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#ifndef lint
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static const char RCSid[] = "$Id: cmbsdf.c,v 2.9 2021/01/19 23:32:00 greg Exp $";
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#endif
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/*
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* Load and convert BSDF into color coefficient matrix representation.
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*
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* G. Ward
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*/
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#include "standard.h"
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#include "cmatrix.h"
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#include "paths.h"
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#include "bsdf.h"
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#include "bsdf_m.h"
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/* Convert a BSDF to our matrix representation */
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static CMATRIX *
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cm_bsdf(const COLOR diffBSDF, const SDMat *bsdf)
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{
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CMATRIX *cm = cm_alloc(bsdf->nout, bsdf->ninc);
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int nbadohm = 0;
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int nneg = 0;
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int r, c;
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/* loop over incident angles */
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for (c = 0; c < cm->ncols; c++) {
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const double dom = mBSDF_incohm(bsdf,c);
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/* projected solid angle */
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nbadohm += (dom <= 0);
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for (r = 0; r < cm->nrows; r++) {
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float f = mBSDF_value(bsdf,r,c);
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COLORV *mp = cm_lval(cm,r,c);
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/* check BSDF value */
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if ((f <= 0) | (dom <= 0)) {
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nneg += (f < -FTINY);
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setcolor(mp, .0f, .0f, .0f);
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} else if (bsdf->chroma != NULL) {
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C_COLOR cxy;
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c_decodeChroma(&cxy, mBSDF_chroma(bsdf,r,c));
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ccy2rgb(&cxy, f, mp);
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} else
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setcolor(mp, f, f, f);
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addcolor(mp, diffBSDF);
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scalecolor(mp, dom);
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}
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}
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if (nneg | nbadohm) {
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sprintf(errmsg,
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"BTDF has %d negatives and %d bad incoming solid angles",
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nneg, nbadohm);
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error(WARNING, errmsg);
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}
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return(cm);
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}
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/* Convert between input and output indices for reciprocity */
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static int
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recip_out_from_in(const SDMat *bsdf, int in_recip)
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{
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FVECT v;
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if (!mBSDF_incvec(v, bsdf, in_recip+.5))
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return(in_recip); /* XXX should be error! */
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v[2] = -v[2];
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return(mBSDF_outndx(bsdf, v));
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}
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/* Convert between output and input indices for reciprocity */
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static int
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recip_in_from_out(const SDMat *bsdf, int out_recip)
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{
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FVECT v;
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if (!mBSDF_outvec(v, bsdf, out_recip+.5))
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return(out_recip); /* XXX should be error! */
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v[2] = -v[2];
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return(mBSDF_incndx(bsdf, v));
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}
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/* Convert a BSDF to our matrix representation, applying reciprocity */
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static CMATRIX *
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cm_bsdf_recip(const COLOR diffBSDF, const SDMat *bsdf)
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{
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CMATRIX *cm = cm_alloc(bsdf->ninc, bsdf->nout);
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int nbadohm = 0;
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int nneg = 0;
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int r, c;
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/* loop over incident angles */
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for (c = 0; c < cm->ncols; c++) {
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const int ro = recip_out_from_in(bsdf,c);
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const double dom = mBSDF_outohm(bsdf,ro);
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/* projected solid angle */
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nbadohm += (dom <= 0);
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for (r = 0; r < cm->nrows; r++) {
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const int ri = recip_in_from_out(bsdf,r);
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float f = mBSDF_value(bsdf,ro,ri);
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COLORV *mp = cm_lval(cm,r,c);
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/* check BSDF value */
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if ((f <= 0) | (dom <= 0)) {
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nneg += (f < -FTINY);
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setcolor(mp, .0f, .0f, .0f);
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} else if (bsdf->chroma != NULL) {
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C_COLOR cxy;
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c_decodeChroma(&cxy, mBSDF_chroma(bsdf,ro,ri));
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ccy2rgb(&cxy, f, mp);
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} else
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setcolor(mp, f, f, f);
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addcolor(mp, diffBSDF);
