Actual source code: cmap.c

  1: #include <petscsys.h>
  2: #include <petscdraw.h>

  4: /*
  5:     Set up a color map, using uniform separation in hue space.
  6:     Map entries are Red, Green, Blue.
  7:     Values are "gamma" corrected.
  8:  */

 10: /*
 11:    Gamma is a monitor dependent value.  The value here is an
 12:    approximate that gives somewhat better results than Gamma = 1.
 13:  */
 14: static PetscReal Gamma = 2.0;

 16: PetscErrorCode PetscDrawUtilitySetGamma(PetscReal g)
 17: {
 18:   Gamma = g;
 19:   return 0;
 20: }

 22: static inline double PetscHlsHelper(double m1, double m2, double h)
 23: {
 24:   while (h > 1.0) h -= 1.0;
 25:   while (h < 0.0) h += 1.0;
 26:   if (h < 1 / 6.0) return m1 + (m2 - m1) * h * 6;
 27:   if (h < 1 / 2.0) return m2;
 28:   if (h < 2 / 3.0) return m1 + (m2 - m1) * (2 / 3.0 - h) * 6;
 29:   return m1;
 30: }

 32: static inline void PetscHlsToRgb(double h, double l, double s, double *r, double *g, double *b)
 33: {
 34:   if (s > 0.0) {
 35:     double m2 = l <= 0.5 ? l * (1.0 + s) : l + s - (l * s);
 36:     double m1 = 2 * l - m2;
 37:     *r        = PetscHlsHelper(m1, m2, h + 1 / 3.);
 38:     *g        = PetscHlsHelper(m1, m2, h);
 39:     *b        = PetscHlsHelper(m1, m2, h - 1 / 3.);
 40:   } else {
 41:     /* ignore hue */
 42:     *r = *g = *b = l;
 43:   }
 44: }

 46: static inline void PetscGammaCorrect(double *r, double *g, double *b)
 47: {
 48:   PetscReal igamma = 1 / Gamma;
 49:   *r               = (double)PetscPowReal((PetscReal)*r, igamma);
 50:   *g               = (double)PetscPowReal((PetscReal)*g, igamma);
 51:   *b               = (double)PetscPowReal((PetscReal)*b, igamma);
 52: }

 54: static PetscErrorCode PetscDrawCmap_Hue(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
 55: {
 56:   int    i;
 57:   double maxhue = 212.0 / 360, lightness = 0.5, saturation = 1.0;

 59:   for (i = 0; i < mapsize; i++) {
 60:     double hue = maxhue * (double)i / (mapsize - 1), r, g, b;
 61:     PetscHlsToRgb(hue, lightness, saturation, &r, &g, &b);
 62:     PetscGammaCorrect(&r, &g, &b);
 63:     R[i] = (unsigned char)(255 * PetscMin(r, 1.0));
 64:     G[i] = (unsigned char)(255 * PetscMin(g, 1.0));
 65:     B[i] = (unsigned char)(255 * PetscMin(b, 1.0));
 66:   }
 67:   return 0;
 68: }

 70: static PetscErrorCode PetscDrawCmap_Gray(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
 71: {
 72:   int i;
 73:   for (i = 0; i < mapsize; i++) R[i] = G[i] = B[i] = (unsigned char)((255.0 * i) / (mapsize - 1));
 74:   return 0;
 75: }

 77: static PetscErrorCode PetscDrawCmap_Jet(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
 78: {
 79:   int          i;
 80:   const double knots[] = {0, 1 / 8., 3 / 8., 5 / 8., 7 / 8., 1};

