, zz);

    *ip = (PetscInt)il;
  }

  sc_array_reset(array);
  sc_array_init_size(array, sizeof(PetscInt), count);
  sc_array_copy(array, newarray);
  sc_array_destroy(newarray);
  PetscFunctionReturn(0);
}

static PetscErrorCode coords_double_to_PetscScalar(sc_array_t *array, PetscInt dim) {
  sc_array_t *newarray;
  size_t      zz, count = array->elem_count;

  PetscFunctionBegin;
  PetscCheck(array->elem_size == 3 * sizeof(double), PETSC_COMM_SELF, PETSC_ERR_PLIB, "Wrong coordinate size");
#if !defined(PETSC_USE_COMPLEX)
  if (sizeof(double) == sizeof(PetscScalar) && dim == 3) PetscFunctionReturn(0);
#endif

  newarray = sc_array_new_size(dim * sizeof(PetscScalar), array->elem_count);
  for (zz = 0; zz < count; zz++) {
    int          i;
    double      *id = (double *)sc_array_index(array, zz);
    PetscScalar *ip = (PetscScalar *)sc_array_index(newarray, zz);

    for (i = 0; i < dim; i++) ip[i] = 0.;
    for (i = 0; i < PetscMin(dim, 3); i++) ip[i] = (PetscScalar)id[i];
  }

  sc_array_reset(array);
  sc_array_init_size(array, dim * sizeof(PetscScalar), count);
  sc_array_copy(array, newarray);
  sc_array_destroy(newarray);
  PetscFunctionReturn(0);
}

static PetscErrorCode locidx_pair_to_PetscSFNode(sc_array_t *array) {
  sc_array_t *newarray;
  size_t      zz, count = array->elem_count;

  PetscFunctionBegin;
  PetscCheck(array->elem_size == 2 * sizeof(p4est_locidx_t), PETSC_COMM_SELF, PETSC_ERR_PLIB, "Wrong locidx size");

  newarray = sc_array_new_size(sizeof(PetscSFNode), array->elem_count);
  for (zz = 0; zz < count; zz++) {
    p4est_locidx_t *il = (p4est_locidx_t *)sc_array_index(array, zz);
    PetscSFNode    *ip = (PetscSFNode *)sc_array_index(newarray, zz);

    ip->rank  = (PetscInt)il[0];
    ip->index = (PetscInt)il[1];
  }

  sc_array_reset(array);
  sc_array_init_size(array, sizeof(PetscSFNode), count);
  sc_array_copy(array, newarray);
  sc_array_destroy(newarray);
  PetscFunctionReturn(0);
}

static PetscErrorCode P4estToPlex_Local(p4est_t *p4est, DM *plex) {
  PetscFunctionBegin;
  {
    sc_array_t    *points_per_dim    = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *cone_sizes        = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *cones             = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *cone_orientations = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *coords            = sc_array_new(3 * sizeof(double));
    sc_array_t    *children          = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *parents           = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *childids          = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *leaves            = sc_array_new(sizeof(p4est_locidx_t));
    sc_array_t    *remotes           = sc_array_new(2 * sizeof(p4est_locidx_t));
    p4est_locidx_t first_local_quad;

    PetscCallP4est(p4est_get_plex_data, (p4est, P4EST_CONNECT_FULL, 0, &first_local_quad, points_per_dim, cone_sizes, cones, cone_orientations, coords, children, parents, childids, leaves, remotes));

    PetscCall(locidx_to_PetscInt(points_per_dim));
    PetscCall(locidx_to_PetscInt(cone_sizes));
    PetscCall(locidx_to_PetscInt(cones));
    PetscCall(locidx_to_PetscInt(cone_orientations));
    PetscCall(coords_double_to_PetscScalar(coords, P4EST_DIM));

    PetscCall(DMPlexCreate(PETSC_COMM_SELF, plex));
    PetscCall(DMSetDimension(*plex, P4EST_DIM));
    PetscCall(DMPlexCreateFromDAG(*plex, P4EST_DIM, (PetscInt *)points_per_dim->array, (PetscInt *)cone_sizes->array, (PetscInt *)cones->array, (PetscInt *)cone_orientations->array, (PetscScalar *)coords->array));
    PetscCall(DMPlexConvertOldOrientations_Internal(*plex));
    sc_array_destroy(points_per_dim);
    sc_array_destroy(cone_sizes);
    sc_array_destroy(cones);
    sc_array_destroy(cone_orientations);
    sc_array_destroy(coords);
    sc_array_destroy(children);
    sc_array_destroy(parents);
    sc_array_destroy(childids);
    sc_array_destroy(leaves);
    sc_array_destroy(remotes);
  }
  PetscFunctionReturn(0);
}

#define DMReferenceTreeGetChildSymmetry_pforest _append_pforest(DMReferenceTreeGetChildSymmetry)
static PetscErrorCode DMReferenceTreeGetChildSymmetry_pforest(DM dm, PetscInt parent, PetscInt parentOrientA, PetscInt childOrientA, PetscInt childA, PetscInt parentOrientB, PetscInt *childOrientB, PetscInt *childB) {
  PetscInt coneSize, dStart, dEnd, vStart, vEnd, dim, ABswap, oAvert, oBvert, ABswapVert;

  PetscFunctionBegin;
  if (parentOrientA == parentOrientB) {
    if (childOrientB) *childOrientB = childOrientA;
    if (childB) *childB = childA;
    PetscFunctionReturn(0);
  }
  PetscCall(DMPlexGetDepthStratum(dm, 0, &vStart, &vEnd));
  if (childA >= vStart && childA < vEnd) { /* vertices (always in the middle) are invariant under rotation */
    if (childOrientB) *childOrientB = 0;
    if (childB) *childB = childA;
    PetscFunctionReturn(0);
  }
  for (dim = 0; dim < 3; dim++) {
    PetscCall(DMPlexGetDepthStratum(dm, dim, &dStart, &dEnd));
    if (parent >= dStart && parent <= dEnd) break;
  }
  PetscCheck(dim <= 2, PETSC_COMM_SELF, PETSC_ERR_SUP, "Cannot perform child symmetry for %" PetscInt_FMT "-cells", dim);
  PetscCheck(dim, PETSC_COMM_SELF, PETSC_ERR_PLIB, "A vertex has no children");
  if (childA < dStart || childA >= dEnd) { /* a 1-cell in a 2-cell */
    /* this is a lower-dimensional child: bootstrap */
    PetscInt        size, i, sA = -1, sB, sOrientB, sConeSize;
    const PetscInt *supp, *coneA, *coneB, *oA, *oB;

    PetscCall(DMPlexGetSupportSize(dm, childA, &size));
    PetscCall(DMPlexGetSupport(dm, childA, &supp));

    /* find a point sA in supp(childA) that has the same parent */
    for (i = 0; i < size; i++) {
      PetscInt sParent;

      sA = supp[i];
      if (sA == parent) continue;
      PetscCall(DMPlexGetTreeParent(dm, sA, &sParent, NULL));
      if (sParent == parent) break;
    }
    PetscCheck(i != size, PETSC_COMM_SELF, PETSC_ERR_PLIB, "could not find support in children");
    /* find out which point sB is in an equivalent position to sA under
     * parentOrientB */
    PetscCall(DMReferenceTreeGetChildSymmetry_pforest(dm, parent, parentOrientA, 0, sA, parentOrientB, &sOrientB, &sB));
    PetscCall(DMPlexGetConeSize(dm, sA, &sConeSize));
    PetscCall(DMPlexGetCone(dm, sA, &coneA));
    PetscCall(DMPlexGetCone(dm, sB, &coneB));
    PetscCall(DMPlexGetConeOrientation(dm, sA, &oA));
    PetscCall(DMPlexGetConeOrientation(dm, sB, &oB));
    /* step through the cone of sA in natural order */
    for (i = 0; i < sConeSize; i++) {
      if (coneA[i] == childA) {
        /* if childA is at position i in coneA,
         * then we want the point that is at sOrientB*i in coneB */
        PetscInt j = (sOrientB >= 0) ? ((sOrientB + i) % sConeSize) : ((sConeSize - (sOrientB + 1) - i) % sConeSize);
        if (childB) *childB = coneB[j];
        if (childOrientB) {
          DMPolytopeType ct;
          PetscInt       oBtrue;

          PetscCall(DMPlexGetConeSize(dm, childA, &coneSize));
          /* compose sOrientB and oB[j] */
          PetscCheck(coneSize == 0 || coneSize == 2, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Expected a vertex or an edge");
          ct            = coneSize ? DM_POLYTOPE_SEGMENT : DM_POLYTOPE_POINT;
          /* we may have to flip an edge */
          oBtrue        = (sOrientB >= 0) ? oB[j] : DMPolytopeTypeComposeOrientationInv(ct, -1, oB[j]);
          oBtrue        = DMPolytopeConvertNewOrientation_Internal(ct, oBtrue);
          ABswap        = DihedralSwap(coneSize, DMPolytopeConvertNewOrientation_Internal(ct, oA[i]), oBtrue);
          *childOrientB = DihedralCompose(coneSize, childOrientA, ABswap);
        }
        break;
      }
    }
    PetscCheck(i != sConeSize, PETSC_COMM_SELF, PETSC_ERR_PLIB, "support cone mismatch");
    PetscFunctionReturn(0);
  }
  /* get the cone size and symmetry swap */
  PetscCall(DMPlexGetConeSize(dm, parent, &coneSize));
  ABswap = DihedralSwap(coneSize, parentOrientA, parentOrientB);
  if (dim == 2) {
    /* orientations refer to cones: we want them to refer to vertices:
     * if it's a rotation, they are the same, but if the order is reversed, a
     * permutation that puts side i first does *not* put vertex i first */
    oAvert     = (parentOrientA >= 0) ? parentOrientA : -((-parentOrientA % coneSize) + 1);
    oBvert     = (parentOrientB >= 0) ? parentOrientB : -((-parentOrientB % coneSize) + 1);
    ABswapVert = DihedralSwap(coneSize, oAvert, oBvert);
  } else {
    oAvert     = parentOrientA;
    oBvert     = parentOrientB;
    ABswapVert = ABswap;
  }
  if (childB) {
    /* assume that each child corresponds to a vertex, in the same order */
    PetscInt        p, posA = -1, numChildren, i;
    const PetscInt *children;

    /* count which position the child is in */
    PetscCall(DMPlexGetTreeChildren(dm, parent, &numChildren, &children));
    for (i = 0; i < numChildren; i++) {
      p = children[i];
      if (p == childA) {
        if (dim == 1) {
          posA = i;
        } else { /* 2D Morton to rotation */
          posA = (i & 2) ? (i ^ 1) : i;
        }
        break;
      }
    }
    if (posA >= coneSize) {
      SETERRQ(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Could not find childA in children of parent");
    } else {
      /* figure out position B by applying ABswapVert */
      PetscInt posB, childIdB;

      posB = (ABswapVert >= 0) ? ((ABswapVert + posA) % coneSize) : ((coneSize - (ABswapVert + 1) - posA) % coneSize);
      if (dim == 1) {
        childIdB = posB;
      } else { /* 2D rotation to Morton */
        childIdB = (posB & 2) ? (posB ^ 1) : posB;
      }
      if (childB) *childB = children[childIdB];
    }
  }
  if (childOrientB) *childOrientB = DihedralCompose(coneSize, childOrientA, ABswap);
  PetscFunctionReturn(0);
}

#define DMCreateReferenceTree_pforest _append_pforest(DMCreateReferenceTree)
static PetscErrorCode DMCreateReferenceTree_pforest(MPI_Comm comm, DM *dm) {
  p4est_connectivity_t *refcube;
  p4est_t              *root, *refined;
  DM                    dmRoot, dmRefined;
  DM_Plex              *mesh;
  PetscMPIInt           rank;
#if defined(PETSC_HAVE_MPIUNI)
  sc_MPI_Comm comm_self = sc_MPI_COMM_SELF;
#else
  MPI_Comm comm_self = PETSC_COMM_SELF;
#endif

  PetscFunctionBegin;
  PetscCallP4estReturn(refcube, p4est_connectivity_new_byname, ("unit"));
  { /* [-1,1]^d geometry */
    PetscInt i, j;

    for (i = 0; i < P4EST_CHILDREN; i++) {
      for (j = 0; j < 3; j++) {
        refcube->vertices[3 * i + j] *= 2.;
        refcube->vertices[3 * i + j] -= 1.;
      }
    }
  }
  PetscCallP4estReturn(root, p4est_new, (comm_self, refcube, 0, NULL, NULL));
  PetscCallP4estReturn(refined, p4est_new_ext, (comm_self, refcube, 0, 1, 1, 0, NULL, NULL));
  PetscCall(P4estToPlex_Local(root, &dmRoot));
  PetscCall(P4estToPlex_Local(refined, &dmRefined));
  {
#if !defined(P4_TO_P8)
    PetscInt nPoints   = 25;
    PetscInt perm[25]  = {0, 1, 2, 3, 4, 12, 8, 14, 6, 9, 15, 5, 13, 10, 7, 11, 16, 22, 20, 24, 17, 21, 18, 23, 19};
    PetscInt ident[25] = {0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 0, 0, 0, 0, 5, 6, 7, 8, 1, 2, 3, 4, 0};
#else
    PetscInt nPoints    = 125;
    PetscInt perm[125]  = {0,  1,  2,  3,  4,  5,  6,  7,  8,  32, 16, 36, 24, 40, 12, 17,  37,  25,  41,  9,   33,  20,  26, 42,  13,  21,  27,  43,  10,  34,  18,  38,  28,  14,  19,  39,  29,  11,  35,  22,  30, 15,
                           23, 31, 44, 84, 76, 92, 52, 86, 68, 94, 60, 78, 70, 96, 45, 85,  77,  93,  54,  72,  62,  74,  46, 80,  53,  87,  69,  95,  64,  82,  47,  81,  55,  73,  66,  48,  88,  56,  90,  61,  79, 71,
                           97, 49, 89, 58, 63, 75, 50, 57, 91, 65, 83, 51, 59, 67, 98, 106, 110, 122, 114, 120, 118, 124, 99, 111, 115, 119, 100, 107, 116, 121, 101, 117, 102, 108, 112, 123, 103, 113, 104, 109, 105};
    PetscInt ident[125] = {0,  0,  0,  0,  0,  0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 0, 0, 0, 0,  0,  0,  0,  0,  0,  0,  0,  0, 7, 7, 8,  8,  9,  9,  10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16,
                           16, 17, 17, 18, 18, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 0, 0, 0, 0, 0, 0, 19, 20, 21, 22, 23, 24, 25, 26, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 1,  2,  3,  4,  5,  6,  0};

#endif
    IS permIS;
    DM dmPerm;

    PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nPoints, perm, PETSC_USE_POINTER, &permIS));
    PetscCall(DMPlexPermute(dmRefined, permIS, &dmPerm));
    if (dmPerm) {
      PetscCall(DMDestroy(&dmRefined));
      dmRefined = dmPerm;
    }
    PetscCall(ISDestroy(&permIS));
    {
      PetscInt p;
      PetscCall(DMCreateLabel(dmRoot, "identity"));
      PetscCall(DMCreateLabel(dmRefined, "identity"));
      for (p = 0; p < P4EST_INSUL; p++) PetscCall(DMSetLabelValue(dmRoot, "identity", p, p));
      for (p = 0; p < nPoints; p++) PetscCall(DMSetLabelValue(dmRefined, "identity", p, ident[p]));
    }
  }
  PetscCall(DMPlexCreateReferenceTree_Union(dmRoot, dmRefined, "identity", dm));
  mesh                   = (DM_Plex *)(*dm)->data;
  mesh->getchildsymmetry = DMReferenceTreeGetChildSymmetry_pforest;
  PetscCallMPI(MPI_Comm_rank(comm, &rank));
  if (rank == 0) {
    PetscCall(DMViewFromOptions(dmRoot, NULL, "-dm_p4est_ref_root_view"));
    PetscCall(DMViewFromOptions(dmRefined, NULL, "-dm_p4est_ref_refined_view"));
    PetscCall(DMViewFromOptions(dmRefined, NULL, "-dm_p4est_ref_tree_view"));
  }
  PetscCall(DMDestroy(&dmRefined));
  PetscCall(DMDestroy(&dmRoot));
  PetscCallP4est(p4est_destroy, (refined));
  PetscCallP4est(p4est_destroy, (root));
  PetscCallP4est(p4est_connectivity_destroy, (refcube));
  PetscFunctionReturn(0);
}

static PetscErrorCode DMShareDiscretization(DM dmA, DM dmB) {
  void     *ctx;
  PetscInt  num;
  PetscReal val;

  PetscFunctionBegin;
  PetscCall(DMGetApplicationContext(dmA, &ctx));
  PetscCall(DMSetApplicationContext(dmB, ctx));
  PetscCall(DMCopyDisc(dmA, dmB));
  PetscCall(DMGetOutputSequenceNumber(dmA, &num, &val));
  PetscCall(DMSetOutputSequenceNumber(dmB, num, val));
  if (dmB->localSection != dmA->localSection || dmB->globalSection != dmA->globalSection) {
    PetscCall(DMClearLocalVectors(dmB));
    PetscCall(PetscObjectReference((PetscObject)dmA->localSection));
    PetscCall(PetscSectionDestroy(&(dmB->localSection)));
    dmB->localSection = dmA->localSection;
    PetscCall(DMClearGlobalVectors(dmB));
    PetscCall(PetscObjectReference((PetscObject)dmA->globalSection));
    PetscCall(PetscSectionDestroy(&(dmB->globalSection)));
    dmB->globalSection = dmA->globalSection;
    PetscCall(PetscObjectReference((PetscObject)dmA->defaultConstraint.section));
    PetscCall(PetscSectionDestroy(&(dmB->defaultConstraint.section)));
    dmB->defaultConstraint.section = dmA->defaultConstraint.section;
    PetscCall(PetscObjectReference((PetscObject)dmA->defaultConstraint.mat));
    PetscCall(MatDestroy(&(dmB->defaultConstraint.mat)));
    dmB->defaultConstraint.mat = dmA->defaultConstraint.mat;
    if (dmA->map) PetscCall(PetscLayoutReference(dmA->map, &dmB->map));
  }
  if (dmB->sectionSF != dmA->sectionSF) {
    PetscCall(PetscObjectReference((PetscObject)dmA->sectionSF));
    PetscCall(PetscSFDestroy(&dmB->sectionSF));
    dmB->sectionSF = dmA->sectionSF;
  }
  PetscFunctionReturn(0);
}

/* Get an SF that broadcasts a coarse-cell covering of the local fine cells */
static PetscErrorCode DMPforestGetCellCoveringSF(MPI_Comm comm, p4est_t *p4estC, p4est_t *p4estF, PetscInt cStart, PetscInt cEnd, PetscSF *coveringSF) {
  PetscInt     startF, endF, startC, endC, p, nLeaves;
  PetscSFNode *leaves;
  PetscSF      sf;
  PetscInt    *recv, *send;
  PetscMPIInt  tag;
  MPI_Request *recvReqs, *sendReqs;
  PetscSection section;

  PetscFunctionBegin;
  PetscCall(DMPforestComputeOverlappingRanks(p4estC->mpisize, p4estC->mpirank, p4estF, p4estC, &startC, &endC));
  PetscCall(PetscMalloc2(2 * (endC - startC), &recv, endC - startC, &recvReqs));
  PetscCall(PetscCommGetNewTag(comm, &tag));
  for (p = startC; p < endC; p++) {
    recvReqs[p - startC] = MPI_REQUEST_NULL;                                        /* just in case we don't initiate a receive */
    if (p4estC->global_first_quadrant[p] == p4estC->global_first_quadrant[p + 1]) { /* empty coarse partition */
      recv[2 * (p - startC)]     = 0;
      recv[2 * (p - startC) + 1] = 0;
      continue;
    }

    PetscCallMPI(MPI_Irecv(&recv[2 * (p - startC)], 2, MPIU_INT, p, tag, comm, &recvReqs[p - startC]));
  }
  PetscCall(DMPforestComputeOverlappingRanks(p4estC->mpisize, p4estC->mpirank, p4estC, p4estF, &startF, &endF));
  PetscCall(PetscMalloc2(2 * (endF - startF), &send, endF - startF, &sendReqs));
  /* count the quadrants rank will send to each of [startF,endF) */
  for (p = startF; p < endF; p++) {
    p4est_quadrant_t *myFineStart = &p4estF->global_first_position[p];
    p4est_quadrant_t *myFineEnd   = &p4estF->global_first_position[p + 1];
    PetscInt          tStart      = (PetscInt)myFineStart->p.which_tree;
    PetscInt          tEnd        = (PetscInt)myFineEnd->p.which_tree;
    PetscInt          firstCell = -1, lastCell = -1;
    p4est_tree_t     *treeStart = &(((p4est_tree_t *)p4estC->trees->array)[tStart]);
    p4est_tree_t     *treeEnd   = (size_t)tEnd < p4estC->trees->elem_count ? &(((p4est_tree_t *)p4estC->trees->array)[tEnd]) : NULL;
    ssize_t           overlapIndex;

    sendReqs[p - startF] = MPI_REQUEST_NULL; /* just in case we don't initiate a send */
    if (p4estF->global_first_quadrant[p] == p4estF->global_first_quadrant[p + 1]) continue;

