| 1 |
#ifndef lint |
| 2 |
static const char RCSid[] = "$Id$"; |
| 3 |
#endif |
| 4 |
/* |
| 5 |
* Shading functions for anisotropic materials. |
| 6 |
*/ |
| 7 |
|
| 8 |
#include "copyright.h" |
| 9 |
|
| 10 |
#include "ray.h" |
| 11 |
|
| 12 |
#include "otypes.h" |
| 13 |
|
| 14 |
#include "func.h" |
| 15 |
|
| 16 |
#include "random.h" |
| 17 |
|
| 18 |
#ifndef MAXITER |
| 19 |
#define MAXITER 10 /* maximum # specular ray attempts */ |
| 20 |
#endif |
| 21 |
|
| 22 |
/* |
| 23 |
* This routine implements the anisotropic Gaussian |
| 24 |
* model described by Ward in Siggraph `92 article. |
| 25 |
* We orient the surface towards the incoming ray, so a single |
| 26 |
* surface can be used to represent an infinitely thin object. |
| 27 |
* |
| 28 |
* Arguments for MAT_PLASTIC2 and MAT_METAL2 are: |
| 29 |
* 4+ ux uy uz funcfile [transform...] |
| 30 |
* 0 |
| 31 |
* 6 red grn blu specular-frac. u-facet-slope v-facet-slope |
| 32 |
* |
| 33 |
* Real arguments for MAT_TRANS2 are: |
| 34 |
* 8 red grn blu rspec u-rough v-rough trans tspec |
| 35 |
*/ |
| 36 |
|
| 37 |
/* specularity flags */ |
| 38 |
#define SP_REFL 01 /* has reflected specular component */ |
| 39 |
#define SP_TRAN 02 /* has transmitted specular */ |
| 40 |
#define SP_FLAT 04 /* reflecting surface is flat */ |
| 41 |
#define SP_RBLT 010 /* reflection below sample threshold */ |
| 42 |
#define SP_TBLT 020 /* transmission below threshold */ |
| 43 |
#define SP_BADU 040 /* bad u direction calculation */ |
| 44 |
|
| 45 |
typedef struct { |
| 46 |
OBJREC *mp; /* material pointer */ |
| 47 |
RAY *rp; /* ray pointer */ |
| 48 |
short specfl; /* specularity flags, defined above */ |
| 49 |
COLOR mcolor; /* color of this material */ |
| 50 |
COLOR scolor; /* color of specular component */ |
| 51 |
FVECT vrefl; /* vector in reflected direction */ |
| 52 |
FVECT prdir; /* vector in transmitted direction */ |
| 53 |
FVECT u, v; /* u and v vectors orienting anisotropy */ |
| 54 |
double u_alpha; /* u roughness */ |
| 55 |
double v_alpha; /* v roughness */ |
| 56 |
double rdiff, rspec; /* reflected specular, diffuse */ |
| 57 |
double trans; /* transmissivity */ |
| 58 |
double tdiff, tspec; /* transmitted specular, diffuse */ |
| 59 |
FVECT pnorm; /* perturbed surface normal */ |
| 60 |
double pdot; /* perturbed dot product */ |
| 61 |
} ANISODAT; /* anisotropic material data */ |
| 62 |
|
| 63 |
static void getacoords(); |
| 64 |
static void agaussamp(); |
| 65 |
|
| 66 |
|
| 67 |
static void |
| 68 |
diraniso(cval, np, ldir, omega) /* compute source contribution */ |
| 69 |
COLOR cval; /* returned coefficient */ |
| 70 |
register ANISODAT *np; /* material data */ |
| 71 |
FVECT ldir; /* light source direction */ |
| 72 |
double omega; /* light source size */ |
| 73 |
{ |
| 74 |
double ldot; |
| 75 |
double dtmp, dtmp1, dtmp2; |
| 76 |
FVECT h; |
| 77 |
double au2, av2; |
| 78 |
COLOR ctmp; |
| 79 |
|
| 80 |
