| 1 |
#ifndef lint |
| 2 |
static const char RCSid[] = "$Id: normal.c,v 2.53 2010/09/26 15:51:15 greg Exp $"; |
| 3 |
#endif |
| 4 |
/* |
| 5 |
* normal.c - shading function for normal materials. |
| 6 |
* |
| 7 |
* 8/19/85 |
| 8 |
* 12/19/85 - added stuff for metals. |
| 9 |
* 6/26/87 - improved specular model. |
| 10 |
* 9/28/87 - added model for translucent materials. |
| 11 |
* Later changes described in delta comments. |
| 12 |
*/ |
| 13 |
|
| 14 |
#include "copyright.h" |
| 15 |
|
| 16 |
#include "ray.h" |
| 17 |
#include "ambient.h" |
| 18 |
#include "source.h" |
| 19 |
#include "otypes.h" |
| 20 |
#include "rtotypes.h" |
| 21 |
#include "random.h" |
| 22 |
|
| 23 |
#ifndef MAXITER |
| 24 |
#define MAXITER 10 /* maximum # specular ray attempts */ |
| 25 |
#endif |
| 26 |
/* estimate of Fresnel function */ |
| 27 |
#define FRESNE(ci) (exp(-5.85*(ci)) - 0.00287989916) |
| 28 |
#define FRESTHRESH 0.017999 /* minimum specularity for approx. */ |
| 29 |
|
| 30 |
|
| 31 |
/* |
| 32 |
* This routine implements the isotropic Gaussian |
| 33 |
* model described by Ward in Siggraph `92 article. |
| 34 |
* We orient the surface towards the incoming ray, so a single |
| 35 |
* surface can be used to represent an infinitely thin object. |
| 36 |
* |
| 37 |
* Arguments for MAT_PLASTIC and MAT_METAL are: |
| 38 |
* red grn blu specular-frac. facet-slope |
| 39 |
* |
| 40 |
* Arguments for MAT_TRANS are: |
| 41 |
* red grn blu rspec rough trans tspec |
| 42 |
*/ |
| 43 |
|
| 44 |
/* specularity flags */ |
| 45 |
#define SP_REFL 01 /* has reflected specular component */ |
| 46 |
#define SP_TRAN 02 /* has transmitted specular */ |
| 47 |
#define SP_PURE 04 /* purely specular (zero roughness) */ |
| 48 |
#define SP_FLAT 010 /* flat reflecting surface */ |
| 49 |
#define SP_RBLT 020 /* reflection below sample threshold */ |
| 50 |
#define SP_TBLT 040 /* transmission below threshold */ |
| 51 |
|
| 52 |
typedef struct { |
| 53 |
OBJREC *mp; /* material pointer */ |
| 54 |
RAY *rp; /* ray pointer */ |
| 55 |
short specfl; /* specularity flags, defined above */ |
| 56 |
COLOR mcolor; /* color of this material */ |
| 57 |
COLOR scolor; /* color of specular component */ |
| 58 |
FVECT vrefl; /* vector in direction of reflected ray */ |
| 59 |
FVECT prdir; /* vector in transmitted direction */ |
| 60 |
double alpha2; /* roughness squared */ |
| 61 |
double rdiff, rspec; /* reflected specular, diffuse */ |
| 62 |
double trans; /* transmissivity */ |
| 63 |
double tdiff, tspec; /* transmitted specular, diffuse */ |
| 64 |
FVECT pnorm; /* perturbed surface normal */ |
| 65 |
double pdot; /* perturbed dot product */ |
| 66 |
} NORMDAT; /* normal material data */ |