    /* locate myFineStart in (or before) a cell */
    if (treeStart->quadrants.elem_count) {
      PetscCallP4estReturn(overlapIndex, sc_array_bsearch, (&(treeStart->quadrants), myFineStart, p4est_quadrant_disjoint));
      if (overlapIndex < 0) {
        firstCell = 0;
      } else {
        firstCell = treeStart->quadrants_offset + overlapIndex;
      }
    } else {
      firstCell = 0;
    }
    if (treeEnd && treeEnd->quadrants.elem_count) {
      PetscCallP4estReturn(overlapIndex, sc_array_bsearch, (&(treeEnd->quadrants), myFineEnd, p4est_quadrant_disjoint));
      if (overlapIndex < 0) { /* all of this local section is overlapped */
        lastCell = p4estC->local_num_quadrants;
      } else {
        p4est_quadrant_t *container = &(((p4est_quadrant_t *)treeEnd->quadrants.array)[overlapIndex]);
        p4est_quadrant_t  first_desc;
        int               equal;

        PetscCallP4est(p4est_quadrant_first_descendant, (container, &first_desc, P4EST_QMAXLEVEL));
        PetscCallP4estReturn(equal, p4est_quadrant_is_equal, (myFineEnd, &first_desc));
        if (equal) {
          lastCell = treeEnd->quadrants_offset + overlapIndex;
        } else {
          lastCell = treeEnd->quadrants_offset + overlapIndex + 1;
        }
      }
    } else {
      lastCell = p4estC->local_num_quadrants;
    }
    send[2 * (p - startF)]     = firstCell;
    send[2 * (p - startF) + 1] = lastCell - firstCell;
    PetscCallMPI(MPI_Isend(&send[2 * (p - startF)], 2, MPIU_INT, p, tag, comm, &sendReqs[p - startF]));
  }
  PetscCallMPI(MPI_Waitall((PetscMPIInt)(endC - startC), recvReqs, MPI_STATUSES_IGNORE));
  PetscCall(PetscSectionCreate(PETSC_COMM_SELF, &section));
  PetscCall(PetscSectionSetChart(section, startC, endC));
  for (p = startC; p < endC; p++) {
    PetscInt numCells = recv[2 * (p - startC) + 1];
    PetscCall(PetscSectionSetDof(section, p, numCells));
  }
  PetscCall(PetscSectionSetUp(section));
  PetscCall(PetscSectionGetStorageSize(section, &nLeaves));
  PetscCall(PetscMalloc1(nLeaves, &leaves));
  for (p = startC; p < endC; p++) {
    PetscInt firstCell = recv[2 * (p - startC)];
    PetscInt numCells  = recv[2 * (p - startC) + 1];
    PetscInt off, i;

    PetscCall(PetscSectionGetOffset(section, p, &off));
    for (i = 0; i < numCells; i++) {
      leaves[off + i].rank  = p;
      leaves[off + i].index = firstCell + i;
    }
  }
  PetscCall(PetscSFCreate(comm, &sf));
  PetscCall(PetscSFSetGraph(sf, cEnd - cStart, nLeaves, NULL, PETSC_OWN_POINTER, leaves, PETSC_OWN_POINTER));
  PetscCall(PetscSectionDestroy(&section));
  PetscCallMPI(MPI_Waitall((PetscMPIInt)(endF - startF), sendReqs, MPI_STATUSES_IGNORE));
  PetscCall(PetscFree2(send, sendReqs));
  PetscCall(PetscFree2(recv, recvReqs));
  *coveringSF = sf;
  PetscFunctionReturn(0);
}

/* closure points for locally-owned cells */
static PetscErrorCode DMPforestGetCellSFNodes(DM dm, PetscInt numClosureIndices, PetscInt *numClosurePoints, PetscSFNode **closurePoints, PetscBool redirect) {
  PetscInt           cStart, cEnd;
  PetscInt           count, c;
  PetscMPIInt        rank;
  PetscInt           closureSize = -1;
  PetscInt          *closure     = NULL;
  PetscSF            pointSF;
  PetscInt           nleaves, nroots;
  const PetscInt    *ilocal;
  const PetscSFNode *iremote;
  DM                 plex;
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;

  PetscFunctionBegin;
  forest  = (DM_Forest *)dm->data;
  pforest = (DM_Forest_pforest *)forest->data;
  cStart  = pforest->cLocalStart;
  cEnd    = pforest->cLocalEnd;
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMGetPointSF(dm, &pointSF));
  PetscCall(PetscSFGetGraph(pointSF, &nroots, &nleaves, &ilocal, &iremote));
  nleaves           = PetscMax(0, nleaves);
  nroots            = PetscMax(0, nroots);
  *numClosurePoints = numClosureIndices * (cEnd - cStart);
  PetscCall(PetscMalloc1(*numClosurePoints, closurePoints));
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)dm), &rank));
  for (c = cStart, count = 0; c < cEnd; c++) {
    PetscInt i;
    PetscCall(DMPlexGetTransitiveClosure(plex, c, PETSC_TRUE, &closureSize, &closure));

    for (i = 0; i < numClosureIndices; i++, count++) {
      PetscInt p   = closure[2 * i];
      PetscInt loc = -1;

      PetscCall(PetscFindInt(p, nleaves, ilocal, &loc));
      if (redirect && loc >= 0) {
        (*closurePoints)[count].rank  = iremote[loc].rank;
        (*closurePoints)[count].index = iremote[loc].index;
      } else {
        (*closurePoints)[count].rank  = rank;
        (*closurePoints)[count].index = p;
      }
    }
    PetscCall(DMPlexRestoreTransitiveClosure(plex, c, PETSC_TRUE, &closureSize, &closure));
  }
  PetscFunctionReturn(0);
}

static void MPIAPI DMPforestMaxSFNode(void *a, void *b, PetscMPIInt *len, MPI_Datatype *type) {
  PetscMPIInt i;

  for (i = 0; i < *len; i++) {
    PetscSFNode *A = (PetscSFNode *)a;
    PetscSFNode *B = (PetscSFNode *)b;

    if (B->rank < 0) *B = *A;
  }
}

static PetscErrorCode DMPforestGetTransferSF_Point(DM coarse, DM fine, PetscSF *sf, PetscBool transferIdent, PetscInt *childIds[]) {
  MPI_Comm           comm;
  PetscMPIInt        rank, size;
  DM_Forest_pforest *pforestC, *pforestF;
  p4est_t           *p4estC, *p4estF;
  PetscInt           numClosureIndices;
  PetscInt           numClosurePointsC, numClosurePointsF;
  PetscSFNode       *closurePointsC, *closurePointsF;
  p4est_quadrant_t  *coverQuads = NULL;
  p4est_quadrant_t **treeQuads;
  PetscInt          *treeQuadCounts;
  MPI_Datatype       nodeType;
  MPI_Datatype       nodeClosureType;
  MPI_Op             sfNodeReduce;
  p4est_topidx_t     fltF, lltF, t;
  DM                 plexC, plexF;
  PetscInt           pStartF, pEndF, pStartC, pEndC;
  PetscBool          saveInCoarse = PETSC_FALSE;
  PetscBool          saveInFine   = PETSC_FALSE;
  PetscBool          formCids     = (childIds != NULL) ? PETSC_TRUE : PETSC_FALSE;
  PetscInt          *cids         = NULL;

  PetscFunctionBegin;
  pforestC = (DM_Forest_pforest *)((DM_Forest *)coarse->data)->data;
  pforestF = (DM_Forest_pforest *)((DM_Forest *)fine->data)->data;
  p4estC   = pforestC->forest;
  p4estF   = pforestF->forest;
  PetscCheck(pforestC->topo == pforestF->topo, PetscObjectComm((PetscObject)coarse), PETSC_ERR_ARG_INCOMP, "DM's must have the same base DM");
  comm = PetscObjectComm((PetscObject)coarse);
  PetscCallMPI(MPI_Comm_rank(comm, &rank));
  PetscCallMPI(MPI_Comm_size(comm, &size));
  PetscCall(DMPforestGetPlex(fine, &plexF));
  PetscCall(DMPlexGetChart(plexF, &pStartF, &pEndF));
  PetscCall(DMPforestGetPlex(coarse, &plexC));
  PetscCall(DMPlexGetChart(plexC, &pStartC, &pEndC));
  { /* check if the results have been cached */
    DM adaptCoarse, adaptFine;

    PetscCall(DMForestGetAdaptivityForest(coarse, &adaptCoarse));
    PetscCall(DMForestGetAdaptivityForest(fine, &adaptFine));
    if (adaptCoarse && adaptCoarse->data == fine->data) { /* coarse is adapted from fine */
      if (pforestC->pointSelfToAdaptSF) {
        PetscCall(PetscObjectReference((PetscObject)(pforestC->pointSelfToAdaptSF)));
        *sf = pforestC->pointSelfToAdaptSF;
        if (childIds) {
          PetscCall(PetscMalloc1(pEndF - pStartF, &cids));
          PetscCall(PetscArraycpy(cids, pforestC->pointSelfToAdaptCids, pEndF - pStartF));
          *childIds = cids;
        }
        PetscFunctionReturn(0);
      } else {
        saveInCoarse = PETSC_TRUE;
        formCids     = PETSC_TRUE;
      }
    } else if (adaptFine && adaptFine->data == coarse->data) { /* fine is adapted from coarse */
      if (pforestF->pointAdaptToSelfSF) {
        PetscCall(PetscObjectReference((PetscObject)(pforestF->pointAdaptToSelfSF)));
        *sf = pforestF->pointAdaptToSelfSF;
        if (childIds) {
          PetscCall(PetscMalloc1(pEndF - pStartF, &cids));
          PetscCall(PetscArraycpy(cids, pforestF->pointAdaptToSelfCids, pEndF - pStartF));
          *childIds = cids;
        }
        PetscFunctionReturn(0);
      } else {
        saveInFine = PETSC_TRUE;
        formCids   = PETSC_TRUE;
      }
    }
  }

  /* count the number of closure points that have dofs and create a list */
  numClosureIndices = P4EST_INSUL;
  /* create the datatype */
  PetscCallMPI(MPI_Type_contiguous(2, MPIU_INT, &nodeType));
  PetscCallMPI(MPI_Type_commit(&nodeType));
  PetscCallMPI(MPI_Op_create(DMPforestMaxSFNode, PETSC_FALSE, &sfNodeReduce));
  PetscCallMPI(MPI_Type_contiguous(numClosureIndices * 2, MPIU_INT, &nodeClosureType));
  PetscCallMPI(MPI_Type_commit(&nodeClosureType));
  /* everything has to go through cells: for each cell, create a list of the sfnodes in its closure */
  /* get lists of closure point SF nodes for every cell */
  PetscCall(DMPforestGetCellSFNodes(coarse, numClosureIndices, &numClosurePointsC, &closurePointsC, PETSC_TRUE));
  PetscCall(DMPforestGetCellSFNodes(fine, numClosureIndices, &numClosurePointsF, &closurePointsF, PETSC_FALSE));
  /* create pointers for tree lists */
  fltF = p4estF->first_local_tree;
  lltF = p4estF->last_local_tree;
  PetscCall(PetscCalloc2(lltF + 1 - fltF, &treeQuads, lltF + 1 - fltF, &treeQuadCounts));
  /* if the partitions don't match, ship the coarse to cover the fine */
  if (size > 1) {
    PetscInt p;

    for (p = 0; p < size; p++) {
      int equal;

      PetscCallP4estReturn(equal, p4est_quadrant_is_equal_piggy, (&p4estC->global_first_position[p], &p4estF->global_first_position[p]));
      if (!equal) break;
    }
    if (p < size) { /* non-matching distribution: send the coarse to cover the fine */
      PetscInt          cStartC, cEndC;
      PetscSF           coveringSF;
      PetscInt          nleaves;
      PetscInt          count;
      PetscSFNode      *newClosurePointsC;
      p4est_quadrant_t *coverQuadsSend;
      p4est_topidx_t    fltC = p4estC->first_local_tree;
      p4est_topidx_t    lltC = p4estC->last_local_tree;
      p4est_topidx_t    t;
      PetscMPIInt       blockSizes[4]   = {P4EST_DIM, 2, 1, 1};
      MPI_Aint          blockOffsets[4] = {offsetof(p4est_quadrant_t, x), offsetof(p4est_quadrant_t, level), offsetof(p4est_quadrant_t, pad16), offsetof(p4est_quadrant_t, p)};
      MPI_Datatype      blockTypes[4]   = {MPI_INT32_T, MPI_INT8_T, MPI_INT16_T, MPI_INT32_T /* p.which_tree */};
      MPI_Datatype      quadStruct, quadType;

      PetscCall(DMPlexGetSimplexOrBoxCells(plexC, 0, &cStartC, &cEndC));
      PetscCall(DMPforestGetCellCoveringSF(comm, p4estC, p4estF, pforestC->cLocalStart, pforestC->cLocalEnd, &coveringSF));
      PetscCall(PetscSFGetGraph(coveringSF, NULL, &nleaves, NULL, NULL));
      PetscCall(PetscMalloc1(numClosureIndices * nleaves, &newClosurePointsC));
      PetscCall(PetscMalloc1(nleaves, &coverQuads));
      PetscCall(PetscMalloc1(cEndC - cStartC, &coverQuadsSend));
      count = 0;
      for (t = fltC; t <= lltC; t++) { /* unfortunately, we need to pack a send array, since quads are not stored packed in p4est */
        p4est_tree_t *tree = &(((p4est_tree_t *)p4estC->trees->array)[t]);
        PetscInt      q;

        PetscCall(PetscMemcpy(&coverQuadsSend[count], tree->quadrants.array, tree->quadrants.elem_count * sizeof(p4est_quadrant_t)));
        for (q = 0; (size_t)q < tree->quadrants.elem_count; q++) coverQuadsSend[count + q].p.which_tree = t;
        count += tree->quadrants.elem_count;
      }
      /* p is of a union type p4est_quadrant_data, but only the p.which_tree field is active at this time. So, we
         have a simple blockTypes[] to use. Note that quadStruct does not count potential padding in array of
         p4est_quadrant_t. We have to call MPI_Type_create_resized() to change upper-bound of quadStruct.
       */
      PetscCallMPI(MPI_Type_create_struct(4, blockSizes, blockOffsets, blockTypes, &quadStruct));
      PetscCallMPI(MPI_Type_create_resized(quadStruct, 0, sizeof(p4est_quadrant_t), &quadType));
      PetscCallMPI(MPI_Type_commit(&quadType));
      PetscCall(PetscSFBcastBegin(coveringSF, nodeClosureType, closurePointsC, newClosurePointsC, MPI_REPLACE));
      PetscCall(PetscSFBcastBegin(coveringSF, quadType, coverQuadsSend, coverQuads, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(coveringSF, nodeClosureType, closurePointsC, newClosurePointsC, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(coveringSF, quadType, coverQuadsSend, coverQuads, MPI_REPLACE));
      PetscCallMPI(MPI_Type_free(&quadStruct));
      PetscCallMPI(MPI_Type_free(&quadType));
      PetscCall(PetscFree(coverQuadsSend));
      PetscCall(PetscFree(closurePointsC));
      PetscCall(PetscSFDestroy(&coveringSF));
      closurePointsC = newClosurePointsC;

      /* assign tree quads based on locations in coverQuads */
      {
        PetscInt q;
        for (q = 0; q < nleaves; q++) {
          p4est_locidx_t t = coverQuads[q].p.which_tree;
          if (!treeQuadCounts[t - fltF]++) treeQuads[t - fltF] = &coverQuads[q];
        }
      }
    }
  }
  if (!coverQuads) { /* matching partitions: assign tree quads based on locations in p4est native arrays */
    for (t = fltF; t <= lltF; t++) {
      p4est_tree_t *tree = &(((p4est_tree_t *)p4estC->trees->array)[t]);

      treeQuadCounts[t - fltF] = tree->quadrants.elem_count;
      treeQuads[t - fltF]      = (p4est_quadrant_t *)tree->quadrants.array;
    }
  }

  {
    PetscInt     p;
    PetscInt     cLocalStartF;
    PetscSF      pointSF;
    PetscSFNode *roots;
    PetscInt    *rootType;
    DM           refTree = NULL;
    DMLabel      canonical;
    PetscInt    *childClosures[P4EST_CHILDREN] = {NULL};
    PetscInt    *rootClosure                   = NULL;
    PetscInt     coarseOffset;
    PetscInt     numCoarseQuads;

    PetscCall(PetscMalloc1(pEndF - pStartF, &roots));
    PetscCall(PetscMalloc1(pEndF - pStartF, &rootType));
    PetscCall(DMGetPointSF(fine, &pointSF));
    for (p = pStartF; p < pEndF; p++) {
      roots[p - pStartF].rank  = -1;
      roots[p - pStartF].index = -1;
      rootType[p - pStartF]    = -1;
    }
    if (formCids) {
      PetscInt child;

      PetscCall(PetscMalloc1(pEndF - pStartF, &cids));
      for (p = pStartF; p < pEndF; p++) cids[p - pStartF] = -2;
      PetscCall(DMPlexGetReferenceTree(plexF, &refTree));
      PetscCall(DMPlexGetTransitiveClosure(refTree, 0, PETSC_TRUE, NULL, &rootClosure));
      for (child = 0; child < P4EST_CHILDREN; child++) { /* get the closures of the child cells in the reference tree */
        PetscCall(DMPlexGetTransitiveClosure(refTree, child + 1, PETSC_TRUE, NULL, &childClosures[child]));
      }
      PetscCall(DMGetLabel(refTree, "canonical", &canonical));
    }
    cLocalStartF = pforestF->cLocalStart;
    for (t = fltF, coarseOffset = 0, numCoarseQuads = 0; t <= lltF; t++, coarseOffset += numCoarseQuads) {
      p4est_tree_t     *tree         = &(((p4est_tree_t *)p4estF->trees->array)[t]);
      PetscInt          numFineQuads = tree->quadrants.elem_count;
      p4est_quadrant_t *coarseQuads  = treeQuads[t - fltF];
      p4est_quadrant_t *fineQuads    = (p4est_quadrant_t *)tree->quadrants.array;
      PetscInt          i, coarseCount = 0;
      PetscInt          offset = tree->quadrants_offset;
      sc_array_t        coarseQuadsArray;

      numCoarseQuads = treeQuadCounts[t - fltF];
      PetscCallP4est(sc_array_init_data, (&coarseQuadsArray, coarseQuads, sizeof(p4est_quadrant_t), (size_t)numCoarseQuads));
      for (i = 0; i < numFineQuads; i++) {
        PetscInt          c          = i + offset;
        p4est_quadrant_t *quad       = &fineQuads[i];
        p4est_quadrant_t *quadCoarse = NULL;
        ssize_t           disjoint   = -1;

        while (disjoint < 0 && coarseCount < numCoarseQuads) {
          quadCoarse = &coarseQuads[coarseCount];
          PetscCallP4estReturn(disjoint, p4est_quadrant_disjoint, (quadCoarse, quad));
          if (disjoint < 0) coarseCount++;
        }
        PetscCheck(disjoint == 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "did not find overlapping coarse quad");
        if (quadCoarse->level > quad->level || (quadCoarse->level == quad->level && !transferIdent)) { /* the "coarse" mesh is finer than the fine mesh at the point: continue */
          if (transferIdent) {                                                                         /* find corners */
            PetscInt j = 0;

            do {
              if (j < P4EST_CHILDREN) {
                p4est_quadrant_t cornerQuad;
                int              equal;

