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/* Copyright (c) 1991 Regents of the University of California */ |
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|
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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|
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/* |
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* Shading for materials with arbitrary BRDF's |
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*/ |
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|
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#include "ray.h" |
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|
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#include "data.h" |
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|
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#include "otypes.h" |
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|
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/* |
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* Arguments to this material include the color and specularity. |
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* String arguments include the reflection function and files. |
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* The BRDF is currently used just for the specular component to light |
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* sources. Reflectance values or data coordinates are functions |
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* of the direction to the light source. |
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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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* Arguments for MAT_PFUNC and MAT_MFUNC are: |
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* 2+ func funcfile transform |
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* 0 |
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* 4+ red grn blu specularity A5 .. |
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* |
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* Arguments for MAT_PDATA and MAT_MDATA are: |
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* 4+ func datafile funcfile v0 .. transform |
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* 0 |
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* 4+ red grn blu specularity A5 .. |
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* |
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* Arguments for MAT_TFUNC are: |
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* 2+ func funcfile transform |
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* 0 |
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* 4+ red grn blu rspec trans tspec A7 .. |
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* |
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* Arguments for MAT_TDATA are: |
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* 4+ func datafile funcfile v0 .. transform |
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* 0 |
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* 4+ red grn blu rspec trans tspec A7 .. |
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* |
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* Arguments for the more general MAT_BRTDF are: |
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* 10+ rrefl grefl brefl |
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* rtrns gtrns btrns |
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* rbrtd gbrtd bbrtd |
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* funcfile transform |
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* 0 |
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* 6+ red grn blu rspec trans tspec A7 .. |
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* |
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* In addition to the normal variables available to functions, |
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* we define the following: |
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* NxP, NyP, NzP - perturbed surface normal |
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* RdotP - perturbed ray dot product |
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* CrP, CgP, CbP - perturbed material color |
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*/ |
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|
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extern double funvalue(), varvalue(); |
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extern XF funcxf; |
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|
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typedef struct { |
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OBJREC *mp; /* material pointer */ |
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RAY *pr; /* intersected ray */ |
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DATARRAY *dp; /* data array for PDATA, MDATA or TDATA */ |
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COLOR mcolor; /* color of this material */ |
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double rspec; /* specular reflection */ |
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double rdiff; /* diffuse reflection */ |
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double trans; /* transmissivity */ |
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double tspec; /* specular transmission */ |
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double tdiff; /* diffuse transmission */ |
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FVECT pnorm; /* perturbed surface normal */ |
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double pdot; /* perturbed dot product */ |
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} BRDFDAT; /* BRDF material data */ |
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|
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|
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dirbrdf(cval, np, ldir, omega) /* compute source contribution */ |
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COLOR cval; /* returned coefficient */ |
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register BRDFDAT *np; /* material data */ |
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FVECT ldir; /* light source direction */ |
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double omega; /* light source size */ |
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{ |
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double ldot; |
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double dtmp; |
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COLOR ctmp; |
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FVECT ldx; |
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double pt[MAXDIM]; |
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register char **sa; |
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register int i; |
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|
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setcolor(cval, 0.0, 0.0, 0.0); |
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|
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ldot = DOT(np->pnorm, ldir); |
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|
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if (ldot <= FTINY && ldot >= -FTINY) |
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return; /* too close to grazing */ |
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if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY) |
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return; /* wrong side */ |
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|
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if (ldot > 0.0 && np->rdiff > FTINY) { |
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/* |
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* Compute and add diffuse reflected component to returned |
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* color. The diffuse reflected component will always be |
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* modified by the color of the material. |
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*/ |
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copycolor(ctmp, np->mcolor); |
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dtmp = ldot * omega * np->rdiff / PI; |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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if (ldot < 0.0 && np->tdiff > FTINY) { |
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/* |
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* Diffuse transmitted component. |
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*/ |
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copycolor(ctmp, np->mcolor); |
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dtmp = -ldot * omega * np->tdiff / PI; |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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if (ldot > 0.0 ? np->rspec <= FTINY : np->tspec <= FTINY) |