| 67 |
|
| 68 |
static srcdirf_t dirnorm; |
| 69 |
static void gaussamp(RAY *r, NORMDAT *np); |
| 70 |
|
| 71 |
|
| 72 |
static void |
| 73 |
dirnorm( /* compute source contribution */ |
| 74 |
COLOR cval, /* returned coefficient */ |
| 75 |
void *nnp, /* material data */ |
| 76 |
FVECT ldir, /* light source direction */ |
| 77 |
double omega /* light source size */ |
| 78 |
) |
| 79 |
{ |
| 80 |
register NORMDAT *np = nnp; |
| 81 |
double ldot; |
| 82 |
double lrdiff, ltdiff; |
| 83 |
double dtmp, d2, d3, d4; |
| 84 |
FVECT vtmp; |
| 85 |
COLOR ctmp; |
| 86 |
|
| 87 |
setcolor(cval, 0.0, 0.0, 0.0); |
| 88 |
|
| 89 |
ldot = DOT(np->pnorm, ldir); |
| 90 |
|
| 91 |
if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY) |
| 92 |
return; /* wrong side */ |
| 93 |
|
| 94 |
/* Fresnel estimate */ |
| 95 |
lrdiff = np->rdiff; |
| 96 |
ltdiff = np->tdiff; |
| 97 |
if (np->specfl & SP_PURE && np->rspec >= FRESTHRESH && |
| 98 |
(lrdiff > FTINY) | (ltdiff > FTINY)) { |
| 99 |
dtmp = 1. - FRESNE(fabs(ldot)); |
| 100 |
lrdiff *= dtmp; |
| 101 |
ltdiff *= dtmp; |
| 102 |
} |
| 103 |
|
| 104 |
if (ldot > FTINY && lrdiff > FTINY) { |
| 105 |
/* |
| 106 |
* Compute and add diffuse reflected component to returned |
| 107 |
* color. The diffuse reflected component will always be |
| 108 |
* modified by the color of the material. |
| 109 |
*/ |
| 110 |
copycolor(ctmp, np->mcolor); |
| 111 |
dtmp = ldot * omega * lrdiff * (1.0/PI); |
| 112 |
scalecolor(ctmp, dtmp); |
| 113 |
addcolor(cval, ctmp); |
| 114 |
} |
| 115 |
if (ldot > FTINY && (np->specfl&(SP_REFL|SP_PURE)) == SP_REFL) { |
| 116 |
/* |
| 117 |
* Compute specular reflection coefficient using |
| 118 |
* Gaussian distribution model. |
| 119 |
*/ |
| 120 |
/* roughness */ |
| 121 |
dtmp = np->alpha2; |
| 122 |
/* + source if flat */ |
| 123 |
if (np->specfl & SP_FLAT) |
| 124 |
dtmp += omega * (0.25/PI); |
| 125 |
/* half vector */ |
| 126 |
vtmp[0] = ldir[0] - np->rp->rdir[0]; |
| 127 |
vtmp[1] = ldir[1] - np->rp->rdir[1]; |
| 128 |
vtmp[2] = ldir[2] - np->rp->rdir[2]; |
| 129 |
d2 = DOT(vtmp, np->pnorm); |
| 130 |
d2 *= d2; |
| 131 |
d3 = DOT(vtmp,vtmp); |
| 132 |
d4 = (d3 - d2) / d2; |
| 133 |
/* new W-G-M-D model */ |
| 134 |
dtmp = exp(-d4/dtmp) * d3 / (PI * d2*d2 * dtmp); |
| 135 |
/* worth using? */ |
| 136 |
if (dtmp > FTINY) { |
| 137 |
copycolor(ctmp, np->scolor); |
| 138 |
dtmp *= ldot * omega; |
| 139 |
scalecolor(ctmp, dtmp); |
| 140 |
addcolor(cval, ctmp); |
| 141 |
} |
| 142 |
} |
| 143 |
if (ldot < -FTINY && ltdiff > FTINY) { |
| 144 |
/* |
| 145 |
* Compute diffuse transmission. |
| 146 |
*/ |
| 147 |
copycolor(ctmp, np->mcolor); |
| 148 |
