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root/radiance/ray/src/rt/m_brdf.c
Revision: 2.10
Committed: Wed Jan 12 16:46:35 1994 UTC (30 years, 3 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.9: +6 -2 lines
Log Message:
made mixtures work with materials

File Contents

# User Rev Content
1 greg 1.7 /* Copyright (c) 1991 Regents of the University of California */
2 greg 1.1
3     #ifndef lint
4     static char SCCSid[] = "$SunId$ LBL";
5     #endif
6    
7     /*
8     * Shading for materials with arbitrary BRDF's
9     */
10    
11     #include "ray.h"
12    
13     #include "data.h"
14    
15     #include "otypes.h"
16    
17 greg 2.2 #include "func.h"
18    
19 greg 1.1 /*
20     * Arguments to this material include the color and specularity.
21     * String arguments include the reflection function and files.
22     * The BRDF is currently used just for the specular component to light
23     * sources. Reflectance values or data coordinates are functions
24 greg 2.7 * of the direction to the light source. (Data modification functions
25     * are passed the source direction as args 2-4.)
26 greg 1.1 * We orient the surface towards the incoming ray, so a single
27     * surface can be used to represent an infinitely thin object.
28     *
29     * Arguments for MAT_PFUNC and MAT_MFUNC are:
30 greg 1.4 * 2+ func funcfile transform
31 greg 1.1 * 0
32 greg 1.4 * 4+ red grn blu specularity A5 ..
33 greg 1.1 *
34     * Arguments for MAT_PDATA and MAT_MDATA are:
35 greg 1.4 * 4+ func datafile funcfile v0 .. transform
36 greg 1.1 * 0
37 greg 1.4 * 4+ red grn blu specularity A5 ..
38 greg 1.5 *
39     * Arguments for MAT_TFUNC are:
40     * 2+ func funcfile transform
41     * 0
42     * 4+ red grn blu rspec trans tspec A7 ..
43     *
44     * Arguments for MAT_TDATA are:
45     * 4+ func datafile funcfile v0 .. transform
46     * 0
47     * 4+ red grn blu rspec trans tspec A7 ..
48     *
49     * Arguments for the more general MAT_BRTDF are:
50     * 10+ rrefl grefl brefl
51     * rtrns gtrns btrns
52     * rbrtd gbrtd bbrtd
53     * funcfile transform
54     * 0
55 greg 2.6 * 9+ rdf gdf bdf
56     * rdb gdb bdb
57     * rdt gdt bdt A10 ..
58 greg 1.5 *
59     * In addition to the normal variables available to functions,
60     * we define the following:
61     * NxP, NyP, NzP - perturbed surface normal
62     * RdotP - perturbed ray dot product
63 greg 2.6 * CrP, CgP, CbP - perturbed material color (or pattern)
64 greg 1.1 */
65    
66     typedef struct {
67     OBJREC *mp; /* material pointer */
68     RAY *pr; /* intersected ray */
69 greg 1.5 DATARRAY *dp; /* data array for PDATA, MDATA or TDATA */
70 greg 2.6 COLOR mcolor; /* material (or pattern) color */
71     COLOR rdiff; /* diffuse reflection */
72     COLOR tdiff; /* diffuse transmission */
73     double rspec; /* specular reflectance (1 for BRDTF) */
74     double trans; /* transmissivity (.5 for BRDTF) */
75     double tspec; /* specular transmittance (1 for BRDTF) */
76 greg 1.1 FVECT pnorm; /* perturbed surface normal */
77     double pdot; /* perturbed dot product */
78     } BRDFDAT; /* BRDF material data */
79    
80    
81     dirbrdf(cval, np, ldir, omega) /* compute source contribution */
82     COLOR cval; /* returned coefficient */
83     register BRDFDAT *np; /* material data */
84     FVECT ldir; /* light source direction */
85     double omega; /* light source size */
86     {
87     double ldot;
88     double dtmp;
89     COLOR ctmp;
90 greg 1.4 FVECT ldx;
91 greg 2.3 double lddx[3], pt[MAXDIM];
92 greg 2.7 double vldx[4];
93 greg 1.5 register char **sa;
94 greg 1.1 register int i;
95    
96     setcolor(cval, 0.0, 0.0, 0.0);
97    
98     ldot = DOT(np->pnorm, ldir);
99    
100 greg 1.5 if (ldot <= FTINY && ldot >= -FTINY)
101     return; /* too close to grazing */
102 greg 2.6
103 greg 1.5 if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
104 greg 1.1 return; /* wrong side */
105    
106 greg 2.6 if (ldot > 0.0) {
107 greg 1.1 /*
108     * Compute and add diffuse reflected component to returned
109     * color. The diffuse reflected component will always be
110     * modified by the color of the material.