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return; /* no specular component */ |
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/* set up function */ |
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setbrdfunc(np); |
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sa = np->mp->oargs.sarg; |
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errno = 0; |
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/* transform light vector */ |
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multv3(ldx, ldir, funcxf.xfm); |
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for (i = 0; i < 3; i++) |
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ldx[i] /= funcxf.sca; |
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/* compute BRTDF */ |
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if (np->mp->otype == MAT_BRTDF) { |
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colval(ctmp,RED) = funvalue(sa[6], 3, ldx); |
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if (!strcmp(sa[7],sa[6])) |
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colval(ctmp,GRN) = colval(ctmp,RED); |
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else |
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colval(ctmp,GRN) = funvalue(sa[7], 3, ldx); |
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if (!strcmp(sa[8],sa[6])) |
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colval(ctmp,BLU) = colval(ctmp,RED); |
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else if (!strcmp(sa[8],sa[7])) |
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colval(ctmp,BLU) = colval(ctmp,GRN); |
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else |
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colval(ctmp,BLU) = funvalue(sa[8], 3, ldx); |
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dtmp = bright(ctmp); |
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} else if (np->dp == NULL) { |
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dtmp = funvalue(sa[0], 3, ldx); |
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setcolor(ctmp, dtmp, dtmp, dtmp); |
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} else { |
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for (i = 0; i < np->dp->nd; i++) |
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pt[i] = funvalue(sa[3+i], 3, ldx); |
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dtmp = datavalue(np->dp, pt); |
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dtmp = funvalue(sa[0], 1, &dtmp); |
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setcolor(ctmp, dtmp, dtmp, dtmp); |
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} |
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if (errno) |
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goto computerr; |
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if (dtmp <= FTINY) |
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return; |
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if (ldot > 0.0) { |
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/* |
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* Compute reflected non-diffuse component. |
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*/ |
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if (np->mp->otype == MAT_MFUNC || np->mp->otype == MAT_MDATA) |
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multcolor(ctmp, np->mcolor); |
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dtmp = ldot * omega * np->rspec; |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} else { |
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/* |
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* Compute transmitted non-diffuse component. |
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*/ |
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if (np->mp->otype == MAT_TFUNC || np->mp->otype == MAT_TDATA) |
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multcolor(ctmp, np->mcolor); |
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dtmp = -ldot * omega * np->tspec; |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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return; |
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computerr: |
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objerror(np->mp, WARNING, "compute error"); |
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return; |
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} |
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|
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|
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m_brdf(m, r) /* color a ray which hit a BRDF material */ |
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register OBJREC *m; |
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register RAY *r; |
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{ |
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int minsa, minfa; |
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BRDFDAT nd; |
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double transtest, transdist; |
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COLOR ctmp; |
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double dtmp; |
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register int i; |
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/* check arguments */ |
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switch (m->otype) { |
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case MAT_PFUNC: case MAT_MFUNC: |
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minsa = 2; minfa = 4; break; |
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case MAT_PDATA: case MAT_MDATA: |
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minsa = 4; minfa = 4; break; |
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case MAT_TFUNC: |
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minsa = 2; minfa = 6; break; |
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case MAT_TDATA: |
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minsa = 4; minfa = 6; break; |
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case MAT_BRTDF: |
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minsa = 10; minfa = 6; break; |
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} |
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if (m->oargs.nsargs < minsa || m->oargs.nfargs < minfa) |
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objerror(m, USER, "bad # arguments"); |
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nd.mp = m; |
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nd.pr = r; |
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/* get specular component */ |
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nd.rspec = m->oargs.farg[3]; |
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/* compute transmission */ |
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if (m->otype == MAT_TFUNC || m->otype == MAT_TDATA |
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|| m->otype == MAT_BRTDF) { |
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nd.trans = m->oargs.farg[4]*(1.0 - nd.rspec); |
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nd.tspec = nd.trans * m->oargs.farg[5]; |
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nd.tdiff = nd.trans - nd.tspec; |
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} else |
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nd.tdiff = nd.tspec = nd.trans = 0.0; |
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/* early shadow check */ |
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if (r->crtype & SHADOW && (m->otype != MAT_BRTDF || nd.tspec <= FTINY)) |
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return; |
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/* diffuse reflection */ |
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nd.rdiff = 1.0 - nd.trans - nd.rspec; |
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/* get material color */ |
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setcolor(nd.mcolor, m->oargs.farg[0], |
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m->oargs.farg[1], |
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m->oargs.farg[2]); |
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/* fix orientation */ |
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if (r->rod < 0.0) |
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flipsurface(r); |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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nd.pdot = raynormal(nd.pnorm, r); /* perturb normal */ |
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multcolor(nd.mcolor, r->pcol); /* modify material color */ |
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transtest = 0; |
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/* load auxiliary files */ |
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if (m->otype == MAT_PDATA || m->otype == MAT_MDATA |
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|| m->otype == MAT_TDATA) { |
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nd.dp = getdata(m->oargs.sarg[1]); |
