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root/radiance/ray/src/rt/m_brdf.c
Revision: 2.13
Committed: Mon Nov 6 12:03:22 1995 UTC (28 years, 5 months ago) by greg
Content type: text/plain
Branch: MAIN
Changes since 2.12: +5 -5 lines
Log Message:
added texturing to ambient value computation using extambient()

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 2.11 extern int backvis; /* back faces visible? */
20    
21 greg 1.1 /*
22     * Arguments to this material include the color and specularity.
23     * String arguments include the reflection function and files.
24     * The BRDF is currently used just for the specular component to light
25     * sources. Reflectance values or data coordinates are functions
26 greg 2.7 * of the direction to the light source. (Data modification functions
27     * are passed the source direction as args 2-4.)
28 greg 1.1 * We orient the surface towards the incoming ray, so a single
29     * surface can be used to represent an infinitely thin object.
30     *
31     * Arguments for MAT_PFUNC and MAT_MFUNC are:
32 greg 1.4 * 2+ func funcfile transform
33 greg 1.1 * 0
34 greg 1.4 * 4+ red grn blu specularity A5 ..
35 greg 1.1 *
36     * Arguments for MAT_PDATA and MAT_MDATA are:
37 greg 1.4 * 4+ func datafile funcfile v0 .. transform
38 greg 1.1 * 0
39 greg 1.4 * 4+ red grn blu specularity A5 ..
40 greg 1.5 *
41     * Arguments for MAT_TFUNC are:
42     * 2+ func funcfile transform
43     * 0
44     * 4+ red grn blu rspec trans tspec A7 ..
45     *
46     * Arguments for MAT_TDATA are:
47     * 4+ func datafile funcfile v0 .. transform
48     * 0
49     * 4+ red grn blu rspec trans tspec A7 ..
50     *
51     * Arguments for the more general MAT_BRTDF are:
52     * 10+ rrefl grefl brefl
53     * rtrns gtrns btrns
54     * rbrtd gbrtd bbrtd
55     * funcfile transform
56     * 0
57 greg 2.6 * 9+ rdf gdf bdf
58     * rdb gdb bdb
59     * rdt gdt bdt A10 ..
60 greg 1.5 *
61     * In addition to the normal variables available to functions,
62     * we define the following:
63     * NxP, NyP, NzP - perturbed surface normal
64     * RdotP - perturbed ray dot product
65 greg 2.6 * CrP, CgP, CbP - perturbed material color (or pattern)
66 greg 1.1 */
67    
68     typedef struct {
69     OBJREC *mp; /* material pointer */
70     RAY *pr; /* intersected ray */
71 greg 1.5 DATARRAY *dp; /* data array for PDATA, MDATA or TDATA */
72 greg 2.6 COLOR mcolor; /* material (or pattern) color */
73     COLOR rdiff; /* diffuse reflection */
74     COLOR tdiff; /* diffuse transmission */
75     double rspec; /* specular reflectance (1 for BRDTF) */
76     double trans; /* transmissivity (.5 for BRDTF) */
77     double tspec; /* specular transmittance (1 for BRDTF) */
78 greg 1.1 FVECT pnorm; /* perturbed surface normal */
79     double pdot; /* perturbed dot product */
80     } BRDFDAT; /* BRDF material data */
81    
82    
83     dirbrdf(cval, np, ldir, omega) /* compute source contribution */
84     COLOR cval; /* returned coefficient */
85     register BRDFDAT *np; /* material data */
86     FVECT ldir; /* light source direction */
87     double omega; /* light source size */
88     {
89     double ldot;
90     double dtmp;
91     COLOR ctmp;
92 greg 1.4 FVECT ldx;
93 greg 2.12 static double vldx[5], pt[MAXDIM];
94 greg 1.5 register char **sa;
95 greg 1.1 register int i;
96 greg 2.12 #define lddx (vldx+1)
97 greg 1.1
98     setcolor(cval, 0.0, 0.0, 0.0);
99    
100     ldot = DOT(np->pnorm, ldir);
101    
102 greg 1.5 if (ldot <= FTINY && ldot >= -FTINY)
103     return; /* too close to grazing */
104 greg 2.6
105 greg 1.5 if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
106 greg 1.1 return; /* wrong side */
107    
108 greg 2.6 if (ldot > 0.0) {
109 greg 1.1 /*
110     * Compute and add diffuse reflected component to returned
111     * color. The diffuse reflected component will always be
112     * modified by the color of the material.
113     */
114 greg 2.6 copycolor(ctmp, np->rdiff);
115     dtmp = ldot * omega / PI;
116 greg 1.1 scalecolor(ctmp, dtmp);
117     addcolor(cval, ctmp);
118 greg 2.6 } else {
119 greg 1.1 /*
120 greg 1.5 * Diffuse transmitted component.
