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root/radiance/ray/src/cv/mgflib/context.c
Revision: 1.20
Committed: Wed Apr 12 17:16:33 1995 UTC (29 years ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 1.19: +9 -5 lines
Log Message:
improved box filtering of detailed spectra in setspectrum()

File Contents

# Content
1 /* Copyright (c) 1994 Regents of the University of California */
2
3 #ifndef lint
4 static char SCCSid[] = "$SunId$ LBL";
5 #endif
6
7 /*
8 * Context handlers
9 */
10
11 #include <stdio.h>
12 #include <math.h>
13 #include <string.h>
14 #include "parser.h"
15 #include "lookup.h"
16
17 /* default context values */
18 static C_COLOR c_dfcolor = C_DEFCOLOR;
19 static C_MATERIAL c_dfmaterial = C_DEFMATERIAL;
20 static C_VERTEX c_dfvertex = C_DEFVERTEX;
21
22 /* the unnamed contexts */
23 static C_COLOR c_uncolor = C_DEFCOLOR;
24 static C_MATERIAL c_unmaterial = C_DEFMATERIAL;
25 static C_VERTEX c_unvertex = C_DEFVERTEX;
26
27 /* the current contexts */
28 C_COLOR *c_ccolor = &c_uncolor;
29 char *c_ccname = NULL;
30 C_MATERIAL *c_cmaterial = &c_unmaterial;
31 char *c_cmname = NULL;
32 C_VERTEX *c_cvertex = &c_unvertex;
33 char *c_cvname = NULL;
34
35 static LUTAB clr_tab = LU_SINIT(free,free); /* color lookup table */
36 static LUTAB mat_tab = LU_SINIT(free,free); /* material lookup table */
37 static LUTAB vtx_tab = LU_SINIT(free,free); /* vertex lookup table */
38
39 /* CIE 1931 Standard Observer curves */
40 static C_COLOR cie_xf = { 1, C_CDSPEC|C_CSSPEC|C_CSXY|C_CSEFF,
41 {14,42,143,435,1344,2839,3483,3362,2908,1954,956,
42 320,49,93,633,1655,2904,4334,5945,7621,9163,10263,
43 10622,10026,8544,6424,4479,2835,1649,874,468,227,
44 114,58,29,14,7,3,2,1,0}, 106836L, .467, .368, 362.230
45 };
46 static C_COLOR cie_yf = { 1, C_CDSPEC|C_CSSPEC|C_CSXY|C_CSEFF,
47 {0,1,4,12,40,116,230,380,600,910,1390,2080,3230,
48 5030,7100,8620,9540,9950,9950,9520,8700,7570,6310,
49 5030,3810,2650,1750,1070,610,320,170,82,41,21,10,
50 5,2,1,1,0,0}, 106856L, .398, .542, 493.525
51 };
52 static C_COLOR cie_zf = { 1, C_CDSPEC|C_CSSPEC|C_CSXY|C_CSEFF,
53 {65,201,679,2074,6456,13856,17471,17721,16692,
54 12876,8130,4652,2720,1582,782,422,203,87,39,21,17,
55 11,8,3,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
56 106770L, .147, .077, 54.363
57 };
58 /* Derived CIE 1931 Primaries (imaginary) */
59 static C_COLOR cie_xp = { 1, C_CDSPEC|C_CSSPEC|C_CSXY,
60 {-174,-198,-195,-197,-202,-213,-235,-272,-333,
61 -444,-688,-1232,-2393,-4497,-6876,-6758,-5256,
62 -3100,-815,1320,3200,4782,5998,6861,7408,7754,
63 7980,8120,8199,8240,8271,8292,8309,8283,8469,
64 8336,8336,8336,8336,8336,8336},
65 127424L, 1., .0,
66 };
67 static C_COLOR cie_yp = { 1, C_CDSPEC|C_CSSPEC|C_CSXY,
68 {-451,-431,-431,-430,-427,-417,-399,-366,-312,
69 -204,57,691,2142,4990,8810,9871,9122,7321,5145,
70 3023,1123,-473,-1704,-2572,-3127,-3474,-3704,
71 -3846,-3927,-3968,-3999,-4021,-4038,-4012,-4201,
72 -4066,-4066,-4066,-4066,-4066,-4066},
