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#ifndef lint |
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static const char RCSid[] = "$Id: m_bsdf.c,v 2.2 2011/02/18 02:41:55 greg Exp $"; |
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#endif |
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/* |
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* Shading for materials with BSDFs taken from XML data files |
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*/ |
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|
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#include "copyright.h" |
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|
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#include "ray.h" |
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#include "ambient.h" |
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#include "source.h" |
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#include "func.h" |
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#include "bsdf.h" |
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#include "random.h" |
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|
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/* |
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* Arguments to this material include optional diffuse colors. |
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* String arguments include the BSDF and function files. |
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* A thickness variable causes the strange but useful behavior |
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* of translating transmitted rays this distance past the surface |
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* intersection in the normal direction to bypass intervening geometry. |
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* This only affects scattered, non-source directed samples. Thus, |
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* thickness is relevant only if there is a transmitted component. |
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* A positive thickness has the further side-effect that an unscattered |
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* (view) ray will pass right through our material if it has any |
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* non-diffuse transmission, making our BSDF invisible. This allows the |
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* underlying geometry to become visible. A matching surface should be |
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* placed on the other side, less than the thickness away, if the backside |
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* reflectance is non-zero. |
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* The "up" vector for the BSDF is given by three variables, defined |
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* (along with the thickness) by the named function file, or '.' if none. |
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* Together with the surface normal, this defines the local coordinate |
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* system for the BSDF. |
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* We do not reorient the surface, so if the BSDF has no back-side |
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* reflectance and none is given in the real arguments, the surface will |
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* appear as black when viewed from behind (unless backvis is false). |
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* The diffuse compnent arguments are added to components in the BSDF file, |
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* not multiplied. However, patterns affect this material as a multiplier |
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* on everything except non-diffuse reflection. |
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* |
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* Arguments for MAT_BSDF are: |
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* 6+ thick BSDFfile ux uy uz funcfile transform |
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* 0 |
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* 0|3|9 rdf gdf bdf |
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* rdb gdb bdb |
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* rdt gdt bdt |
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*/ |
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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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FVECT pnorm; /* perturbed surface normal */ |
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FVECT vinc; /* local incident vector */ |
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RREAL toloc[3][3]; /* world to local BSDF coords */ |
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RREAL fromloc[3][3]; /* local BSDF coords to world */ |
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double thick; /* surface thickness */ |
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SDData *sd; /* loaded BSDF data */ |
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COLOR runsamp; /* BSDF hemispherical reflection */ |
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COLOR rdiff; /* added diffuse reflection */ |
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COLOR tunsamp; /* BSDF hemispherical transmission */ |
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COLOR tdiff; /* added diffuse transmission */ |
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} BSDFDAT; /* BSDF material data */ |
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|
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#define cvt_sdcolor(cv, svp) ccy2rgb(&(svp)->spec, (svp)->cieY, cv) |
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|
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/* Compute source contribution for BSDF */ |
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static void |
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dirbsdf( |
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COLOR cval, /* returned coefficient */ |
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void *nnp, /* 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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{ |
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BSDFDAT *np = (BSDFDAT *)nnp; |
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SDError ec; |
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SDValue sv; |
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FVECT vout; |
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double ldot; |
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double dtmp; |
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COLOR ctmp; |
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|
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setcolor(cval, .0, .0, .0); |
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|
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ldot = DOT(np->pnorm, ldir); |
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if ((-FTINY <= ldot) & (ldot <= FTINY)) |
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return; |