                PetscCallP4est(p4est_quadrant_corner_descendant, (quad, &cornerQuad, j, quadCoarse->level));
                PetscCallP4estReturn(equal, p4est_quadrant_is_equal, (&cornerQuad, quadCoarse));
                if (equal) {
                  PetscInt    petscJ = P4estVertToPetscVert[j];
                  PetscInt    p      = closurePointsF[numClosureIndices * c + (P4EST_INSUL - P4EST_CHILDREN) + petscJ].index;
                  PetscSFNode q      = closurePointsC[numClosureIndices * (coarseCount + coarseOffset) + (P4EST_INSUL - P4EST_CHILDREN) + petscJ];

                  roots[p - pStartF]    = q;
                  rootType[p - pStartF] = PETSC_MAX_INT;
                  cids[p - pStartF]     = -1;
                  j++;
                }
              }
              coarseCount++;
              disjoint = 1;
              if (coarseCount < numCoarseQuads) {
                quadCoarse = &coarseQuads[coarseCount];
                PetscCallP4estReturn(disjoint, p4est_quadrant_disjoint, (quadCoarse, quad));
              }
            } while (!disjoint);
          }
          continue;
        }
        if (quadCoarse->level == quad->level) { /* same quad present in coarse and fine mesh */
          PetscInt j;
          for (j = 0; j < numClosureIndices; j++) {
            PetscInt p = closurePointsF[numClosureIndices * c + j].index;

            roots[p - pStartF]    = closurePointsC[numClosureIndices * (coarseCount + coarseOffset) + j];
            rootType[p - pStartF] = PETSC_MAX_INT; /* unconditionally accept */
            cids[p - pStartF]     = -1;
          }
        } else {
          PetscInt levelDiff                 = quad->level - quadCoarse->level;
          PetscInt proposedCids[P4EST_INSUL] = {0};

          if (formCids) {
            PetscInt  cl;
            PetscInt *pointClosure = NULL;
            int       cid;

            PetscCheck(levelDiff <= 1, PETSC_COMM_SELF, PETSC_ERR_USER, "Recursive child ids not implemented");
            PetscCallP4estReturn(cid, p4est_quadrant_child_id, (quad));
            PetscCall(DMPlexGetTransitiveClosure(plexF, c + cLocalStartF, PETSC_TRUE, NULL, &pointClosure));
            for (cl = 0; cl < P4EST_INSUL; cl++) {
              PetscInt       p      = pointClosure[2 * cl];
              PetscInt       point  = childClosures[cid][2 * cl];
              PetscInt       ornt   = childClosures[cid][2 * cl + 1];
              PetscInt       newcid = -1;
              DMPolytopeType ct;

              if (rootType[p - pStartF] == PETSC_MAX_INT) continue;
              PetscCall(DMPlexGetCellType(refTree, point, &ct));
              ornt = DMPolytopeConvertNewOrientation_Internal(ct, ornt);
              if (!cl) {
                newcid = cid + 1;
              } else {
                PetscInt rcl, parent, parentOrnt = 0;

                PetscCall(DMPlexGetTreeParent(refTree, point, &parent, NULL));
                if (parent == point) {
                  newcid = -1;
                } else if (!parent) { /* in the root */
                  newcid = point;
                } else {
                  DMPolytopeType rct = DM_POLYTOPE_UNKNOWN;

                  for (rcl = 1; rcl < P4EST_INSUL; rcl++) {
                    if (rootClosure[2 * rcl] == parent) {
                      PetscCall(DMPlexGetCellType(refTree, parent, &rct));
                      parentOrnt = DMPolytopeConvertNewOrientation_Internal(rct, rootClosure[2 * rcl + 1]);
                      break;
                    }
                  }
                  PetscCheck(rcl < P4EST_INSUL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Couldn't find parent in root closure");
                  PetscCall(DMPlexReferenceTreeGetChildSymmetry(refTree, parent, parentOrnt, ornt, point, DMPolytopeConvertNewOrientation_Internal(rct, pointClosure[2 * rcl + 1]), NULL, &newcid));
                }
              }
              if (newcid >= 0) {
                if (canonical) PetscCall(DMLabelGetValue(canonical, newcid, &newcid));
                proposedCids[cl] = newcid;
              }
            }
            PetscCall(DMPlexRestoreTransitiveClosure(plexF, c + cLocalStartF, PETSC_TRUE, NULL, &pointClosure));
          }
          p4est_qcoord_t coarseBound[2][P4EST_DIM] = {
            {quadCoarse->x, quadCoarse->y,
#if defined(P4_TO_P8)
             quadCoarse->z
#endif
            },
            {0                    }
          };
          p4est_qcoord_t fineBound[2][P4EST_DIM] = {
            {quad->x, quad->y,
#if defined(P4_TO_P8)
             quad->z
#endif
            },
            {0              }
          };
          PetscInt j;
          for (j = 0; j < P4EST_DIM; j++) { /* get the coordinates of cell boundaries in each direction */
            coarseBound[1][j] = coarseBound[0][j] + P4EST_QUADRANT_LEN(quadCoarse->level);
            fineBound[1][j]   = fineBound[0][j] + P4EST_QUADRANT_LEN(quad->level);
          }
          for (j = 0; j < numClosureIndices; j++) {
            PetscInt    l, p;
            PetscSFNode q;

            p = closurePointsF[numClosureIndices * c + j].index;
            if (rootType[p - pStartF] == PETSC_MAX_INT) continue;
            if (j == 0) { /* volume: ancestor is volume */
              l = 0;
            } else if (j < 1 + P4EST_FACES) { /* facet */
              PetscInt face       = PetscFaceToP4estFace[j - 1];
              PetscInt direction  = face / 2;
              PetscInt coarseFace = -1;

              if (coarseBound[face % 2][direction] == fineBound[face % 2][direction]) {
                coarseFace = face;
                l          = 1 + P4estFaceToPetscFace[coarseFace];
              } else {
                l = 0;
              }
#if defined(P4_TO_P8)
            } else if (j < 1 + P4EST_FACES + P8EST_EDGES) {
              PetscInt  edge       = PetscEdgeToP4estEdge[j - (1 + P4EST_FACES)];
              PetscInt  direction  = edge / 4;
              PetscInt  mod        = edge % 4;
              PetscInt  coarseEdge = -1, coarseFace = -1;
              PetscInt  minDir = PetscMin((direction + 1) % 3, (direction + 2) % 3);
              PetscInt  maxDir = PetscMax((direction + 1) % 3, (direction + 2) % 3);
              PetscBool dirTest[2];

              dirTest[0] = (PetscBool)(coarseBound[mod % 2][minDir] == fineBound[mod % 2][minDir]);
              dirTest[1] = (PetscBool)(coarseBound[mod / 2][maxDir] == fineBound[mod / 2][maxDir]);

              if (dirTest[0] && dirTest[1]) { /* fine edge falls on coarse edge */
                coarseEdge = edge;
                l          = 1 + P4EST_FACES + P4estEdgeToPetscEdge[coarseEdge];
              } else if (dirTest[0]) { /* fine edge falls on a coarse face in the minDir direction */
                coarseFace = 2 * minDir + (mod % 2);
                l          = 1 + P4estFaceToPetscFace[coarseFace];
              } else if (dirTest[1]) { /* fine edge falls on a coarse face in the maxDir direction */
                coarseFace = 2 * maxDir + (mod / 2);
                l          = 1 + P4estFaceToPetscFace[coarseFace];
              } else {
                l = 0;
              }
#endif
            } else {
              PetscInt  vertex = PetscVertToP4estVert[P4EST_CHILDREN - (P4EST_INSUL - j)];
              PetscBool dirTest[P4EST_DIM];
              PetscInt  m;
              PetscInt  numMatch     = 0;
              PetscInt  coarseVertex = -1, coarseFace = -1;
#if defined(P4_TO_P8)
              PetscInt coarseEdge = -1;
#endif

              for (m = 0; m < P4EST_DIM; m++) {
                dirTest[m] = (PetscBool)(coarseBound[(vertex >> m) & 1][m] == fineBound[(vertex >> m) & 1][m]);
                if (dirTest[m]) numMatch++;
              }
              if (numMatch == P4EST_DIM) { /* vertex on vertex */
                coarseVertex = vertex;
                l            = P4EST_INSUL - (P4EST_CHILDREN - P4estVertToPetscVert[coarseVertex]);
              } else if (numMatch == 1) { /* vertex on face */
                for (m = 0; m < P4EST_DIM; m++) {
                  if (dirTest[m]) {
                    coarseFace = 2 * m + ((vertex >> m) & 1);
                    break;
                  }
                }
                l = 1 + P4estFaceToPetscFace[coarseFace];
#if defined(P4_TO_P8)
              } else if (numMatch == 2) { /* vertex on edge */
                for (m = 0; m < P4EST_DIM; m++) {
                  if (!dirTest[m]) {
                    PetscInt otherDir1 = (m + 1) % 3;
                    PetscInt otherDir2 = (m + 2) % 3;
                    PetscInt minDir    = PetscMin(otherDir1, otherDir2);
                    PetscInt maxDir    = PetscMax(otherDir1, otherDir2);

                    coarseEdge = m * 4 + 2 * ((vertex >> maxDir) & 1) + ((vertex >> minDir) & 1);
                    break;
                  }
                }
                l = 1 + P4EST_FACES + P4estEdgeToPetscEdge[coarseEdge];
#endif
              } else { /* volume */
                l = 0;
              }
            }
            q = closurePointsC[numClosureIndices * (coarseCount + coarseOffset) + l];
            if (l > rootType[p - pStartF]) {
              if (l >= P4EST_INSUL - P4EST_CHILDREN) { /* vertex on vertex: unconditional acceptance */
                if (transferIdent) {
                  roots[p - pStartF]    = q;
                  rootType[p - pStartF] = PETSC_MAX_INT;
                  if (formCids) cids[p - pStartF] = -1;
                }
              } else {
                PetscInt k, thisp = p, limit;

                roots[p - pStartF]    = q;
                rootType[p - pStartF] = l;
                if (formCids) cids[p - pStartF] = proposedCids[j];
                limit = transferIdent ? levelDiff : (levelDiff - 1);
                for (k = 0; k < limit; k++) {
                  PetscInt parent;

                  PetscCall(DMPlexGetTreeParent(plexF, thisp, &parent, NULL));
                  if (parent == thisp) break;

                  roots[parent - pStartF]    = q;
                  rootType[parent - pStartF] = PETSC_MAX_INT;
                  if (formCids) cids[parent - pStartF] = -1;
                  thisp = parent;
                }
              }
            }
          }
        }
      }
    }

    /* now every cell has labeled the points in its closure, so we first make sure everyone agrees by reducing to roots, and the broadcast the agreements */
    if (size > 1) {
      PetscInt *rootTypeCopy, p;

      PetscCall(PetscMalloc1(pEndF - pStartF, &rootTypeCopy));
      PetscCall(PetscArraycpy(rootTypeCopy, rootType, pEndF - pStartF));
      PetscCall(PetscSFReduceBegin(pointSF, MPIU_INT, rootTypeCopy, rootTypeCopy, MPI_MAX));
      PetscCall(PetscSFReduceEnd(pointSF, MPIU_INT, rootTypeCopy, rootTypeCopy, MPI_MAX));
      PetscCall(PetscSFBcastBegin(pointSF, MPIU_INT, rootTypeCopy, rootTypeCopy, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(pointSF, MPIU_INT, rootTypeCopy, rootTypeCopy, MPI_REPLACE));
      for (p = pStartF; p < pEndF; p++) {
        if (rootTypeCopy[p - pStartF] > rootType[p - pStartF]) { /* another process found a root of higher type (e.g. vertex instead of edge), which we want to accept, so nullify this */
          roots[p - pStartF].rank  = -1;
          roots[p - pStartF].index = -1;
        }
        if (formCids && rootTypeCopy[p - pStartF] == PETSC_MAX_INT) { cids[p - pStartF] = -1; /* we have found an antecedent that is the same: no child id */ }
      }
      PetscCall(PetscFree(rootTypeCopy));
      PetscCall(PetscSFReduceBegin(pointSF, nodeType, roots, roots, sfNodeReduce));
      PetscCall(PetscSFReduceEnd(pointSF, nodeType, roots, roots, sfNodeReduce));
      PetscCall(PetscSFBcastBegin(pointSF, nodeType, roots, roots, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(pointSF, nodeType, roots, roots, MPI_REPLACE));
    }
    PetscCall(PetscFree(rootType));

    {
      PetscInt     numRoots;
      PetscInt     numLeaves;
      PetscInt    *leaves;
      PetscSFNode *iremote;
      /* count leaves */

      numRoots = pEndC - pStartC;

      numLeaves = 0;
      for (p = pStartF; p < pEndF; p++) {
        if (roots[p - pStartF].index >= 0) numLeaves++;
      }
      PetscCall(PetscMalloc1(numLeaves, &leaves));
      PetscCall(PetscMalloc1(numLeaves, &iremote));
      numLeaves = 0;
      for (p = pStartF; p < pEndF; p++) {
        if (roots[p - pStartF].index >= 0) {
          leaves[numLeaves]  = p - pStartF;
          iremote[numLeaves] = roots[p - pStartF];
          numLeaves++;
        }
      }
      PetscCall(PetscFree(roots));
      PetscCall(PetscSFCreate(comm, sf));
      if (numLeaves == (pEndF - pStartF)) {
        PetscCall(PetscFree(leaves));
        PetscCall(PetscSFSetGraph(*sf, numRoots, numLeaves, NULL, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER));
      } else {
        PetscCall(PetscSFSetGraph(*sf, numRoots, numLeaves, leaves, PETSC_OWN_POINTER, iremote, PETSC_OWN_POINTER));
      }
    }
    if (formCids) {
      PetscSF  pointSF;
      PetscInt child;

      PetscCall(DMPlexGetReferenceTree(plexF, &refTree));
      PetscCall(DMGetPointSF(plexF, &pointSF));
      PetscCall(PetscSFReduceBegin(pointSF, MPIU_INT, cids, cids, MPI_MAX));
      PetscCall(PetscSFReduceEnd(pointSF, MPIU_INT, cids, cids, MPI_MAX));
      if (childIds) *childIds = cids;
      for (child = 0; child < P4EST_CHILDREN; child++) PetscCall(DMPlexRestoreTransitiveClosure(refTree, child + 1, PETSC_TRUE, NULL, &childClosures[child]));
      PetscCall(DMPlexRestoreTransitiveClosure(refTree, 0, PETSC_TRUE, NULL, &rootClosure));
    }
  }
  if (saveInCoarse) { /* cache results */
    PetscCall(PetscObjectReference((PetscObject)*sf));
    pforestC->pointSelfToAdaptSF = *sf;
    if (!childIds) {
      pforestC->pointSelfToAdaptCids = cids;
    } else {
      PetscCall(PetscMalloc1(pEndF - pStartF, &pforestC->pointSelfToAdaptCids));
      PetscCall(PetscArraycpy(pforestC->pointSelfToAdaptCids, cids, pEndF - pStartF));
    }
  } else if (saveInFine) {
    PetscCall(PetscObjectReference((PetscObject)*sf));
    pforestF->pointAdaptToSelfSF = *sf;
    if (!childIds) {
      pforestF->pointAdaptToSelfCids = cids;
    } else {
      PetscCall(PetscMalloc1(pEndF - pStartF, &pforestF->pointAdaptToSelfCids));
      PetscCall(PetscArraycpy(pforestF->pointAdaptToSelfCids, cids, pEndF - pStartF));
    }
  }
  PetscCall(PetscFree2(treeQuads, treeQuadCounts));
  PetscCall(PetscFree(coverQuads));
  PetscCall(PetscFree(closurePointsC));
  PetscCall(PetscFree(closurePointsF));
  PetscCallMPI(MPI_Type_free(&nodeClosureType));
  PetscCallMPI(MPI_Op_free(&sfNodeReduce));
  PetscCallMPI(MPI_Type_free(&nodeType));
  PetscFunctionReturn(0);
}

/* children are sf leaves of parents */
static PetscErrorCode DMPforestGetTransferSF_Internal(DM coarse, DM fine, const PetscInt dofPerDim[], PetscSF *sf, PetscBool transferIdent, PetscInt *childIds[]) {
  MPI_Comm           comm;
  PetscMPIInt        rank;
  DM_Forest_pforest *pforestC, *pforestF;
  DM                 plexC, plexF;
  PetscInt           pStartC, pEndC, pStartF, pEndF;
  PetscSF            pointTransferSF;
  PetscBool          allOnes = PETSC_TRUE;

  PetscFunctionBegin;
  pforestC = (DM_Forest_pforest *)((DM_Forest *)coarse->data)->data;
  pforestF = (DM_Forest_pforest *)((DM_Forest *)fine->data)->data;
  PetscCheck(pforestC->topo == pforestF->topo, PetscObjectComm((PetscObject)coarse), PETSC_ERR_ARG_INCOMP, "DM's must have the same base DM");
  comm = PetscObjectComm((PetscObject)coarse);
  PetscCallMPI(MPI_Comm_rank(comm, &rank));

  {
    PetscInt i;
    for (i = 0; i <= P4EST_DIM; i++) {
      if (dofPerDim[i] != 1) {
        allOnes = PETSC_FALSE;
        break;
      }
    }
  }
  PetscCall(DMPforestGetTransferSF_Point(coarse, fine, &pointTransferSF, transferIdent, childIds));
  if (allOnes) {
    *sf = pointTransferSF;
    PetscFunctionReturn(0);
  }

  PetscCall(DMPforestGetPlex(fine, &plexF));
  PetscCall(DMPlexGetChart(plexF, &pStartF, &pEndF));
  PetscCall(DMPforestGetPlex(coarse, &plexC));
  PetscCall(DMPlexGetChart(plexC, &pStartC, &pEndC));
  {
    PetscInt           numRoots;
    PetscInt           numLeaves;
    const PetscInt    *leaves;
    const PetscSFNode *iremote;
    PetscInt           d;
    PetscSection       leafSection, rootSection;
    /* count leaves */

    PetscCall(PetscSFGetGraph(pointTransferSF, &numRoots, &numLeaves, &leaves, &iremote));
    PetscCall(PetscSectionCreate(PETSC_COMM_SELF, &rootSection));
    PetscCall(PetscSectionCreate(PETSC_COMM_SELF, &leafSection));
    PetscCall(PetscSectionSetChart(rootSection, pStartC, pEndC));
    PetscCall(PetscSectionSetChart(leafSection, pStartF, pEndF));

    for (d = 0; d <= P4EST_DIM; d++) {
      PetscInt startC, endC, e;

      PetscCall(DMPlexGetSimplexOrBoxCells(plexC, P4EST_DIM - d, &startC, &endC));
      for (e = startC; e < endC; e++) PetscCall(PetscSectionSetDof(rootSection, e, dofPerDim[d]));
    }

    for (d = 0; d <= P4EST_DIM; d++) {
      PetscInt startF, endF, e;

      PetscCall(DMPlexGetSimplexOrBoxCells(plexF, P4EST_DIM - d, &startF, &endF));
      for (e = startF; e < endF; e++) PetscCall(PetscSectionSetDof(leafSection, e, dofPerDim[d]));
    }

    PetscCall(PetscSectionSetUp(rootSection));
    PetscCall(PetscSectionSetUp(leafSection));
    {
      PetscInt     nroots, nleaves;
      PetscInt    *mine, i, p;
      PetscInt    *offsets, *offsetsRoot;
      PetscSFNode *remote;

      PetscCall(PetscMalloc1(pEndF - pStartF, &offsets));
      PetscCall(PetscMalloc1(pEndC - pStartC, &offsetsRoot));
      for (p = pStartC; p < pEndC; p++) PetscCall(PetscSectionGetOffset(rootSection, p, &offsetsRoot[p - pStartC]));
      PetscCall(PetscSFBcastBegin(pointTransferSF, MPIU_INT, offsetsRoot, offsets, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(pointTransferSF, MPIU_INT, offsetsRoot, offsets, MPI_REPLACE));
      PetscCall(PetscSectionGetStorageSize(rootSection, &nroots));
      nleaves = 0;
      for (i = 0; i < numLeaves; i++) {
        PetscInt leaf = leaves ? leaves[i] : i;
        PetscInt dof;

        PetscCall(PetscSectionGetDof(leafSection, leaf, &dof));
        nleaves += dof;
      }
      PetscCall(PetscMalloc1(nleaves, &mine));
      PetscCall(PetscMalloc1(nleaves, &remote));
      nleaves = 0;
      for (i = 0; i < numLeaves; i++) {
        PetscInt leaf = leaves ? leaves[i] : i;
        PetscInt dof;
        PetscInt off, j;

        PetscCall(PetscSectionGetDof(leafSection, leaf, &dof));
        PetscCall(PetscSectionGetOffset(leafSection, leaf, &off));
        for (j = 0; j < dof; j++) {
          remote[nleaves].rank  = iremote[i].rank;
          remote[nleaves].index = offsets[leaf] + j;
          mine[nleaves++]       = off + j;
        }
      }
      PetscCall(PetscFree(offsetsRoot));
      PetscCall(PetscFree(offsets));
      PetscCall(PetscSFCreate(comm, sf));
      PetscCall(PetscSFSetGraph(*sf, nroots, nleaves, mine, PETSC_OWN_POINTER, remote, PETSC_OWN_POINTER));
    }
    PetscCall(PetscSectionDestroy(&leafSection));
    PetscCall(PetscSectionDestroy(&rootSection));
    PetscCall(PetscSFDestroy(&pointTransferSF));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestGetTransferSF(DM dmA, DM dmB, const PetscInt dofPerDim[], PetscSF *sfAtoB, PetscSF *sfBtoA) {
  DM          adaptA, adaptB;
  DMAdaptFlag purpose;

