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extern double specthresh; /* specular sampling threshold */ |
| 20 |
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extern double specjitter; /* specular sampling jitter */ |
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|
| 22 |
+ |
extern int backvis; /* back faces visible? */ |
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+ |
|
| 24 |
+ |
static agaussamp(), getacoords(); |
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+ |
|
| 26 |
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/* |
| 27 |
< |
* This anisotropic reflection model uses a variant on the |
| 28 |
< |
* exponential Gaussian used in normal.c. |
| 27 |
> |
* This routine implements the anisotropic Gaussian |
| 28 |
> |
* model described by Ward in Siggraph `92 article. |
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* We orient the surface towards the incoming ray, so a single |
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* surface can be used to represent an infinitely thin object. |
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* |
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* 8 red grn blu rspec u-rough v-rough trans tspec |
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*/ |
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|
| 37 |
– |
#define BSPEC(m) (6.0) /* specularity parameter b */ |
| 38 |
– |
|
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/* specularity flags */ |
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#define SP_REFL 01 /* has reflected specular component */ |
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#define SP_TRAN 02 /* has transmitted specular */ |
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h[0] = ldir[0] - np->rp->rdir[0]; |
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h[1] = ldir[1] - np->rp->rdir[1]; |
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h[2] = ldir[2] - np->rp->rdir[2]; |
| 112 |
– |
normalize(h); |
| 114 |
|
/* ellipse */ |
| 115 |
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dtmp1 = DOT(np->u, h); |
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dtmp1 *= dtmp1 / au2; |
| 117 |
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dtmp2 = DOT(np->v, h); |
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dtmp2 *= dtmp2 / av2; |
| 119 |
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/* gaussian */ |
| 120 |
< |
dtmp = (dtmp1 + dtmp2) / (1.0 + DOT(np->pnorm, h)); |
| 121 |
< |
dtmp = exp(-2.0*dtmp) * 1.0/(4.0*PI) |
| 120 |
> |
dtmp = DOT(np->pnorm, h); |
| 121 |
> |
dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp); |
| 122 |
> |
dtmp = exp(-dtmp) * (0.25/PI) |
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* sqrt(ldot/(np->pdot*au2*av2)); |
| 124 |
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/* worth using? */ |
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if (dtmp > FTINY) { |
| 157 |
|
dtmp = 1.0 - dtmp1*dtmp1/dtmp; |
| 158 |
|
if (dtmp > FTINY*FTINY) { |
| 159 |
|
dtmp1 = DOT(h,np->u); |
| 160 |
< |
dtmp1 = dtmp1*dtmp1 / au2; |
| 160 |
> |
dtmp1 *= dtmp1 / au2; |
| 161 |
|
dtmp2 = DOT(h,np->v); |
| 162 |
< |
dtmp2 = dtmp2*dtmp2 / av2; |
| 162 |
> |
dtmp2 *= dtmp2 / av2; |
| 163 |
|
dtmp = (dtmp1 + dtmp2) / dtmp; |
| 164 |
|
} |
| 165 |
|
} else |
| 166 |
|
dtmp = 0.0; |
| 167 |
|
/* gaussian */ |
| 168 |
< |
dtmp = exp(-dtmp) * 1.0/(4.0*PI) |
| 168 |
> |
dtmp = exp(-dtmp) * (1.0/PI) |
| 169 |
|
* sqrt(-ldot/(np->pdot*au2*av2)); |
| 170 |
|
/* worth using? */ |
| 171 |
|
if (dtmp > FTINY) { |
| 183 |
|
register RAY *r; |
| 184 |
|
{ |
| 185 |
|
ANISODAT nd; |
| 184 |
– |
double dtmp; |
| 186 |
|
COLOR ctmp; |
| 187 |
|
register int i; |
| 188 |
|
/* easy shadow test */ |
| 189 |
|
if (r->crtype & SHADOW) |
| 190 |
< |
return; |
| 190 |
> |
return(1); |
| 191 |
|
|
| 192 |
|
if (m->oargs.nfargs != (m->otype == MAT_TRANS2 ? 8 : 6)) |
| 193 |
|
objerror(m, USER, "bad number of real arguments"); |
| 203 |
|
nd.v_alpha = m->oargs.farg[5]; |
| 204 |
|
if (nd.u_alpha < FTINY || nd.v_alpha <= FTINY) |
| 205 |
|
objerror(m, USER, "roughness too small"); |
| 206 |
< |
/* reorient if necessary */ |
| 207 |
< |
if (r->rod < 0.0) |
| 208 |
< |
flipsurface(r); |
| 206 |
> |
/* check for back side */ |
| 207 |
> |
if (r->rod < 0.0) { |
| 208 |
> |
if (!backvis && m->otype != MAT_TRANS2) { |
| 209 |
> |
raytrans(r); |
| 210 |
> |
return(1); |
| 211 |
> |
} |
| 212 |
> |
flipsurface(r); /* reorient if backvis */ |
| 213 |
> |
} |
| 214 |
|
/* get modifiers */ |
| 215 |
|
raytexture(r, m->omod); |
| 216 |
|
nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
| 226 |
|
else |
| 227 |
|
setcolor(nd.scolor, 1.0, 1.0, 1.0); |
| 228 |
|
scalecolor(nd.scolor, nd.rspec); |
| 223 |
– |
/* improved model */ |
| 224 |
– |
dtmp = exp(-BSPEC(m)*nd.pdot); |
| 225 |
– |
for (i = 0; i < 3; i++) |
| 226 |
– |
colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp; |
| 227 |
– |
nd.rspec += (1.0-nd.rspec)*dtmp; |
| 229 |
|
/* check threshold */ |
| 230 |
< |
if (specthresh > FTINY && |
| 230 |
< |
(specthresh >= 1.-FTINY || |
| 231 |
< |
specthresh + .05 - .1*frandom() > nd.rspec)) |
| 230 |
> |
if (specthresh >= nd.rspec-FTINY) |
| 231 |
|
nd.specfl |= SP_RBLT; |
| 232 |
|
/* compute refl. direction */ |
| 233 |
|
for (i = 0; i < 3; i++) |
| 244 |
|
if (nd.tspec > FTINY) { |
| 245 |
|
nd.specfl |= SP_TRAN; |
| 246 |
|
/* check threshold */ |
| 247 |
< |
if (specthresh > FTINY && |
| 249 |
< |
(specthresh >= 1.-FTINY || |
| 250 |
< |
specthresh + .05 - .1*frandom() > nd.tspec)) |
| 247 |
> |
if (specthresh >= nd.tspec-FTINY) |
| 248 |
|
nd.specfl |= SP_TBLT; |
| 249 |
|
if (DOT(r->pert,r->pert) <= FTINY*FTINY) { |
| 250 |
|
VCOPY(nd.prdir, r->rdir); |
| 294 |
|
} |
| 295 |
|
/* add direct component */ |
| 296 |
|
direct(r, diraniso, &nd); |
| 297 |
+ |
|
| 298 |
+ |
return(1); |
| 299 |
|
} |
| 300 |
|
|
| 301 |
|
|