121 greg 1.1 */
122 greg 2.6 copycolor(ctmp, np->tdiff);
123     dtmp = -ldot * omega / PI;
124 greg 1.5 scalecolor(ctmp, dtmp);
125     addcolor(cval, ctmp);
126 greg 1.1 }
127 greg 1.5 if (ldot > 0.0 ? np->rspec <= FTINY : np->tspec <= FTINY)
128     return; /* no specular component */
129     /* set up function */
130 greg 1.10 setbrdfunc(np);
131 greg 1.5 sa = np->mp->oargs.sarg;
132     errno = 0;
133     /* transform light vector */
134     multv3(ldx, ldir, funcxf.xfm);
135     for (i = 0; i < 3; i++)
136 greg 2.3 lddx[i] = ldx[i]/funcxf.sca;
137 greg 2.12 lddx[3] = omega;
138 greg 1.5 /* compute BRTDF */
139     if (np->mp->otype == MAT_BRTDF) {
140 greg 2.6 if (sa[6][0] == '0') /* special case */
141     colval(ctmp,RED) = 0.0;
142     else
143 greg 2.12 colval(ctmp,RED) = funvalue(sa[6], 4, lddx);
144 greg 1.7 if (!strcmp(sa[7],sa[6]))
145 greg 1.5 colval(ctmp,GRN) = colval(ctmp,RED);
146     else
147 greg 2.12 colval(ctmp,GRN) = funvalue(sa[7], 4, lddx);
148 greg 1.7 if (!strcmp(sa[8],sa[6]))
149 greg 1.5 colval(ctmp,BLU) = colval(ctmp,RED);
150 greg 1.7 else if (!strcmp(sa[8],sa[7]))
151 greg 1.5 colval(ctmp,BLU) = colval(ctmp,GRN);
152     else
153 greg 2.12 colval(ctmp,BLU) = funvalue(sa[8], 4, lddx);
154 greg 1.5 dtmp = bright(ctmp);
155     } else if (np->dp == NULL) {
156 greg 2.12 dtmp = funvalue(sa[0], 4, lddx);
157 greg 1.5 setcolor(ctmp, dtmp, dtmp, dtmp);
158     } else {
159     for (i = 0; i < np->dp->nd; i++)
160 greg 2.12 pt[i] = funvalue(sa[3+i], 4, lddx);
161 greg 2.7 vldx[0] = datavalue(np->dp, pt);
162 greg 2.12 dtmp = funvalue(sa[0], 5, vldx);
163 greg 1.5 setcolor(ctmp, dtmp, dtmp, dtmp);
164     }
165 greg 2.2 if (errno) {
166     objerror(np->mp, WARNING, "compute error");
167     return;
168     }
169 greg 1.5 if (dtmp <= FTINY)
170     return;
171     if (ldot > 0.0) {
172     /*
173     * Compute reflected non-diffuse component.
174     */
175 greg 2.6 if (np->mp->otype == MAT_MFUNC | np->mp->otype == MAT_MDATA)
176 greg 1.6 multcolor(ctmp, np->mcolor);
177     dtmp = ldot * omega * np->rspec;
178 greg 1.5 scalecolor(ctmp, dtmp);
179     addcolor(cval, ctmp);
180     } else {
181     /*
182     * Compute transmitted non-diffuse component.