  PetscFunctionBegin;
  PetscCall(DMForestGetAdaptivityForest(dmA, &adaptA));
  PetscCall(DMForestGetAdaptivityForest(dmB, &adaptB));
  /* it is more efficient when the coarser mesh is the first argument: reorder if we know one is coarser than the other */
  if (adaptA && adaptA->data == dmB->data) { /* dmA was adapted from dmB */
    PetscCall(DMForestGetAdaptivityPurpose(dmA, &purpose));
    if (purpose == DM_ADAPT_REFINE) {
      PetscCall(DMPforestGetTransferSF(dmB, dmA, dofPerDim, sfBtoA, sfAtoB));
      PetscFunctionReturn(0);
    }
  } else if (adaptB && adaptB->data == dmA->data) { /* dmB was adapted from dmA */
    PetscCall(DMForestGetAdaptivityPurpose(dmB, &purpose));
    if (purpose == DM_ADAPT_COARSEN) {
      PetscCall(DMPforestGetTransferSF(dmB, dmA, dofPerDim, sfBtoA, sfAtoB));
      PetscFunctionReturn(0);
    }
  }
  if (sfAtoB) PetscCall(DMPforestGetTransferSF_Internal(dmA, dmB, dofPerDim, sfAtoB, PETSC_TRUE, NULL));
  if (sfBtoA) PetscCall(DMPforestGetTransferSF_Internal(dmB, dmA, dofPerDim, sfBtoA, (PetscBool)(sfAtoB == NULL), NULL));
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestLabelsInitialize(DM dm, DM plex) {
  DM_Forest         *forest  = (DM_Forest *)dm->data;
  DM_Forest_pforest *pforest = (DM_Forest_pforest *)forest->data;
  PetscInt           cLocalStart, cLocalEnd, cStart, cEnd, fStart, fEnd, eStart, eEnd, vStart, vEnd;
  PetscInt           cStartBase, cEndBase, fStartBase, fEndBase, vStartBase, vEndBase, eStartBase, eEndBase;
  PetscInt           pStart, pEnd, pStartBase, pEndBase, p;
  DM                 base;
  PetscInt          *star      = NULL, starSize;
  DMLabelLink        next      = dm->labels;
  PetscInt           guess     = 0;
  p4est_topidx_t     num_trees = pforest->topo->conn->num_trees;

  PetscFunctionBegin;
  pforest->labelsFinalized = PETSC_TRUE;
  cLocalStart              = pforest->cLocalStart;
  cLocalEnd                = pforest->cLocalEnd;
  PetscCall(DMForestGetBaseDM(dm, &base));
  if (!base) {
    if (pforest->ghostName) { /* insert a label to make the boundaries, with stratum values denoting which face of the element touches the boundary */
      p4est_connectivity_t *conn  = pforest->topo->conn;
      p4est_t              *p4est = pforest->forest;
      p4est_tree_t         *trees = (p4est_tree_t *)p4est->trees->array;
      p4est_topidx_t        t, flt = p4est->first_local_tree;
      p4est_topidx_t        llt = pforest->forest->last_local_tree;
      DMLabel               ghostLabel;
      PetscInt              c;

      PetscCall(DMCreateLabel(plex, pforest->ghostName));
      PetscCall(DMGetLabel(plex, pforest->ghostName, &ghostLabel));
      for (c = cLocalStart, t = flt; t <= llt; t++) {
        p4est_tree_t     *tree     = &trees[t];
        p4est_quadrant_t *quads    = (p4est_quadrant_t *)tree->quadrants.array;
        PetscInt          numQuads = (PetscInt)tree->quadrants.elem_count;
        PetscInt          q;

        for (q = 0; q < numQuads; q++, c++) {
          p4est_quadrant_t *quad = &quads[q];
          PetscInt          f;

          for (f = 0; f < P4EST_FACES; f++) {
            p4est_quadrant_t neigh;
            int              isOutside;

            PetscCallP4est(p4est_quadrant_face_neighbor, (quad, f, &neigh));
            PetscCallP4estReturn(isOutside, p4est_quadrant_is_outside_face, (&neigh));
            if (isOutside) {
              p4est_topidx_t nt;
              PetscInt       nf;

              nt = conn->tree_to_tree[t * P4EST_FACES + f];
              nf = (PetscInt)conn->tree_to_face[t * P4EST_FACES + f];
              nf = nf % P4EST_FACES;
              if (nt == t && nf == f) {
                PetscInt        plexF = P4estFaceToPetscFace[f];
                const PetscInt *cone;

                PetscCall(DMPlexGetCone(plex, c, &cone));
                PetscCall(DMLabelSetValue(ghostLabel, cone[plexF], plexF + 1));
              }
            }
          }
        }
      }
    }
    PetscFunctionReturn(0);
  }
  PetscCall(DMPlexGetSimplexOrBoxCells(base, 0, &cStartBase, &cEndBase));
  PetscCall(DMPlexGetSimplexOrBoxCells(base, 1, &fStartBase, &fEndBase));
  PetscCall(DMPlexGetSimplexOrBoxCells(base, P4EST_DIM - 1, &eStartBase, &eEndBase));
  PetscCall(DMPlexGetDepthStratum(base, 0, &vStartBase, &vEndBase));

  PetscCall(DMPlexGetSimplexOrBoxCells(plex, 0, &cStart, &cEnd));
  PetscCall(DMPlexGetSimplexOrBoxCells(plex, 1, &fStart, &fEnd));
  PetscCall(DMPlexGetSimplexOrBoxCells(plex, P4EST_DIM - 1, &eStart, &eEnd));
  PetscCall(DMPlexGetDepthStratum(plex, 0, &vStart, &vEnd));

  PetscCall(DMPlexGetChart(plex, &pStart, &pEnd));
  PetscCall(DMPlexGetChart(base, &pStartBase, &pEndBase));
  /* go through the mesh: use star to find a quadrant that borders a point.  Use the closure to determine the
   * orientation of the quadrant relative to that point.  Use that to relate the point to the numbering in the base
   * mesh, and extract a label value (since the base mesh is redundantly distributed, can be found locally). */
  while (next) {
    DMLabel     baseLabel;
    DMLabel     label = next->label;
    PetscBool   isDepth, isCellType, isGhost, isVTK, isSpmap;
    const char *name;

    PetscCall(PetscObjectGetName((PetscObject)label, &name));
    PetscCall(PetscStrcmp(name, "depth", &isDepth));
    if (isDepth) {
      next = next->next;
      continue;
    }
    PetscCall(PetscStrcmp(name, "celltype", &isCellType));
    if (isCellType) {
      next = next->next;
      continue;
    }
    PetscCall(PetscStrcmp(name, "ghost", &isGhost));
    if (isGhost) {
      next = next->next;
      continue;
    }
    PetscCall(PetscStrcmp(name, "vtk", &isVTK));
    if (isVTK) {
      next = next->next;
      continue;
    }
    PetscCall(PetscStrcmp(name, "_forest_base_subpoint_map", &isSpmap));
    if (!isSpmap) {
      PetscCall(DMGetLabel(base, name, &baseLabel));
      if (!baseLabel) {
        next = next->next;
        continue;
      }
      PetscCall(DMLabelCreateIndex(baseLabel, pStartBase, pEndBase));
    } else baseLabel = NULL;

    for (p = pStart; p < pEnd; p++) {
      PetscInt          s, c = -1, l;
      PetscInt         *closure = NULL, closureSize;
      p4est_quadrant_t *ghosts  = (p4est_quadrant_t *)pforest->ghost->ghosts.array;
      p4est_tree_t     *trees   = (p4est_tree_t *)pforest->forest->trees->array;
      p4est_quadrant_t *q;
      PetscInt          t, val;
      PetscBool         zerosupportpoint = PETSC_FALSE;

      PetscCall(DMPlexGetTransitiveClosure(plex, p, PETSC_FALSE, &starSize, &star));
      for (s = 0; s < starSize; s++) {
        PetscInt point = star[2 * s];

        if (cStart <= point && point < cEnd) {
          PetscCall(DMPlexGetTransitiveClosure(plex, point, PETSC_TRUE, &closureSize, &closure));
          for (l = 0; l < closureSize; l++) {
            PetscInt qParent = closure[2 * l], q, pp = p, pParent = p;
            do { /* check parents of q */
              q = qParent;
              if (q == p) {
                c = point;
                break;
              }
              PetscCall(DMPlexGetTreeParent(plex, q, &qParent, NULL));
            } while (qParent != q);
            if (c != -1) break;
            PetscCall(DMPlexGetTreeParent(plex, pp, &pParent, NULL));
            q = closure[2 * l];
            while (pParent != pp) { /* check parents of p */
              pp = pParent;
              if (pp == q) {
                c = point;
                break;
              }
              PetscCall(DMPlexGetTreeParent(plex, pp, &pParent, NULL));
            }
            if (c != -1) break;
          }
          PetscCall(DMPlexRestoreTransitiveClosure(plex, point, PETSC_TRUE, NULL, &closure));
          if (l < closureSize) break;
        } else {
          PetscInt supportSize;

          PetscCall(DMPlexGetSupportSize(plex, point, &supportSize));
          zerosupportpoint = (PetscBool)(zerosupportpoint || !supportSize);
        }
      }
      if (c < 0) {
        const char *prefix;
        PetscBool   print = PETSC_FALSE;

        PetscCall(PetscObjectGetOptionsPrefix((PetscObject)dm, &prefix));
        PetscCall(PetscOptionsGetBool(((PetscObject)dm)->options, prefix, "-dm_forest_print_label_error", &print, NULL));
        if (print) {
          PetscInt i;

          PetscCall(PetscPrintf(PETSC_COMM_SELF, "[%d] Failed to find cell with point %" PetscInt_FMT " in its closure for label %s (starSize %" PetscInt_FMT ")\n", PetscGlobalRank, p, baseLabel ? ((PetscObject)baseLabel)->name : "_forest_base_subpoint_map", starSize));
          for (i = 0; i < starSize; i++) PetscCall(PetscPrintf(PETSC_COMM_SELF, "  star[%" PetscInt_FMT "] = %" PetscInt_FMT ",%" PetscInt_FMT "\n", i, star[2 * i], star[2 * i + 1]));
        }
        PetscCall(DMPlexRestoreTransitiveClosure(plex, p, PETSC_FALSE, NULL, &star));
        if (zerosupportpoint) continue;
        else
          SETERRQ(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Failed to find cell with point %" PetscInt_FMT " in its closure for label %s. Rerun with -dm_forest_print_label_error for more information", p, baseLabel ? ((PetscObject)baseLabel)->name : "_forest_base_subpoint_map");
      }
      PetscCall(DMPlexRestoreTransitiveClosure(plex, p, PETSC_FALSE, NULL, &star));

      if (c < cLocalStart) {
        /* get from the beginning of the ghost layer */
        q = &(ghosts[c]);
        t = (PetscInt)q->p.which_tree;
      } else if (c < cLocalEnd) {
        PetscInt lo = 0, hi = num_trees;
        /* get from local quadrants: have to find the right tree */

        c -= cLocalStart;

        do {
          p4est_tree_t *tree;

          PetscCheck(guess >= lo && guess < num_trees && lo < hi, PETSC_COMM_SELF, PETSC_ERR_PLIB, "failed binary search");
          tree = &trees[guess];
          if (c < tree->quadrants_offset) {
            hi = guess;
          } else if (c < tree->quadrants_offset + (PetscInt)tree->quadrants.elem_count) {
            q = &((p4est_quadrant_t *)tree->quadrants.array)[c - (PetscInt)tree->quadrants_offset];
            t = guess;
            break;
          } else {
            lo = guess + 1;
          }
          guess = lo + (hi - lo) / 2;
        } while (1);
      } else {
        /* get from the end of the ghost layer */
        c -= (cLocalEnd - cLocalStart);

        q = &(ghosts[c]);
        t = (PetscInt)q->p.which_tree;
      }

      if (l == 0) { /* cell */
        if (baseLabel) {
          PetscCall(DMLabelGetValue(baseLabel, t + cStartBase, &val));
        } else {
          val = t + cStartBase;
        }
        PetscCall(DMLabelSetValue(label, p, val));
      } else if (l >= 1 && l < 1 + P4EST_FACES) { /* facet */
        p4est_quadrant_t nq;
        int              isInside;

        l = PetscFaceToP4estFace[l - 1];
        PetscCallP4est(p4est_quadrant_face_neighbor, (q, l, &nq));
        PetscCallP4estReturn(isInside, p4est_quadrant_is_inside_root, (&nq));
        if (isInside) {
          /* this facet is in the interior of a tree, so it inherits the label of the tree */
          if (baseLabel) {
            PetscCall(DMLabelGetValue(baseLabel, t + cStartBase, &val));
          } else {
            val = t + cStartBase;
          }
          PetscCall(DMLabelSetValue(label, p, val));
        } else {
          PetscInt f = pforest->topo->tree_face_to_uniq[P4EST_FACES * t + l];

          if (baseLabel) {
            PetscCall(DMLabelGetValue(baseLabel, f + fStartBase, &val));
          } else {
            val = f + fStartBase;
          }
          PetscCall(DMLabelSetValue(label, p, val));
        }
#if defined(P4_TO_P8)
      } else if (l >= 1 + P4EST_FACES && l < 1 + P4EST_FACES + P8EST_EDGES) { /* edge */
        p4est_quadrant_t nq;
        int              isInside;

        l = PetscEdgeToP4estEdge[l - (1 + P4EST_FACES)];
        PetscCallP4est(p8est_quadrant_edge_neighbor, (q, l, &nq));
        PetscCallP4estReturn(isInside, p4est_quadrant_is_inside_root, (&nq));
        if (isInside) {
          /* this edge is in the interior of a tree, so it inherits the label of the tree */
          if (baseLabel) {
            PetscCall(DMLabelGetValue(baseLabel, t + cStartBase, &val));
          } else {
            val = t + cStartBase;
          }
          PetscCall(DMLabelSetValue(label, p, val));
        } else {
          int isOutsideFace;

          PetscCallP4estReturn(isOutsideFace, p4est_quadrant_is_outside_face, (&nq));
          if (isOutsideFace) {
            PetscInt f;

            if (nq.x < 0) {
              f = 0;
            } else if (nq.x >= P4EST_ROOT_LEN) {
              f = 1;
            } else if (nq.y < 0) {
              f = 2;
            } else if (nq.y >= P4EST_ROOT_LEN) {
              f = 3;
            } else if (nq.z < 0) {
              f = 4;
            } else {
              f = 5;
            }
            f = pforest->topo->tree_face_to_uniq[P4EST_FACES * t + f];
            if (baseLabel) {
              PetscCall(DMLabelGetValue(baseLabel, f + fStartBase, &val));
            } else {
              val = f + fStartBase;
            }
            PetscCall(DMLabelSetValue(label, p, val));
          } else { /* the quadrant edge corresponds to the tree edge */
            PetscInt e = pforest->topo->conn->tree_to_edge[P8EST_EDGES * t + l];

            if (baseLabel) {
              PetscCall(DMLabelGetValue(baseLabel, e + eStartBase, &val));
            } else {
              val = e + eStartBase;
            }
            PetscCall(DMLabelSetValue(label, p, val));
          }
        }
#endif
      } else { /* vertex */
        p4est_quadrant_t nq;
        int              isInside;

#if defined(P4_TO_P8)
        l = PetscVertToP4estVert[l - (1 + P4EST_FACES + P8EST_EDGES)];
#else
        l = PetscVertToP4estVert[l - (1 + P4EST_FACES)];
#endif
        PetscCallP4est(p4est_quadrant_corner_neighbor, (q, l, &nq));
        PetscCallP4estReturn(isInside, p4est_quadrant_is_inside_root, (&nq));
        if (isInside) {
          if (baseLabel) {
            PetscCall(DMLabelGetValue(baseLabel, t + cStartBase, &val));
          } else {
            val = t + cStartBase;
          }
          PetscCall(DMLabelSetValue(label, p, val));
        } else {
          int isOutside;

          PetscCallP4estReturn(isOutside, p4est_quadrant_is_outside_face, (&nq));
          if (isOutside) {
            PetscInt f = -1;

            if (nq.x < 0) {
              f = 0;
            } else if (nq.x >= P4EST_ROOT_LEN) {
              f = 1;
            } else if (nq.y < 0) {
              f = 2;
            } else if (nq.y >= P4EST_ROOT_LEN) {
              f = 3;
#if defined(P4_TO_P8)
            } else if (nq.z < 0) {
              f = 4;
            } else {
              f = 5;
#endif
            }
            f = pforest->topo->tree_face_to_uniq[P4EST_FACES * t + f];
            if (baseLabel) {
              PetscCall(DMLabelGetValue(baseLabel, f + fStartBase, &val));
            } else {
              val = f + fStartBase;
            }
            PetscCall(DMLabelSetValue(label, p, val));
            continue;
          }
#if defined(P4_TO_P8)
          PetscCallP4estReturn(isOutside, p8est_quadrant_is_outside_edge, (&nq));
          if (isOutside) {
            /* outside edge */
            PetscInt e = -1;

            if (nq.x >= 0 && nq.x < P4EST_ROOT_LEN) {
              if (nq.z < 0) {
                if (nq.y < 0) {
                  e = 0;
                } else {
                  e = 1;
                }
              } else {
                if (nq.y < 0) {
                  e = 2;
                } else {
                  e = 3;
                }
              }
            } else if (nq.y >= 0 && nq.y < P4EST_ROOT_LEN) {
              if (nq.z < 0) {
                if (nq.x < 0) {
                  e = 4;
                } else {
                  e = 5;
                }
              } else {
                if (nq.x < 0) {
                  e = 6;
                } else {
                  e = 7;
                }
              }
            } else {
              if (nq.y < 0) {
                if (nq.x < 0) {
                  e = 8;
                } else {
                  e = 9;
                }
              } else {
                if (nq.x < 0) {
                  e = 10;
                } else {
                  e = 11;
                }
              }
            }

            e = pforest->topo->conn->tree_to_edge[P8EST_EDGES * t + e];
            if (baseLabel) {
              PetscCall(DMLabelGetValue(baseLabel, e + eStartBase, &val));
            } else {
              val = e + eStartBase;
            }
            PetscCall(DMLabelSetValue(label, p, val));
            continue;
          }
#endif
          {
            /* outside vertex: same corner as quadrant corner */
            PetscInt v = pforest->topo->conn->tree_to_corner[P4EST_CHILDREN * t + l];

            if (baseLabel) {
              PetscCall(DMLabelGetValue(baseLabel, v + vStartBase, &val));
            } else {
              val = v + vStartBase;
            }
            PetscCall(DMLabelSetValue(label, p, val));
          }
        }
      }
    }
    next = next->next;
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestLabelsFinalize(DM dm, DM plex) {
  DM_Forest_pforest *pforest = (DM_Forest_pforest *)((DM_Forest *)dm->data)->data;
  DM                 adapt;

  PetscFunctionBegin;
  if (pforest->labelsFinalized) PetscFunctionReturn(0);
  pforest->labelsFinalized = PETSC_TRUE;
  PetscCall(DMForestGetAdaptivityForest(dm, &adapt));
  if (!adapt) {
    /* Initialize labels from the base dm */
    PetscCall(DMPforestLabelsInitialize(dm, plex));
  } else {
    PetscInt    dofPerDim[4] = {1, 1, 1, 1};
    PetscSF     transferForward, transferBackward, pointSF;
    PetscInt    pStart, pEnd, pStartA, pEndA;
    PetscInt   *values, *adaptValues;
    DMLabelLink next = adapt->labels;
    DMLabel     adaptLabel;
    DM          adaptPlex;

    PetscCall(DMForestGetAdaptivityLabel(dm, &adaptLabel));
    PetscCall(DMPforestGetPlex(adapt, &adaptPlex));
    PetscCall(DMPforestGetTransferSF(adapt, dm, dofPerDim, &transferForward, &transferBackward));
    PetscCall(DMPlexGetChart(plex, &pStart, &pEnd));
    PetscCall(DMPlexGetChart(adaptPlex, &pStartA, &pEndA));
    PetscCall(PetscMalloc2(pEnd - pStart, &values, pEndA - pStartA, &adaptValues));
    PetscCall(DMGetPointSF(plex, &pointSF));
    if (PetscDefined(USE_DEBUG)) {
      PetscInt p;
      for (p = pStartA; p < pEndA; p++) adaptValues[p - pStartA] = -1;
      for (p = pStart; p < pEnd; p++) values[p - pStart] = -2;
      if (transferForward) {
        PetscCall(PetscSFBcastBegin(transferForward, MPIU_INT, adaptValues, values, MPI_REPLACE));
        PetscCall(PetscSFBcastEnd(transferForward, MPIU_INT, adaptValues, values, MPI_REPLACE));
      }
      if (transferBackward) {
        PetscCall(PetscSFReduceBegin(transferBackward, MPIU_INT, adaptValues, values, MPI_MAX));
        PetscCall(PetscSFReduceEnd(transferBackward, MPIU_INT, adaptValues, values, MPI_MAX));
      }
      for (p = pStart; p < pEnd; p++) {
        PetscInt q = p, parent;