 82:   for (i = 0; i < mapsize; i++) {
 83:     double u = (double)i / (mapsize - 1);
 84:     double m, r = 0, g = 0, b = 0;
 85:     int    k = 0;
 86:     while (k < 4 && u > knots[k + 1]) k++;
 87:     m = (u - knots[k]) / (knots[k + 1] - knots[k]);
 88:     switch (k) {
 89:     case 0:
 90:       r = 0;
 91:       g = 0;
 92:       b = (m + 1) / 2;
 93:       break;
 94:     case 1:
 95:       r = 0;
 96:       g = m;
 97:       b = 1;
 98:       break;
 99:     case 2:
100:       r = m;
101:       g = 1;
102:       b = 1 - m;
103:       break;
104:     case 3:
105:       r = 1;
106:       g = 1 - m;
107:       b = 0;
108:       break;
109:     case 4:
110:       r = 1 - m / 2;
111:       g = 0;
112:       b = 0;
113:       break;
114:     }
115:     R[i] = (unsigned char)(255 * PetscMin(r, 1.0));
116:     G[i] = (unsigned char)(255 * PetscMin(g, 1.0));
117:     B[i] = (unsigned char)(255 * PetscMin(b, 1.0));
118:   }
119:   return 0;
120: }

122: static PetscErrorCode PetscDrawCmap_Hot(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
123: {
124:   int          i;
125:   const double knots[] = {0, 3 / 8., 3 / 4., 1};

127:   for (i = 0; i < mapsize; i++) {
128:     double u = (double)i / (mapsize - 1);
129:     double m, r = 0, g = 0, b = 0;
130:     int    k = 0;
131:     while (k < 2 && u > knots[k + 1]) k++;
132:     m = (u - knots[k]) / (knots[k + 1] - knots[k]);
133:     switch (k) {
134:     case 0:
135:       r = m;
136:       g = 0;
137:       b = 0;
138:       break;
139:     case 1:
140:       r = 1;
141:       g = m;
142:       b = 0;
143:       break;
144:     case 2:
145:       r = 1;
146:       g = 1;
147:       b = m;
148:       break;
149:     }
150:     R[i] = (unsigned char)(255 * PetscMin(r, 1.0));
151:     G[i] = (unsigned char)(255 * PetscMin(g, 1.0));
152:     B[i] = (unsigned char)(255 * PetscMin(b, 1.0));
153:   }
154:   return 0;
155: }

157: static PetscErrorCode PetscDrawCmap_Bone(int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
158: {
159:   int i;
160:   (void)PetscDrawCmap_Hot(mapsize, R, G, B);
161:   for (i = 0; i < mapsize; i++) {
162:     double u = (double)i / (mapsize - 1);
163:     double r = (7 * u + B[i] / 255.0) / 8;
164:     double g = (7 * u + G[i] / 255.0) / 8;
165:     double b = (7 * u + R[i] / 255.0) / 8;
166:     R[i]     = (unsigned char)(255 * PetscMin(r, 1.0));
167:     G[i]     = (unsigned char)(255 * PetscMin(g, 1.0));
168:     B[i]     = (unsigned char)(255 * PetscMin(b, 1.0));
169:   }
170:   return 0;
171: }

173: #include "../src/sys/classes/draw/utils/cmap/coolwarm.h"
174: #include "../src/sys/classes/draw/utils/cmap/parula.h"
175: #include "../src/sys/classes/draw/utils/cmap/viridis.h"
176: #include "../src/sys/classes/draw/utils/cmap/plasma.h"
177: #include "../src/sys/classes/draw/utils/cmap/inferno.h"
178: #include "../src/sys/classes/draw/utils/cmap/magma.h"