73 -23035L, .0, 1.,
74 };
75 static C_COLOR cie_zp = { 1, C_CDSPEC|C_CSSPEC|C_CSXY,
76 {4051,4054,4052,4053,4054,4056,4059,4064,4071,
77 4074,4056,3967,3677,2933,1492,313,-440,-795,
78 -904,-918,-898,-884,-869,-863,-855,-855,-851,
79 -848,-847,-846,-846,-846,-845,-846,-843,-845,
80 -845,-845,-845,-845,-845},
81 36057L, .0, .0,
82 };
83
84 static int setspectrum();
85 static int setbbtemp();
86 static void mixcolors();
87
88
89 int
90 c_hcolor(ac, av) /* handle color entity */
91 int ac;
92 register char **av;
93 {
94 double w, wsum;
95 register int i;
96 register LUENT *lp;
97
98 switch (mg_entity(av[0])) {
99 case MG_E_COLOR: /* get/set color context */
100 if (ac > 4)
101 return(MG_EARGC);
102 if (ac == 1) { /* set unnamed color context */
103 c_uncolor = c_dfcolor;
104 c_ccolor = &c_uncolor;
105 c_ccname = NULL;
106 return(MG_OK);
107 }
108 lp = lu_find(&clr_tab, av[1]); /* lookup context */
109 if (lp == NULL)
110 return(MG_EMEM);
111 c_ccname = lp->key;
112 c_ccolor = (C_COLOR *)lp->data;
113 if (ac == 2) { /* reestablish previous context */
114 if (c_ccolor == NULL)
115 return(MG_EUNDEF);
116 return(MG_OK);
117 }
118 if (av[2][0] != '=' || av[2][1])
119 return(MG_ETYPE);
120 if (c_ccolor == NULL) { /* create new color context */
121 lp->key = (char *)malloc(strlen(av[1])+1);
122 if (lp->key == NULL)
123 return(MG_EMEM);
124 strcpy(lp->key, av[1]);
125 lp->data = (char *)malloc(sizeof(C_COLOR));
126 if (lp->data == NULL)
127 return(MG_EMEM);
128 c_ccname = lp->key;
129 c_ccolor = (C_COLOR *)lp->data;
130 c_ccolor->clock = 0;
131 }
132 i = c_ccolor->clock;
133 if (ac == 3) { /* use default template */
134 *c_ccolor = c_dfcolor;
135 c_ccolor->clock = i + 1;
136 return(MG_OK);
137 }
138 lp = lu_find(&clr_tab, av[3]); /* lookup template */
139 if (lp == NULL)
140 return(MG_EMEM);
141 if (lp->data == NULL)
142 return(MG_EUNDEF);
143 *c_ccolor = *(C_COLOR *)lp->data;
144 c_ccolor->clock = i + 1;
145 return(MG_OK);
146 case MG_E_CXY: /* assign CIE XY value */
147 if (ac != 3)
148 return(MG_EARGC);
149 if (!isflt(av[1]) | !isflt(av[2]))
150 return(MG_ETYPE);
151 c_ccolor->cx = atof(av[1]);
152 c_ccolor->cy = atof(av[2]);
153 c_ccolor->flags = C_CDXY|C_CSXY;
154 if (c_ccolor->cx < 0. | c_ccolor->cy < 0. |
155 c_ccolor->cx + c_ccolor->cy > 1.)
156 return(MG_EILL);
157 c_ccolor->clock++;
158 return(MG_OK);
159 case MG_E_CSPEC: /* assign spectral values */
160 if (ac < 5)
161 return(MG_EARGC);
162 if (!isflt(av[1]) | !isflt(av[2]))
163 return(MG_ETYPE);
164 return(setspectrum(c_ccolor, atof(av[1]), atof(av[2]),
165 ac-3, av+3));
166 case MG_E_CCT: /* assign black body spectrum */
167 if (ac != 2)
168 return(MG_EARGC);
169 if (!isflt(av[1]))
170 return(MG_ETYPE);
171 return(setbbtemp(c_ccolor, atof(av[1])));
172 case MG_E_CMIX: /* mix colors */
173 if (ac < 5 || (ac-1)%2)
174 return(MG_EARGC);
175 if (!isflt(av[1]))
176 return(MG_ETYPE);
177 wsum = atof(av[1]);
178 if (wsum < 0.)
