| 19 |
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extern double specthresh; /* specular sampling threshold */ |
| 20 |
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extern double specjitter; /* specular sampling jitter */ |
| 21 |
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|
| 22 |
+ |
static agaussamp(); |
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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. |
| 27 |
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* We orient the surface towards the incoming ray, so a single |
| 28 |
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* surface can be used to represent an infinitely thin object. |
| 29 |
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* |
| 111 |
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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 |
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/* 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); |
| 118 |
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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) |
| 123 |
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* sqrt(ldot/(np->pdot*au2*av2)); |
| 124 |
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/* worth using? */ |
| 125 |
|
if (dtmp > FTINY) { |
| 157 |
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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 |
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} else |
| 166 |
|
dtmp = 0.0; |
| 167 |
|
/* gaussian */ |
| 168 |
< |
dtmp = exp(-dtmp) * 1.0/PI |
| 168 |
> |
dtmp = exp(-dtmp) * (1.0/PI) |
| 169 |
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* sqrt(-ldot/(np->pdot*au2*av2)); |
| 170 |
|
/* worth using? */ |
| 171 |
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if (dtmp > FTINY) { |
