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{ RCSid $Id: LaFortune.cal,v 1.2 2014/03/18 19:03:41 greg Exp $ } |
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{ LaFortune reflectance model with N lobes } |
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|
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{ Sample parameters (change these) } |
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rho_d : 0.017615787130711; |
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rho_s : 0.654729812719232; |
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Cx(i) : select(i, -0.75, -0.78); |
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Cy(i) : select(i, -0.91, -.81); |
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Cz(i) : select(i, .75, .83); |
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n(i) : select(i, 30, 15); |
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NL : n(0); |
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{ Useful functions } |
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abs(x) : if(x, x, -x); |
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noneg(x) : if(x, x, 0); |
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|
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{ Normalization factor based on parameters } |
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snf(i) : (n(i)+2)/(2*PI*max(abs(Cx(i)),max(abs(Cy(i)),abs(Cz(i))))^n(i)); |
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|
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{ CHANGE THE FOLOWING TO MATCH NL } |
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snfk(i) : select(i, snf(1), snf(2)); |
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{ Note that we assume i and o vectors are normalized, both pointing away } |
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|
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sum(i,dx,dy,dz) : if(.5-i, 0, sum(i-1,dx,dy,dz) + |
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snfk(i)*noneg(Cx(i)*dx + Cy(i)*dy + Cz(i)*dz)^n(i)); |
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|
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lafortune(ix,iy,iz,ox,oy,oz) : if( -iz*oz, 0, |
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rho_d/PI + rho_s*sum(NL,ix*ox,iy*oy,iz*oz) ); |