        PetscCall(DMPlexGetTreeParent(plex, q, &parent, NULL));
        while (parent != q) {
          if (values[parent] == -2) values[parent] = values[q];
          q = parent;
          PetscCall(DMPlexGetTreeParent(plex, q, &parent, NULL));
        }
      }
      PetscCall(PetscSFReduceBegin(pointSF, MPIU_INT, values, values, MPI_MAX));
      PetscCall(PetscSFReduceEnd(pointSF, MPIU_INT, values, values, MPI_MAX));
      PetscCall(PetscSFBcastBegin(pointSF, MPIU_INT, values, values, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(pointSF, MPIU_INT, values, values, MPI_REPLACE));
      for (p = pStart; p < pEnd; p++) PetscCheck(values[p - pStart] != -2, PETSC_COMM_SELF, PETSC_ERR_PLIB, "uncovered point %" PetscInt_FMT, p);
    }
    while (next) {
      DMLabel     nextLabel = next->label;
      const char *name;
      PetscBool   isDepth, isCellType, isGhost, isVTK;
      DMLabel     label;
      PetscInt    p;

      PetscCall(PetscObjectGetName((PetscObject)nextLabel, &name));
      PetscCall(PetscStrcmp(name, "depth", &isDepth));
      if (isDepth) {
        next = next->next;
        continue;
      }
      PetscCall(PetscStrcmp(name, "celltype", &isCellType));
      if (isCellType) {
        next = next->next;
        continue;
      }
      PetscCall(PetscStrcmp(name, "ghost", &isGhost));
      if (isGhost) {
        next = next->next;
        continue;
      }
      PetscCall(PetscStrcmp(name, "vtk", &isVTK));
      if (isVTK) {
        next = next->next;
        continue;
      }
      if (nextLabel == adaptLabel) {
        next = next->next;
        continue;
      }
      /* label was created earlier */
      PetscCall(DMGetLabel(dm, name, &label));
      for (p = pStartA; p < pEndA; p++) PetscCall(DMLabelGetValue(nextLabel, p, &adaptValues[p]));
      for (p = pStart; p < pEnd; p++) values[p] = PETSC_MIN_INT;

      if (transferForward) PetscCall(PetscSFBcastBegin(transferForward, MPIU_INT, adaptValues, values, MPI_REPLACE));
      if (transferBackward) PetscCall(PetscSFReduceBegin(transferBackward, MPIU_INT, adaptValues, values, MPI_MAX));
      if (transferForward) PetscCall(PetscSFBcastEnd(transferForward, MPIU_INT, adaptValues, values, MPI_REPLACE));
      if (transferBackward) PetscCall(PetscSFReduceEnd(transferBackward, MPIU_INT, adaptValues, values, MPI_MAX));
      for (p = pStart; p < pEnd; p++) {
        PetscInt q = p, parent;

        PetscCall(DMPlexGetTreeParent(plex, q, &parent, NULL));
        while (parent != q) {
          if (values[parent] == PETSC_MIN_INT) values[parent] = values[q];
          q = parent;
          PetscCall(DMPlexGetTreeParent(plex, q, &parent, NULL));
        }
      }
      PetscCall(PetscSFReduceBegin(pointSF, MPIU_INT, values, values, MPI_MAX));
      PetscCall(PetscSFReduceEnd(pointSF, MPIU_INT, values, values, MPI_MAX));
      PetscCall(PetscSFBcastBegin(pointSF, MPIU_INT, values, values, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(pointSF, MPIU_INT, values, values, MPI_REPLACE));

      for (p = pStart; p < pEnd; p++) PetscCall(DMLabelSetValue(label, p, values[p]));
      next = next->next;
    }
    PetscCall(PetscFree2(values, adaptValues));
    PetscCall(PetscSFDestroy(&transferForward));
    PetscCall(PetscSFDestroy(&transferBackward));
    pforest->labelsFinalized = PETSC_TRUE;
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestMapCoordinates_Cell(DM plex, p4est_geometry_t *geom, PetscInt cell, p4est_quadrant_t *q, p4est_topidx_t t, p4est_connectivity_t *conn, PetscScalar *coords) {
  PetscInt     closureSize, c, coordStart, coordEnd, coordDim;
  PetscInt    *closure = NULL;
  PetscSection coordSec;

  PetscFunctionBegin;
  PetscCall(DMGetCoordinateSection(plex, &coordSec));
  PetscCall(PetscSectionGetChart(coordSec, &coordStart, &coordEnd));
  PetscCall(DMGetCoordinateDim(plex, &coordDim));
  PetscCall(DMPlexGetTransitiveClosure(plex, cell, PETSC_TRUE, &closureSize, &closure));
  for (c = 0; c < closureSize; c++) {
    PetscInt point = closure[2 * c];

    if (point >= coordStart && point < coordEnd) {
      PetscInt dof, off;
      PetscInt nCoords, i;
      PetscCall(PetscSectionGetDof(coordSec, point, &dof));
      PetscCheck(dof % coordDim == 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Did not understand coordinate layout");
      nCoords = dof / coordDim;
      PetscCall(PetscSectionGetOffset(coordSec, point, &off));
      for (i = 0; i < nCoords; i++) {
        PetscScalar *coord               = &coords[off + i * coordDim];
        double       coordP4est[3]       = {0.};
        double       coordP4estMapped[3] = {0.};
        PetscInt     j;
        PetscReal    treeCoords[P4EST_CHILDREN][3] = {{0.}};
        PetscReal    eta[3]                        = {0.};
        PetscInt     numRounds                     = 10;
        PetscReal    coordGuess[3]                 = {0.};

        eta[0] = (PetscReal)q->x / (PetscReal)P4EST_ROOT_LEN;
        eta[1] = (PetscReal)q->y / (PetscReal)P4EST_ROOT_LEN;
#if defined(P4_TO_P8)
        eta[2] = (PetscReal)q->z / (PetscReal)P4EST_ROOT_LEN;
#endif

        for (j = 0; j < P4EST_CHILDREN; j++) {
          PetscInt k;

          for (k = 0; k < 3; k++) treeCoords[j][k] = conn->vertices[3 * conn->tree_to_vertex[P4EST_CHILDREN * t + j] + k];
        }

        for (j = 0; j < P4EST_CHILDREN; j++) {
          PetscInt  k;
          PetscReal prod = 1.;

          for (k = 0; k < P4EST_DIM; k++) prod *= (j & (1 << k)) ? eta[k] : (1. - eta[k]);
          for (k = 0; k < 3; k++) coordGuess[k] += prod * treeCoords[j][k];
        }

        for (j = 0; j < numRounds; j++) {
          PetscInt dir;

          for (dir = 0; dir < P4EST_DIM; dir++) {
            PetscInt  k;
            PetscReal diff[3];
            PetscReal dXdeta[3] = {0.};
            PetscReal rhs, scale, update;

            for (k = 0; k < 3; k++) diff[k] = coordP4est[k] - coordGuess[k];
            for (k = 0; k < P4EST_CHILDREN; k++) {
              PetscInt  l;
              PetscReal prod = 1.;

              for (l = 0; l < P4EST_DIM; l++) {
                if (l == dir) {
                  prod *= (k & (1 << l)) ? 1. : -1.;
                } else {
                  prod *= (k & (1 << l)) ? eta[l] : (1. - eta[l]);
                }
              }
              for (l = 0; l < 3; l++) dXdeta[l] += prod * treeCoords[k][l];
            }
            rhs   = 0.;
            scale = 0;
            for (k = 0; k < 3; k++) {
              rhs += diff[k] * dXdeta[k];
              scale += dXdeta[k] * dXdeta[k];
            }
            update = rhs / scale;
            eta[dir] += update;
            eta[dir] = PetscMin(eta[dir], 1.);
            eta[dir] = PetscMax(eta[dir], 0.);

            coordGuess[0] = coordGuess[1] = coordGuess[2] = 0.;
            for (k = 0; k < P4EST_CHILDREN; k++) {
              PetscInt  l;
              PetscReal prod = 1.;

              for (l = 0; l < P4EST_DIM; l++) prod *= (k & (1 << l)) ? eta[l] : (1. - eta[l]);
              for (l = 0; l < 3; l++) coordGuess[l] += prod * treeCoords[k][l];
            }
          }
        }
        for (j = 0; j < 3; j++) coordP4est[j] = (double)eta[j];

        if (geom) {
          (geom->X)(geom, t, coordP4est, coordP4estMapped);
          for (j = 0; j < coordDim; j++) coord[j] = (PetscScalar)coordP4estMapped[j];
        } else SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP, "Not coded");
      }
    }
  }
  PetscCall(DMPlexRestoreTransitiveClosure(plex, cell, PETSC_TRUE, &closureSize, &closure));
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestMapCoordinates(DM dm, DM plex) {
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;
  p4est_geometry_t  *geom;
  PetscInt           cLocalStart, cLocalEnd;
  Vec                coordLocalVec;
  PetscScalar       *coords;
  p4est_topidx_t     flt, llt, t;
  p4est_tree_t      *trees;
  PetscErrorCode (*map)(DM, PetscInt, PetscInt, const PetscReal[], PetscReal[], void *);
  void *mapCtx;

  PetscFunctionBegin;
  forest  = (DM_Forest *)dm->data;
  pforest = (DM_Forest_pforest *)forest->data;
  geom    = pforest->topo->geom;
  PetscCall(DMForestGetBaseCoordinateMapping(dm, &map, &mapCtx));
  if (!geom && !map) PetscFunctionReturn(0);
  PetscCall(DMGetCoordinatesLocal(plex, &coordLocalVec));
  PetscCall(VecGetArray(coordLocalVec, &coords));
  cLocalStart = pforest->cLocalStart;
  cLocalEnd   = pforest->cLocalEnd;
  flt         = pforest->forest->first_local_tree;
  llt         = pforest->forest->last_local_tree;
  trees       = (p4est_tree_t *)pforest->forest->trees->array;
  if (map) { /* apply the map directly to the existing coordinates */
    PetscSection coordSec;
    PetscInt     coordStart, coordEnd, p, coordDim, p4estCoordDim, cStart, cEnd, cEndInterior;
    DM           base;

    PetscCall(DMPlexGetHeightStratum(plex, 0, &cStart, &cEnd));
    PetscCall(DMPlexGetGhostCellStratum(plex, &cEndInterior, NULL));
    cEnd = cEndInterior < 0 ? cEnd : cEndInterior;
    PetscCall(DMForestGetBaseDM(dm, &base));
    PetscCall(DMGetCoordinateSection(plex, &coordSec));
    PetscCall(PetscSectionGetChart(coordSec, &coordStart, &coordEnd));
    PetscCall(DMGetCoordinateDim(plex, &coordDim));
    p4estCoordDim = PetscMin(coordDim, 3);
    for (p = coordStart; p < coordEnd; p++) {
      PetscInt *star = NULL, starSize;
      PetscInt  dof, off, cell = -1, coarsePoint = -1;
      PetscInt  nCoords, i;
      PetscCall(PetscSectionGetDof(coordSec, p, &dof));
      PetscCheck(dof % coordDim == 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Did not understand coordinate layout");
      nCoords = dof / coordDim;
      PetscCall(PetscSectionGetOffset(coordSec, p, &off));
      PetscCall(DMPlexGetTransitiveClosure(plex, p, PETSC_FALSE, &starSize, &star));
      for (i = 0; i < starSize; i++) {
        PetscInt point = star[2 * i];

        if (cStart <= point && point < cEnd) {
          cell = point;
          break;
        }
      }
      PetscCall(DMPlexRestoreTransitiveClosure(plex, p, PETSC_FALSE, &starSize, &star));
      if (cell >= 0) {
        if (cell < cLocalStart) {
          p4est_quadrant_t *ghosts = (p4est_quadrant_t *)pforest->ghost->ghosts.array;

          coarsePoint = ghosts[cell].p.which_tree;
        } else if (cell < cLocalEnd) {
          cell -= cLocalStart;
          for (t = flt; t <= llt; t++) {
            p4est_tree_t *tree = &(trees[t]);

            if (cell >= tree->quadrants_offset && (size_t)cell < tree->quadrants_offset + tree->quadrants.elem_count) {
              coarsePoint = t;
              break;
            }
          }
        } else {
          p4est_quadrant_t *ghosts = (p4est_quadrant_t *)pforest->ghost->ghosts.array;

          coarsePoint = ghosts[cell - cLocalEnd].p.which_tree;
        }
      }
      for (i = 0; i < nCoords; i++) {
        PetscScalar *coord               = &coords[off + i * coordDim];
        PetscReal    coordP4est[3]       = {0.};
        PetscReal    coordP4estMapped[3] = {0.};
        PetscInt     j;

        for (j = 0; j < p4estCoordDim; j++) coordP4est[j] = PetscRealPart(coord[j]);
        PetscCall((map)(base, coarsePoint, p4estCoordDim, coordP4est, coordP4estMapped, mapCtx));
        for (j = 0; j < p4estCoordDim; j++) coord[j] = (PetscScalar)coordP4estMapped[j];
      }
    }
  } else { /* we have to transform coordinates back to the unit cube (where geom is defined), and then apply geom */
    PetscInt cStart, cEnd, cEndInterior;

    PetscCall(DMPlexGetHeightStratum(plex, 0, &cStart, &cEnd));
    PetscCall(DMPlexGetGhostCellStratum(plex, &cEndInterior, NULL));
    cEnd = cEndInterior < 0 ? cEnd : cEndInterior;
    if (cLocalStart > 0) {
      p4est_quadrant_t *ghosts = (p4est_quadrant_t *)pforest->ghost->ghosts.array;
      PetscInt          count;

      for (count = 0; count < cLocalStart; count++) {
        p4est_quadrant_t *quad = &ghosts[count];
        p4est_topidx_t    t    = quad->p.which_tree;

        PetscCall(DMPforestMapCoordinates_Cell(plex, geom, count, quad, t, pforest->topo->conn, coords));
      }
    }
    for (t = flt; t <= llt; t++) {
      p4est_tree_t     *tree     = &(trees[t]);
      PetscInt          offset   = cLocalStart + tree->quadrants_offset, i;
      PetscInt          numQuads = (PetscInt)tree->quadrants.elem_count;
      p4est_quadrant_t *quads    = (p4est_quadrant_t *)tree->quadrants.array;

      for (i = 0; i < numQuads; i++) {
        PetscInt count = i + offset;

        PetscCall(DMPforestMapCoordinates_Cell(plex, geom, count, &quads[i], t, pforest->topo->conn, coords));
      }
    }
    if (cLocalEnd - cLocalStart < cEnd - cStart) {
      p4est_quadrant_t *ghosts    = (p4est_quadrant_t *)pforest->ghost->ghosts.array;
      PetscInt          numGhosts = (PetscInt)pforest->ghost->ghosts.elem_count;
      PetscInt          count;

      for (count = 0; count < numGhosts - cLocalStart; count++) {
        p4est_quadrant_t *quad = &ghosts[count + cLocalStart];
        p4est_topidx_t    t    = quad->p.which_tree;

        PetscCall(DMPforestMapCoordinates_Cell(plex, geom, count + cLocalEnd, quad, t, pforest->topo->conn, coords));
      }
    }
  }
  PetscCall(VecRestoreArray(coordLocalVec, &coords));
  PetscFunctionReturn(0);
}

static PetscErrorCode PforestQuadrantIsInterior(p4est_quadrant_t *quad, PetscBool *is_interior) {
  PetscFunctionBegin;
  p4est_qcoord_t h = P4EST_QUADRANT_LEN(quad->level);
  if ((quad->x > 0) && (quad->x + h < P4EST_ROOT_LEN)
#ifdef P4_TO_P8
      && (quad->z > 0) && (quad->z + h < P4EST_ROOT_LEN)
#endif
      && (quad->y > 0) && (quad->y + h < P4EST_ROOT_LEN)) {
    *is_interior = PETSC_TRUE;
  } else {
    *is_interior = PETSC_FALSE;
  }
  PetscFunctionReturn(0);
}

/* We always use DG coordinates with p4est: if they do not match the vertex
   coordinates, add space for them in the section */
static PetscErrorCode PforestCheckLocalizeCell(DM plex, PetscInt cDim, Vec cVecOld, DM_Forest_pforest *pforest, PetscSection oldSection, PetscSection newSection, PetscInt cell, PetscInt coarsePoint, p4est_quadrant_t *quad) {
  PetscBool is_interior;

  PetscFunctionBegin;
  PetscCall(PforestQuadrantIsInterior(quad, &is_interior));
  if (is_interior) { // quads in the interior of a coarse cell can't touch periodic interfaces
    PetscCall(PetscSectionSetDof(newSection, cell, 0));
    PetscCall(PetscSectionSetFieldDof(newSection, cell, 0, 0));
  } else {
    PetscInt     cSize;
    PetscScalar *values      = NULL;
    PetscBool    same_coords = PETSC_TRUE;

    PetscCall(DMPlexVecGetClosure(plex, oldSection, cVecOld, cell, &cSize, &values));
    PetscAssert(cSize == cDim * P4EST_CHILDREN, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Unexpected closure size");
    for (int c = 0; c < P4EST_CHILDREN; c++) {
      p4est_qcoord_t quad_coords[3];
      p4est_qcoord_t h = P4EST_QUADRANT_LEN(quad->level);
      double         corner_coords[3];
      double         vert_coords[3];
      PetscInt       corner = PetscVertToP4estVert[c];

      for (PetscInt d = 0; d < PetscMin(cDim, 3); d++) vert_coords[d] = PetscRealPart(values[c * cDim + d]);

      quad_coords[0] = quad->x;
      quad_coords[1] = quad->y;
#ifdef P4_TO_P8
      quad_coords[2] = quad->z;
#endif
      for (int d = 0; d < 3; d++) quad_coords[d] += (corner & (1 << d)) ? h : 0;
#ifndef P4_TO_P8
      PetscCallP4est(p4est_qcoord_to_vertex, (pforest->forest->connectivity, coarsePoint, quad_coords[0], quad_coords[1], corner_coords));
#else
      PetscCallP4est(p4est_qcoord_to_vertex, (pforest->forest->connectivity, coarsePoint, quad_coords[0], quad_coords[1], quad_coords[2], corner_coords));
#endif
      for (PetscInt d = 0; d < PetscMin(cDim, 3); d++) {
        if (fabs(vert_coords[d] - corner_coords[d]) > PETSC_SMALL) {
          same_coords = PETSC_FALSE;
          break;
        }
      }
    }
    if (same_coords) {
      PetscCall(PetscSectionSetDof(newSection, cell, 0));
      PetscCall(PetscSectionSetFieldDof(newSection, cell, 0, 0));
    } else {
      PetscCall(PetscSectionSetDof(newSection, cell, cSize));
      PetscCall(PetscSectionSetFieldDof(newSection, cell, 0, cSize));
    }
    PetscCall(DMPlexVecRestoreClosure(plex, oldSection, cVecOld, cell, &cSize, &values));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode PforestLocalizeCell(DM plex, PetscInt cDim, DM_Forest_pforest *pforest, PetscSection newSection, PetscInt cell, PetscInt coarsePoint, p4est_quadrant_t *quad, PetscScalar coords[]) {
  PetscInt cdof, off;

  PetscFunctionBegin;
  PetscCall(PetscSectionGetDof(newSection, cell, &cdof));
  if (!cdof) PetscFunctionReturn(0);