179 return(MG_EILL);
180 if ((lp = lu_find(&clr_tab, av[2])) == NULL)
181 return(MG_EMEM);
182 if (lp->data == NULL)
183 return(MG_EUNDEF);
184 *c_ccolor = *(C_COLOR *)lp->data;
185 for (i = 3; i < ac; i += 2) {
186 if (!isflt(av[i]))
187 return(MG_ETYPE);
188 w = atof(av[i]);
189 if (w < 0.)
190 return(MG_EILL);
191 if ((lp = lu_find(&clr_tab, av[i+1])) == NULL)
192 return(MG_EMEM);
193 if (lp->data == NULL)
194 return(MG_EUNDEF);
195 mixcolors(c_ccolor, wsum, c_ccolor,
196 w, (C_COLOR *)lp->data);
197 wsum += w;
198 }
199 c_ccolor->clock++;
200 return(MG_OK);
201 }
202 return(MG_EUNK);
203 }
204
205
206 int
207 c_hmaterial(ac, av) /* handle material entity */
208 int ac;
209 register char **av;
210 {
211 int i;
212 register LUENT *lp;
213
214 switch (mg_entity(av[0])) {
215 case MG_E_MATERIAL: /* get/set material context */
216 if (ac > 4)
217 return(MG_EARGC);
218 if (ac == 1) { /* set unnamed material context */
219 c_unmaterial = c_dfmaterial;
220 c_cmaterial = &c_unmaterial;
221 c_cmname = NULL;
222 return(MG_OK);
223 }
224 lp = lu_find(&mat_tab, av[1]); /* lookup context */
225 if (lp == NULL)
226 return(MG_EMEM);
227 c_cmname = lp->key;
228 c_cmaterial = (C_MATERIAL *)lp->data;
229 if (ac == 2) { /* reestablish previous context */
230 if (c_cmaterial == NULL)
231 return(MG_EUNDEF);
232 return(MG_OK);
233 }
234 if (av[2][0] != '=' || av[2][1])
235 return(MG_ETYPE);
236 if (c_cmaterial == NULL) { /* create new material */
237 lp->key = (char *)malloc(strlen(av[1])+1);
238 if (lp->key == NULL)
239 return(MG_EMEM);
240 strcpy(lp->key, av[1]);
241 lp->data = (char *)malloc(sizeof(C_MATERIAL));
242 if (lp->data == NULL)
243 return(MG_EMEM);
244 c_cmname = lp->key;
245 c_cmaterial = (C_MATERIAL *)lp->data;
246 c_cmaterial->clock = 0;
247 }
248 i = c_cmaterial->clock;
249 if (ac == 3) { /* use default template */
250 *c_cmaterial = c_dfmaterial;
251 c_cmaterial->clock = i + 1;
252 return(MG_OK);
253 }
254 lp = lu_find(&mat_tab, av[3]); /* lookup template */
255 if (lp == NULL)
256 return(MG_EMEM);
257 if (lp->data == NULL)
258 return(MG_EUNDEF);
259 *c_cmaterial = *(C_MATERIAL *)lp->data;
260 c_cmaterial->clock = i + 1;
261 return(MG_OK);
262 case MG_E_RD: /* set diffuse reflectance */
263 if (ac != 2)
264 return(MG_EARGC);
265 if (!isflt(av[1]))
266 return(MG_ETYPE);
267 c_cmaterial->rd = atof(av[1]);
268 if (c_cmaterial->rd < 0. | c_cmaterial->rd > 1.)
