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extern double specjitter; /* specular sampling jitter */ |
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/* |
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< |
* This anisotropic reflection model uses a variant on the |
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< |
* exponential Gaussian used in normal.c. |
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> |
* This routine implements the anisotropic Gaussian |
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* 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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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); |
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/* ellipse */ |
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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); |
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dtmp2 *= dtmp2 / av2; |
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/* gaussian */ |
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< |
dtmp = (dtmp1 + dtmp2) / (1.0 + DOT(np->pnorm, h)); |
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< |
dtmp = exp(-2.0*dtmp) * 1.0/(4.0*PI) |
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> |
dtmp = DOT(np->pnorm, h); |
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> |
dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp); |
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> |
dtmp = exp(-dtmp) * (0.25/PI) |
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* sqrt(ldot/(np->pdot*au2*av2)); |
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/* worth using? */ |
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if (dtmp > FTINY) { |
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dtmp = 1.0 - dtmp1*dtmp1/dtmp; |
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if (dtmp > FTINY*FTINY) { |
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dtmp1 = DOT(h,np->u); |
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< |
dtmp1 = dtmp1*dtmp1 / au2; |
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> |
dtmp1 *= dtmp1 / au2; |
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dtmp2 = DOT(h,np->v); |
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< |
dtmp2 = dtmp2*dtmp2 / av2; |
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> |
dtmp2 *= dtmp2 / av2; |
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dtmp = (dtmp1 + dtmp2) / dtmp; |
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} |
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} else |
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dtmp = 0.0; |
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/* gaussian */ |
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< |
dtmp = exp(-dtmp) * 1.0/PI |
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> |
dtmp = exp(-dtmp) * (1.0/PI) |
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* sqrt(-ldot/(np->pdot*au2*av2)); |
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/* worth using? */ |
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if (dtmp > FTINY) { |