111     */
112 greg 2.6 copycolor(ctmp, np->rdiff);
113     dtmp = ldot * omega / PI;
114 greg 1.1 scalecolor(ctmp, dtmp);
115     addcolor(cval, ctmp);
116 greg 2.6 } else {
117 greg 1.1 /*
118 greg 1.5 * Diffuse transmitted component.
119 greg 1.1 */
120 greg 2.6 copycolor(ctmp, np->tdiff);
121     dtmp = -ldot * omega / PI;
122 greg 1.5 scalecolor(ctmp, dtmp);
123     addcolor(cval, ctmp);
124 greg 1.1 }
125 greg 1.5 if (ldot > 0.0 ? np->rspec <= FTINY : np->tspec <= FTINY)
126     return; /* no specular component */
127     /* set up function */
128 greg 1.10 setbrdfunc(np);
129 greg 1.5 sa = np->mp->oargs.sarg;
130     errno = 0;
131     /* transform light vector */
132     multv3(ldx, ldir, funcxf.xfm);
133     for (i = 0; i < 3; i++)
134 greg 2.3 lddx[i] = ldx[i]/funcxf.sca;
135 greg 1.5 /* compute BRTDF */
136     if (np->mp->otype == MAT_BRTDF) {
137 greg 2.6 if (sa[6][0] == '0') /* special case */
138     colval(ctmp,RED) = 0.0;
139     else
140     colval(ctmp,RED) = funvalue(sa[6], 3, lddx);
141 greg 1.7 if (!strcmp(sa[7],sa[6]))
142 greg 1.5 colval(ctmp,GRN) = colval(ctmp,RED);
143     else
144 greg 2.3 colval(ctmp,GRN) = funvalue(sa[7], 3, lddx);
145 greg 1.7 if (!strcmp(sa[8],sa[6]))
146 greg 1.5 colval(ctmp,BLU) = colval(ctmp,RED);
147 greg 1.7 else if (!strcmp(sa[8],sa[7]))
148 greg 1.5 colval(ctmp,BLU) = colval(ctmp,GRN);
149     else
150 greg 2.3 colval(ctmp,BLU) = funvalue(sa[8], 3, lddx);
151 greg 1.5 dtmp = bright(ctmp);
152     } else if (np->dp == NULL) {
153 greg 2.3 dtmp = funvalue(sa[0], 3, lddx);
154 greg 1.5 setcolor(ctmp, dtmp, dtmp, dtmp);
155     } else {
156     for (i = 0; i < np->dp->nd; i++)
157 greg 2.3 pt[i] = funvalue(sa[3+i], 3, lddx);
158 greg 2.7 vldx[0] = datavalue(np->dp, pt);
159     vldx[1] = lddx[0]; vldx[2] = lddx[1]; vldx[3] = lddx[2];
160     dtmp = funvalue(sa[0], 4, vldx);
161 greg 1.5 setcolor(ctmp, dtmp, dtmp, dtmp);
162     }
163 greg 2.2 if (errno) {
164     objerror(np->mp, WARNING, "compute error");
165     return;
166     }
167 greg 1.5 if (dtmp <= FTINY)
168     return;
169     if (ldot > 0.0) {
170     /*
171     * Compute reflected non-diffuse component.
172     */
173 greg 2.6 if (np->mp->otype == MAT_MFUNC | np->mp->otype == MAT_MDATA)
174 greg 1.6 multcolor(ctmp, np->mcolor);
175     dtmp = ldot * omega * np->rspec;
176 greg 1.5 scalecolor(ctmp, dtmp);
177     addcolor(cval, ctmp);
178     } else {
179     /*
180     * Compute transmitted non-diffuse component.