269 return(MG_EILL);
270 c_cmaterial->rd_c = *c_ccolor;
271 c_cmaterial->clock++;
272 return(MG_OK);
273 case MG_E_ED: /* set diffuse emittance */
274 if (ac != 2)
275 return(MG_EARGC);
276 if (!isflt(av[1]))
277 return(MG_ETYPE);
278 c_cmaterial->ed = atof(av[1]);
279 if (c_cmaterial->ed < 0.)
280 return(MG_EILL);
281 c_cmaterial->ed_c = *c_ccolor;
282 c_cmaterial->clock++;
283 return(MG_OK);
284 case MG_E_TD: /* set diffuse transmittance */
285 if (ac != 2)
286 return(MG_EARGC);
287 if (!isflt(av[1]))
288 return(MG_ETYPE);
289 c_cmaterial->td = atof(av[1]);
290 if (c_cmaterial->td < 0. | c_cmaterial->td > 1.)
291 return(MG_EILL);
292 c_cmaterial->td_c = *c_ccolor;
293 c_cmaterial->clock++;
294 return(MG_OK);
295 case MG_E_RS: /* set specular reflectance */
296 if (ac != 3)
297 return(MG_EARGC);
298 if (!isflt(av[1]) | !isflt(av[2]))
299 return(MG_ETYPE);
300 c_cmaterial->rs = atof(av[1]);
301 c_cmaterial->rs_a = atof(av[2]);
302 if (c_cmaterial->rs < 0. | c_cmaterial->rs > 1. |
303 c_cmaterial->rs_a < 0.)
304 return(MG_EILL);
305 c_cmaterial->rs_c = *c_ccolor;
306 c_cmaterial->clock++;
307 return(MG_OK);
308 case MG_E_TS: /* set specular transmittance */
309 if (ac != 3)
310 return(MG_EARGC);
311 if (!isflt(av[1]) | !isflt(av[2]))
312 return(MG_ETYPE);
313 c_cmaterial->ts = atof(av[1]);
314 c_cmaterial->ts_a = atof(av[2]);
315 if (c_cmaterial->ts < 0. | c_cmaterial->ts > 1. |
316 c_cmaterial->ts_a < 0.)
317 return(MG_EILL);
318 c_cmaterial->ts_c = *c_ccolor;
319 c_cmaterial->clock++;
320 return(MG_OK);
321 case MG_E_SIDES: /* set number of sides */
322 if (ac != 2)
323 return(MG_EARGC);
324 if (!isint(av[1]))
325 return(MG_ETYPE);
326 i = atoi(av[1]);
327 if (i == 1)
328 c_cmaterial->sided = 1;
329 else if (i == 2)
330 c_cmaterial->sided = 0;
331 else
332 return(MG_EILL);
333 c_cmaterial->clock++;
334 return(MG_OK);
335 }
336 return(MG_EUNK);
337 }
338
339
340 int
341 c_hvertex(ac, av) /* handle a vertex entity */
342 int ac;
343 register char **av;
344 {
345 int i;
346 register LUENT *lp;
347
348 switch (mg_entity(av[0])) {
349 case MG_E_VERTEX: /* get/set vertex context */
350 if (ac > 4)
351 return(MG_EARGC);
352 if (ac == 1) { /* set unnamed vertex context */
353 c_unvertex = c_dfvertex;
354 c_cvertex = &c_unvertex;
355 c_cvname = NULL;
356 return(MG_OK);
357 }
358 lp = lu_find(&vtx_tab, av[1]); /* lookup context */
359 if (lp == NULL)
360 return(MG_EMEM);
361 c_cvname = lp->key;
362 c_cvertex = (C_VERTEX *)lp->data;
363 if (ac == 2) { /* reestablish previous context */
364 if (c_cvertex == NULL)
365 return(MG_EUNDEF);
366 return(MG_OK);
367 }
368 if (av[2][0] != '=' || av[2][1])
369 return(MG_ETYPE);
370 if (c_cvertex == NULL) { /* create new vertex context */
