| 19 |
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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 |
+ |
static agaussamp(), getacoords(); |
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+ |
|
| 24 |
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/* |
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< |
* This anisotropic reflection model uses a variant on the |
| 26 |
< |
* exponential Gaussian used in normal.c. |
| 25 |
> |
* This routine implements the anisotropic Gaussian |
| 26 |
> |
* 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. |
| 29 |
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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 */ |
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– |
|
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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]; |
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– |
normalize(h); |
| 112 |
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/* ellipse */ |
| 113 |
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dtmp1 = DOT(np->u, h); |
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dtmp1 *= dtmp1 / au2; |
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dtmp2 = DOT(np->v, h); |
| 116 |
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dtmp2 *= dtmp2 / av2; |
| 117 |
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/* gaussian */ |
| 118 |
< |
dtmp = (dtmp1 + dtmp2) / (1.0 + DOT(np->pnorm, h)); |
| 119 |
< |
dtmp = exp(-2.0*dtmp) * 1.0/(4.0*PI) |
| 118 |
> |
dtmp = DOT(np->pnorm, h); |
| 119 |
> |
dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp); |
| 120 |
> |
dtmp = exp(-dtmp) * (0.25/PI) |
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* sqrt(ldot/(np->pdot*au2*av2)); |
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/* worth using? */ |
| 123 |
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if (dtmp > FTINY) { |
| 155 |
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dtmp = 1.0 - dtmp1*dtmp1/dtmp; |
| 156 |
|
if (dtmp > FTINY*FTINY) { |
| 157 |
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dtmp1 = DOT(h,np->u); |
| 158 |
< |
dtmp1 = dtmp1*dtmp1 / au2; |
| 158 |
> |
dtmp1 *= dtmp1 / au2; |
| 159 |
|
dtmp2 = DOT(h,np->v); |
| 160 |
< |
dtmp2 = dtmp2*dtmp2 / av2; |
| 160 |
> |
dtmp2 *= dtmp2 / av2; |
| 161 |
|
dtmp = (dtmp1 + dtmp2) / dtmp; |
| 162 |
|
} |
| 163 |
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} else |
| 164 |
|
dtmp = 0.0; |
| 165 |
|
/* gaussian */ |
| 166 |
< |
dtmp = exp(-dtmp) * 1.0/PI |
| 166 |
> |
dtmp = exp(-dtmp) * (1.0/PI) |
| 167 |
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* sqrt(-ldot/(np->pdot*au2*av2)); |
| 168 |
|
/* worth using? */ |
| 169 |
|
if (dtmp > FTINY) { |
| 181 |
|
register RAY *r; |
| 182 |
|
{ |
| 183 |
|
ANISODAT nd; |
| 184 |
– |
double dtmp; |
| 184 |
|
COLOR ctmp; |
| 185 |
|
register int i; |
| 186 |
|
/* easy shadow test */ |
| 219 |
|
else |
| 220 |
|
setcolor(nd.scolor, 1.0, 1.0, 1.0); |
| 221 |
|
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; |
| 222 |
|
/* check threshold */ |
| 223 |
< |
if (specthresh > FTINY && |
| 230 |
< |
(specthresh >= 1.-FTINY || |
| 231 |
< |
specthresh + .05 - .1*frandom() > nd.rspec)) |
| 223 |
> |
if (specthresh >= nd.rspec-FTINY) |
| 224 |
|
nd.specfl |= SP_RBLT; |
| 225 |
|
/* compute refl. direction */ |
| 226 |
|
for (i = 0; i < 3; i++) |
| 237 |
|
if (nd.tspec > FTINY) { |
| 238 |
|
nd.specfl |= SP_TRAN; |
| 239 |
|
/* check threshold */ |
| 240 |
< |
if (specthresh > FTINY && |
| 249 |
< |
(specthresh >= 1.-FTINY || |
| 250 |
< |
specthresh + .05 - .1*frandom() > nd.tspec)) |
| 240 |
> |
if (specthresh >= nd.tspec-FTINY) |
| 241 |
|
nd.specfl |= SP_TBLT; |
| 242 |
|
if (DOT(r->pert,r->pert) <= FTINY*FTINY) { |
| 243 |
|
VCOPY(nd.prdir, r->rdir); |
