1 |
/* Copyright (c) 1996 Regents of the University of California */ |
2 |
|
3 |
#ifndef lint |
4 |
static char SCCSid[] = "$SunId$ LBL"; |
5 |
#endif |
6 |
|
7 |
/* |
8 |
* normal.c - shading function for normal materials. |
9 |
* |
10 |
* 8/19/85 |
11 |
* 12/19/85 - added stuff for metals. |
12 |
* 6/26/87 - improved specular model. |
13 |
* 9/28/87 - added model for translucent materials. |
14 |
* Later changes described in delta comments. |
15 |
*/ |
16 |
|
17 |
#include "ray.h" |
18 |
|
19 |
#include "otypes.h" |
20 |
|
21 |
#include "random.h" |
22 |
|
23 |
extern double specthresh; /* specular sampling threshold */ |
24 |
extern double specjitter; /* specular sampling jitter */ |
25 |
|
26 |
extern int backvis; /* back faces visible? */ |
27 |
|
28 |
#ifndef MAXITER |
29 |
#define MAXITER 10 /* maximum # specular ray attempts */ |
30 |
#endif |
31 |
|
32 |
static gaussamp(); |
33 |
|
34 |
/* |
35 |
* This routine implements the isotropic Gaussian |
36 |
* model described by Ward in Siggraph `92 article. |
37 |
* We orient the surface towards the incoming ray, so a single |
38 |
* surface can be used to represent an infinitely thin object. |
39 |
* |
40 |
* Arguments for MAT_PLASTIC and MAT_METAL are: |
41 |
* red grn blu specular-frac. facet-slope |
42 |
* |
43 |
* Arguments for MAT_TRANS are: |
44 |
* red grn blu rspec rough trans tspec |
45 |
*/ |
46 |
|
47 |
/* specularity flags */ |
48 |
#define SP_REFL 01 /* has reflected specular component */ |
49 |
#define SP_TRAN 02 /* has transmitted specular */ |
50 |
#define SP_PURE 04 /* purely specular (zero roughness) */ |
51 |
#define SP_FLAT 010 /* flat reflecting surface */ |
52 |
#define SP_RBLT 020 /* reflection below sample threshold */ |
53 |
#define SP_TBLT 040 /* transmission below threshold */ |
54 |
|
55 |
typedef struct { |
56 |
OBJREC *mp; /* material pointer */ |
57 |
RAY *rp; /* ray pointer */ |
58 |
short specfl; /* specularity flags, defined above */ |
59 |
COLOR mcolor; /* color of this material */ |
60 |
COLOR scolor; /* color of specular component */ |
61 |
FVECT vrefl; /* vector in direction of reflected ray */ |
62 |
FVECT prdir; /* vector in transmitted direction */ |
63 |
double alpha2; /* roughness squared */ |
64 |
double rdiff, rspec; /* reflected specular, diffuse */ |
65 |
double trans; /* transmissivity */ |
66 |
double tdiff, tspec; /* transmitted specular, diffuse */ |
67 |
FVECT pnorm; /* perturbed surface normal */ |
68 |
double pdot; /* perturbed dot product */ |
69 |
} NORMDAT; /* normal material data */ |
70 |
|
71 |
|
72 |
dirnorm(cval, np, ldir, omega) /* compute source contribution */ |
73 |
COLOR cval; /* returned coefficient */ |
74 |
register NORMDAT *np; /* material data */ |
75 |
FVECT ldir; /* light source direction */ |
76 |
double omega; /* light source size */ |