371 lp->key = (char *)malloc(strlen(av[1])+1);
372 if (lp->key == NULL)
373 return(MG_EMEM);
374 strcpy(lp->key, av[1]);
375 lp->data = (char *)malloc(sizeof(C_VERTEX));
376 if (lp->data == NULL)
377 return(MG_EMEM);
378 c_cvname = lp->key;
379 c_cvertex = (C_VERTEX *)lp->data;
380 }
381 i = c_cvertex->clock;
382 if (ac == 3) { /* use default template */
383 *c_cvertex = c_dfvertex;
384 c_cvertex->clock = i + 1;
385 return(MG_OK);
386 }
387 lp = lu_find(&vtx_tab, av[3]); /* lookup template */
388 if (lp == NULL)
389 return(MG_EMEM);
390 if (lp->data == NULL)
391 return(MG_EUNDEF);
392 *c_cvertex = *(C_VERTEX *)lp->data;
393 c_cvertex->clock = i + 1;
394 return(MG_OK);
395 case MG_E_POINT: /* set point */
396 if (ac != 4)
397 return(MG_EARGC);
398 if (!isflt(av[1]) | !isflt(av[2]) | !isflt(av[3]))
399 return(MG_ETYPE);
400 c_cvertex->p[0] = atof(av[1]);
401 c_cvertex->p[1] = atof(av[2]);
402 c_cvertex->p[2] = atof(av[3]);
403 c_cvertex->clock++;
404 return(MG_OK);
405 case MG_E_NORMAL: /* set normal */
406 if (ac != 4)
407 return(MG_EARGC);
408 if (!isflt(av[1]) | !isflt(av[2]) | !isflt(av[3]))
409 return(MG_ETYPE);
410 c_cvertex->n[0] = atof(av[1]);
411 c_cvertex->n[1] = atof(av[2]);
412 c_cvertex->n[2] = atof(av[3]);
413 (void)normalize(c_cvertex->n);
414 c_cvertex->clock++;
415 return(MG_OK);
416 }
417 return(MG_EUNK);
418 }
419
420
421 void
422 c_clearall() /* empty context tables */
423 {
424 c_uncolor = c_dfcolor;
425 c_ccolor = &c_uncolor;
426 c_ccname = NULL;
427 lu_done(&clr_tab);
428 c_unmaterial = c_dfmaterial;
429 c_cmaterial = &c_unmaterial;
430 c_cmname = NULL;
431 lu_done(&mat_tab);
432 c_unvertex = c_dfvertex;
433 c_cvertex = &c_unvertex;
434 c_cvname = NULL;
435 lu_done(&vtx_tab);
436 }
437
438
439 C_MATERIAL *
440 c_getmaterial(name) /* get a named material */
441 char *name;
442 {
443 register LUENT *lp;
444
445 if ((lp = lu_find(&mat_tab, name)) == NULL)
446 return(NULL);
447 return((C_MATERIAL *)lp->data);
448 }
449
450
451 C_VERTEX *
452 c_getvert(name) /* get a named vertex */
453 char *name;
454 {
455 register LUENT *lp;
456
457 if ((lp = lu_find(&vtx_tab, name)) == NULL)
458 return(NULL);
459 return((C_VERTEX *)lp->data);
460 }
461
462
463 C_COLOR *
464 c_getcolor(name) /* get a named color */
465 char *name;
466 {
467 register LUENT *lp;
468
469 if ((lp = lu_find(&clr_tab, name)) == NULL)
470 return(NULL);
471 return((C_COLOR *)lp->data);
472 }
473
474
475 int
476 c_isgrey(clr) /* check if color is grey */
477 register C_COLOR *clr;
478 {
479 if (!(clr->flags & (C_CSXY|C_CSSPEC)))
480 return(1); /* no settings == grey */
481 c_ccvt(clr, C_CSXY);
482 return(clr->cx >= .323 && clr->cx <= .343 &&
483 clr->cy >= .323 && clr->cy <= .343);
484 }
485
486
487 void