dtmp = -ldot * omega * ltdiff * (1.0/PI); |
| 149 |
scalecolor(ctmp, dtmp); |
| 150 |
addcolor(cval, ctmp); |
| 151 |
} |
| 152 |
if (ldot < -FTINY && (np->specfl&(SP_TRAN|SP_PURE)) == SP_TRAN) { |
| 153 |
/* |
| 154 |
* Compute specular transmission. Specular transmission |
| 155 |
* is always modified by material color. |
| 156 |
*/ |
| 157 |
/* roughness + source */ |
| 158 |
dtmp = np->alpha2 + omega*(1.0/PI); |
| 159 |
/* Gaussian */ |
| 160 |
dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(PI*dtmp); |
| 161 |
/* worth using? */ |
| 162 |
if (dtmp > FTINY) { |
| 163 |
copycolor(ctmp, np->mcolor); |
| 164 |
dtmp *= np->tspec * omega * sqrt(-ldot/np->pdot); |
| 165 |
scalecolor(ctmp, dtmp); |
| 166 |
addcolor(cval, ctmp); |
| 167 |
} |
| 168 |
} |
| 169 |
} |
| 170 |
|
| 171 |
|
| 172 |
extern int |
| 173 |
m_normal( /* color a ray that hit something normal */ |
| 174 |
register OBJREC *m, |
| 175 |
register RAY *r |
| 176 |
) |
| 177 |
{ |
| 178 |
NORMDAT nd; |
| 179 |
double fest; |
| 180 |
double transtest, transdist; |
| 181 |
double mirtest, mirdist; |
| 182 |
int hastexture; |
| 183 |
double d; |
| 184 |
COLOR ctmp; |
| 185 |
register int i; |
| 186 |
/* easy shadow test */ |
| 187 |
if (r->crtype & SHADOW && m->otype != MAT_TRANS) |
| 188 |
return(1); |
| 189 |
|
| 190 |
if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5)) |
| 191 |
objerror(m, USER, "bad number of arguments"); |
| 192 |
/* check for back side */ |
| 193 |
if (r->rod < 0.0) { |
| 194 |
if (!backvis && m->otype != MAT_TRANS) { |
| 195 |
raytrans(r); |
| 196 |
return(1); |
| 197 |
} |
| 198 |
raytexture(r, m->omod); |
| 199 |
flipsurface(r); /* reorient if backvis */ |
| 200 |
} else |
| 201 |
raytexture(r, m->omod); |
| 202 |
nd.mp = m; |
| 203 |
nd.rp = r; |
| 204 |
/* get material color */ |
| 205 |
setcolor(nd.mcolor, m->oargs.farg[0], |
| 206 |
m->oargs.farg[1], |
| 207 |
m->oargs.farg[2]); |
| 208 |
/* get roughness */ |
| 209 |
nd.specfl = 0; |
| 210 |
nd.alpha2 = m->oargs.farg[4]; |
| 211 |
if ((nd.alpha2 *= nd.alpha2) <= FTINY) |
| 212 |
nd.specfl |= SP_PURE; |
| 213 |
|
| 214 |
if ( (hastexture = (DOT(r->pert,r->pert) > FTINY*FTINY)) ) { |
| 215 |
nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
| 216 |
} else { |
| 217 |
VCOPY(nd.pnorm, r->ron); |
| 218 |
nd.pdot = r->rod; |
| 219 |
} |
| 220 |
if (r->ro != NULL && isflat(r->ro->otype)) |
| 221 |
nd.specfl |= SP_FLAT; |
| 222 |
if (nd.pdot < .001) |
| 223 |
nd.pdot = .001; /* non-zero for dirnorm() */ |
| 224 |
multcolor(nd.mcolor, r->pcol); /* modify material color */ |
| 225 |
mirtest = transtest = 0; |
| 226 |
mirdist = transdist = r->rot; |
| 227 |
nd.rspec = m->oargs.farg[3]; |