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|
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if (ldot > .0 && bright(np->rdiff) > FTINY) { |
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/* |
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* Compute added diffuse reflected component. |
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*/ |
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copycolor(ctmp, np->rdiff); |
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dtmp = ldot * omega * (1./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 && bright(np->tdiff) > FTINY) { |
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/* |
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* Compute added diffuse transmission. |
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*/ |
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copycolor(ctmp, np->tdiff); |
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dtmp = -ldot * omega * (1.0/PI); |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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/* |
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* Compute scattering coefficient using BSDF. |
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*/ |
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if (SDmapDir(vout, np->toloc, ldir) != SDEnone) |
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return; |
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ec = SDevalBSDF(&sv, vout, np->vinc, np->sd); |
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if (ec) |
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objerror(np->mp, USER, transSDError(ec)); |
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|
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if (sv.cieY <= FTINY) /* not worth using? */ |
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return; |
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cvt_sdcolor(ctmp, &sv); |
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if (ldot > .0) { /* pattern only diffuse reflection */ |
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COLOR ctmp1, ctmp2; |
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dtmp = (np->pr->rod > .0) ? np->sd->rLambFront.cieY |
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: np->sd->rLambBack.cieY; |
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dtmp /= PI * sv.cieY; /* diffuse fraction */ |
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copycolor(ctmp2, np->pr->pcol); |
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scalecolor(ctmp2, dtmp); |
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setcolor(ctmp1, 1.-dtmp, 1.-dtmp, 1.-dtmp); |
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addcolor(ctmp1, ctmp2); |
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multcolor(ctmp, ctmp1); /* apply derated pattern */ |
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dtmp = ldot * omega; |
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} else { /* full pattern on transmission */ |
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multcolor(ctmp, np->pr->pcol); |
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dtmp = -ldot * omega; |
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} |
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scalecolor(ctmp, dtmp); |
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addcolor(cval, ctmp); |
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} |
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|
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/* Sample separate BSDF component */ |
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static int |
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sample_sdcomp(BSDFDAT *ndp, SDComponent *dcp, int usepat) |
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{ |
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int nstarget = 1; |
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int nsent = 0; |
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SDError ec; |
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SDValue bsv; |
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double sthick; |
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FVECT vout; |
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RAY sr; |
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int ntrials; |
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/* multiple samples? */ |
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if (specjitter > 1.5) { |
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nstarget = specjitter*ndp->pr->rweight + .5; |
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if (nstarget < 1) |
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nstarget = 1; |
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} |
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/* run through our trials */ |
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for (ntrials = 0; nsent < nstarget && ntrials < 9*nstarget; ntrials++) { |
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SDerrorDetail[0] = '\0'; |
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/* sample direction & coef. */ |
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ec = SDsampComponent(&bsv, vout, ndp->vinc, |
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ntrials ? frandom() |
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: urand(ilhash(dimlist,ndims)+samplendx), |
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dcp); |
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if (ec) |
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objerror(ndp->mp, USER, transSDError(ec)); |
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/* zero component? */ |
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if (bsv.cieY <= FTINY) |
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break; |
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/* map vector to world */ |
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if (SDmapDir(sr.rdir, ndp->fromloc, vout) != SDEnone) |
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break; |
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/* unintentional penetration? */ |
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if (DOT(sr.rdir, ndp->pr->ron) > .0 ^ vout[2] > .0) |
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continue; |
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/* spawn a specular ray */ |
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if (nstarget > 1) |
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bsv.cieY /= (double)nstarget; |
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cvt_sdcolor(sr.rcoef, &bsv); /* use color */ |
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if (usepat) /* pattern on transmission */ |
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multcolor(sr.rcoef, ndp->pr->pcol); |
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if (rayorigin(&sr, SPECULAR, ndp->pr, sr.rcoef) < 0) { |
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if (maxdepth > 0) |
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break; |
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++nsent; /* Russian roulette victim */ |