setcolor(cval, 0.0, 0.0, 0.0); |
| 81 |
|
| 82 |
ldot = DOT(np->pnorm, ldir); |
| 83 |
|
| 84 |
if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY) |
| 85 |
return; /* wrong side */ |
| 86 |
|
| 87 |
if (ldot > FTINY && np->rdiff > FTINY) { |
| 88 |
/* |
| 89 |
* Compute and add diffuse reflected component to returned |
| 90 |
* color. The diffuse reflected component will always be |
| 91 |
* modified by the color of the material. |
| 92 |
*/ |
| 93 |
copycolor(ctmp, np->mcolor); |
| 94 |
dtmp = ldot * omega * np->rdiff / PI; |
| 95 |
scalecolor(ctmp, dtmp); |
| 96 |
addcolor(cval, ctmp); |
| 97 |
} |
| 98 |
if (ldot > FTINY && (np->specfl&(SP_REFL|SP_BADU)) == SP_REFL) { |
| 99 |
/* |
| 100 |
* Compute specular reflection coefficient using |
| 101 |
* anisotropic gaussian distribution model. |
| 102 |
*/ |
| 103 |
/* add source width if flat */ |
| 104 |
if (np->specfl & SP_FLAT) |
| 105 |
au2 = av2 = omega/(4.0*PI); |
| 106 |
else |
| 107 |
au2 = av2 = 0.0; |
| 108 |
au2 += np->u_alpha*np->u_alpha; |
| 109 |
av2 += np->v_alpha*np->v_alpha; |
| 110 |
/* half vector */ |
| 111 |
h[0] = ldir[0] - np->rp->rdir[0]; |
| 112 |
h[1] = ldir[1] - np->rp->rdir[1]; |
| 113 |
h[2] = ldir[2] - np->rp->rdir[2]; |
| 114 |
/* ellipse */ |
| 115 |
dtmp1 = DOT(np->u, h); |
| 116 |
dtmp1 *= dtmp1 / au2; |
| 117 |
dtmp2 = DOT(np->v, h); |
| 118 |
dtmp2 *= dtmp2 / av2; |
| 119 |
/* gaussian */ |
| 120 |
dtmp = DOT(np->pnorm, h); |
| 121 |
dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp); |
| 122 |
dtmp = exp(-dtmp) * (0.25/PI) |
| 123 |
* sqrt(ldot/(np->pdot*au2*av2)); |
| 124 |
/* worth using? */ |
| 125 |
if (dtmp > FTINY) { |
| 126 |
copycolor(ctmp, np->scolor); |
| 127 |
dtmp *= omega; |
| 128 |
scalecolor(ctmp, dtmp); |
| 129 |
addcolor(cval, ctmp); |
| 130 |
} |
| 131 |
} |
| 132 |
if (ldot < -FTINY && np->tdiff > FTINY) { |
| 133 |
/* |
| 134 |
* Compute diffuse transmission. |
| 135 |
*/ |
| 136 |
copycolor(ctmp, np->mcolor); |
| 137 |
dtmp = -ldot * omega * np->tdiff / PI; |
| 138 |
scalecolor(ctmp, dtmp); |
| 139 |
addcolor(cval, ctmp); |
| 140 |
} |
| 141 |
if (ldot < -FTINY && (np->specfl&(SP_TRAN|SP_BADU)) == SP_TRAN) { |
| 142 |
/* |
| 143 |
* Compute specular transmission. Specular transmission |
| 144 |
* is always modified by material color. |
| 145 |
*/ |
| 146 |
/* roughness + source */ |
| 147 |
au2 = av2 = omega / PI; |
| 148 |
au2 += np->u_alpha*np->u_alpha; |
| 149 |
av2 += np->v_alpha*np->v_alpha; |
| 150 |
/* "half vector" */ |
| 151 |
h[0] = ldir[0] - np->prdir[0]; |
| 152 |
h[1] = ldir[1] - np->prdir[1]; |
| 153 |
h[2] = ldir[2] - np->prdir[2]; |
| 154 |
dtmp = DOT(h,h); |
| 155 |
if (dtmp > FTINY*FTINY) { |
| 156 |
dtmp1 = DOT(h,np->pnorm); |
| 157 |
dtmp = 1.0 - dtmp1*dtmp1/dtmp; |
| 158 |
if (dtmp > FTINY*FTINY) { |
| 159 |
dtmp1 = DOT(h,np->u); |
| 160 |
dtmp1 *= dtmp1 / au2; |
| 161 |
dtmp2 = DOT(h,np->v); |
| 162 |
dtmp2 *= dtmp2 / av2; |