| 228 |
/* compute Fresnel approx. */ |
| 229 |
if (nd.specfl & SP_PURE && nd.rspec >= FRESTHRESH) { |
| 230 |
fest = FRESNE(r->rod); |
| 231 |
nd.rspec += fest*(1. - nd.rspec); |
| 232 |
} else |
| 233 |
fest = 0.; |
| 234 |
/* compute transmission */ |
| 235 |
if (m->otype == MAT_TRANS) { |
| 236 |
nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec); |
| 237 |
nd.tspec = nd.trans * m->oargs.farg[6]; |
| 238 |
nd.tdiff = nd.trans - nd.tspec; |
| 239 |
if (nd.tspec > FTINY) { |
| 240 |
nd.specfl |= SP_TRAN; |
| 241 |
/* check threshold */ |
| 242 |
if (!(nd.specfl & SP_PURE) && |
| 243 |
specthresh >= nd.tspec-FTINY) |
| 244 |
nd.specfl |= SP_TBLT; |
| 245 |
if (!hastexture || r->crtype & SHADOW) { |
| 246 |
VCOPY(nd.prdir, r->rdir); |
| 247 |
transtest = 2; |
| 248 |
} else { |
| 249 |
for (i = 0; i < 3; i++) /* perturb */ |
| 250 |
nd.prdir[i] = r->rdir[i] - r->pert[i]; |
| 251 |
if (DOT(nd.prdir, r->ron) < -FTINY) |
| 252 |
normalize(nd.prdir); /* OK */ |
| 253 |
else |
| 254 |
VCOPY(nd.prdir, r->rdir); |
| 255 |
} |
| 256 |
} |
| 257 |
} else |
| 258 |
nd.tdiff = nd.tspec = nd.trans = 0.0; |
| 259 |
/* transmitted ray */ |
| 260 |
if ((nd.specfl&(SP_TRAN|SP_PURE|SP_TBLT)) == (SP_TRAN|SP_PURE)) { |
| 261 |
RAY lr; |
| 262 |
copycolor(lr.rcoef, nd.mcolor); /* modified by color */ |
| 263 |
scalecolor(lr.rcoef, nd.tspec); |
| 264 |
if (rayorigin(&lr, TRANS, r, lr.rcoef) == 0) { |
| 265 |
VCOPY(lr.rdir, nd.prdir); |
| 266 |
rayvalue(&lr); |
| 267 |
multcolor(lr.rcol, lr.rcoef); |
| 268 |
addcolor(r->rcol, lr.rcol); |
| 269 |
transtest *= bright(lr.rcol); |
| 270 |
transdist = r->rot + lr.rt; |
| 271 |
} |
| 272 |
} else |
| 273 |
transtest = 0; |
| 274 |
|
| 275 |
if (r->crtype & SHADOW) { /* the rest is shadow */ |
| 276 |
r->rt = transdist; |
| 277 |
return(1); |
| 278 |
} |
| 279 |
/* get specular reflection */ |
| 280 |
if (nd.rspec > FTINY) { |
| 281 |
nd.specfl |= SP_REFL; |
| 282 |
/* compute specular color */ |
| 283 |
if (m->otype != MAT_METAL) { |
| 284 |
setcolor(nd.scolor, nd.rspec, nd.rspec, nd.rspec); |
| 285 |
} else if (fest > FTINY) { |
| 286 |
d = nd.rspec*(1. - fest); |
| 287 |
for (i = 0; i < 3; i++) |
| 288 |
nd.scolor[i] = fest + nd.mcolor[i]*d; |
| 289 |
} else { |
| 290 |
copycolor(nd.scolor, nd.mcolor); |
| 291 |
scalecolor(nd.scolor, nd.rspec); |
| 292 |
} |
| 293 |
/* check threshold */ |
| 294 |
if (!(nd.specfl & SP_PURE) && specthresh >= nd.rspec-FTINY) |
| 295 |
nd.specfl |= SP_RBLT; |
| 296 |
/* compute reflected ray */ |
| 297 |
for (i = 0; i < 3; i++) |
| 298 |
nd.vrefl[i] = r->rdir[i] + 2.*nd.pdot*nd.pnorm[i]; |
| 299 |
/* penetration? */ |
| 300 |
if (hastexture && DOT(nd.vrefl, r->ron) <= FTINY) |