  PetscCall(PetscSectionGetOffset(newSection, cell, &off));
  for (PetscInt c = 0, pos = off; c < P4EST_CHILDREN; c++) {
    p4est_qcoord_t quad_coords[3];
    p4est_qcoord_t h = P4EST_QUADRANT_LEN(quad->level);
    double         corner_coords[3];
    PetscInt       corner = PetscVertToP4estVert[c];

    quad_coords[0] = quad->x;
    quad_coords[1] = quad->y;
#ifdef P4_TO_P8
    quad_coords[2] = quad->z;
#endif
    for (int d = 0; d < 3; d++) quad_coords[d] += (corner & (1 << d)) ? h : 0;
#ifndef P4_TO_P8
    PetscCallP4est(p4est_qcoord_to_vertex, (pforest->forest->connectivity, coarsePoint, quad_coords[0], quad_coords[1], corner_coords));
#else
    PetscCallP4est(p4est_qcoord_to_vertex, (pforest->forest->connectivity, coarsePoint, quad_coords[0], quad_coords[1], quad_coords[2], corner_coords));
#endif
    for (PetscInt d = 0; d < PetscMin(cDim, 3); d++) coords[pos++] = corner_coords[d];
    for (PetscInt d = PetscMin(cDim, 3); d < cDim; d++) coords[pos++] = 0.;
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestLocalizeCoordinates(DM dm, DM plex) {
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;
  DM                 base, cdm, cdmCell;
  Vec                cVec, cVecOld;
  PetscSection       oldSection, newSection;
  PetscScalar       *coords2;
  const PetscReal   *L;
  PetscInt           cLocalStart, cLocalEnd, coarsePoint;
  PetscInt           cDim, newStart, newEnd;
  PetscInt           v, vStart, vEnd, cp, cStart, cEnd, cEndInterior;
  p4est_topidx_t     flt, llt, t;
  p4est_tree_t      *trees;
  PetscBool          baseLocalized = PETSC_FALSE;

  PetscFunctionBegin;
  PetscCall(DMGetPeriodicity(dm, NULL, NULL, &L));
  /* we localize on all cells if we don't have a base DM or the base DM coordinates have not been localized */
  PetscCall(DMGetCoordinateDim(dm, &cDim));
  PetscCall(DMForestGetBaseDM(dm, &base));
  if (base) PetscCall(DMGetCoordinatesLocalized(base, &baseLocalized));
  if (!baseLocalized) base = NULL;
  if (!baseLocalized && !L) PetscFunctionReturn(0);
  PetscCall(DMPlexGetChart(plex, &newStart, &newEnd));

  PetscCall(PetscSectionCreate(PetscObjectComm((PetscObject)dm), &newSection));
  PetscCall(PetscSectionSetNumFields(newSection, 1));
  PetscCall(PetscSectionSetFieldComponents(newSection, 0, cDim));
  PetscCall(PetscSectionSetChart(newSection, newStart, newEnd));

  PetscCall(DMGetCoordinateSection(plex, &oldSection));
  PetscCall(DMPlexGetDepthStratum(plex, 0, &vStart, &vEnd));
  PetscCall(DMGetCoordinatesLocal(plex, &cVecOld));

  forest      = (DM_Forest *)dm->data;
  pforest     = (DM_Forest_pforest *)forest->data;
  cLocalStart = pforest->cLocalStart;
  cLocalEnd   = pforest->cLocalEnd;
  flt         = pforest->forest->first_local_tree;
  llt         = pforest->forest->last_local_tree;
  trees       = (p4est_tree_t *)pforest->forest->trees->array;

  PetscCall(DMPlexGetHeightStratum(plex, 0, &cStart, &cEnd));
  PetscCall(DMPlexGetGhostCellStratum(plex, &cEndInterior, NULL));
  cEnd = cEndInterior < 0 ? cEnd : cEndInterior;
  cp   = 0;
  if (cLocalStart > 0) {
    p4est_quadrant_t *ghosts = (p4est_quadrant_t *)pforest->ghost->ghosts.array;
    PetscInt          cell;

    for (cell = 0; cell < cLocalStart; ++cell, cp++) {
      p4est_quadrant_t *quad = &ghosts[cell];

      coarsePoint = quad->p.which_tree;
      PetscCall(PforestCheckLocalizeCell(plex, cDim, cVecOld, pforest, oldSection, newSection, cell, coarsePoint, quad));
    }
  }
  for (t = flt; t <= llt; t++) {
    p4est_tree_t     *tree     = &(trees[t]);
    PetscInt          offset   = cLocalStart + tree->quadrants_offset;
    PetscInt          numQuads = (PetscInt)tree->quadrants.elem_count;
    p4est_quadrant_t *quads    = (p4est_quadrant_t *)tree->quadrants.array;
    PetscInt          i;

    if (!numQuads) continue;
    coarsePoint = t;
    for (i = 0; i < numQuads; i++, cp++) {
      PetscInt          cell = i + offset;
      p4est_quadrant_t *quad = &quads[i];

      PetscCall(PforestCheckLocalizeCell(plex, cDim, cVecOld, pforest, oldSection, newSection, cell, coarsePoint, quad));
    }
  }
  if (cLocalEnd - cLocalStart < cEnd - cStart) {
    p4est_quadrant_t *ghosts    = (p4est_quadrant_t *)pforest->ghost->ghosts.array;
    PetscInt          numGhosts = (PetscInt)pforest->ghost->ghosts.elem_count;
    PetscInt          count;

    for (count = 0; count < numGhosts - cLocalStart; count++, cp++) {
      p4est_quadrant_t *quad = &ghosts[count + cLocalStart];
      coarsePoint            = quad->p.which_tree;
      PetscInt cell          = count + cLocalEnd;

      PetscCall(PforestCheckLocalizeCell(plex, cDim, cVecOld, pforest, oldSection, newSection, cell, coarsePoint, quad));
    }
  }
  PetscAssert(cp == cEnd - cStart, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Unexpected number of fine cells %" PetscInt_FMT " != %" PetscInt_FMT, cp, cEnd - cStart);

  PetscCall(PetscSectionSetUp(newSection));
  PetscCall(DMGetCoordinateDM(plex, &cdm));
  PetscCall(DMClone(cdm, &cdmCell));
  PetscCall(DMSetCellCoordinateDM(plex, cdmCell));
  PetscCall(DMDestroy(&cdmCell));
  PetscCall(DMSetCellCoordinateSection(plex, cDim, newSection));
  PetscCall(PetscSectionGetStorageSize(newSection, &v));
  PetscCall(VecCreate(PETSC_COMM_SELF, &cVec));
  PetscCall(PetscObjectSetName((PetscObject)cVec, "coordinates"));
  PetscCall(VecSetBlockSize(cVec, cDim));
  PetscCall(VecSetSizes(cVec, v, PETSC_DETERMINE));
  PetscCall(VecSetType(cVec, VECSTANDARD));
  PetscCall(VecSet(cVec, PETSC_MIN_REAL));

  /* Localize coordinates on cells if needed */
  PetscCall(VecGetArray(cVec, &coords2));
  cp = 0;
  if (cLocalStart > 0) {
    p4est_quadrant_t *ghosts = (p4est_quadrant_t *)pforest->ghost->ghosts.array;
    PetscInt          cell;

    for (cell = 0; cell < cLocalStart; ++cell, cp++) {
      p4est_quadrant_t *quad = &ghosts[cell];

      coarsePoint = quad->p.which_tree;
      PetscCall(PforestLocalizeCell(plex, cDim, pforest, newSection, cell, coarsePoint, quad, coords2));
    }
  }
  for (t = flt; t <= llt; t++) {
    p4est_tree_t     *tree     = &(trees[t]);
    PetscInt          offset   = cLocalStart + tree->quadrants_offset;
    PetscInt          numQuads = (PetscInt)tree->quadrants.elem_count;
    p4est_quadrant_t *quads    = (p4est_quadrant_t *)tree->quadrants.array;
    PetscInt          i;

    if (!numQuads) continue;
    coarsePoint = t;
    for (i = 0; i < numQuads; i++, cp++) {
      PetscInt          cell = i + offset;
      p4est_quadrant_t *quad = &quads[i];

      PetscCall(PforestLocalizeCell(plex, cDim, pforest, newSection, cell, coarsePoint, quad, coords2));
    }
  }
  if (cLocalEnd - cLocalStart < cEnd - cStart) {
    p4est_quadrant_t *ghosts    = (p4est_quadrant_t *)pforest->ghost->ghosts.array;
    PetscInt          numGhosts = (PetscInt)pforest->ghost->ghosts.elem_count;
    PetscInt          count;

    for (count = 0; count < numGhosts - cLocalStart; count++, cp++) {
      p4est_quadrant_t *quad = &ghosts[count + cLocalStart];
      coarsePoint            = quad->p.which_tree;
      PetscInt cell          = count + cLocalEnd;

      PetscCall(PforestLocalizeCell(plex, cDim, pforest, newSection, cell, coarsePoint, quad, coords2));
    }
  }
  PetscCall(VecRestoreArray(cVec, &coords2));
  PetscCall(DMSetCellCoordinatesLocal(plex, cVec));
  PetscCall(VecDestroy(&cVec));
  PetscCall(PetscSectionDestroy(&newSection));
  PetscFunctionReturn(0);
}

#define DMForestClearAdaptivityForest_pforest _append_pforest(DMForestClearAdaptivityForest)
static PetscErrorCode DMForestClearAdaptivityForest_pforest(DM dm) {
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;

  PetscFunctionBegin;
  forest  = (DM_Forest *)dm->data;
  pforest = (DM_Forest_pforest *)forest->data;
  PetscCall(PetscSFDestroy(&(pforest->pointAdaptToSelfSF)));
  PetscCall(PetscSFDestroy(&(pforest->pointSelfToAdaptSF)));
  PetscCall(PetscFree(pforest->pointAdaptToSelfCids));
  PetscCall(PetscFree(pforest->pointSelfToAdaptCids));
  PetscFunctionReturn(0);
}

static PetscErrorCode DMConvert_pforest_plex(DM dm, DMType newtype, DM *plex) {
  DM_Forest           *forest;
  DM_Forest_pforest   *pforest;
  DM                   refTree, newPlex, base;
  PetscInt             adjDim, adjCodim, coordDim;
  MPI_Comm             comm;
  PetscBool            isPforest;
  PetscInt             dim;
  PetscInt             overlap;
  p4est_connect_type_t ctype;
  p4est_locidx_t       first_local_quad = -1;
  sc_array_t          *points_per_dim, *cone_sizes, *cones, *cone_orientations, *coords, *children, *parents, *childids, *leaves, *remotes;
  PetscSection         parentSection;
  PetscSF              pointSF;
  size_t               zz, count;
  PetscInt             pStart, pEnd;
  DMLabel              ghostLabelBase = NULL;

  PetscFunctionBegin;

  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  comm = PetscObjectComm((PetscObject)dm);
  PetscCall(PetscObjectTypeCompare((PetscObject)dm, DMPFOREST, &isPforest));
  PetscCheck(isPforest, comm, PETSC_ERR_ARG_WRONG, "Expected DM type %s, got %s", DMPFOREST, ((PetscObject)dm)->type_name);
  PetscCall(DMGetDimension(dm, &dim));
  PetscCheck(dim == P4EST_DIM, comm, PETSC_ERR_ARG_WRONG, "Expected DM dimension %d, got %" PetscInt_FMT, P4EST_DIM, dim);
  forest  = (DM_Forest *)dm->data;
  pforest = (DM_Forest_pforest *)forest->data;
  PetscCall(DMForestGetBaseDM(dm, &base));
  if (base) PetscCall(DMGetLabel(base, "ghost", &ghostLabelBase));
  if (!pforest->plex) {
    PetscMPIInt size;

    PetscCallMPI(MPI_Comm_size(comm, &size));
    PetscCall(DMCreate(comm, &newPlex));
    PetscCall(DMSetType(newPlex, DMPLEX));
    PetscCall(DMSetMatType(newPlex, dm->mattype));
    /* share labels */
    PetscCall(DMCopyLabels(dm, newPlex, PETSC_OWN_POINTER, PETSC_TRUE, DM_COPY_LABELS_FAIL));
    PetscCall(DMForestGetAdjacencyDimension(dm, &adjDim));
    PetscCall(DMForestGetAdjacencyCodimension(dm, &adjCodim));
    PetscCall(DMGetCoordinateDim(dm, &coordDim));
    if (adjDim == 0) {
      ctype = P4EST_CONNECT_FULL;
    } else if (adjCodim == 1) {
      ctype = P4EST_CONNECT_FACE;
#if defined(P4_TO_P8)
    } else if (adjDim == 1) {
      ctype = P8EST_CONNECT_EDGE;
#endif
    } else {
      SETERRQ(PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Invalid adjacency dimension %" PetscInt_FMT, adjDim);
    }
    PetscCheck(ctype == P4EST_CONNECT_FULL, PetscObjectComm((PetscObject)dm), PETSC_ERR_ARG_WRONG, "Adjacency dimension %" PetscInt_FMT " / codimension %" PetscInt_FMT " not supported yet", adjDim, adjCodim);
    PetscCall(DMForestGetPartitionOverlap(dm, &overlap));
    PetscCall(DMPlexSetOverlap_Plex(newPlex, NULL, overlap));

    points_per_dim    = sc_array_new(sizeof(p4est_locidx_t));
    cone_sizes        = sc_array_new(sizeof(p4est_locidx_t));
    cones             = sc_array_new(sizeof(p4est_locidx_t));
    cone_orientations = sc_array_new(sizeof(p4est_locidx_t));
    coords            = sc_array_new(3 * sizeof(double));
    children          = sc_array_new(sizeof(p4est_locidx_t));
    parents           = sc_array_new(sizeof(p4est_locidx_t));
    childids          = sc_array_new(sizeof(p4est_locidx_t));
    leaves            = sc_array_new(sizeof(p4est_locidx_t));
    remotes           = sc_array_new(2 * sizeof(p4est_locidx_t));

    PetscCallP4est(p4est_get_plex_data_ext, (pforest->forest, &pforest->ghost, &pforest->lnodes, ctype, (int)((size > 1) ? overlap : 0), &first_local_quad, points_per_dim, cone_sizes, cones, cone_orientations, coords, children, parents, childids, leaves, remotes, 1));

    pforest->cLocalStart = (PetscInt)first_local_quad;
    pforest->cLocalEnd   = pforest->cLocalStart + (PetscInt)pforest->forest->local_num_quadrants;
    PetscCall(locidx_to_PetscInt(points_per_dim));
    PetscCall(locidx_to_PetscInt(cone_sizes));
    PetscCall(locidx_to_PetscInt(cones));
    PetscCall(locidx_to_PetscInt(cone_orientations));
    PetscCall(coords_double_to_PetscScalar(coords, coordDim));
    PetscCall(locidx_to_PetscInt(children));
    PetscCall(locidx_to_PetscInt(parents));
    PetscCall(locidx_to_PetscInt(childids));
    PetscCall(locidx_to_PetscInt(leaves));
    PetscCall(locidx_pair_to_PetscSFNode(remotes));

    PetscCall(DMSetDimension(newPlex, P4EST_DIM));
    PetscCall(DMSetCoordinateDim(newPlex, coordDim));
    PetscCall(DMPlexSetMaxProjectionHeight(newPlex, P4EST_DIM - 1));
    PetscCall(DMPlexCreateFromDAG(newPlex, P4EST_DIM, (PetscInt *)points_per_dim->array, (PetscInt *)cone_sizes->array, (PetscInt *)cones->array, (PetscInt *)cone_orientations->array, (PetscScalar *)coords->array));
    PetscCall(DMPlexConvertOldOrientations_Internal(newPlex));
    PetscCall(DMCreateReferenceTree_pforest(comm, &refTree));
    PetscCall(DMPlexSetReferenceTree(newPlex, refTree));
    PetscCall(PetscSectionCreate(comm, &parentSection));
    PetscCall(DMPlexGetChart(newPlex, &pStart, &pEnd));
    PetscCall(PetscSectionSetChart(parentSection, pStart, pEnd));
    count = children->elem_count;
    for (zz = 0; zz < count; zz++) {
      PetscInt child = *((PetscInt *)sc_array_index(children, zz));

      PetscCall(PetscSectionSetDof(parentSection, child, 1));
    }
    PetscCall(PetscSectionSetUp(parentSection));
    PetscCall(DMPlexSetTree(newPlex, parentSection, (PetscInt *)parents->array, (PetscInt *)childids->array));
    PetscCall(PetscSectionDestroy(&parentSection));
    PetscCall(PetscSFCreate(comm, &pointSF));
    /*
       These arrays defining the sf are from the p4est library, but the code there shows the leaves being populated in increasing order.
       https://gitlab.com/petsc/petsc/merge_requests/2248#note_240186391
    */
    PetscCall(PetscSFSetGraph(pointSF, pEnd - pStart, (PetscInt)leaves->elem_count, (PetscInt *)leaves->array, PETSC_COPY_VALUES, (PetscSFNode *)remotes->array, PETSC_COPY_VALUES));
    PetscCall(DMSetPointSF(newPlex, pointSF));
    PetscCall(DMSetPointSF(dm, pointSF));
    {
      DM coordDM;

      PetscCall(DMGetCoordinateDM(newPlex, &coordDM));
      PetscCall(DMSetPointSF(coordDM, pointSF));
    }
    PetscCall(PetscSFDestroy(&pointSF));
    sc_array_destroy(points_per_dim);
    sc_array_destroy(cone_sizes);
    sc_array_destroy(cones);
    sc_array_destroy(cone_orientations);
    sc_array_destroy(coords);
    sc_array_destroy(children);
    sc_array_destroy(parents);
    sc_array_destroy(childids);
    sc_array_destroy(leaves);
    sc_array_destroy(remotes);

    {
      const PetscReal *maxCell, *Lstart, *L;

      PetscCall(DMGetPeriodicity(dm, &maxCell, &Lstart, &L));
      PetscCall(DMSetPeriodicity(newPlex, maxCell, Lstart, L));
      PetscCall(DMPforestLocalizeCoordinates(dm, newPlex));
    }

    if (overlap > 0) { /* the p4est routine can't set all of the coordinates in its routine if there is overlap */
      Vec                coordsGlobal, coordsLocal;
      const PetscScalar *globalArray;
      PetscScalar       *localArray;
      PetscSF            coordSF;
      DM                 coordDM;

      PetscCall(DMGetCoordinateDM(newPlex, &coordDM));
      PetscCall(DMGetSectionSF(coordDM, &coordSF));
      PetscCall(DMGetCoordinates(newPlex, &coordsGlobal));
      PetscCall(DMGetCoordinatesLocal(newPlex, &coordsLocal));
      PetscCall(VecGetArrayRead(coordsGlobal, &globalArray));
      PetscCall(VecGetArray(coordsLocal, &localArray));
      PetscCall(PetscSFBcastBegin(coordSF, MPIU_SCALAR, globalArray, localArray, MPI_REPLACE));
      PetscCall(PetscSFBcastEnd(coordSF, MPIU_SCALAR, globalArray, localArray, MPI_REPLACE));
      PetscCall(VecRestoreArray(coordsLocal, &localArray));
      PetscCall(VecRestoreArrayRead(coordsGlobal, &globalArray));
      PetscCall(DMSetCoordinatesLocal(newPlex, coordsLocal));
    }
    PetscCall(DMPforestMapCoordinates(dm, newPlex));

    pforest->plex = newPlex;

    /* copy labels */
    PetscCall(DMPforestLabelsFinalize(dm, newPlex));

    if (ghostLabelBase || pforest->ghostName) { /* we have to do this after copying labels because the labels drive the construction of ghost cells */
      PetscInt numAdded;
      DM       newPlexGhosted;
      void    *ctx;

      PetscCall(DMPlexConstructGhostCells(newPlex, pforest->ghostName, &numAdded, &newPlexGhosted));
      PetscCall(DMGetApplicationContext(newPlex, &ctx));
      PetscCall(DMSetApplicationContext(newPlexGhosted, ctx));
      /* we want the sf for the ghost dm to be the one for the p4est dm as well */
      PetscCall(DMGetPointSF(newPlexGhosted, &pointSF));
      PetscCall(DMSetPointSF(dm, pointSF));
      PetscCall(DMDestroy(&newPlex));
      PetscCall(DMPlexSetReferenceTree(newPlexGhosted, refTree));
      PetscCall(DMForestClearAdaptivityForest_pforest(dm));
      newPlex = newPlexGhosted;

      /* share the labels back */
      PetscCall(DMDestroyLabelLinkList_Internal(dm));
      PetscCall(DMCopyLabels(newPlex, dm, PETSC_OWN_POINTER, PETSC_TRUE, DM_COPY_LABELS_FAIL));
      pforest->plex = newPlex;
    }
    PetscCall(DMDestroy(&refTree));
    if (dm->setfromoptionscalled) {
      PetscObjectOptionsBegin((PetscObject)newPlex);
      PetscCall(DMSetFromOptions_NonRefinement_Plex(newPlex, PetscOptionsObject));
      PetscCall(PetscObjectProcessOptionsHandlers((PetscObject)newPlex, PetscOptionsObject));
      PetscOptionsEnd();
    }
    PetscCall(DMViewFromOptions(newPlex, NULL, "-dm_p4est_plex_view"));
    {
      DM           cdm;
      PetscSection coordsSec;
      Vec          coords;
      PetscInt     cDim;