181     */
182 greg 2.6 if (np->mp->otype == MAT_TFUNC | np->mp->otype == MAT_TDATA)
183 greg 1.6 multcolor(ctmp, np->mcolor);
184 greg 1.5 dtmp = -ldot * omega * np->tspec;
185     scalecolor(ctmp, dtmp);
186     addcolor(cval, ctmp);
187     }
188 greg 1.1 }
189    
190    
191 greg 2.6 m_brdf(m, r) /* color a ray which hit a BRDTF material */
192 greg 1.1 register OBJREC *m;
193     register RAY *r;
194     {
195     BRDFDAT nd;
196 greg 2.6 RAY sr;
197 greg 1.7 double transtest, transdist;
198 greg 2.6 int hasrefl, hastrans;
199 greg 1.1 COLOR ctmp;
200 greg 2.6 register MFUNC *mf;
201 greg 1.1 register int i;
202 greg 1.5 /* check arguments */
203 greg 2.6 if (m->oargs.nsargs < 10 | m->oargs.nfargs < 9)
204     objerror(m, USER, "bad # arguments");
205     nd.mp = m;
206     nd.pr = r;
207     /* dummy values */
208     nd.rspec = nd.tspec = 1.0;
209     nd.trans = 0.5;
210     /* diffuse reflectance */
211     if (r->rod > 0.0)
212     setcolor(nd.rdiff, m->oargs.farg[0],
213     m->oargs.farg[1],
214     m->oargs.farg[2]);
215     else
216     setcolor(nd.rdiff, m->oargs.farg[3],
217     m->oargs.farg[4],
218     m->oargs.farg[5]);
219     /* diffuse transmittance */
220     setcolor(nd.tdiff, m->oargs.farg[6],
221     m->oargs.farg[7],
222     m->oargs.farg[8]);
223     /* get modifiers */
224     raytexture(r, m->omod);
225     nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
226     if (r->rod < 0.0) { /* orient perturbed values */
227     nd.pdot = -nd.pdot;
228     for (i = 0; i < 3; i++) {
229     nd.pnorm[i] = -nd.pnorm[i];
230     r->pert[i] = -r->pert[i];
231     }
232 greg 1.5 }
233 greg 2.6 copycolor(nd.mcolor, r->pcol); /* get pattern color */
234     multcolor(nd.rdiff, nd.mcolor); /* modify diffuse values */
235     multcolor(nd.tdiff, nd.mcolor);
236     hasrefl = bright(nd.rdiff) > FTINY;
237     hastrans = bright(nd.tdiff) > FTINY;
238     /* load cal file */
239     nd.dp = NULL;
240     mf = getfunc(m, 9, 0x3f, 0);
241     /* compute transmitted ray */
242     setbrdfunc(&nd);
243     transtest = 0;
244 greg 2.8 transdist = r->rot;
245 greg 2.6 errno = 0;
246     setcolor(ctmp, evalue(mf->ep[3]),
247     evalue(mf->ep[4]),
248     evalue(mf->ep[5]));
249     if (errno)
250     objerror(m, WARNING, "compute error");
251     else if (rayorigin(&sr, r, TRANS, bright(ctmp)) == 0) {
252     if (!(r->crtype & SHADOW) &&
253     DOT(r->pert,r->pert) > FTINY*FTINY) {
254     for (i = 0; i < 3; i++) /* perturb direction */
255     sr.rdir[i] = r->rdir[i] - .75*r->pert[i];
256     if (normalize(sr.rdir) == 0.0) {
257     objerror(m, WARNING, "illegal perturbation");
258     VCOPY(sr.rdir, r->rdir);
259     }
260     } else {
261     VCOPY(sr.rdir, r->rdir);
262     transtest = 2;
263     }
264     rayvalue(&sr);
265     multcolor(sr.rcol, ctmp);
266     addcolor(r->rcol, sr.rcol);
267     transtest *= bright(sr.rcol);
268     transdist = r->rot + sr.rt;
269     }
270     if (r->crtype & SHADOW) /* the rest is shadow */
271 greg 2.10 return(1);
272 greg 2.6 /* compute reflected ray */
273     setbrdfunc(&nd);
274     errno = 0;
275     setcolor(ctmp, evalue(mf->ep[0]),
276     evalue(mf->ep[1]),
277     evalue(mf->ep[2]));
278     if (errno)
279     objerror(m, WARNING, "compute error");
280     else if (rayorigin(&sr, r, REFLECTED, bright(ctmp)) == 0) {
281     for (i = 0; i < 3; i++)
282     sr.rdir[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i];
283     rayvalue(&sr);
284     multcolor(sr.rcol, ctmp);
285     addcolor(r->rcol, sr.rcol);
286     }
287     /* compute ambient */
288     if (hasrefl) {
289     if (nd.pdot < 0.0)
290     flipsurface(r);
291     ambient(ctmp, r);
292     multcolor(ctmp, nd.rdiff);
293     addcolor(r->rcol, ctmp); /* add to returned color */
294     if (nd.pdot < 0.0)
295     flipsurface(r);
296     }
297     if (hastrans) { /* from other side */