| 301 |
for (i = 0; i < 3; i++) /* safety measure */ |
| 302 |
nd.vrefl[i] = r->rdir[i] + 2.*r->rod*r->ron[i]; |
| 303 |
checknorm(nd.vrefl); |
| 304 |
} |
| 305 |
/* reflected ray */ |
| 306 |
if ((nd.specfl&(SP_REFL|SP_PURE|SP_RBLT)) == (SP_REFL|SP_PURE)) { |
| 307 |
RAY lr; |
| 308 |
if (rayorigin(&lr, REFLECTED, r, nd.scolor) == 0) { |
| 309 |
VCOPY(lr.rdir, nd.vrefl); |
| 310 |
rayvalue(&lr); |
| 311 |
multcolor(lr.rcol, lr.rcoef); |
| 312 |
addcolor(r->rcol, lr.rcol); |
| 313 |
if (!hastexture && nd.specfl & SP_FLAT) { |
| 314 |
mirtest = 2.*bright(lr.rcol); |
| 315 |
mirdist = r->rot + lr.rt; |
| 316 |
} |
| 317 |
} |
| 318 |
} |
| 319 |
/* diffuse reflection */ |
| 320 |
nd.rdiff = 1.0 - nd.trans - nd.rspec; |
| 321 |
|
| 322 |
if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY) |
| 323 |
return(1); /* 100% pure specular */ |
| 324 |
|
| 325 |
if (!(nd.specfl & SP_PURE)) |
| 326 |
gaussamp(r, &nd); /* checks *BLT flags */ |
| 327 |
|
| 328 |
if (nd.rdiff > FTINY) { /* ambient from this side */ |
| 329 |
copycolor(ctmp, nd.mcolor); /* modified by material color */ |
| 330 |
if (nd.specfl & SP_RBLT) |
| 331 |
scalecolor(ctmp, 1.0-nd.trans); |
| 332 |
else |
| 333 |
scalecolor(ctmp, nd.rdiff); |
| 334 |
multambient(ctmp, r, hastexture ? nd.pnorm : r->ron); |
| 335 |
addcolor(r->rcol, ctmp); /* add to returned color */ |
| 336 |
} |
| 337 |
if (nd.tdiff > FTINY) { /* ambient from other side */ |
| 338 |
copycolor(ctmp, nd.mcolor); /* modified by color */ |
| 339 |
if (nd.specfl & SP_TBLT) |
| 340 |
scalecolor(ctmp, nd.trans); |
| 341 |
else |
| 342 |
scalecolor(ctmp, nd.tdiff); |
| 343 |
flipsurface(r); |
| 344 |
if (hastexture) { |
| 345 |
FVECT bnorm; |
| 346 |
bnorm[0] = -nd.pnorm[0]; |
| 347 |
bnorm[1] = -nd.pnorm[1]; |
| 348 |
bnorm[2] = -nd.pnorm[2]; |
| 349 |
multambient(ctmp, r, bnorm); |
| 350 |
} else |
| 351 |
multambient(ctmp, r, r->ron); |
| 352 |
addcolor(r->rcol, ctmp); |
| 353 |
flipsurface(r); |
| 354 |
} |
| 355 |
/* add direct component */ |
| 356 |
direct(r, dirnorm, &nd); |
| 357 |
/* check distance */ |
| 358 |
d = bright(r->rcol); |
| 359 |
if (transtest > d) |
| 360 |
r->rt = transdist; |
| 361 |
else if (mirtest > d) |
| 362 |
r->rt = mirdist; |
| 363 |
|
| 364 |
return(1); |
| 365 |
} |
| 366 |
|
| 367 |
|
| 368 |
static void |
| 369 |
gaussamp( /* sample Gaussian specular */ |
| 370 |
RAY *r, |
| 371 |
register NORMDAT *np |
| 372 |
) |
| 373 |
{ |
| 374 |
RAY sr; |
| 375 |
FVECT u, v, h; |
| 376 |
double rv[2]; |
| 377 |
double d, sinp, cosp; |
| 378 |
int niter; |
| 379 |
register int i; |
| 380 |
/* quick test */ |
| 381 |
if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL && |
| 382 |
(np->specfl & (SP_TRAN|SP_TBLT)) != SP_TRAN) |
| 383 |
return; |
| 384 |
/* set up sample coordinates */ |
| 385 |
v[0] = v[1] = v[2] = 0.0; |
| 386 |
for (i = 0; i < 3; i++) |
| 387 |
if (np->pnorm[i] < 0.6 && np->pnorm[i] > -0.6) |
| 388 |
break; |
| 389 |
v[i] = 1.0; |
| 390 |
fcross(u, v, np->pnorm); |
| 391 |
normalize(u); |
| 392 |
fcross(v, np->pnorm, u); |
| 393 |
/* compute reflection */ |
| 394 |
if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL && |
| 395 |
rayorigin(&sr, SPECULAR, r, np->scolor) == 0) { |
| 396 |
dimlist[ndims++] = (int)np->mp; |
| 397 |
for (niter = 0; niter < MAXITER; niter++) { |
| 398 |
if (niter) |
| 399 |
d = frandom(); |
| 400 |
else |
| 401 |
d = urand(ilhash(dimlist,ndims)+samplendx); |
| 402 |
multisamp(rv, 2, d); |
| 403 |
d = 2.0*PI * rv[0]; |
| 404 |
cosp = tcos(d); |
| 405 |
sinp = tsin(d); |
| 406 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 407 |
if (rv[1] <= FTINY) |
| 408 |
d = 1.0; |
| 409 |
else |
| 410 |
d = sqrt( np->alpha2 * -log(rv[1]) ); |
| 411 |
for (i = 0; i < 3; i++) |
| 412 |
h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*v[i]); |
| 413 |
d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d); |
| 414 |
for (i = 0; i < 3; i++) |
| 415 |
sr.rdir[i] = r->rdir[i] + d*h[i]; |
| 416 |
if (DOT(sr.rdir, r->ron) > FTINY) { |
| 417 |
rayvalue(&sr); |
| 418 |
multcolor(sr.rcol, sr.rcoef); |
| 419 |
addcolor(r->rcol, sr.rcol); |
| 420 |
break; |
| 421 |
} |
| 422 |
} |
| 423 |
ndims--; |
| 424 |
} |
| 425 |
/* compute transmission */ |
| 426 |
copycolor(sr.rcoef, np->mcolor); /* modified by color */ |
| 427 |
scalecolor(sr.rcoef, np->tspec); |
| 428 |
if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN && |
| 429 |
rayorigin(&sr, SPECULAR, r, sr.rcoef) == 0) { |
| 430 |
dimlist[ndims++] = (int)np->mp; |
| 431 |
for (niter = 0; niter < MAXITER; niter++) { |
| 432 |
if (niter) |
| 433 |
d = frandom(); |
| 434 |
else |
| 435 |
d = urand(ilhash(dimlist,ndims)+1823+samplendx); |
| 436 |
multisamp(rv, 2, d); |
| 437 |
d = 2.0*PI * rv[0]; |
| 438 |
cosp = tcos(d); |
| 439 |
sinp = tsin(d); |
| 440 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 441 |
if (rv[1] <= FTINY) |
| 442 |
d = 1.0; |
| 443 |
else |
| 444 |
d = sqrt( np->alpha2 * -log(rv[1]) ); |
| 445 |
for (i = 0; i < 3; i++) |
| 446 |
sr.rdir[i] = np->prdir[i] + d*(cosp*u[i] + sinp*v[i]); |
| 447 |
if (DOT(sr.rdir, r->ron) < -FTINY) { |
| 448 |
normalize(sr.rdir); /* OK, normalize */ |
| 449 |
rayvalue(&sr); |
| 450 |
multcolor(sr.rcol, sr.rcoef); |
| 451 |
addcolor(r->rcol, sr.rcol); |
| 452 |
break; |
| 453 |
} |
| 454 |
} |
| 455 |
ndims--; |
| 456 |
} |
| 457 |
} |