77 |
{ |
78 |
double ldot; |
79 |
double dtmp, d2; |
80 |
FVECT vtmp; |
81 |
COLOR ctmp; |
82 |
|
83 |
setcolor(cval, 0.0, 0.0, 0.0); |
84 |
|
85 |
ldot = DOT(np->pnorm, ldir); |
86 |
|
87 |
if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY) |
88 |
return; /* wrong side */ |
89 |
|
90 |
if (ldot > FTINY && np->rdiff > FTINY) { |
91 |
/* |
92 |
* Compute and add diffuse reflected component to returned |
93 |
* color. The diffuse reflected component will always be |
94 |
* modified by the color of the material. |
95 |
*/ |
96 |
copycolor(ctmp, np->mcolor); |
97 |
dtmp = ldot * omega * np->rdiff / PI; |
98 |
scalecolor(ctmp, dtmp); |
99 |
addcolor(cval, ctmp); |
100 |
} |
101 |
if (ldot > FTINY && (np->specfl&(SP_REFL|SP_PURE)) == SP_REFL) { |
102 |
/* |
103 |
* Compute specular reflection coefficient using |
104 |
* gaussian distribution model. |
105 |
*/ |
106 |
/* roughness */ |
107 |
dtmp = np->alpha2; |
108 |
/* + source if flat */ |
109 |
if (np->specfl & SP_FLAT) |
110 |
dtmp += omega/(4.0*PI); |
111 |
/* half vector */ |
112 |
vtmp[0] = ldir[0] - np->rp->rdir[0]; |
113 |
vtmp[1] = ldir[1] - np->rp->rdir[1]; |
114 |
vtmp[2] = ldir[2] - np->rp->rdir[2]; |
115 |
d2 = DOT(vtmp, np->pnorm); |
116 |
d2 *= d2; |
117 |
d2 = (DOT(vtmp,vtmp) - d2) / d2; |
118 |
/* gaussian */ |
119 |
dtmp = exp(-d2/dtmp)/(4.*PI*dtmp); |
120 |
/* worth using? */ |
121 |
if (dtmp > FTINY) { |
122 |
copycolor(ctmp, np->scolor); |
123 |
dtmp *= omega * sqrt(ldot/np->pdot); |
124 |
scalecolor(ctmp, dtmp); |
125 |
addcolor(cval, ctmp); |
126 |
} |
127 |
} |
128 |
if (ldot < -FTINY && np->tdiff > FTINY) { |
129 |
/* |
130 |
* Compute diffuse transmission. |
131 |
*/ |
132 |
copycolor(ctmp, np->mcolor); |
133 |
dtmp = -ldot * omega * np->tdiff / PI; |
134 |
scalecolor(ctmp, dtmp); |
135 |
addcolor(cval, ctmp); |
136 |
} |
137 |
if (ldot < -FTINY && (np->specfl&(SP_TRAN|SP_PURE)) == SP_TRAN) { |
138 |
/* |
139 |
* Compute specular transmission. Specular transmission |
140 |
* is always modified by material color. |
141 |
*/ |
142 |
/* roughness + source */ |
143 |
dtmp = np->alpha2 + omega/PI; |
144 |
/* gaussian */ |
145 |
dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(PI*dtmp); |
146 |
/* worth using? */ |
147 |
if (dtmp > FTINY) { |
148 |
copycolor(ctmp, np->mcolor); |
149 |
dtmp *= np->tspec * omega * sqrt(-ldot/np->pdot); |
150 |
scalecolor(ctmp, dtmp); |
151 |
addcolor(cval, ctmp); |
152 |
} |
153 |
} |
154 |
} |
155 |
|
156 |
|
157 |
m_normal(m, r) /* color a ray that hit something normal */ |
158 |
register OBJREC *m; |
159 |
register RAY *r; |
160 |
{ |
161 |
NORMDAT nd; |
162 |
double transtest, transdist; |
163 |
double mirtest, mirdist; |
164 |
int hastexture; |
165 |
double d; |
166 |
COLOR ctmp; |
167 |
register int i; |
168 |