183     */
184 greg 2.6 if (np->mp->otype == MAT_TFUNC | np->mp->otype == MAT_TDATA)
185 greg 1.6 multcolor(ctmp, np->mcolor);
186 greg 1.5 dtmp = -ldot * omega * np->tspec;
187     scalecolor(ctmp, dtmp);
188     addcolor(cval, ctmp);
189     }
190 greg 2.12 #undef lddx
191 greg 1.1 }
192    
193    
194 greg 2.13 m_brdf(m, r) /* color a ray which hit a BRDTfunc material */
195 greg 1.1 register OBJREC *m;
196     register RAY *r;
197     {
198     BRDFDAT nd;
199 greg 2.6 RAY sr;
200 greg 1.7 double transtest, transdist;
201 greg 2.6 int hasrefl, hastrans;
202 greg 1.1 COLOR ctmp;
203 greg 2.6 register MFUNC *mf;
204 greg 1.1 register int i;
205 greg 1.5 /* check arguments */
206 greg 2.6 if (m->oargs.nsargs < 10 | m->oargs.nfargs < 9)
207     objerror(m, USER, "bad # arguments");
208     nd.mp = m;
209     nd.pr = r;
210     /* dummy values */
211     nd.rspec = nd.tspec = 1.0;
212     nd.trans = 0.5;
213     /* diffuse reflectance */
214     if (r->rod > 0.0)
215     setcolor(nd.rdiff, m->oargs.farg[0],
216     m->oargs.farg[1],
217     m->oargs.farg[2]);
218     else
219     setcolor(nd.rdiff, m->oargs.farg[3],
220     m->oargs.farg[4],
221     m->oargs.farg[5]);
222     /* diffuse transmittance */
223     setcolor(nd.tdiff, m->oargs.farg[6],
224     m->oargs.farg[7],
225     m->oargs.farg[8]);
226     /* get modifiers */
227     raytexture(r, m->omod);
228     nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
229     if (r->rod < 0.0) { /* orient perturbed values */
230     nd.pdot = -nd.pdot;
231     for (i = 0; i < 3; i++) {
232     nd.pnorm[i] = -nd.pnorm[i];
233     r->pert[i] = -r->pert[i];
234     }
235 greg 1.5 }
236 greg 2.6 copycolor(nd.mcolor, r->pcol); /* get pattern color */
237     multcolor(nd.rdiff, nd.mcolor); /* modify diffuse values */
238     multcolor(nd.tdiff, nd.mcolor);
239     hasrefl = bright(nd.rdiff) > FTINY;
240     hastrans = bright(nd.tdiff) > FTINY;
241     /* load cal file */
242     nd.dp = NULL;
243     mf = getfunc(m, 9, 0x3f, 0);
244     /* compute transmitted ray */
245     setbrdfunc(&nd);
246     transtest = 0;
247 greg 2.8 transdist = r->rot;
248 greg 2.6 errno = 0;
249     setcolor(ctmp, evalue(mf->ep[3]),
250     evalue(mf->ep[4]),
251     evalue(mf->ep[5]));
252     if (errno)
253     objerror(m, WARNING, "compute error");
254     else if (rayorigin(&sr, r, TRANS, bright(ctmp)) == 0) {
255     if (!(r->crtype & SHADOW) &&
256     DOT(r->pert,r->pert) > FTINY*FTINY) {
257     for (i = 0; i < 3; i++) /* perturb direction */
258     sr.rdir[i] = r->rdir[i] - .75*r->pert[i];
259     if (normalize(sr.rdir) == 0.0) {
260     objerror(m, WARNING, "illegal perturbation");
261     VCOPY(sr.rdir, r->rdir);
262     }
263     } else {
264     VCOPY(sr.rdir, r->rdir);
265     transtest = 2;
266     }
267     rayvalue(&sr);
268     multcolor(sr.rcol, ctmp);
269     addcolor(r->rcol, sr.rcol);
270     transtest *= bright(sr.rcol);
271     transdist = r->rot + sr.rt;
272     }
273     if (r->crtype & SHADOW) /* the rest is shadow */
274 greg 2.10 return(1);
275 greg 2.6 /* compute reflected ray */
276     setbrdfunc(&nd);
277     errno = 0;
278     setcolor(ctmp, evalue(mf->ep[0]),
279     evalue(mf->ep[1]),
280     evalue(mf->ep[2]));
281     if (errno)
282     objerror(m, WARNING, "compute error");
283     else if (rayorigin(&sr, r, REFLECTED, bright(ctmp)) == 0) {
284     for (i = 0; i < 3; i++)
285     sr.rdir[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i];
286     rayvalue(&sr);
287     multcolor(sr.rcol, ctmp);
288     addcolor(r->rcol, sr.rcol);
289     }
290     /* compute ambient */
291     if (hasrefl) {
292     if (nd.pdot < 0.0)
293     flipsurface(r);
294 greg 2.13 ambient(ctmp, r, nd.pnorm);
295 greg 2.6 multcolor(ctmp, nd.rdiff);
296     addcolor(r->rcol, ctmp); /* add to returned color */
297     if (nd.pdot < 0.0)
298     flipsurface(r);
299     }
300     if (hastrans) { /* from other side */
301     if (nd.pdot > 0.0)
302     flipsurface(r);
