xref: /petsc/src/sys/classes/draw/utils/cmap.c (revision 4d86920da9ee67c835173a5dfffa1b3a52fd24ca)

#include <petscsys.h> /*I "petscsys.h" I*/
#include <petscdraw.h>

/*
    Set up a color map, using uniform separation in hue space.
    Map entries are Red, Green, Blue.
    Values are "gamma" corrected.
 */

/*
   Gamma is a monitor dependent value.  The value here is an
   approximate that gives somewhat better results than Gamma = 1.
 */
static PetscReal Gamma = 2.0;

PetscErrorCode PetscDrawUtilitySetGamma(PetscReal g)
{
  PetscFunctionBegin;
  Gamma = g;
  PetscFunctionReturn(PETSC_SUCCESS);
}

static inline double PetscHlsHelper(double m1, double m2, double h)
{
  while (h > 1.0) h -= 1.0;
  while (h < 0.0) h += 1.0;
  if (h < 1 / 6.0) return m1 + (m2 - m1) * h * 6;
  if (h < 1 / 2.0) return m2;
  if (h < 2 / 3.0) return m1 + (m2 - m1) * (2 / 3.0 - h) * 6;
  return m1;
}

static inline void PetscHlsToRgb(double h, double l, double s, double *r, double *g, double *b)
{
  if (s > 0.0) {
    double m2 = l <= 0.5 ? l * (1.0 + s) : l + s - (l * s);
    double m1 = 2 * l - m2;
    *r        = PetscHlsHelper(m1, m2, h + 1 / 3.);
    *g        = PetscHlsHelper(m1, m2, h);
    *b        = PetscHlsHelper(m1, m2, h - 1 / 3.);
  } else {
    /* ignore hue */
    *r = *g = *b = l;
  }
}

static inline void PetscGammaCorrect(double *r, double *g, double *b)
{
  PetscReal igamma = 1 / Gamma;
  *r               = (double)PetscPowReal((PetscReal)*r, igamma);
  *g               = (double)PetscPowReal((PetscReal)*g, igamma);
  *b               = (double)PetscPowReal((PetscReal)*b, igamma);
}

static PetscErrorCode PetscDrawCmap_Hue(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
{
  int    i;
  double maxhue = 212.0 / 360, lightness = 0.5, saturation = 1.0;

  PetscFunctionBegin;
  for (i = 0; i < mapsize; i++) {
    double hue = maxhue * (double)i / (mapsize - 1), r, g, b;
    PetscHlsToRgb(hue, lightness, saturation, &r, &g, &b);
    PetscGammaCorrect(&r, &g, &b);
    R[i] = (unsigned char)(255 * PetscMin(r, 1.0));
    G[i] = (unsigned char)(255 * PetscMin(g, 1.0));
    B[i] = (unsigned char)(255 * PetscMin(b, 1.0));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PetscDrawCmap_Gray(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
{
  PetscFunctionBegin;
  for (int i = 0; i < mapsize; i++) R[i] = G[i] = B[i] = (unsigned char)((255.0 * i) / (mapsize - 1));
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PetscDrawCmap_Jet(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
{
  int          i;
  const double knots[] = {0, 1 / 8., 3 / 8., 5 / 8., 7 / 8., 1};

  PetscFunctionBegin;
  for (i = 0; i < mapsize; i++) {
    double u = (double)i / (mapsize - 1);
    double m, r = 0, g = 0, b = 0;
    int    k = 0;
    while (k < 4 && u > knots[k + 1]) k++;
    m = (u - knots[k]) / (knots[k + 1] - knots[k]);
    switch (k) {
    case 0:
      r = 0;
      g = 0;
      b = (m + 1) / 2;
      break;
    case 1:
      r = 0;
      g = m;
      b = 1;
      break;
    case 2:
      r = m;
      g = 1;
      b = 1 - m;
      break;
    case 3:
      r = 1;
      g = 1 - m;
      b = 0;
      break;
    case 4:
      r = 1 - m / 2;
      g = 0;
      b = 0;
      break;
    }
    R[i] = (unsigned char)(255 * PetscMin(r, 1.0));
    G[i] = (unsigned char)(255 * PetscMin(g, 1.0));
    B[i] = (unsigned char)(255 * PetscMin(b, 1.0));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PetscDrawCmap_Hot(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
{
  int          i;
  const double knots[] = {0, 3 / 8., 3 / 4., 1};

  PetscFunctionBegin;
  for (i = 0; i < mapsize; i++) {
    double u = (double)i / (mapsize - 1);
    double m, r = 0, g = 0, b = 0;
    int    k = 0;
    while (k < 2 && u > knots[k + 1]) k++;
    m = (u - knots[k]) / (knots[k + 1] - knots[k]);
    switch (k) {
    case 0:
      r = m;
      g = 0;
      b = 0;
      break;
    case 1:
      r = 1;
      g = m;
      b = 0;
      break;
    case 2:
      r = 1;
      g = 1;
      b = m;
      break;
    }
    R[i] = (unsigned char)(255 * PetscMin(r, 1.0));
    G[i] = (unsigned char)(255 * PetscMin(g, 1.0));
    B[i] = (unsigned char)(255 * PetscMin(b, 1.0));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

static PetscErrorCode PetscDrawCmap_Bone(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
{
  PetscFunctionBegin;
  (void)PetscDrawCmap_Hot(mapsize, R, G, B);
  for (int i = 0; i < mapsize; i++) {
    double u = (double)i / (mapsize - 1);
    double r = (7 * u + B[i] / 255.0) / 8;
    double g = (7 * u + G[i] / 255.0) / 8;
    double b = (7 * u + R[i] / 255.0) / 8;
    R[i]     = (unsigned char)(255 * PetscMin(r, 1.0));
    G[i]     = (unsigned char)(255 * PetscMin(g, 1.0));
    B[i]     = (unsigned char)(255 * PetscMin(b, 1.0));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