| 163 |
dtmp = (dtmp1 + dtmp2) / dtmp; |
| 164 |
} |
| 165 |
} else |
| 166 |
dtmp = 0.0; |
| 167 |
/* gaussian */ |
| 168 |
dtmp = exp(-dtmp) * (1.0/PI) |
| 169 |
* sqrt(-ldot/(np->pdot*au2*av2)); |
| 170 |
/* worth using? */ |
| 171 |
if (dtmp > FTINY) { |
| 172 |
copycolor(ctmp, np->mcolor); |
| 173 |
dtmp *= np->tspec * omega; |
| 174 |
scalecolor(ctmp, dtmp); |
| 175 |
addcolor(cval, ctmp); |
| 176 |
} |
| 177 |
} |
| 178 |
} |
| 179 |
|
| 180 |
|
| 181 |
int |
| 182 |
m_aniso(m, r) /* shade ray that hit something anisotropic */ |
| 183 |
register OBJREC *m; |
| 184 |
register RAY *r; |
| 185 |
{ |
| 186 |
ANISODAT nd; |
| 187 |
COLOR ctmp; |
| 188 |
register int i; |
| 189 |
/* easy shadow test */ |
| 190 |
if (r->crtype & SHADOW) |
| 191 |
return(1); |
| 192 |
|
| 193 |
if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6)) |
| 194 |
objerror(m, USER, "bad number of real arguments"); |
| 195 |
/* check for back side */ |
| 196 |
if (r->rod < 0.0) { |
| 197 |
if (!backvis && m->otype != MAT_TRANS2) { |
| 198 |
raytrans(r); |
| 199 |
return(1); |
| 200 |
} |
| 201 |
raytexture(r, m->omod); |
| 202 |
flipsurface(r); /* reorient if backvis */ |
| 203 |
} else |
| 204 |
raytexture(r, m->omod); |
| 205 |
/* get material color */ |
| 206 |
nd.mp = m; |
| 207 |
nd.rp = r; |
| 208 |
setcolor(nd.mcolor, m->oargs.farg[0], |
| 209 |
m->oargs.farg[1], |
| 210 |
m->oargs.farg[2]); |
| 211 |
/* get roughness */ |
| 212 |
nd.specfl = 0; |
| 213 |
nd.u_alpha = m->oargs.farg[4]; |
| 214 |
nd.v_alpha = m->oargs.farg[5]; |
| 215 |
if (nd.u_alpha < FTINY || nd.v_alpha <= FTINY) |
| 216 |
objerror(m, USER, "roughness too small"); |
| 217 |
|
| 218 |
nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
| 219 |
if (nd.pdot < .001) |
| 220 |
nd.pdot = .001; /* non-zero for diraniso() */ |
| 221 |
multcolor(nd.mcolor, r->pcol); /* modify material color */ |
| 222 |
/* get specular component */ |
| 223 |
if ((nd.rspec = m->oargs.farg[3]) > FTINY) { |
| 224 |
nd.specfl |= SP_REFL; |
| 225 |
/* compute specular color */ |
| 226 |
if (m->otype == MAT_METAL2) |
| 227 |
copycolor(nd.scolor, nd.mcolor); |
| 228 |
else |
| 229 |
setcolor(nd.scolor, 1.0, 1.0, 1.0); |
| 230 |
scalecolor(nd.scolor, nd.rspec); |
| 231 |
/* check threshold */ |
| 232 |
if (specthresh >= nd.rspec-FTINY) |
| 233 |
nd.specfl |= SP_RBLT; |
| 234 |
/* compute refl. direction */ |
| 235 |
for (i = 0; i < 3; i++) |
| 236 |
nd.vrefl[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i]; |
| 237 |
if (DOT(nd.vrefl, r->ron) <= FTINY) /* penetration? */ |
| 238 |
for (i = 0; i < 3; i++) /* safety measure */ |
| 239 |
nd.vrefl[i] = r->rdir[i] + 2.*r->rod*r->ron[i]; |
| 240 |
} |
| 241 |
/* compute transmission */ |
| 242 |
if (m->otype == MAT_TRANS2) { |
| 243 |
nd.trans = m->oargs.farg[6]*(1.0 - nd.rspec); |
| 244 |
nd.tspec = nd.trans * m->oargs.farg[7]; |
| 245 |
nd.tdiff = nd.trans - nd.tspec; |
| 246 |