298     if (nd.pdot > 0.0)
299     flipsurface(r);
300     ambient(ctmp, r);
301     multcolor(ctmp, nd.tdiff);
302     addcolor(r->rcol, ctmp);
303     if (nd.pdot > 0.0)
304     flipsurface(r);
305     }
306     if (hasrefl | hastrans || m->oargs.sarg[6][0] != '0')
307     direct(r, dirbrdf, &nd); /* add direct component */
308     /* check distance */
309     if (transtest > bright(r->rcol))
310     r->rt = transdist;
311 greg 2.10
312     return(1);
313 greg 2.6 }
314    
315    
316    
317     m_brdf2(m, r) /* color a ray which hit a BRDF material */
318     register OBJREC *m;
319     register RAY *r;
320     {
321     BRDFDAT nd;
322     COLOR ctmp;
323     double dtmp;
324     /* always a shadow */
325     if (r->crtype & SHADOW)
326 greg 2.10 return(1);
327 greg 2.6 /* check arguments */
328     if (m->oargs.nsargs < (hasdata(m->otype)?4:2) | m->oargs.nfargs <
329     (m->otype==MAT_TFUNC|m->otype==MAT_TDATA?6:4))
330 greg 1.1 objerror(m, USER, "bad # arguments");
331     nd.mp = m;
332     nd.pr = r;
333 greg 2.6 /* get material color */
334     setcolor(nd.mcolor, m->oargs.farg[0],
335     m->oargs.farg[1],
336     m->oargs.farg[2]);
337 greg 1.5 /* get specular component */
338     nd.rspec = m->oargs.farg[3];
339 greg 2.6 /* compute transmittance */
340     if (m->otype == MAT_TFUNC | m->otype == MAT_TDATA) {
341 greg 1.5 nd.trans = m->oargs.farg[4]*(1.0 - nd.rspec);
342     nd.tspec = nd.trans * m->oargs.farg[5];
343 greg 2.6 dtmp = nd.trans - nd.tspec;
344     setcolor(nd.tdiff, dtmp, dtmp, dtmp);
345     } else {
346     nd.tspec = nd.trans = 0.0;
347     setcolor(nd.tdiff, 0.0, 0.0, 0.0);
348     }
349     /* compute reflectance */
350     dtmp = 1.0 - nd.trans - nd.rspec;
351     setcolor(nd.rdiff, dtmp, dtmp, dtmp);
352 greg 1.5 /* fix orientation */
353 greg 2.6 if (r->rod < 0.0)
354 greg 1.5 flipsurface(r);
355     /* get modifiers */
356     raytexture(r, m->omod);
357     nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
358     multcolor(nd.mcolor, r->pcol); /* modify material color */
359 greg 2.6 multcolor(nd.rdiff, nd.mcolor);
360     multcolor(nd.tdiff, nd.mcolor);
361 greg 1.1 /* load auxiliary files */
362 greg 2.2 if (hasdata(m->otype)) {
363 greg 1.1 nd.dp = getdata(m->oargs.sarg[1]);
364 greg 2.6 getfunc(m, 2, 0, 0);
365 greg 1.1 } else {
366     nd.dp = NULL;
367 greg 2.6 getfunc(m, 1, 0, 0);
368 greg 1.1 }
369     /* compute ambient */
370 greg 2.6 if (nd.trans < 1.0-FTINY) {
371 greg 1.1 ambient(ctmp, r);
372 greg 2.6 scalecolor(ctmp, 1.0-nd.trans);
373 greg 1.1 multcolor(ctmp, nd.mcolor); /* modified by material color */
374     addcolor(r->rcol, ctmp); /* add to returned color */
375 greg 1.5 }
376 greg 2.6 if (nd.trans > FTINY) { /* from other side */
377 greg 1.5 flipsurface(r);
378     ambient(ctmp, r);
379 greg 2.6 scalecolor(ctmp, nd.trans);
380 greg 1.5 multcolor(ctmp, nd.mcolor);
381     addcolor(r->rcol, ctmp);
382     flipsurface(r);
383 greg 1.1 }
384     /* add direct component */
385     direct(r, dirbrdf, &nd);
386 greg 2.10
387     return(1);
388 greg 1.10 }
389    
390    
391     setbrdfunc(np) /* set up brdf function and variables */
392     register BRDFDAT *np;
393     {
394     FVECT vec;
395    
396     if (setfunc(np->mp, np->pr) == 0)
397     return(0); /* it's OK, setfunc says we're done */
398     /* else (re)assign special variables */
399     multv3(vec, np->pnorm, funcxf.xfm);
400     varset("NxP", '=', vec[0]/funcxf.sca);
401     varset("NyP", '=', vec[1]/funcxf.sca);
402     varset("NzP", '=', vec[2]/funcxf.sca);
403 greg 1.11 varset("RdotP", '=', np->pdot <= -1.0 ? -1.0 :
404     np->pdot >= 1.0 ? 1.0 : np->pdot);
405 greg 1.10 varset("CrP", '=', colval(np->mcolor,RED));
406     varset("CgP", '=', colval(np->mcolor,GRN));
407     varset("CbP", '=', colval(np->mcolor,BLU));
408     return(1);
409 greg 1.1 }