      PetscCall(DMGetCoordinateDim(newPlex, &cDim));
      PetscCall(DMGetCoordinateSection(newPlex, &coordsSec));
      PetscCall(DMSetCoordinateSection(dm, cDim, coordsSec));
      PetscCall(DMGetCoordinatesLocal(newPlex, &coords));
      PetscCall(DMSetCoordinatesLocal(dm, coords));
      PetscCall(DMGetCellCoordinateDM(newPlex, &cdm));
      if (cdm) PetscCall(DMSetCellCoordinateDM(dm, cdm));
      PetscCall(DMGetCellCoordinateSection(newPlex, &coordsSec));
      if (coordsSec) PetscCall(DMSetCellCoordinateSection(dm, cDim, coordsSec));
      PetscCall(DMGetCellCoordinatesLocal(newPlex, &coords));
      if (coords) PetscCall(DMSetCellCoordinatesLocal(dm, coords));
    }
  }
  newPlex = pforest->plex;
  if (plex) {
    PetscCall(DMClone(newPlex, plex));
#if 0
    PetscCall(DMGetCoordinateDM(newPlex,&coordDM));
    PetscCall(DMSetCoordinateDM(*plex,coordDM));
    PetscCall(DMGetCellCoordinateDM(newPlex,&coordDM));
    PetscCall(DMSetCellCoordinateDM(*plex,coordDM));
#endif
    PetscCall(DMShareDiscretization(dm, *plex));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMSetFromOptions_pforest(DM dm, PetscOptionItems *PetscOptionsObject) {
  DM_Forest_pforest *pforest = (DM_Forest_pforest *)((DM_Forest *)dm->data)->data;
  char               stringBuffer[256];
  PetscBool          flg;

  PetscFunctionBegin;
  PetscCall(DMSetFromOptions_Forest(dm, PetscOptionsObject));
  PetscOptionsHeadBegin(PetscOptionsObject, "DM" P4EST_STRING " options");
  PetscCall(PetscOptionsBool("-dm_p4est_partition_for_coarsening", "partition forest to allow for coarsening", "DMP4estSetPartitionForCoarsening", pforest->partition_for_coarsening, &(pforest->partition_for_coarsening), NULL));
  PetscCall(PetscOptionsString("-dm_p4est_ghost_label_name", "the name of the ghost label when converting from a DMPlex", NULL, NULL, stringBuffer, sizeof(stringBuffer), &flg));
  PetscOptionsHeadEnd();
  if (flg) {
    PetscCall(PetscFree(pforest->ghostName));
    PetscCall(PetscStrallocpy(stringBuffer, &pforest->ghostName));
  }
  PetscFunctionReturn(0);
}

#if !defined(P4_TO_P8)
#define DMPforestGetPartitionForCoarsening DMP4estGetPartitionForCoarsening
#define DMPforestSetPartitionForCoarsening DMP4estSetPartitionForCoarsening
#else
#define DMPforestGetPartitionForCoarsening DMP8estGetPartitionForCoarsening
#define DMPforestSetPartitionForCoarsening DMP8estSetPartitionForCoarsening
#endif

PETSC_EXTERN PetscErrorCode DMPforestGetPartitionForCoarsening(DM dm, PetscBool *flg) {
  DM_Forest_pforest *pforest;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  pforest = (DM_Forest_pforest *)((DM_Forest *)dm->data)->data;
  *flg    = pforest->partition_for_coarsening;
  PetscFunctionReturn(0);
}

PETSC_EXTERN PetscErrorCode DMPforestSetPartitionForCoarsening(DM dm, PetscBool flg) {
  DM_Forest_pforest *pforest;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  pforest                           = (DM_Forest_pforest *)((DM_Forest *)dm->data)->data;
  pforest->partition_for_coarsening = flg;
  PetscFunctionReturn(0);
}

static PetscErrorCode DMPforestGetPlex(DM dm, DM *plex) {
  DM_Forest_pforest *pforest;

  PetscFunctionBegin;
  if (plex) *plex = NULL;
  PetscCall(DMSetUp(dm));
  pforest = (DM_Forest_pforest *)((DM_Forest *)dm->data)->data;
  if (!pforest->plex) PetscCall(DMConvert_pforest_plex(dm, DMPLEX, NULL));
  PetscCall(DMShareDiscretization(dm, pforest->plex));
  if (plex) *plex = pforest->plex;
  PetscFunctionReturn(0);
}

#define DMCreateInterpolation_pforest _append_pforest(DMCreateInterpolation)
static PetscErrorCode DMCreateInterpolation_pforest(DM dmCoarse, DM dmFine, Mat *interpolation, Vec *scaling) {
  PetscSection gsc, gsf;
  PetscInt     m, n;
  DM           cdm;

  PetscFunctionBegin;
  PetscCall(DMGetGlobalSection(dmFine, &gsf));
  PetscCall(PetscSectionGetConstrainedStorageSize(gsf, &m));
  PetscCall(DMGetGlobalSection(dmCoarse, &gsc));
  PetscCall(PetscSectionGetConstrainedStorageSize(gsc, &n));

  PetscCall(MatCreate(PetscObjectComm((PetscObject)dmFine), interpolation));
  PetscCall(MatSetSizes(*interpolation, m, n, PETSC_DETERMINE, PETSC_DETERMINE));
  PetscCall(MatSetType(*interpolation, MATAIJ));

  PetscCall(DMGetCoarseDM(dmFine, &cdm));
  PetscCheck(cdm == dmCoarse, PetscObjectComm((PetscObject)dmFine), PETSC_ERR_SUP, "Only interpolation from coarse DM for now");

  {
    DM        plexF, plexC;
    PetscSF   sf;
    PetscInt *cids;
    PetscInt  dofPerDim[4] = {1, 1, 1, 1};

    PetscCall(DMPforestGetPlex(dmCoarse, &plexC));
    PetscCall(DMPforestGetPlex(dmFine, &plexF));
    PetscCall(DMPforestGetTransferSF_Internal(dmCoarse, dmFine, dofPerDim, &sf, PETSC_TRUE, &cids));
    PetscCall(PetscSFSetUp(sf));
    PetscCall(DMPlexComputeInterpolatorTree(plexC, plexF, sf, cids, *interpolation));
    PetscCall(PetscSFDestroy(&sf));
    PetscCall(PetscFree(cids));
  }
  PetscCall(MatViewFromOptions(*interpolation, NULL, "-interp_mat_view"));
  /* Use naive scaling */
  PetscCall(DMCreateInterpolationScale(dmCoarse, dmFine, *interpolation, scaling));
  PetscFunctionReturn(0);
}

#define DMCreateInjection_pforest _append_pforest(DMCreateInjection)
static PetscErrorCode DMCreateInjection_pforest(DM dmCoarse, DM dmFine, Mat *injection) {
  PetscSection gsc, gsf;
  PetscInt     m, n;
  DM           cdm;

  PetscFunctionBegin;
  PetscCall(DMGetGlobalSection(dmFine, &gsf));
  PetscCall(PetscSectionGetConstrainedStorageSize(gsf, &n));
  PetscCall(DMGetGlobalSection(dmCoarse, &gsc));
  PetscCall(PetscSectionGetConstrainedStorageSize(gsc, &m));

  PetscCall(MatCreate(PetscObjectComm((PetscObject)dmFine), injection));
  PetscCall(MatSetSizes(*injection, m, n, PETSC_DETERMINE, PETSC_DETERMINE));
  PetscCall(MatSetType(*injection, MATAIJ));

  PetscCall(DMGetCoarseDM(dmFine, &cdm));
  PetscCheck(cdm == dmCoarse, PetscObjectComm((PetscObject)dmFine), PETSC_ERR_SUP, "Only injection to coarse DM for now");

  {
    DM        plexF, plexC;
    PetscSF   sf;
    PetscInt *cids;
    PetscInt  dofPerDim[4] = {1, 1, 1, 1};

    PetscCall(DMPforestGetPlex(dmCoarse, &plexC));
    PetscCall(DMPforestGetPlex(dmFine, &plexF));
    PetscCall(DMPforestGetTransferSF_Internal(dmCoarse, dmFine, dofPerDim, &sf, PETSC_TRUE, &cids));
    PetscCall(PetscSFSetUp(sf));
    PetscCall(DMPlexComputeInjectorTree(plexC, plexF, sf, cids, *injection));
    PetscCall(PetscSFDestroy(&sf));
    PetscCall(PetscFree(cids));
  }
  PetscCall(MatViewFromOptions(*injection, NULL, "-inject_mat_view"));
  /* Use naive scaling */
  PetscFunctionReturn(0);
}

#define DMForestTransferVecFromBase_pforest _append_pforest(DMForestTransferVecFromBase)
static PetscErrorCode DMForestTransferVecFromBase_pforest(DM dm, Vec vecIn, Vec vecOut) {
  DM        dmIn, dmVecIn, base, basec, plex, coarseDM;
  DM       *hierarchy;
  PetscSF   sfRed = NULL;
  PetscDS   ds;
  Vec       vecInLocal, vecOutLocal;
  DMLabel   subpointMap;
  PetscInt  minLevel, mh, n_hi, i;
  PetscBool hiforest, *hierarchy_forest;

  PetscFunctionBegin;
  PetscCall(VecGetDM(vecIn, &dmVecIn));
  PetscCall(DMGetDS(dmVecIn, &ds));
  PetscCheck(ds, PetscObjectComm((PetscObject)dmVecIn), PETSC_ERR_SUP, "Cannot transfer without a PetscDS object");
  { /* we cannot stick user contexts into function callbacks for DMProjectFieldLocal! */
    PetscSection section;
    PetscInt     Nf;

    PetscCall(DMGetLocalSection(dmVecIn, &section));
    PetscCall(PetscSectionGetNumFields(section, &Nf));
    PetscCheck(Nf <= 3, PetscObjectComm((PetscObject)dmVecIn), PETSC_ERR_SUP, "Number of fields %" PetscInt_FMT " are currently not supported! Send an email at petsc-dev@mcs.anl.gov", Nf);
  }
  PetscCall(DMForestGetMinimumRefinement(dm, &minLevel));
  PetscCheck(!minLevel, PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Cannot transfer with minimum refinement set to %" PetscInt_FMT ". Rerun with DMForestSetMinimumRefinement(dm,0)", minLevel);
  PetscCall(DMForestGetBaseDM(dm, &base));
  PetscCheck(base, PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Missing base DM");

  PetscCall(VecSet(vecOut, 0.0));
  if (dmVecIn == base) { /* sequential runs */
    PetscCall(PetscObjectReference((PetscObject)vecIn));
  } else {
    PetscSection secIn, secInRed;
    Vec          vecInRed, vecInLocal;

    PetscCall(PetscObjectQuery((PetscObject)base, "_base_migration_sf", (PetscObject *)&sfRed));
    PetscCheck(sfRed, PETSC_COMM_SELF, PETSC_ERR_SUP, "Not the DM set with DMForestSetBaseDM()");
    PetscCall(PetscSectionCreate(PetscObjectComm((PetscObject)dmVecIn), &secInRed));
    PetscCall(VecCreate(PETSC_COMM_SELF, &vecInRed));
    PetscCall(DMGetLocalSection(dmVecIn, &secIn));
    PetscCall(DMGetLocalVector(dmVecIn, &vecInLocal));
    PetscCall(DMGlobalToLocalBegin(dmVecIn, vecIn, INSERT_VALUES, vecInLocal));
    PetscCall(DMGlobalToLocalEnd(dmVecIn, vecIn, INSERT_VALUES, vecInLocal));
    PetscCall(DMPlexDistributeField(dmVecIn, sfRed, secIn, vecInLocal, secInRed, vecInRed));
    PetscCall(DMRestoreLocalVector(dmVecIn, &vecInLocal));
    PetscCall(PetscSectionDestroy(&secInRed));
    vecIn = vecInRed;
  }

  /* we first search through the AdaptivityForest hierarchy
     once we found the first disconnected forest, we upsweep the DM hierarchy */
  hiforest = PETSC_TRUE;

  /* upsweep to the coarsest DM */
  n_hi     = 0;
  coarseDM = dm;
  do {
    PetscBool isforest;

    dmIn = coarseDM;
    /* need to call DMSetUp to have the hierarchy recursively setup */
    PetscCall(DMSetUp(dmIn));
    PetscCall(DMIsForest(dmIn, &isforest));
    PetscCheck(isforest, PetscObjectComm((PetscObject)dmIn), PETSC_ERR_SUP, "Cannot currently transfer through a mixed hierarchy! Found DM type %s", ((PetscObject)dmIn)->type_name);
    coarseDM = NULL;
    if (hiforest) PetscCall(DMForestGetAdaptivityForest(dmIn, &coarseDM));
    if (!coarseDM) { /* DMForest hierarchy ended, we keep upsweeping through the DM hierarchy */
      hiforest = PETSC_FALSE;
      PetscCall(DMGetCoarseDM(dmIn, &coarseDM));
    }
    n_hi++;
  } while (coarseDM);

  PetscCall(PetscMalloc2(n_hi, &hierarchy, n_hi, &hierarchy_forest));

  i        = 0;
  hiforest = PETSC_TRUE;
  coarseDM = dm;
  do {
    dmIn     = coarseDM;
    coarseDM = NULL;
    if (hiforest) PetscCall(DMForestGetAdaptivityForest(dmIn, &coarseDM));
    if (!coarseDM) { /* DMForest hierarchy ended, we keep upsweeping through the DM hierarchy */
      hiforest = PETSC_FALSE;
      PetscCall(DMGetCoarseDM(dmIn, &coarseDM));
    }
    i++;
    hierarchy[n_hi - i] = dmIn;
  } while (coarseDM);

  /* project base vector on the coarsest forest (minimum refinement = 0) */
  PetscCall(DMPforestGetPlex(dmIn, &plex));

  /* Check this plex is compatible with the base */
  {
    IS       gnum[2];
    PetscInt ncells[2], gncells[2];

    PetscCall(DMPlexGetCellNumbering(base, &gnum[0]));
    PetscCall(DMPlexGetCellNumbering(plex, &gnum[1]));
    PetscCall(ISGetMinMax(gnum[0], NULL, &ncells[0]));
    PetscCall(ISGetMinMax(gnum[1], NULL, &ncells[1]));
    PetscCall(MPIU_Allreduce(ncells, gncells, 2, MPIU_INT, MPI_MAX, PetscObjectComm((PetscObject)dm)));
    PetscCheck(gncells[0] == gncells[1], PetscObjectComm((PetscObject)dm), PETSC_ERR_SUP, "Invalid number of base cells! Expected %" PetscInt_FMT ", found %" PetscInt_FMT, gncells[0] + 1, gncells[1] + 1);
  }

  PetscCall(DMGetLabel(dmIn, "_forest_base_subpoint_map", &subpointMap));
  PetscCheck(subpointMap, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Missing _forest_base_subpoint_map label");

  PetscCall(DMPlexGetMaxProjectionHeight(base, &mh));
  PetscCall(DMPlexSetMaxProjectionHeight(plex, mh));

  PetscCall(DMClone(base, &basec));
  PetscCall(DMCopyDisc(dmVecIn, basec));
  if (sfRed) {
    PetscCall(PetscObjectReference((PetscObject)vecIn));
    vecInLocal = vecIn;
  } else {
    PetscCall(DMCreateLocalVector(basec, &vecInLocal));
    PetscCall(DMGlobalToLocalBegin(basec, vecIn, INSERT_VALUES, vecInLocal));
    PetscCall(DMGlobalToLocalEnd(basec, vecIn, INSERT_VALUES, vecInLocal));
  }

  PetscCall(DMGetLocalVector(dmIn, &vecOutLocal));
  { /* get degrees of freedom ordered onto dmIn */
    PetscSF            basetocoarse;
    PetscInt           bStart, bEnd, nroots;
    PetscInt           iStart, iEnd, nleaves, leaf;
    PetscMPIInt        rank;
    PetscSFNode       *remotes;
    PetscSection       secIn, secOut;
    PetscInt          *remoteOffsets;
    PetscSF            transferSF;
    const PetscScalar *inArray;
    PetscScalar       *outArray;

    PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)basec), &rank));
    PetscCall(DMPlexGetChart(basec, &bStart, &bEnd));
    nroots = PetscMax(bEnd - bStart, 0);
    PetscCall(DMPlexGetChart(plex, &iStart, &iEnd));
    nleaves = PetscMax(iEnd - iStart, 0);

    PetscCall(PetscMalloc1(nleaves, &remotes));
    for (leaf = iStart; leaf < iEnd; leaf++) {
      PetscInt index;

      remotes[leaf - iStart].rank = rank;
      PetscCall(DMLabelGetValue(subpointMap, leaf, &index));
      remotes[leaf - iStart].index = index;
    }

    PetscCall(PetscSFCreate(PetscObjectComm((PetscObject)basec), &basetocoarse));
    PetscCall(PetscSFSetGraph(basetocoarse, nroots, nleaves, NULL, PETSC_OWN_POINTER, remotes, PETSC_OWN_POINTER));
    PetscCall(PetscSFSetUp(basetocoarse));
    PetscCall(DMGetLocalSection(basec, &secIn));
    PetscCall(PetscSectionCreate(PetscObjectComm((PetscObject)dmIn), &secOut));
    PetscCall(PetscSFDistributeSection(basetocoarse, secIn, &remoteOffsets, secOut));
    PetscCall(PetscSFCreateSectionSF(basetocoarse, secIn, remoteOffsets, secOut, &transferSF));
    PetscCall(PetscFree(remoteOffsets));
    PetscCall(VecGetArrayWrite(vecOutLocal, &outArray));
    PetscCall(VecGetArrayRead(vecInLocal, &inArray));
    PetscCall(PetscSFBcastBegin(transferSF, MPIU_SCALAR, inArray, outArray, MPI_REPLACE));
    PetscCall(PetscSFBcastEnd(transferSF, MPIU_SCALAR, inArray, outArray, MPI_REPLACE));
    PetscCall(VecRestoreArrayRead(vecInLocal, &inArray));
    PetscCall(VecRestoreArrayWrite(vecOutLocal, &outArray));
    PetscCall(PetscSFDestroy(&transferSF));
    PetscCall(PetscSectionDestroy(&secOut));
    PetscCall(PetscSFDestroy(&basetocoarse));
  }
  PetscCall(VecDestroy(&vecInLocal));
  PetscCall(DMDestroy(&basec));
  PetscCall(VecDestroy(&vecIn));

  /* output */
  if (n_hi > 1) { /* downsweep the stored hierarchy */
    Vec vecOut1, vecOut2;
    DM  fineDM;

    PetscCall(DMGetGlobalVector(dmIn, &vecOut1));
    PetscCall(DMLocalToGlobal(dmIn, vecOutLocal, INSERT_VALUES, vecOut1));
    PetscCall(DMRestoreLocalVector(dmIn, &vecOutLocal));
    for (i = 1; i < n_hi - 1; i++) {
      fineDM = hierarchy[i];
      PetscCall(DMGetGlobalVector(fineDM, &vecOut2));
      PetscCall(DMForestTransferVec(dmIn, vecOut1, fineDM, vecOut2, PETSC_TRUE, 0.0));
      PetscCall(DMRestoreGlobalVector(dmIn, &vecOut1));
      vecOut1 = vecOut2;
      dmIn    = fineDM;
    }
    PetscCall(DMForestTransferVec(dmIn, vecOut1, dm, vecOut, PETSC_TRUE, 0.0));
    PetscCall(DMRestoreGlobalVector(dmIn, &vecOut1));
  } else {
    PetscCall(DMLocalToGlobal(dmIn, vecOutLocal, INSERT_VALUES, vecOut));
    PetscCall(DMRestoreLocalVector(dmIn, &vecOutLocal));
  }
  PetscCall(PetscFree2(hierarchy, hierarchy_forest));
  PetscFunctionReturn(0);
}

#define DMForestTransferVec_pforest _append_pforest(DMForestTransferVec)
static PetscErrorCode DMForestTransferVec_pforest(DM dmIn, Vec vecIn, DM dmOut, Vec vecOut, PetscBool useBCs, PetscReal time) {
  DM          adaptIn, adaptOut, plexIn, plexOut;
  DM_Forest  *forestIn, *forestOut, *forestAdaptIn, *forestAdaptOut;
  PetscInt    dofPerDim[] = {1, 1, 1, 1};
  PetscSF     inSF = NULL, outSF = NULL;
  PetscInt   *inCids = NULL, *outCids = NULL;
  DMAdaptFlag purposeIn, purposeOut;

  PetscFunctionBegin;
  forestOut = (DM_Forest *)dmOut->data;
  forestIn  = (DM_Forest *)dmIn->data;

  PetscCall(DMForestGetAdaptivityForest(dmOut, &adaptOut));
  PetscCall(DMForestGetAdaptivityPurpose(dmOut, &purposeOut));
  forestAdaptOut = adaptOut ? (DM_Forest *)adaptOut->data : NULL;