#include "../src/sys/classes/draw/utils/cmap/coolwarm.h"
#include "../src/sys/classes/draw/utils/cmap/parula.h"
#include "../src/sys/classes/draw/utils/cmap/viridis.h"
#include "../src/sys/classes/draw/utils/cmap/plasma.h"
#include "../src/sys/classes/draw/utils/cmap/inferno.h"
#include "../src/sys/classes/draw/utils/cmap/magma.h"

static struct {
  const char *name;
  const unsigned char (*data)[3];
  PetscErrorCode (*cmap)(int, unsigned char[], unsigned char[], unsigned char[]);
} PetscDrawCmapTable[] = {
  {"hue",      NULL,                   PetscDrawCmap_Hue }, /* varying hue with constant lightness and saturation */
  {"gray",     NULL,                   PetscDrawCmap_Gray}, /* black to white with shades of gray */
  {"bone",     NULL,                   PetscDrawCmap_Bone}, /* black to white with gray-blue shades */
  {"jet",      NULL,                   PetscDrawCmap_Jet }, /* rainbow-like colormap from NCSA, University of Illinois */
  {"hot",      NULL,                   PetscDrawCmap_Hot }, /* black-body radiation */
  {"coolwarm", PetscDrawCmap_coolwarm, NULL              }, /* ParaView default (Cool To Warm with Diverging interpolation) */
  {"parula",   PetscDrawCmap_parula,   NULL              }, /* MATLAB (default since R2014b) */
  {"viridis",  PetscDrawCmap_viridis,  NULL              }, /* matplotlib 1.5 (default since 2.0) */
  {"plasma",   PetscDrawCmap_plasma,   NULL              }, /* matplotlib 1.5 */
  {"inferno",  PetscDrawCmap_inferno,  NULL              }, /* matplotlib 1.5 */
  {"magma",    PetscDrawCmap_magma,    NULL              }, /* matplotlib 1.5 */
};

PetscErrorCode PetscDrawUtilitySetCmap(const char colormap[], int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
{
  int         i, j;
  const char *cmap_name_list[PETSC_STATIC_ARRAY_LENGTH(PetscDrawCmapTable)];
  PetscInt    id = 0, count = PETSC_STATIC_ARRAY_LENGTH(cmap_name_list);
  PetscBool   reverse = PETSC_FALSE, brighten = PETSC_FALSE;
  PetscReal   beta = 0;

  PetscFunctionBegin;
  for (i = 0; i < count; i++) cmap_name_list[i] = PetscDrawCmapTable[i].name;
  if (colormap && colormap[0]) {
    PetscBool match = PETSC_FALSE;
    for (id = 0; !match && id < count; id++) PetscCall(PetscStrcasecmp(colormap, cmap_name_list[id], &match));
    PetscCheck(match, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Colormap '%s' not found", colormap);
  }
  PetscCall(PetscOptionsGetEList(NULL, NULL, "-draw_cmap", cmap_name_list, count, &id, NULL));
  PetscCall(PetscOptionsGetBool(NULL, NULL, "-draw_cmap_reverse", &reverse, NULL));
  PetscCall(PetscOptionsGetReal(NULL, NULL, "-draw_cmap_brighten", &beta, &brighten));
  PetscCheck(!brighten || (beta > (PetscReal)-1 && beta < (PetscReal) + 1), PETSC_COMM_SELF, PETSC_ERR_ARG_OUTOFRANGE, "brighten parameter %g must be in the range (-1,1)", (double)beta);

  if (PetscDrawCmapTable[id].cmap) {
    PetscCall(PetscDrawCmapTable[id].cmap(mapsize, R, G, B));
  } else {
    const unsigned char(*rgb)[3] = PetscDrawCmapTable[id].data;
    PetscCheck(mapsize == 256 - PETSC_DRAW_BASIC_COLORS, PETSC_COMM_SELF, PETSC_ERR_SUP, "Colormap '%s' with size %d not supported", cmap_name_list[id], mapsize);
    for (i = 0; i < mapsize; i++) {
      R[i] = rgb[i][0];
      G[i] = rgb[i][1];
      B[i] = rgb[i][2];
    }
  }

  if (reverse) {
    i = 0;
    j = mapsize - 1;
    while (i < j) {
#define SWAP(a, i, j) \
  do { \
    unsigned char t = a[i]; \
    a[i]            = a[j]; \
    a[j]            = t; \
  } while (0)
      SWAP(R, i, j);
      SWAP(G, i, j);
      SWAP(B, i, j);
#undef SWAP
      i++;
      j--;
    }
  }

  if (brighten) {
    PetscReal gamma = (beta > 0.0) ? (1 - beta) : (1 / (1 + beta));
    for (i = 0; i < mapsize; i++) {
      PetscReal r = PetscPowReal((PetscReal)R[i] / 255, gamma);
      PetscReal g = PetscPowReal((PetscReal)G[i] / 255, gamma);
      PetscReal b = PetscPowReal((PetscReal)B[i] / 255, gamma);
      R[i]        = (unsigned char)(255 * PetscMin(r, (PetscReal)1.0));
      G[i]        = (unsigned char)(255 * PetscMin(g, (PetscReal)1.0));
      B[i]        = (unsigned char)(255 * PetscMin(b, (PetscReal)1.0));
    }
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}