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scalecolor(mp, dom);
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}
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}
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if (nneg | nbadohm) {
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sprintf(errmsg,
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"BTDF has %d negatives and %d bad incoming solid angles",
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nneg, nbadohm);
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error(WARNING, errmsg);
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}
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return(cm);
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}
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/* Return a Lambertian (diffuse) matrix */
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static CMATRIX *
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cm_bsdf_Lamb(const COLOR diffBSDF)
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{
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CMATRIX *cm = cm_alloc(145, 145); /* this is a hack */
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ANGLE_BASIS *abase = abase_list;
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int r, c;
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while (abase->nangles != cm->nrows)
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if (++abase >= abase_list+nabases)
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error(INTERNAL, "Code error in cm_bsdf_Lamb()");
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for (c = 0; c < cm->ncols; c++) {
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const double dom = io_getohm(c,abase);
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for (r = 0; r < cm->nrows; r++) {
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COLORV *mp = cm_lval(cm,r,c);
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copycolor(mp, diffBSDF);
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scalecolor(mp, dom);
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}
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}
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return(cm);
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}
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/* Load and convert a matrix BTDF from the given XML file */
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CMATRIX *
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cm_loadBTDF(const char *fname)
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{
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CMATRIX *Tmat;
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int recip;
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SDError ec;
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SDData myBSDF;
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SDSpectralDF *tdf;
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COLOR diffBTDF;
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SDclearBSDF(&myBSDF, fname); /* load XML and check type */
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ec = SDloadFile(&myBSDF, fname);
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if (ec)
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error(USER, transSDError(ec));
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recip = (myBSDF.tb == NULL);
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if (recip)
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ccy2rgb(&myBSDF.tLambFront.spec, myBSDF.tLambFront.cieY/PI, diffBTDF);
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else
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ccy2rgb(&myBSDF.tLambBack.spec, myBSDF.tLambBack.cieY/PI, diffBTDF);
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tdf = recip ? myBSDF.tf : myBSDF.tb;
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if (tdf == NULL) { /* no non-Lambertian transmission? */
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SDfreeBSDF(&myBSDF);
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return(cm_bsdf_Lamb(diffBTDF));
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}
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if (tdf->ncomp != 1 || tdf->comp[0].func != &SDhandleMtx) {
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sprintf(errmsg, "unsupported BSDF '%s'", fname);
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error(USER, errmsg);
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}
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/* convert BTDF to matrix */
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Tmat = recip ? cm_bsdf_recip(diffBTDF, (SDMat *)tdf->comp[0].dist)
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: cm_bsdf(diffBTDF, (SDMat *)tdf->comp[0].dist);
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/* free BSDF and return */
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SDfreeBSDF(&myBSDF);
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return(Tmat);
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}
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/* Load and convert a matrix BRDF from the given XML file */
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CMATRIX *
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cm_loadBRDF(const char *fname, int backside)
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{
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CMATRIX *Rmat;
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SDError ec;
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SDData myBSDF;
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SDSpectralDF *rdf;
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COLOR diffBRDF;
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SDclearBSDF(&myBSDF, fname); /* load XML and check type */
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ec = SDloadFile(&myBSDF, fname);
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if (ec)
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error(USER, transSDError(ec));
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if (backside) {
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ccy2rgb(&myBSDF.rLambBack.spec, myBSDF.rLambBack.cieY/PI, diffBRDF);
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rdf = myBSDF.rb;
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} else {
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ccy2rgb(&myBSDF.rLambFront.spec, myBSDF.rLambFront.cieY/PI, diffBRDF);
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rdf = myBSDF.rf;
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}
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if (rdf == NULL) { /* no non-Lambertian reflection? */
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SDfreeBSDF(&myBSDF);
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return(cm_bsdf_Lamb(diffBRDF));
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}
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if (rdf->ncomp != 1 || rdf->comp[0].func != &SDhandleMtx) {
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sprintf(errmsg, "unsupported BSDF '%s'", fname);
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error(USER, errmsg);
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}
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/* convert BRDF to matrix */
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Rmat = cm_bsdf(diffBRDF, (SDMat *)rdf->comp[0].dist);
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/* free BSDF and return */
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SDfreeBSDF(&myBSDF);
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return(Rmat);
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}
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