if (nd.tspec > FTINY) { |
| 247 |
nd.specfl |= SP_TRAN; |
| 248 |
/* check threshold */ |
| 249 |
if (specthresh >= nd.tspec-FTINY) |
| 250 |
nd.specfl |= SP_TBLT; |
| 251 |
if (DOT(r->pert,r->pert) <= FTINY*FTINY) { |
| 252 |
VCOPY(nd.prdir, r->rdir); |
| 253 |
} else { |
| 254 |
for (i = 0; i < 3; i++) /* perturb */ |
| 255 |
nd.prdir[i] = r->rdir[i] - r->pert[i]; |
| 256 |
if (DOT(nd.prdir, r->ron) < -FTINY) |
| 257 |
normalize(nd.prdir); /* OK */ |
| 258 |
else |
| 259 |
VCOPY(nd.prdir, r->rdir); |
| 260 |
} |
| 261 |
} |
| 262 |
} else |
| 263 |
nd.tdiff = nd.tspec = nd.trans = 0.0; |
| 264 |
|
| 265 |
/* diffuse reflection */ |
| 266 |
nd.rdiff = 1.0 - nd.trans - nd.rspec; |
| 267 |
|
| 268 |
if (r->ro != NULL && isflat(r->ro->otype)) |
| 269 |
nd.specfl |= SP_FLAT; |
| 270 |
|
| 271 |
getacoords(r, &nd); /* set up coordinates */ |
| 272 |
|
| 273 |
if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_BADU)) |
| 274 |
agaussamp(r, &nd); |
| 275 |
|
| 276 |
if (nd.rdiff > FTINY) { /* ambient from this side */ |
| 277 |
ambient(ctmp, r, nd.pnorm); |
| 278 |
if (nd.specfl & SP_RBLT) |
| 279 |
scalecolor(ctmp, 1.0-nd.trans); |
| 280 |
else |
| 281 |
scalecolor(ctmp, nd.rdiff); |
| 282 |
multcolor(ctmp, nd.mcolor); /* modified by material color */ |
| 283 |
addcolor(r->rcol, ctmp); /* add to returned color */ |
| 284 |
} |
| 285 |
if (nd.tdiff > FTINY) { /* ambient from other side */ |
| 286 |
FVECT bnorm; |
| 287 |
|
| 288 |
flipsurface(r); |
| 289 |
bnorm[0] = -nd.pnorm[0]; |
| 290 |
bnorm[1] = -nd.pnorm[1]; |
| 291 |
bnorm[2] = -nd.pnorm[2]; |
| 292 |
ambient(ctmp, r, bnorm); |
| 293 |
if (nd.specfl & SP_TBLT) |
| 294 |
scalecolor(ctmp, nd.trans); |
| 295 |
else |
| 296 |
scalecolor(ctmp, nd.tdiff); |
| 297 |
multcolor(ctmp, nd.mcolor); /* modified by color */ |
| 298 |
addcolor(r->rcol, ctmp); |
| 299 |
flipsurface(r); |
| 300 |
} |
| 301 |
/* add direct component */ |
| 302 |
direct(r, diraniso, &nd); |
| 303 |
|
| 304 |
return(1); |
| 305 |
} |
| 306 |
|
| 307 |
|
| 308 |
static void |
| 309 |
getacoords(r, np) /* set up coordinate system */ |
| 310 |
RAY *r; |
| 311 |
register ANISODAT *np; |
| 312 |
{ |
| 313 |
register MFUNC *mf; |
| 314 |
register int i; |
| 315 |
|
| 316 |
mf = getfunc(np->mp, 3, 0x7, 1); |
| 317 |
setfunc(np->mp, r); |
| 318 |
errno = 0; |
| 319 |
for (i = 0; i < 3; i++) |
| 320 |
np->u[i] = evalue(mf->ep[i]); |
| 321 |
if (errno == EDOM || errno == ERANGE) { |
| 322 |
objerror(np->mp, WARNING, "compute error"); |
| 323 |
np->specfl |= SP_BADU; |
| 324 |
return; |
| 325 |
} |
| 326 |
if (mf->f != &unitxf) |
| 327 |
multv3(np->u, np->u, mf->f->xfm); |
| 328 |
fcross(np->v, np->pnorm, np->u); |
| 329 |
if (normalize(np->v) == 0.0) { |
| 330 |
objerror(np->mp, WARNING, "illegal orientation vector"); |
| 331 |
np->specfl |= SP_BADU; |
| 332 |
return; |
| 333 |
} |
| 334 |
fcross(np->u, np->v, np->pnorm); |
| 335 |
} |
| 336 |
|
| 337 |
|
| 338 |