/* easy shadow test */ |
169 |
if (r->crtype & SHADOW && m->otype != MAT_TRANS) |
170 |
return(1); |
171 |
|
172 |
if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5)) |
173 |
objerror(m, USER, "bad number of arguments"); |
174 |
/* check for back side */ |
175 |
if (r->rod < 0.0) { |
176 |
if (!backvis && m->otype != MAT_TRANS) { |
177 |
raytrans(r); |
178 |
return(1); |
179 |
} |
180 |
flipsurface(r); /* reorient if backvis */ |
181 |
} |
182 |
nd.mp = m; |
183 |
nd.rp = r; |
184 |
/* get material color */ |
185 |
setcolor(nd.mcolor, m->oargs.farg[0], |
186 |
m->oargs.farg[1], |
187 |
m->oargs.farg[2]); |
188 |
/* get roughness */ |
189 |
nd.specfl = 0; |
190 |
nd.alpha2 = m->oargs.farg[4]; |
191 |
if ((nd.alpha2 *= nd.alpha2) <= FTINY) |
192 |
nd.specfl |= SP_PURE; |
193 |
if (r->ro != NULL && isflat(r->ro->otype)) |
194 |
nd.specfl |= SP_FLAT; |
195 |
/* get modifiers */ |
196 |
raytexture(r, m->omod); |
197 |
if (hastexture = DOT(r->pert,r->pert) > FTINY*FTINY) |
198 |
nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
199 |
else { |
200 |
VCOPY(nd.pnorm, r->ron); |
201 |
nd.pdot = r->rod; |
202 |
} |
203 |
if (nd.pdot < .001) |
204 |
nd.pdot = .001; /* non-zero for dirnorm() */ |
205 |
multcolor(nd.mcolor, r->pcol); /* modify material color */ |
206 |
mirtest = transtest = 0; |
207 |
mirdist = transdist = r->rot; |
208 |
nd.rspec = m->oargs.farg[3]; |
209 |
/* compute transmission */ |
210 |
if (m->otype == MAT_TRANS) { |
211 |
nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec); |
212 |
nd.tspec = nd.trans * m->oargs.farg[6]; |
213 |
nd.tdiff = nd.trans - nd.tspec; |
214 |
if (nd.tspec > FTINY) { |
215 |
nd.specfl |= SP_TRAN; |
216 |
/* check threshold */ |
217 |
if (!(nd.specfl & SP_PURE) && |
218 |
specthresh >= nd.tspec-FTINY) |
219 |
nd.specfl |= SP_TBLT; |
220 |
if (!hastexture || r->crtype & SHADOW) { |
221 |
VCOPY(nd.prdir, r->rdir); |
222 |
transtest = 2; |
223 |
} else { |
224 |
for (i = 0; i < 3; i++) /* perturb */ |
225 |
nd.prdir[i] = r->rdir[i] - r->pert[i]; |
226 |
if (DOT(nd.prdir, r->ron) < -FTINY) |
227 |
normalize(nd.prdir); /* OK */ |
228 |
else |
229 |
VCOPY(nd.prdir, r->rdir); |
230 |
} |
231 |
} |
232 |
} else |
233 |
nd.tdiff = nd.tspec = nd.trans = 0.0; |
234 |
/* transmitted ray */ |
235 |
if (nd.specfl&SP_TRAN && (nd.specfl&SP_PURE || r->crtype&SHADOW)) { |
236 |
RAY lr; |
237 |
if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) { |
238 |
VCOPY(lr.rdir, nd.prdir); |
239 |
rayvalue(&lr); |
240 |
scalecolor(lr.rcol, nd.tspec); |
241 |
multcolor(lr.rcol, nd.mcolor); /* modified by color */ |
242 |
addcolor(r->rcol, lr.rcol); |
243 |
transtest *= bright(lr.rcol); |
244 |
transdist = r->rot + lr.rt; |
245 |
} |
246 |
} else |
247 |
transtest = 0; |
248 |
|
249 |
if (r->crtype & SHADOW) { /* the rest is shadow */ |