180: static struct {
181:   const char *name;
182:   const unsigned char (*data)[3];
183:   PetscErrorCode (*cmap)(int, unsigned char[], unsigned char[], unsigned char[]);
184: } PetscDrawCmapTable[] = {
185:   {"hue",      NULL,                   PetscDrawCmap_Hue }, /* varying hue with constant lightness and saturation */
186:   {"gray",     NULL,                   PetscDrawCmap_Gray}, /* black to white with shades of gray */
187:   {"bone",     NULL,                   PetscDrawCmap_Bone}, /* black to white with gray-blue shades */
188:   {"jet",      NULL,                   PetscDrawCmap_Jet }, /* rainbow-like colormap from NCSA, University of Illinois */
189:   {"hot",      NULL,                   PetscDrawCmap_Hot }, /* black-body radiation */
190:   {"coolwarm", PetscDrawCmap_coolwarm, NULL              }, /* ParaView default (Cool To Warm with Diverging interpolation) */
191:   {"parula",   PetscDrawCmap_parula,   NULL              }, /* MATLAB (default since R2014b) */
192:   {"viridis",  PetscDrawCmap_viridis,  NULL              }, /* matplotlib 1.5 (default since 2.0) */
193:   {"plasma",   PetscDrawCmap_plasma,   NULL              }, /* matplotlib 1.5 */
194:   {"inferno",  PetscDrawCmap_inferno,  NULL              }, /* matplotlib 1.5 */
195:   {"magma",    PetscDrawCmap_magma,    NULL              }, /* matplotlib 1.5 */
196: };

198: PetscErrorCode PetscDrawUtilitySetCmap(const char colormap[], int mapsize, unsigned char R[], unsigned char G[], unsigned char B[])
199: {
200:   int         i, j;
201:   const char *cmap_name_list[PETSC_STATIC_ARRAY_LENGTH(PetscDrawCmapTable)];
202:   PetscInt    id = 0, count = (PetscInt)(sizeof(cmap_name_list) / sizeof(char *));
203:   PetscBool   reverse = PETSC_FALSE, brighten = PETSC_FALSE;
204:   PetscReal   beta = 0;

206:   for (i = 0; i < count; i++) cmap_name_list[i] = PetscDrawCmapTable[i].name;
207:   if (colormap && colormap[0]) {
208:     PetscBool match = PETSC_FALSE;
209:     for (id = 0; !match && id < count; id++) PetscStrcasecmp(colormap, cmap_name_list[id], &match);
211:   }
212:   PetscOptionsGetEList(NULL, NULL, "-draw_cmap", cmap_name_list, count, &id, NULL);
213:   PetscOptionsGetBool(NULL, NULL, "-draw_cmap_reverse", &reverse, NULL);
214:   PetscOptionsGetReal(NULL, NULL, "-draw_cmap_brighten", &beta, &brighten);

217:   if (PetscDrawCmapTable[id].cmap) {
218:     PetscDrawCmapTable[id].cmap(mapsize, R, G, B);
219:   } else {
220:     const unsigned char(*rgb)[3] = PetscDrawCmapTable[id].data;
222:     for (i = 0; i < mapsize; i++) {
223:       R[i] = rgb[i][0];
224:       G[i] = rgb[i][1];
225:       B[i] = rgb[i][2];
226:     }
227:   }

229:   if (reverse) {
230:     i = 0;
231:     j = mapsize - 1;
232:     while (i < j) {
233: #define SWAP(a, i, j) \
234:   do { \
235:     unsigned char t = a[i]; \
236:     a[i]            = a[j]; \
237:     a[j]            = t; \
238:   } while (0)
239:       SWAP(R, i, j);
240:       SWAP(G, i, j);
241:       SWAP(B, i, j);
242: #undef SWAP
243:       i++;
244:       j--;
245:     }
246:   }

248:   if (brighten) {
249:     PetscReal gamma = (beta > 0.0) ? (1 - beta) : (1 / (1 + beta));
250:     for (i = 0; i < mapsize; i++) {
251:       PetscReal r = PetscPowReal((PetscReal)R[i] / 255, gamma);
252:       PetscReal g = PetscPowReal((PetscReal)G[i] / 255, gamma);
253:       PetscReal b = PetscPowReal((PetscReal)B[i] / 255, gamma);
254:       R[i]        = (unsigned char)(255 * PetscMin(r, (PetscReal)1.0));
255:       G[i]        = (unsigned char)(255 * PetscMin(g, (PetscReal)1.0));
256:       B[i]        = (unsigned char)(255 * PetscMin(b, (PetscReal)1.0));
257:     }
258:   }
259:   return 0;
260: }