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continue; |
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} |
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if (ndp->thick > FTINY) { /* need to move origin? */ |
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sthick = (ndp->pr->rod > .0) ? -ndp->thick : ndp->thick; |
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if (sthick < .0 ^ vout[2] > .0) |
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VSUM(sr.rorg, sr.rorg, ndp->pr->ron, sthick); |
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} |
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rayvalue(&sr); /* send & evaluate sample */ |
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multcolor(sr.rcol, sr.rcoef); |
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addcolor(ndp->pr->rcol, sr.rcol); |
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++nsent; |
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} |
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return(nsent); |
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} |
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|
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/* Sample non-diffuse components of BSDF */ |
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static int |
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sample_sdf(BSDFDAT *ndp, int sflags) |
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{ |
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int n, ntotal = 0; |
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SDSpectralDF *dfp; |
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COLORV *unsc; |
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|
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if (sflags == SDsampSpT) { |
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unsc = ndp->tunsamp; |
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dfp = ndp->sd->tf; |
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cvt_sdcolor(unsc, &ndp->sd->tLamb); |
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} else /* sflags == SDsampSpR */ { |
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unsc = ndp->runsamp; |
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if (ndp->pr->rod > .0) { |
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dfp = ndp->sd->rf; |
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cvt_sdcolor(unsc, &ndp->sd->rLambFront); |
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} else { |
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dfp = ndp->sd->rb; |
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cvt_sdcolor(unsc, &ndp->sd->rLambBack); |
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} |
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} |
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multcolor(unsc, ndp->pr->pcol); |
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if (dfp == NULL) /* no specular component? */ |
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return(0); |
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/* below sampling threshold? */ |
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if (dfp->maxHemi <= specthresh+FTINY) { |
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if (dfp->maxHemi > FTINY) { /* XXX no color from BSDF */ |
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double d = SDdirectHemi(ndp->vinc, sflags, ndp->sd); |
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COLOR ctmp; |
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if (sflags == SDsampSpT) { |
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copycolor(ctmp, ndp->pr->pcol); |
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scalecolor(ctmp, d); |
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} else /* no pattern on reflection */ |
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setcolor(ctmp, d, d, d); |
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addcolor(unsc, ctmp); |
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} |
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return(0); |
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} |
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/* else need to sample */ |
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dimlist[ndims++] = (int)(size_t)ndp->mp; |
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ndims++; |
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for (n = dfp->ncomp; n--; ) { /* loop over components */ |
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dimlist[ndims-1] = n + 9438; |
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ntotal += sample_sdcomp(ndp, &dfp->comp[n], sflags==SDsampSpT); |
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} |
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ndims -= 2; |
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return(ntotal); |
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} |
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|
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/* Color a ray that hit a BSDF material */ |
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int |
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m_bsdf(OBJREC *m, RAY *r) |
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{ |
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COLOR ctmp; |
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SDError ec; |
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FVECT upvec, outVec; |
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MFUNC *mf; |
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BSDFDAT nd; |
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/* check arguments */ |
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if ((m->oargs.nsargs < 6) | (m->oargs.nfargs > 9) | |
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(m->oargs.nfargs % 3)) |
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objerror(m, USER, "bad # arguments"); |
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|
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/* get BSDF data */ |
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nd.sd = loadBSDF(m->oargs.sarg[1]); |
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/* load cal file */ |
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mf = getfunc(m, 5, 0x1d, 1); |
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/* get thickness */ |
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nd.thick = evalue(mf->ep[0]); |
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if (nd.thick < .0) |
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nd.thick = .0; |
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/* check shadow */ |
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if (r->crtype & SHADOW) { |
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if ((nd.thick > FTINY) & (nd.sd->tf != NULL)) |
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raytrans(r); /* pass-through */ |
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SDfreeCache(nd.sd); |
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return(1); /* else shadow */ |
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} |
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/* check unscattered ray */ |