250 |
r->rt = transdist; |
251 |
return(1); |
252 |
} |
253 |
/* get specular reflection */ |
254 |
if (nd.rspec > FTINY) { |
255 |
nd.specfl |= SP_REFL; |
256 |
/* compute specular color */ |
257 |
if (m->otype == MAT_METAL) |
258 |
copycolor(nd.scolor, nd.mcolor); |
259 |
else |
260 |
setcolor(nd.scolor, 1.0, 1.0, 1.0); |
261 |
scalecolor(nd.scolor, nd.rspec); |
262 |
/* check threshold */ |
263 |
if (!(nd.specfl & SP_PURE) && specthresh >= nd.rspec-FTINY) |
264 |
nd.specfl |= SP_RBLT; |
265 |
/* compute reflected ray */ |
266 |
for (i = 0; i < 3; i++) |
267 |
nd.vrefl[i] = r->rdir[i] + 2.*nd.pdot*nd.pnorm[i]; |
268 |
/* penetration? */ |
269 |
if (hastexture && DOT(nd.vrefl, r->ron) <= FTINY) |
270 |
for (i = 0; i < 3; i++) /* safety measure */ |
271 |
nd.vrefl[i] = r->rdir[i] + 2.*r->rod*r->ron[i]; |
272 |
|
273 |
if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) { |
274 |
RAY lr; |
275 |
if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) { |
276 |
VCOPY(lr.rdir, nd.vrefl); |
277 |
rayvalue(&lr); |
278 |
multcolor(lr.rcol, nd.scolor); |
279 |
addcolor(r->rcol, lr.rcol); |
280 |
if (!hastexture && nd.specfl & SP_FLAT) { |
281 |
mirtest = 2.*bright(lr.rcol); |
282 |
mirdist = r->rot + lr.rt; |
283 |
} |
284 |
} |
285 |
} |
286 |
} |
287 |
/* diffuse reflection */ |
288 |
nd.rdiff = 1.0 - nd.trans - nd.rspec; |
289 |
|
290 |
if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY) |
291 |
return(1); /* 100% pure specular */ |
292 |
|
293 |
if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_PURE)) |
294 |
gaussamp(r, &nd); |
295 |
|
296 |
if (nd.rdiff > FTINY) { /* ambient from this side */ |
297 |
ambient(ctmp, r, hastexture?nd.pnorm:r->ron); |
298 |
if (nd.specfl & SP_RBLT) |
299 |
scalecolor(ctmp, 1.0-nd.trans); |
300 |
else |
301 |
scalecolor(ctmp, nd.rdiff); |
302 |
multcolor(ctmp, nd.mcolor); /* modified by material color */ |
303 |
addcolor(r->rcol, ctmp); /* add to returned color */ |
304 |
} |
305 |
if (nd.tdiff > FTINY) { /* ambient from other side */ |
306 |
flipsurface(r); |
307 |
if (hastexture) { |
308 |
FVECT bnorm; |
309 |
bnorm[0] = -nd.pnorm[0]; |
310 |
bnorm[1] = -nd.pnorm[1]; |
311 |
bnorm[2] = -nd.pnorm[2]; |
312 |
ambient(ctmp, r, bnorm); |
313 |
} else |
314 |
ambient(ctmp, r, r->ron); |
315 |
if (nd.specfl & SP_TBLT) |
316 |
scalecolor(ctmp, nd.trans); |
317 |
else |
318 |
scalecolor(ctmp, nd.tdiff); |
319 |
multcolor(ctmp, nd.mcolor); /* modified by color */ |
320 |
addcolor(r->rcol, ctmp); |
321 |
flipsurface(r); |
322 |
} |
323 |
/* add direct component */ |
324 |
direct(r, dirnorm, &nd); |
325 |
/* check distance */ |
326 |
d = bright(r->rcol); |
327 |
if (transtest > d) |
328 |
r->rt = transdist; |
329 |
else if (mirtest > d) |
330 |
r->rt = mirdist; |
331 |
|
332 |
return(1); |
333 |