303 greg 2.13 ambient(ctmp, r, nd.pnorm);
304 greg 2.6 multcolor(ctmp, nd.tdiff);
305     addcolor(r->rcol, ctmp);
306     if (nd.pdot > 0.0)
307     flipsurface(r);
308     }
309     if (hasrefl | hastrans || m->oargs.sarg[6][0] != '0')
310     direct(r, dirbrdf, &nd); /* add direct component */
311     /* check distance */
312     if (transtest > bright(r->rcol))
313     r->rt = transdist;
314 greg 2.10
315     return(1);
316 greg 2.6 }
317    
318    
319    
320     m_brdf2(m, r) /* color a ray which hit a BRDF material */
321     register OBJREC *m;
322     register RAY *r;
323     {
324     BRDFDAT nd;
325     COLOR ctmp;
326     double dtmp;
327     /* always a shadow */
328     if (r->crtype & SHADOW)
329 greg 2.10 return(1);
330 greg 2.6 /* check arguments */
331     if (m->oargs.nsargs < (hasdata(m->otype)?4:2) | m->oargs.nfargs <
332     (m->otype==MAT_TFUNC|m->otype==MAT_TDATA?6:4))
333 greg 1.1 objerror(m, USER, "bad # arguments");
334     nd.mp = m;
335     nd.pr = r;
336 greg 2.6 /* get material color */
337     setcolor(nd.mcolor, m->oargs.farg[0],
338     m->oargs.farg[1],
339     m->oargs.farg[2]);
340 greg 1.5 /* get specular component */
341     nd.rspec = m->oargs.farg[3];
342 greg 2.6 /* compute transmittance */
343     if (m->otype == MAT_TFUNC | m->otype == MAT_TDATA) {
344 greg 1.5 nd.trans = m->oargs.farg[4]*(1.0 - nd.rspec);
345     nd.tspec = nd.trans * m->oargs.farg[5];
346 greg 2.6 dtmp = nd.trans - nd.tspec;
347     setcolor(nd.tdiff, dtmp, dtmp, dtmp);
348     } else {
349     nd.tspec = nd.trans = 0.0;
350     setcolor(nd.tdiff, 0.0, 0.0, 0.0);
351     }
352     /* compute reflectance */
353     dtmp = 1.0 - nd.trans - nd.rspec;
354     setcolor(nd.rdiff, dtmp, dtmp, dtmp);
355 greg 2.11 /* check for back side */
356     if (r->rod < 0.0) {
357     if (!backvis && m->otype != MAT_TFUNC
358     && m->otype != MAT_TDATA) {
359     raytrans(r);
360     return(1);
361     }
362     flipsurface(r); /* reorient if backvis */
363     }
364 greg 1.5 /* get modifiers */
365     raytexture(r, m->omod);
366     nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */
367     multcolor(nd.mcolor, r->pcol); /* modify material color */
368 greg 2.6 multcolor(nd.rdiff, nd.mcolor);
369     multcolor(nd.tdiff, nd.mcolor);
370 greg 1.1 /* load auxiliary files */
371 greg 2.2 if (hasdata(m->otype)) {
372 greg 1.1 nd.dp = getdata(m->oargs.sarg[1]);
373 greg 2.6 getfunc(m, 2, 0, 0);
374 greg 1.1 } else {
375     nd.dp = NULL;
376 greg 2.6 getfunc(m, 1, 0, 0);
377 greg 1.1 }
378     /* compute ambient */
379 greg 2.6 if (nd.trans < 1.0-FTINY) {
380 greg 2.13 ambient(ctmp, r, nd.pnorm);
381 greg 2.6 scalecolor(ctmp, 1.0-nd.trans);
382 greg 1.1 multcolor(ctmp, nd.mcolor); /* modified by material color */
383     addcolor(r->rcol, ctmp); /* add to returned color */
384 greg 1.5 }
385 greg 2.6 if (nd.trans > FTINY) { /* from other side */
386 greg 1.5 flipsurface(r);
387 greg 2.13 ambient(ctmp, r, nd.pnorm);
388 greg 2.6 scalecolor(ctmp, nd.trans);
389 greg 1.5 multcolor(ctmp, nd.mcolor);
390     addcolor(r->rcol, ctmp);
391     flipsurface(r);
392 greg 1.1 }
393     /* add direct component */
394     direct(r, dirbrdf, &nd);
395 greg 2.10
396     return(1);
397 greg 1.10 }
398    
399    
400     setbrdfunc(np) /* set up brdf function and variables */
401     register BRDFDAT *np;
402     {
403     FVECT vec;
404    
405     if (setfunc(np->mp, np->pr) == 0)
406     return(0); /* it's OK, setfunc says we're done */
407     /* else (re)assign special variables */
408     multv3(vec, np->pnorm, funcxf.xfm);
409     varset("NxP", '=', vec[0]/funcxf.sca);
410     varset("NyP", '=', vec[1]/funcxf.sca);
411     varset("NzP", '=', vec[2]/funcxf.sca);
412 greg 1.11 varset("RdotP", '=', np->pdot <= -1.0 ? -1.0 :
413     np->pdot >= 1.0 ? 1.0 : np->pdot);
414 greg 1.10 varset("CrP", '=', colval(np->mcolor,RED));
415     varset("CgP", '=', colval(np->mcolor,GRN));
416     varset("CbP", '=', colval(np->mcolor,BLU));
417     return(1);
418 greg 1.1 }