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for (i = 3; i < m->oargs.nsargs; i++) |
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if (m->oargs.sarg[i][0] == '-') |
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break; |
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if (i-3 != nd.dp->nd) |
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objerror(m, USER, "dimension error"); |
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if (!fundefined(m->oargs.sarg[3])) |
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loadfunc(m->oargs.sarg[2]); |
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} else if (m->otype == MAT_BRTDF) { |
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nd.dp = NULL; |
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if (!fundefined(m->oargs.sarg[7])) |
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loadfunc(m->oargs.sarg[9]); |
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} else { |
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nd.dp = NULL; |
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if (!fundefined(m->oargs.sarg[0])) |
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loadfunc(m->oargs.sarg[1]); |
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} |
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/* set special variables */ |
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setbrdfunc(&nd); |
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/* compute transmitted ray */ |
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if (m->otype == MAT_BRTDF && nd.tspec > FTINY) { |
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RAY sr; |
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errno = 0; |
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setcolor(ctmp, varvalue(m->oargs.sarg[0]), |
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varvalue(m->oargs.sarg[1]), |
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varvalue(m->oargs.sarg[2])); |
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scalecolor(ctmp, nd.tspec); |
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if (errno) |
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objerror(m, WARNING, "compute error"); |
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else if ((dtmp = bright(ctmp)) > FTINY && |
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rayorigin(&sr, r, TRANS, dtmp) == 0) { |
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if (DOT(r->pert,r->pert) > FTINY*FTINY) { |
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for (i = 0; i < 3; i++) /* perturb direction */ |
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sr.rdir[i] = r->rdir[i] - |
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.75*r->pert[i]; |
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normalize(sr.rdir); |
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} else { |
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VCOPY(sr.rdir, r->rdir); |
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transtest = 2; |
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} |
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rayvalue(&sr); |
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multcolor(sr.rcol, ctmp); |
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addcolor(r->rcol, sr.rcol); |
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transtest *= bright(sr.rcol); |
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transdist = r->rot + sr.rt; |
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} |
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} |
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if (r->crtype & SHADOW) /* the rest is shadow */ |
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return; |
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/* compute reflected ray */ |
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if (m->otype == MAT_BRTDF && nd.rspec > FTINY) { |
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RAY sr; |
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errno = 0; |
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setcolor(ctmp, varvalue(m->oargs.sarg[3]), |
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varvalue(m->oargs.sarg[4]), |
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varvalue(m->oargs.sarg[5])); |
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scalecolor(ctmp, nd.rspec); |
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if (errno) |
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objerror(m, WARNING, "compute error"); |
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else if ((dtmp = bright(ctmp)) > FTINY && |
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rayorigin(&sr, r, REFLECTED, dtmp) == 0) { |
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for (i = 0; i < 3; i++) |
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sr.rdir[i] = r->rdir[i] + |
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2.0*nd.pdot*nd.pnorm[i]; |
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rayvalue(&sr); |
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multcolor(sr.rcol, ctmp); |
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addcolor(r->rcol, sr.rcol); |
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} |
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} |
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/* compute ambient */ |
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if (nd.rdiff > FTINY) { |
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ambient(ctmp, r); |
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if (m->otype == MAT_BRTDF) |
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scalecolor(ctmp, nd.rdiff); |
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else |
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scalecolor(ctmp, 1.0-nd.trans); |
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multcolor(ctmp, nd.mcolor); /* modified by material color */ |
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addcolor(r->rcol, ctmp); /* add to returned color */ |
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} |
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if (nd.tdiff > FTINY) { /* from other side */ |
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flipsurface(r); |
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ambient(ctmp, r); |
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if (m->otype == MAT_BRTDF) |
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scalecolor(ctmp, nd.tdiff); |
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else |
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scalecolor(ctmp, nd.trans); |
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multcolor(ctmp, nd.mcolor); |
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addcolor(r->rcol, ctmp); |
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flipsurface(r); |
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} |
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/* add direct component */ |
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direct(r, dirbrdf, &nd); |
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/* check distance */ |
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if (transtest > bright(r->rcol)) |
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r->rt = transdist; |
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} |
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|
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|
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setbrdfunc(np) /* set up brdf function and variables */ |
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register BRDFDAT *np; |
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{ |
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FVECT vec; |
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|
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if (setfunc(np->mp, np->pr) == 0) |
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return(0); /* it's OK, setfunc says we're done */ |
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/* else (re)assign special variables */ |
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multv3(vec, np->pnorm, funcxf.xfm); |
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varset("NxP", '=', vec[0]/funcxf.sca); |
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varset("NyP", '=', vec[1]/funcxf.sca); |
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varset("NzP", '=', vec[2]/funcxf.sca); |
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varset("RdotP", '=', np->pdot); |
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varset("CrP", '=', colval(np->mcolor,RED)); |
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varset("CgP", '=', colval(np->mcolor,GRN)); |
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varset("CbP", '=', colval(np->mcolor,BLU)); |
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return(1); |
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} |