488 c_ccvt(clr, fl) /* convert color representations */
489 register C_COLOR *clr;
490 int fl;
491 {
492 double x, y, z;
493 register int i;
494
495 fl &= ~clr->flags; /* ignore what's done */
496 if (!fl) /* everything's done! */
497 return;
498 if (!(clr->flags & (C_CSXY|C_CSSPEC))) /* nothing set! */
499 *clr = c_dfcolor;
500 if (fl & C_CSXY) { /* cspec -> cxy */
501 x = y = z = 0.;
502 for (i = 0; i < C_CNSS; i++) {
503 x += cie_xf.ssamp[i] * clr->ssamp[i];
504 y += cie_yf.ssamp[i] * clr->ssamp[i];
505 z += cie_zf.ssamp[i] * clr->ssamp[i];
506 }
507 x /= (double)cie_xf.ssum;
508 y /= (double)cie_yf.ssum;
509 z /= (double)cie_zf.ssum;
510 z += x + y;
511 clr->cx = x / z;
512 clr->cy = y / z;
513 clr->flags |= C_CSXY;
514 } else if (fl & C_CSSPEC) { /* cxy -> cspec */
515 x = clr->cx;
516 y = clr->cy;
517 z = 1. - x - y;
518 clr->ssum = 0;
519 for (i = 0; i < C_CNSS; i++) {
520 clr->ssamp[i] = x*cie_xp.ssamp[i] + y*cie_yp.ssamp[i]
521 + z*cie_zp.ssamp[i] + .5;
522 if (clr->ssamp[i] < 0) /* out of gamut! */
523 clr->ssamp[i] = 0;
524 else
525 clr->ssum += clr->ssamp[i];
526 }
527 clr->flags |= C_CSSPEC;
528 }
529 if (fl & C_CSEFF) { /* compute efficacy */
530 if (clr->flags & C_CSSPEC) { /* from spectrum */
531 y = 0.;
532 for (i = 0; i < C_CNSS; i++)
533 y += cie_yf.ssamp[i] * clr->ssamp[i];
534 clr->eff = C_CLPWM * y / clr->ssum;
535 } else /* clr->flags & C_CSXY */ { /* from (x,y) */
536 clr->eff = clr->cx*cie_xf.eff + clr->cy*cie_yf.eff +
537 (1. - clr->cx - clr->cy)*cie_zf.eff;
538 }
539 clr->flags |= C_CSEFF;
540 }
541 }
542
543
544 static int
545 setspectrum(clr, wlmin, wlmax, ac, av) /* convert a spectrum */
546 register C_COLOR *clr;
547 double wlmin, wlmax;
548 int ac;
549 char **av;
550 {
551 double scale;
552 float va[C_CNSS];
553 register int i, pos;
554 int n, imax;
555 int wl;
556 double wl0, wlstep;
557 double boxpos, boxstep;
558 /* check bounds */
559 if (wlmax <= C_CMINWL | wlmax <= wlmin | wlmin >= C_CMAXWL)
560 return(MG_EILL);
561 wlstep = (wlmax - wlmin)/(ac-1);
562 while (wlmin < C_CMINWL) {
563 wlmin += wlstep;
564 ac--; av++;
565 }
566 while (wlmax > C_CMAXWL) {
567 wlmax -= wlstep;
568 ac--;
569 }
570 imax = ac; /* box filter if necessary */
571 boxpos = 0;
572 boxstep = 1;
573 if (wlstep < C_CWLI) {
574 imax = (wlmax - wlmin)/C_CWLI + (1-FTINY);
575 boxpos = (wlmin - C_CMINWL)/C_CWLI;
576 boxstep = wlstep/C_CWLI;
577 wlstep = C_CWLI;
578 }
579 scale = 0.; /* get values and maximum */
580 pos = 0;
581 for (i = 0; i < imax; i++) {
582 va[i] = 0.; n = 0;
583 while (boxpos < i+.5 && pos < ac) {
584 if (!isflt(av[pos]))
585 return(MG_ETYPE);
586 va[i] += atof(av[pos++]);
587 n++;
588 boxpos += boxstep;
589 }
590 if (n > 1)
591 va[i] /= (double)n;
592 if (va[i] < 0.)