static void |
| 339 |
agaussamp(r, np) /* sample anisotropic gaussian specular */ |
| 340 |
RAY *r; |
| 341 |
register ANISODAT *np; |
| 342 |
{ |
| 343 |
RAY sr; |
| 344 |
FVECT h; |
| 345 |
double rv[2]; |
| 346 |
double d, sinp, cosp; |
| 347 |
int niter; |
| 348 |
register int i; |
| 349 |
/* compute reflection */ |
| 350 |
if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL && |
| 351 |
rayorigin(&sr, r, SPECULAR, np->rspec) == 0) { |
| 352 |
dimlist[ndims++] = (int)np->mp; |
| 353 |
for (niter = 0; niter < MAXITER; niter++) { |
| 354 |
if (niter) |
| 355 |
d = frandom(); |
| 356 |
else |
| 357 |
d = urand(ilhash(dimlist,ndims)+samplendx); |
| 358 |
multisamp(rv, 2, d); |
| 359 |
d = 2.0*PI * rv[0]; |
| 360 |
cosp = tcos(d) * np->u_alpha; |
| 361 |
sinp = tsin(d) * np->v_alpha; |
| 362 |
d = sqrt(cosp*cosp + sinp*sinp); |
| 363 |
cosp /= d; |
| 364 |
sinp /= d; |
| 365 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 366 |
if (rv[1] <= FTINY) |
| 367 |
d = 1.0; |
| 368 |
else |
| 369 |
d = sqrt(-log(rv[1]) / |
| 370 |
(cosp*cosp/(np->u_alpha*np->u_alpha) + |
| 371 |
sinp*sinp/(np->v_alpha*np->v_alpha))); |
| 372 |
for (i = 0; i < 3; i++) |
| 373 |
h[i] = np->pnorm[i] + |
| 374 |
d*(cosp*np->u[i] + sinp*np->v[i]); |
| 375 |
d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d); |
| 376 |
for (i = 0; i < 3; i++) |
| 377 |
sr.rdir[i] = r->rdir[i] + d*h[i]; |
| 378 |
if (DOT(sr.rdir, r->ron) > FTINY) { |
| 379 |
rayvalue(&sr); |
| 380 |
multcolor(sr.rcol, np->scolor); |
| 381 |
addcolor(r->rcol, sr.rcol); |
| 382 |
break; |
| 383 |
} |
| 384 |
} |
| 385 |
ndims--; |
| 386 |
} |
| 387 |
/* compute transmission */ |
| 388 |
if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN && |
| 389 |
rayorigin(&sr, r, SPECULAR, np->tspec) == 0) { |
| 390 |
dimlist[ndims++] = (int)np->mp; |
| 391 |
for (niter = 0; niter < MAXITER; niter++) { |
| 392 |
if (niter) |
| 393 |
d = frandom(); |
| 394 |
else |
| 395 |
d = urand(ilhash(dimlist,ndims)+1823+samplendx); |
| 396 |
multisamp(rv, 2, d); |
| 397 |
d = 2.0*PI * rv[0]; |
| 398 |
cosp = tcos(d) * np->u_alpha; |
| 399 |
sinp = tsin(d) * np->v_alpha; |
| 400 |
d = sqrt(cosp*cosp + sinp*sinp); |
| 401 |
cosp /= d; |
| 402 |
sinp /= d; |
| 403 |
rv[1] = 1.0 - specjitter*rv[1]; |
| 404 |
if (rv[1] <= FTINY) |
| 405 |
d = 1.0; |
| 406 |
else |
| 407 |
d = sqrt(-log(rv[1]) / |
| 408 |
(cosp*cosp/(np->u_alpha*np->u_alpha) + |
| 409 |
sinp*sinp/(np->v_alpha*np->v_alpha))); |
| 410 |
for (i = 0; i < 3; i++) |
| 411 |
sr.rdir[i] = np->prdir[i] + |
| 412 |
d*(cosp*np->u[i] + sinp*np->v[i]); |
| 413 |
if (DOT(sr.rdir, r->ron) < -FTINY) { |
| 414 |
normalize(sr.rdir); /* OK, normalize */ |
| 415 |
rayvalue(&sr); |
| 416 |
scalecolor(sr.rcol, np->tspec); |
| 417 |
multcolor(sr.rcol, np->mcolor); /* modify */ |
| 418 |
addcolor(r->rcol, sr.rcol); |
| 419 |
break; |
| 420 |
} |
| 421 |
} |
| 422 |
ndims--; |
| 423 |
} |
| 424 |
} |