} |
334 |
|
335 |
|
336 |
static |
337 |
gaussamp(r, np) /* sample gaussian specular */ |
338 |
RAY *r; |
339 |
register NORMDAT *np; |
340 |
{ |
341 |
RAY sr; |
342 |
FVECT u, v, h; |
343 |
double rv[2]; |
344 |
double d, sinp, cosp; |
345 |
int niter; |
346 |
register int i; |
347 |
/* quick test */ |
348 |
if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL && |
349 |
(np->specfl & (SP_TRAN|SP_TBLT)) != SP_TRAN) |
350 |
return; |
351 |
/* set up sample coordinates */ |
352 |
v[0] = v[1] = v[2] = 0.0; |
353 |
for (i = 0; i < 3; i++) |
354 |
if (np->pnorm[i] < 0.6 && np->pnorm[i] > -0.6) |
355 |
break; |
356 |
v[i] = 1.0; |
357 |
fcross(u, v, np->pnorm); |
358 |
normalize(u); |
359 |
fcross(v, np->pnorm, u); |
360 |
/* compute reflection */ |
361 |
if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL && |
362 |
rayorigin(&sr, r, SPECULAR, np->rspec) == 0) { |
363 |
dimlist[ndims++] = (int)np->mp; |
364 |
for (niter = 0; niter < MAXITER; niter++) { |
365 |
if (niter) |
366 |
d = frandom(); |
367 |
else |
368 |
d = urand(ilhash(dimlist,ndims)+samplendx); |
369 |
multisamp(rv, 2, d); |
370 |
d = 2.0*PI * rv[0]; |
371 |
cosp = cos(d); |
372 |
sinp = sin(d); |
373 |
rv[1] = 1.0 - specjitter*rv[1]; |
374 |
if (rv[1] <= FTINY) |
375 |
d = 1.0; |
376 |
else |
377 |
d = sqrt( np->alpha2 * -log(rv[1]) ); |
378 |
for (i = 0; i < 3; i++) |
379 |
h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*v[i]); |
380 |
d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d); |
381 |
for (i = 0; i < 3; i++) |
382 |
sr.rdir[i] = r->rdir[i] + d*h[i]; |
383 |
if (DOT(sr.rdir, r->ron) > FTINY) { |
384 |
rayvalue(&sr); |
385 |
multcolor(sr.rcol, np->scolor); |
386 |
addcolor(r->rcol, sr.rcol); |
387 |
break; |
388 |
} |
389 |
} |
390 |
ndims--; |
391 |
} |
392 |
/* compute transmission */ |
393 |
if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN && |
394 |
rayorigin(&sr, r, SPECULAR, np->tspec) == 0) { |
395 |
dimlist[ndims++] = (int)np->mp; |
396 |
for (niter = 0; niter < MAXITER; niter++) { |
397 |
if (niter) |
398 |
d = frandom(); |
399 |
else |
400 |
d = urand(ilhash(dimlist,ndims)+1823+samplendx); |
401 |
multisamp(rv, 2, d); |
402 |
d = 2.0*PI * rv[0]; |
403 |
cosp = cos(d); |
404 |
sinp = sin(d); |
405 |
rv[1] = 1.0 - specjitter*rv[1]; |
406 |
if (rv[1] <= FTINY) |
407 |
d = 1.0; |
408 |
else |
409 |
d = sqrt( -log(rv[1]) * np->alpha2 ); |
410 |
for (i = 0; i < 3; i++) |
411 |
sr.rdir[i] = np->prdir[i] + d*(cosp*u[i] + sinp*v[i]); |
412 |
if (DOT(sr.rdir, r->ron) < -FTINY) { |
413 |
normalize(sr.rdir); /* OK, normalize */ |
414 |
rayvalue(&sr); |
415 |
scalecolor(sr.rcol, np->tspec); |
416 |
multcolor(sr.rcol, np->mcolor); /* modified */ |
417 |
addcolor(r->rcol, sr.rcol); |
418 |
break; |
419 |
} |
420 |
} |
421 |
ndims--; |
422 |
} |
423 |
} |