  PetscCall(DMForestGetAdaptivityForest(dmIn, &adaptIn));
  PetscCall(DMForestGetAdaptivityPurpose(dmIn, &purposeIn));
  forestAdaptIn = adaptIn ? (DM_Forest *)adaptIn->data : NULL;

  if (forestAdaptOut == forestIn) {
    switch (purposeOut) {
    case DM_ADAPT_REFINE:
      PetscCall(DMPforestGetTransferSF_Internal(dmIn, dmOut, dofPerDim, &inSF, PETSC_TRUE, &inCids));
      PetscCall(PetscSFSetUp(inSF));
      break;
    case DM_ADAPT_COARSEN:
    case DM_ADAPT_COARSEN_LAST:
      PetscCall(DMPforestGetTransferSF_Internal(dmOut, dmIn, dofPerDim, &outSF, PETSC_TRUE, &outCids));
      PetscCall(PetscSFSetUp(outSF));
      break;
    default:
      PetscCall(DMPforestGetTransferSF_Internal(dmIn, dmOut, dofPerDim, &inSF, PETSC_TRUE, &inCids));
      PetscCall(DMPforestGetTransferSF_Internal(dmOut, dmIn, dofPerDim, &outSF, PETSC_FALSE, &outCids));
      PetscCall(PetscSFSetUp(inSF));
      PetscCall(PetscSFSetUp(outSF));
    }
  } else if (forestAdaptIn == forestOut) {
    switch (purposeIn) {
    case DM_ADAPT_REFINE:
      PetscCall(DMPforestGetTransferSF_Internal(dmOut, dmIn, dofPerDim, &outSF, PETSC_TRUE, &inCids));
      PetscCall(PetscSFSetUp(outSF));
      break;
    case DM_ADAPT_COARSEN:
    case DM_ADAPT_COARSEN_LAST:
      PetscCall(DMPforestGetTransferSF_Internal(dmIn, dmOut, dofPerDim, &inSF, PETSC_TRUE, &inCids));
      PetscCall(PetscSFSetUp(inSF));
      break;
    default:
      PetscCall(DMPforestGetTransferSF_Internal(dmIn, dmOut, dofPerDim, &inSF, PETSC_TRUE, &inCids));
      PetscCall(DMPforestGetTransferSF_Internal(dmOut, dmIn, dofPerDim, &outSF, PETSC_FALSE, &outCids));
      PetscCall(PetscSFSetUp(inSF));
      PetscCall(PetscSFSetUp(outSF));
    }
  } else SETERRQ(PetscObjectComm((PetscObject)dmIn), PETSC_ERR_SUP, "Only support transfer from pre-adaptivity to post-adaptivity right now");
  PetscCall(DMPforestGetPlex(dmIn, &plexIn));
  PetscCall(DMPforestGetPlex(dmOut, &plexOut));

  PetscCall(DMPlexTransferVecTree(plexIn, vecIn, plexOut, vecOut, inSF, outSF, inCids, outCids, useBCs, time));
  PetscCall(PetscFree(inCids));
  PetscCall(PetscFree(outCids));
  PetscCall(PetscSFDestroy(&inSF));
  PetscCall(PetscSFDestroy(&outSF));
  PetscCall(PetscFree(inCids));
  PetscCall(PetscFree(outCids));
  PetscFunctionReturn(0);
}

#define DMCreateCoordinateDM_pforest _append_pforest(DMCreateCoordinateDM)
static PetscErrorCode DMCreateCoordinateDM_pforest(DM dm, DM *cdm) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMGetCoordinateDM(plex, cdm));
  PetscCall(PetscObjectReference((PetscObject)*cdm));
  PetscFunctionReturn(0);
}

#define VecViewLocal_pforest _append_pforest(VecViewLocal)
static PetscErrorCode VecViewLocal_pforest(Vec vec, PetscViewer viewer) {
  DM dm, plex;

  PetscFunctionBegin;
  PetscCall(VecGetDM(vec, &dm));
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(VecSetDM(vec, plex));
  PetscCall(VecView_Plex_Local(vec, viewer));
  PetscCall(VecSetDM(vec, dm));
  PetscFunctionReturn(0);
}

#define VecView_pforest _append_pforest(VecView)
static PetscErrorCode VecView_pforest(Vec vec, PetscViewer viewer) {
  DM dm, plex;

  PetscFunctionBegin;
  PetscCall(VecGetDM(vec, &dm));
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(VecSetDM(vec, plex));
  PetscCall(VecView_Plex(vec, viewer));
  PetscCall(VecSetDM(vec, dm));
  PetscFunctionReturn(0);
}

#define VecView_pforest_Native _infix_pforest(VecView, _Native)
static PetscErrorCode VecView_pforest_Native(Vec vec, PetscViewer viewer) {
  DM dm, plex;

  PetscFunctionBegin;
  PetscCall(VecGetDM(vec, &dm));
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(VecSetDM(vec, plex));
  PetscCall(VecView_Plex_Native(vec, viewer));
  PetscCall(VecSetDM(vec, dm));
  PetscFunctionReturn(0);
}

#define VecLoad_pforest _append_pforest(VecLoad)
static PetscErrorCode VecLoad_pforest(Vec vec, PetscViewer viewer) {
  DM dm, plex;

  PetscFunctionBegin;
  PetscCall(VecGetDM(vec, &dm));
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(VecSetDM(vec, plex));
  PetscCall(VecLoad_Plex(vec, viewer));
  PetscCall(VecSetDM(vec, dm));
  PetscFunctionReturn(0);
}

#define VecLoad_pforest_Native _infix_pforest(VecLoad, _Native)
static PetscErrorCode VecLoad_pforest_Native(Vec vec, PetscViewer viewer) {
  DM dm, plex;

  PetscFunctionBegin;
  PetscCall(VecGetDM(vec, &dm));
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(VecSetDM(vec, plex));
  PetscCall(VecLoad_Plex_Native(vec, viewer));
  PetscCall(VecSetDM(vec, dm));
  PetscFunctionReturn(0);
}

#define DMCreateGlobalVector_pforest _append_pforest(DMCreateGlobalVector)
static PetscErrorCode DMCreateGlobalVector_pforest(DM dm, Vec *vec) {
  PetscFunctionBegin;
  PetscCall(DMCreateGlobalVector_Section_Private(dm, vec));
  /* PetscCall(VecSetOperation(*vec, VECOP_DUPLICATE, (void(*)(void)) VecDuplicate_MPI_DM)); */
  PetscCall(VecSetOperation(*vec, VECOP_VIEW, (void (*)(void))VecView_pforest));
  PetscCall(VecSetOperation(*vec, VECOP_VIEWNATIVE, (void (*)(void))VecView_pforest_Native));
  PetscCall(VecSetOperation(*vec, VECOP_LOAD, (void (*)(void))VecLoad_pforest));
  PetscCall(VecSetOperation(*vec, VECOP_LOADNATIVE, (void (*)(void))VecLoad_pforest_Native));
  PetscFunctionReturn(0);
}

#define DMCreateLocalVector_pforest _append_pforest(DMCreateLocalVector)
static PetscErrorCode DMCreateLocalVector_pforest(DM dm, Vec *vec) {
  PetscFunctionBegin;
  PetscCall(DMCreateLocalVector_Section_Private(dm, vec));
  PetscCall(VecSetOperation(*vec, VECOP_VIEW, (void (*)(void))VecViewLocal_pforest));
  PetscFunctionReturn(0);
}

#define DMCreateMatrix_pforest _append_pforest(DMCreateMatrix)
static PetscErrorCode DMCreateMatrix_pforest(DM dm, Mat *mat) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  if (plex->prealloc_only != dm->prealloc_only) plex->prealloc_only = dm->prealloc_only; /* maybe this should go into forest->plex */
  PetscCall(DMCreateMatrix(plex, mat));
  PetscCall(MatSetDM(*mat, dm));
  PetscFunctionReturn(0);
}

#define DMProjectFunctionLocal_pforest _append_pforest(DMProjectFunctionLocal)
static PetscErrorCode DMProjectFunctionLocal_pforest(DM dm, PetscReal time, PetscErrorCode (**funcs)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar *, void *), void **ctxs, InsertMode mode, Vec localX) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMProjectFunctionLocal(plex, time, funcs, ctxs, mode, localX));
  PetscFunctionReturn(0);
}

#define DMProjectFunctionLabelLocal_pforest _append_pforest(DMProjectFunctionLabelLocal)
static PetscErrorCode DMProjectFunctionLabelLocal_pforest(DM dm, PetscReal time, DMLabel label, PetscInt numIds, const PetscInt ids[], PetscInt Ncc, const PetscInt comps[], PetscErrorCode (**funcs)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar *, void *), void **ctxs, InsertMode mode, Vec localX) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMProjectFunctionLabelLocal(plex, time, label, numIds, ids, Ncc, comps, funcs, ctxs, mode, localX));
  PetscFunctionReturn(0);
}

#define DMProjectFieldLocal_pforest _append_pforest(DMProjectFieldLocal)
PetscErrorCode DMProjectFieldLocal_pforest(DM dm, PetscReal time, Vec localU, void (**funcs)(PetscInt, PetscInt, PetscInt, const PetscInt[], const PetscInt[], const PetscScalar[], const PetscScalar[], const PetscScalar[], const PetscInt[], const PetscInt[], const PetscScalar[], const PetscScalar[], const PetscScalar[], PetscReal, const PetscReal[], PetscInt, const PetscScalar[], PetscScalar[]), InsertMode mode, Vec localX) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMProjectFieldLocal(plex, time, localU, funcs, mode, localX));
  PetscFunctionReturn(0);
}

#define DMComputeL2Diff_pforest _append_pforest(DMComputeL2Diff)
PetscErrorCode DMComputeL2Diff_pforest(DM dm, PetscReal time, PetscErrorCode (**funcs)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar *, void *), void **ctxs, Vec X, PetscReal *diff) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMComputeL2Diff(plex, time, funcs, ctxs, X, diff));
  PetscFunctionReturn(0);
}

#define DMComputeL2FieldDiff_pforest _append_pforest(DMComputeL2FieldDiff)
PetscErrorCode DMComputeL2FieldDiff_pforest(DM dm, PetscReal time, PetscErrorCode (**funcs)(PetscInt, PetscReal, const PetscReal[], PetscInt, PetscScalar *, void *), void **ctxs, Vec X, PetscReal diff[]) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMComputeL2FieldDiff(plex, time, funcs, ctxs, X, diff));
  PetscFunctionReturn(0);
}

#define DMCreatelocalsection_pforest _append_pforest(DMCreatelocalsection)
static PetscErrorCode DMCreatelocalsection_pforest(DM dm) {
  DM           plex;
  PetscSection section;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMGetLocalSection(plex, &section));
  PetscCall(DMSetLocalSection(dm, section));
  PetscFunctionReturn(0);
}

#define DMCreateDefaultConstraints_pforest _append_pforest(DMCreateDefaultConstraints)
static PetscErrorCode DMCreateDefaultConstraints_pforest(DM dm) {
  DM           plex;
  Mat          mat;
  Vec          bias;
  PetscSection section;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMGetDefaultConstraints(plex, &section, &mat, &bias));
  PetscCall(DMSetDefaultConstraints(dm, section, mat, bias));
  PetscFunctionReturn(0);
}

#define DMGetDimPoints_pforest _append_pforest(DMGetDimPoints)
static PetscErrorCode DMGetDimPoints_pforest(DM dm, PetscInt dim, PetscInt *cStart, PetscInt *cEnd) {
  DM plex;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(dm, DM_CLASSID, 1);
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMGetDimPoints(plex, dim, cStart, cEnd));
  PetscFunctionReturn(0);
}

/* Need to forward declare */
#define DMInitialize_pforest _append_pforest(DMInitialize)
static PetscErrorCode DMInitialize_pforest(DM dm);

#define DMClone_pforest _append_pforest(DMClone)
static PetscErrorCode DMClone_pforest(DM dm, DM *newdm) {
  PetscFunctionBegin;
  PetscCall(DMClone_Forest(dm, newdm));
  PetscCall(DMInitialize_pforest(*newdm));
  PetscFunctionReturn(0);
}

#define DMForestCreateCellChart_pforest _append_pforest(DMForestCreateCellChart)
static PetscErrorCode DMForestCreateCellChart_pforest(DM dm, PetscInt *cStart, PetscInt *cEnd) {
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;
  PetscInt           overlap;

  PetscFunctionBegin;
  PetscCall(DMSetUp(dm));
  forest  = (DM_Forest *)dm->data;
  pforest = (DM_Forest_pforest *)forest->data;
  *cStart = 0;
  PetscCall(DMForestGetPartitionOverlap(dm, &overlap));
  if (overlap && pforest->ghost) {
    *cEnd = pforest->forest->local_num_quadrants + pforest->ghost->proc_offsets[pforest->forest->mpisize];
  } else {
    *cEnd = pforest->forest->local_num_quadrants;
  }
  PetscFunctionReturn(0);
}

#define DMForestCreateCellSF_pforest _append_pforest(DMForestCreateCellSF)
static PetscErrorCode DMForestCreateCellSF_pforest(DM dm, PetscSF *cellSF) {
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;
  PetscMPIInt        rank;
  PetscInt           overlap;
  PetscInt           cStart, cEnd, cLocalStart, cLocalEnd;
  PetscInt           nRoots, nLeaves, *mine = NULL;
  PetscSFNode       *remote = NULL;
  PetscSF            sf;

  PetscFunctionBegin;
  PetscCall(DMForestGetCellChart(dm, &cStart, &cEnd));
  forest      = (DM_Forest *)dm->data;
  pforest     = (DM_Forest_pforest *)forest->data;
  nRoots      = cEnd - cStart;
  cLocalStart = pforest->cLocalStart;
  cLocalEnd   = pforest->cLocalEnd;
  nLeaves     = 0;
  PetscCall(DMForestGetPartitionOverlap(dm, &overlap));
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)dm), &rank));
  if (overlap && pforest->ghost) {
    PetscSFNode      *mirror;
    p4est_quadrant_t *mirror_array;
    PetscInt          nMirror, nGhostPre, nSelf, q;
    void            **mirrorPtrs;

    nMirror   = (PetscInt)pforest->ghost->mirrors.elem_count;
    nSelf     = cLocalEnd - cLocalStart;
    nLeaves   = nRoots - nSelf;
    nGhostPre = (PetscInt)pforest->ghost->proc_offsets[rank];
    PetscCall(PetscMalloc1(nLeaves, &mine));
    PetscCall(PetscMalloc1(nLeaves, &remote));
    PetscCall(PetscMalloc2(nMirror, &mirror, nMirror, &mirrorPtrs));
    mirror_array = (p4est_quadrant_t *)pforest->ghost->mirrors.array;
    for (q = 0; q < nMirror; q++) {
      p4est_quadrant_t *mir = &(mirror_array[q]);

      mirror[q].rank  = rank;
      mirror[q].index = (PetscInt)mir->p.piggy3.local_num + cLocalStart;
      mirrorPtrs[q]   = (void *)&(mirror[q]);
    }
    PetscCallP4est(p4est_ghost_exchange_custom, (pforest->forest, pforest->ghost, sizeof(PetscSFNode), mirrorPtrs, remote));
    PetscCall(PetscFree2(mirror, mirrorPtrs));
    for (q = 0; q < nGhostPre; q++) mine[q] = q;
    for (; q < nLeaves; q++) mine[q] = (q - nGhostPre) + cLocalEnd;
  }
  PetscCall(PetscSFCreate(PetscObjectComm((PetscObject)dm), &sf));
  PetscCall(PetscSFSetGraph(sf, nRoots, nLeaves, mine, PETSC_OWN_POINTER, remote, PETSC_OWN_POINTER));
  *cellSF = sf;
  PetscFunctionReturn(0);
}

static PetscErrorCode DMCreateNeumannOverlap_pforest(DM dm, IS *ovl, Mat *J, PetscErrorCode (**setup)(Mat, PetscReal, Vec, Vec, PetscReal, IS, void *), void **setup_ctx) {
  DM plex;

  PetscFunctionBegin;
  PetscCall(DMPforestGetPlex(dm, &plex));
  PetscCall(DMCreateNeumannOverlap_Plex(plex, ovl, J, setup, setup_ctx));
  if (!*setup) {
    PetscCall(PetscObjectQueryFunction((PetscObject)dm, "MatComputeNeumannOverlap_C", setup));
    if (*setup) PetscCall(PetscObjectCompose((PetscObject)*ovl, "_DM_Original_HPDDM", (PetscObject)dm));
  }
  PetscFunctionReturn(0);
}

static PetscErrorCode DMInitialize_pforest(DM dm) {
  PetscFunctionBegin;
  dm->ops->setup                     = DMSetUp_pforest;
  dm->ops->view                      = DMView_pforest;
  dm->ops->clone                     = DMClone_pforest;
  dm->ops->createinterpolation       = DMCreateInterpolation_pforest;
  dm->ops->createinjection           = DMCreateInjection_pforest;
  dm->ops->setfromoptions            = DMSetFromOptions_pforest;
  dm->ops->createcoordinatedm        = DMCreateCoordinateDM_pforest;
  dm->ops->createglobalvector        = DMCreateGlobalVector_pforest;
  dm->ops->createlocalvector         = DMCreateLocalVector_pforest;
  dm->ops->creatematrix              = DMCreateMatrix_pforest;
  dm->ops->projectfunctionlocal      = DMProjectFunctionLocal_pforest;
  dm->ops->projectfunctionlabellocal = DMProjectFunctionLabelLocal_pforest;
  dm->ops->projectfieldlocal         = DMProjectFieldLocal_pforest;
  dm->ops->createlocalsection        = DMCreatelocalsection_pforest;
  dm->ops->createdefaultconstraints  = DMCreateDefaultConstraints_pforest;
  dm->ops->computel2diff             = DMComputeL2Diff_pforest;
  dm->ops->computel2fielddiff        = DMComputeL2FieldDiff_pforest;
  dm->ops->getdimpoints              = DMGetDimPoints_pforest;

  PetscCall(PetscObjectComposeFunction((PetscObject)dm, PetscStringize(DMConvert_plex_pforest) "_C", DMConvert_plex_pforest));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, PetscStringize(DMConvert_pforest_plex) "_C", DMConvert_pforest_plex));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, "DMCreateNeumannOverlap_C", DMCreateNeumannOverlap_pforest));
  PetscCall(PetscObjectComposeFunction((PetscObject)dm, "DMPlexGetOverlap_C", DMForestGetPartitionOverlap));
  PetscFunctionReturn(0);
}

#define DMCreate_pforest _append_pforest(DMCreate)
PETSC_EXTERN PetscErrorCode DMCreate_pforest(DM dm) {
  DM_Forest         *forest;
  DM_Forest_pforest *pforest;

  PetscFunctionBegin;
  PetscCall(PetscP4estInitialize());
  PetscCall(DMCreate_Forest(dm));
  PetscCall(DMInitialize_pforest(dm));
  PetscCall(DMSetDimension(dm, P4EST_DIM));

  /* set forest defaults */
  PetscCall(DMForestSetTopology(dm, "unit"));
  PetscCall(DMForestSetMinimumRefinement(dm, 0));
  PetscCall(DMForestSetInitialRefinement(dm, 0));
  PetscCall(DMForestSetMaximumRefinement(dm, P4EST_QMAXLEVEL));
  PetscCall(DMForestSetGradeFactor(dm, 2));
  PetscCall(DMForestSetAdjacencyDimension(dm, 0));
  PetscCall(DMForestSetPartitionOverlap(dm, 0));

  /* create p4est data */
  PetscCall(PetscNew(&pforest));

  forest                            = (DM_Forest *)dm->data;
  forest->data                      = pforest;
  forest->destroy                   = DMForestDestroy_pforest;
  forest->ftemplate                 = DMForestTemplate_pforest;
  forest->transfervec               = DMForestTransferVec_pforest;
  forest->transfervecfrombase       = DMForestTransferVecFromBase_pforest;
  forest->createcellchart           = DMForestCreateCellChart_pforest;
  forest->createcellsf              = DMForestCreateCellSF_pforest;
  forest->clearadaptivityforest     = DMForestClearAdaptivityForest_pforest;
  forest->getadaptivitysuccess      = DMForestGetAdaptivitySuccess_pforest;
  pforest->topo                     = NULL;
  pforest->forest                   = NULL;
  pforest->ghost                    = NULL;
  pforest->lnodes                   = NULL;
  pforest->partition_for_coarsening = PETSC_TRUE;
  pforest->coarsen_hierarchy        = PETSC_FALSE;
  pforest->cLocalStart              = -1;
  pforest->cLocalEnd                = -1;
  pforest->labelsFinalized          = PETSC_FALSE;
  pforest->ghostName                = NULL;
  PetscFunctionReturn(0);
}

#endif /* defined(PETSC_HAVE_P4EST) */