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if (!(r->crtype & (SPECULAR|AMBIENT)) && |
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(nd.thick > FTINY) & (nd.sd->tf != NULL)) { |
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SDfreeCache(nd.sd); |
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raytrans(r); /* pass-through */ |
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return(1); |
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} |
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/* diffuse reflectance */ |
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if (r->rod > .0) { |
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if (m->oargs.nfargs < 3) |
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setcolor(nd.rdiff, .0, .0, .0); |
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else |
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setcolor(nd.rdiff, m->oargs.farg[0], |
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m->oargs.farg[1], |
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m->oargs.farg[2]); |
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} else { |
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if (m->oargs.nfargs < 6) { /* check invisible backside */ |
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if (!backvis && (nd.sd->rb == NULL) & |
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(nd.sd->tf == NULL)) { |
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SDfreeCache(nd.sd); |
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raytrans(r); |
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return(1); |
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} |
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setcolor(nd.rdiff, .0, .0, .0); |
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} else |
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setcolor(nd.rdiff, m->oargs.farg[3], |
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m->oargs.farg[4], |
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m->oargs.farg[5]); |
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} |
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/* diffuse transmittance */ |
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if (m->oargs.nfargs < 9) |
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setcolor(nd.tdiff, .0, .0, .0); |
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else |
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setcolor(nd.tdiff, m->oargs.farg[6], |
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m->oargs.farg[7], |
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m->oargs.farg[8]); |
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nd.mp = m; |
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nd.pr = r; |
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/* get modifiers */ |
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raytexture(r, m->omod); |
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if (bright(r->pcol) <= FTINY) { /* black pattern?! */ |
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SDfreeCache(nd.sd); |
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return(1); |
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} |
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/* modify diffuse values */ |
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multcolor(nd.rdiff, r->pcol); |
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multcolor(nd.tdiff, r->pcol); |
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/* get up vector */ |
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upvec[0] = evalue(mf->ep[1]); |
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upvec[1] = evalue(mf->ep[2]); |
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upvec[2] = evalue(mf->ep[3]); |
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/* return to world coords */ |
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if (mf->f != &unitxf) { |
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multv3(upvec, upvec, mf->f->xfm); |
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nd.thick *= mf->f->sca; |
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} |
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raynormal(nd.pnorm, r); |
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/* compute local BSDF xform */ |
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ec = SDcompXform(nd.toloc, nd.pnorm, upvec); |
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if (!ec) { |
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nd.vinc[0] = -r->rdir[0]; |
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nd.vinc[1] = -r->rdir[1]; |
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nd.vinc[2] = -r->rdir[2]; |
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ec = SDmapDir(nd.vinc, nd.toloc, nd.vinc); |
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} |
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if (!ec) |
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ec = SDinvXform(nd.fromloc, nd.toloc); |
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if (ec) { |
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objerror(m, WARNING, transSDError(ec)); |
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SDfreeCache(nd.sd); |
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return(1); |
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} |
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if (r->rod < .0) { /* perturb normal towards hit */ |
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nd.pnorm[0] = -nd.pnorm[0]; |
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nd.pnorm[1] = -nd.pnorm[1]; |
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nd.pnorm[2] = -nd.pnorm[2]; |
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} |
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/* sample reflection */ |
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sample_sdf(&nd, SDsampSpR); |
| 359 |
/* sample transmission */ |
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sample_sdf(&nd, SDsampSpT); |
| 361 |
/* compute indirect diffuse */ |
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copycolor(ctmp, nd.rdiff); |
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addcolor(ctmp, nd.runsamp); |
| 364 |
if (bright(ctmp) > FTINY) { /* ambient from this side */ |
| 365 |
if (r->rod < .0) |
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flipsurface(r); |
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multambient(ctmp, r, nd.pnorm); |
| 368 |
addcolor(r->rcol, ctmp); |
| 369 |
if (r->rod < .0) |
| 370 |
flipsurface(r); |
| 371 |
} |
| 372 |
copycolor(ctmp, nd.tdiff); |
| 373 |
addcolor(ctmp, nd.tunsamp); |
| 374 |
if (bright(ctmp) > FTINY) { /* ambient from other side */ |
| 375 |
FVECT bnorm; |
| 376 |
if (r->rod > .0) |
| 377 |
flipsurface(r); |
| 378 |
bnorm[0] = -nd.pnorm[0]; |
| 379 |
bnorm[1] = -nd.pnorm[1]; |
| 380 |
bnorm[2] = -nd.pnorm[2]; |
| 381 |
multambient(ctmp, r, bnorm); |
| 382 |
addcolor(r->rcol, ctmp); |
| 383 |
if (r->rod > .0) |
| 384 |
flipsurface(r); |
| 385 |
} |
| 386 |
/* add direct component */ |
| 387 |
direct(r, dirbsdf, &nd); |
| 388 |
/* clean up */ |
| 389 |
SDfreeCache(nd.sd); |
| 390 |
return(1); |
| 391 |
} |