593 return(MG_EILL);
594 if (va[i] > scale)
595 scale = va[i];
596 }
597 if (scale <= FTINY)
598 return(MG_EILL);
599 scale = C_CMAXV / scale;
600 clr->ssum = 0; /* convert to our spacing */
601 wl0 = wlmin;
602 pos = 0;
603 for (i = 0, wl = C_CMINWL; i < C_CNSS; i++, wl += C_CWLI)
604 if (wl < wlmin | wl > wlmax)
605 clr->ssamp[i] = 0;
606 else {
607 while (wl0 + wlstep < wl+FTINY) {
608 wl0 += wlstep;
609 pos++;
610 }
611 if (wl+FTINY >= wl0 & wl-FTINY <= wl0)
612 clr->ssamp[i] = scale*va[pos] + .5;
613 else /* interpolate if necessary */
614 clr->ssamp[i] = .5 + scale / wlstep *
615 ( va[pos]*(wl0+wlstep - wl) +
616 va[pos+1]*(wl - wl0) );
617 clr->ssum += clr->ssamp[i];
618 }
619 clr->flags = C_CDSPEC|C_CSSPEC;
620 clr->clock++;
621 return(MG_OK);
622 }
623
624
625 static void
626 mixcolors(cres, w1, c1, w2, c2) /* mix two colors according to weights given */
627 register C_COLOR *cres, *c1, *c2;
628 double w1, w2;
629 {
630 double scale;
631 float cmix[C_CNSS];
632 register int i;
633
634 if ((c1->flags|c2->flags) & C_CDSPEC) { /* spectral mixing */
635 c_ccvt(c1, C_CSSPEC|C_CSEFF);
636 c_ccvt(c2, C_CSSPEC|C_CSEFF);
637 w1 /= c1->eff*c1->ssum;
638 w2 /= c2->eff*c2->ssum;
639 scale = 0.;
640 for (i = 0; i < C_CNSS; i++) {
641 cmix[i] = w1*c1->ssamp[i] + w2*c2->ssamp[i];
642 if (cmix[i] > scale)
643 scale = cmix[i];
644 }
645 scale = C_CMAXV / scale;
646 cres->ssum = 0;
647 for (i = 0; i < C_CNSS; i++)
648 cres->ssum += cres->ssamp[i] = scale*cmix[i] + .5;
649 cres->flags = C_CDSPEC|C_CSSPEC;
650 } else { /* CIE xy mixing */
651 c_ccvt(c1, C_CSXY);
652 c_ccvt(c2, C_CSXY);
653 scale = 1. / (w1/c1->cy + w2/c2->cy);
654 cres->cx = (c1->cx*w1/c1->cy + c2->cx*w2/c2->cy) * scale;
655 cres->cy = (w1 + w2) * scale;
656 cres->flags = C_CDXY|C_CSXY;
657 }
658 }
659
660
661 #define C1 3.741832e-16 /* W-m^2 */
662 #define C2 1.4388e-2 /* m-K */
663
664 #define bbsp(l,t) (C1/((l)*(l)*(l)*(l)*(l)*(exp(C2/((t)*(l)))-1.)))
665 #define bblm(t) (C2/5./(t))
666
667 static int
668 setbbtemp(clr, tk) /* set black body spectrum */
669 register C_COLOR *clr;
670 double tk;
671 {
672 double sf, wl;
673 register int i;
674
675 if (tk < 1000)
676 return(MG_EILL);
677 wl = bblm(tk); /* scalefactor based on peak */
678 if (wl < C_CMINWL*1e-9)
679 wl = C_CMINWL*1e-9;
680 else if (wl > C_CMAXWL*1e-9)
681 wl = C_CMAXWL*1e-9;
682 sf = C_CMAXV/bbsp(wl,tk);
683 clr->ssum = 0;
684 for (i = 0; i < C_CNSS; i++) {
685 wl = (C_CMINWL + i*C_CWLI)*1e-9;
686 clr->ssum += clr->ssamp[i] = sf*bbsp(wl,tk) + .5;
687 }
688 clr->flags = C_CDSPEC|C_CSSPEC;
689 clr->clock++;
690 return(MG_OK);
691 }
692
693 #undef C1
694 #undef C2
695 #undef bbsp
696 #undef bblm