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#ifndef lint
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static const char RCSid[] = "$Id: checkBSDF.c,v 2.9 2022/08/12 23:55:00 greg Exp $";
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#endif
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/*
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* checkBSDF.c
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*
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* Load BSDF XML file and check Helmholtz reciprocity
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*/
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#define _USE_MATH_DEFINES
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#include <math.h>
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#include "rtio.h"
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#include "random.h"
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#include "bsdf.h"
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#include "bsdf_m.h"
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#include "bsdf_t.h"
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#define F_IN_COLOR 0x1
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#define F_ISOTROPIC 0x2
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#define F_MATRIX 0x4
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#define F_TTREE 0x8
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typedef struct {
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double vmin, vmax; /* extrema */
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double vsum; /* straight sum */
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long nvals; /* number of values */
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} SimpleStats;
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const SimpleStats SSinit = {FHUGE, -FHUGE, .0, 0};
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/* relative difference formula */
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#define rdiff(a,b) ((a)>(b) ? ((a)-(b))/((a)+FTINY) : ((b)-(a))/((b)+FTINY))
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/* Figure out BSDF type (and optionally determine if in color) */
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const char *
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getBSDFtype(const SDData *bsdf, int *flags)
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{
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const SDSpectralDF *df = bsdf->tb;
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if (flags) *flags = 0;
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if (!df) df = bsdf->tf;
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if (!df) df = bsdf->rf;
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if (!df) df = bsdf->rb;
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if (!df) return "Pure_Lambertian";
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if (df->comp[0].func == &SDhandleMtx) {
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const SDMat *m = (const SDMat *)df->comp[0].dist;
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if (flags) {
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*flags |= F_MATRIX;
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*flags |= F_IN_COLOR*(m->chroma != NULL);
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}
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switch (m->ninc) {
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case 145:
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return "Klems_Full";
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case 73:
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return "Klems_Half";
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case 41:
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return "Klems_Quarter";
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}
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return "Unknown_Matrix";
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}
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if (df->comp[0].func == &SDhandleTre) {
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const SDTre *t = (const SDTre *)df->comp[0].dist;
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if (flags) {
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*flags |= F_TTREE;
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*flags |= F_IN_COLOR*(t->stc[1] != NULL);
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}
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switch (t->stc[0]->ndim) {
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case 4:
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return "Anisotropic_Tensor_Tree";
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case 3:
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if (flags) *flags |= F_ISOTROPIC;
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return "Isotropic_Tensor_Tree";
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}
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return "Unknown_Tensor_Tree";
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}
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return "Unknown";
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}
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/* Report details related to one hemisphere distribution */
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void
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detailComponent(const char *nm, const SDValue *lamb, const SDSpectralDF *df)
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{
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double Lamb = 0;
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fputs(nm, stdout);
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if (lamb->spec.flags) {
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printf("\t%4.1f %4.1f %4.1f\t\t",
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100.*lamb->cieY*lamb->spec.cx/lamb->spec.cy,
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100.*lamb->cieY,
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100.*lamb->cieY*(1.f - lamb->spec.cx - lamb->spec.cy)/lamb->spec.cy);
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Lamb = lamb->cieY;
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} else
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fputs("\t 0 0 0\t\t", stdout);
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if (df)
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printf("%5.1f%%\t\t%.2f deg\n", 100.*(Lamb+df->maxHemi),
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sqrt(df->minProjSA/M_PI)*(360./M_PI));
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else
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printf("%5.1f%%\t\t180 deg\n", Lamb);
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}
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/* Add a value to stats */
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void
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addStat(SimpleStats *ssp, double v)
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{
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if (v < ssp->vmin) ssp->vmin = v;
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if (v > ssp->vmax) ssp->vmax = v;
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ssp->vsum += v;
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ssp->nvals++;
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}
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/* Sample a BSDF hemisphere with callback (quadtree recursion) */
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int
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qtSampBSDF(double xleft, double ytop, double siz,
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const SDData *bsdf, const int side, const RREAL *v0,
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int (*cf)(const SDData *b, const FVECT v1, const RREAL *v0, void *p),
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void *cdata)
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{
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if (siz < 0.124) { /* make sure we subdivide, first */
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FVECT vsmp;
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double sa;
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square2disk(vsmp, xleft + frandom()*siz, ytop + frandom()*siz);
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vsmp[2] = 1. - vsmp[0]*vsmp[0] - vsmp[1]*vsmp[1];
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if (vsmp[2] <= 0) return 0;
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vsmp[2] = side * sqrt(vsmp[2]);
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if (SDreportError( SDsizeBSDF(&sa, vsmp, v0, SDqueryMin, bsdf), stderr))
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return 0;
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if (sa >= M_PI*siz*siz - FTINY) /* no further division needed */
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return (*cf)(bsdf, vsmp, v0, cdata);
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}
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siz *= .5; /* 4-branch recursion */
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return( qtSampBSDF(xleft, ytop, siz, bsdf, side, v0, cf, cdata) &&
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qtSampBSDF(xleft+siz, ytop, siz, bsdf, side, v0, cf, cdata) &&
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qtSampBSDF(xleft, ytop+siz, siz, bsdf, side, v0, cf, cdata) &&
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qtSampBSDF(xleft+siz, ytop+siz, siz, bsdf, side, v0, cf, cdata) );
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}
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#define sampBSDFhemi(b,s,v0,cf,cd) qtSampBSDF(0,0,1,b,s,v0,cf,cd)
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/* Call-back to compute reciprocity difference */
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int
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diffRecip(const SDData *bsdf, const FVECT v1, const RREAL *v0, void *p)
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{
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SDValue sdv;
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double otherY;
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if (SDreportError( SDevalBSDF(&sdv, v0, v1, bsdf), stderr))
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return 0;
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otherY = sdv.cieY;
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if (SDreportError( SDevalBSDF(&sdv, v1, v0, bsdf), stderr))
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return 0;
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addStat((SimpleStats *)p, rdiff(sdv.cieY, otherY));
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return 1;
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}
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/* Call-back to compute reciprocity over reflected hemisphere */
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int
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reflHemi(const SDData *bsdf, const FVECT v1, const RREAL *v0, void *p)
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{
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return sampBSDFhemi(bsdf, 1 - 2*(v1[2]<0), v1, &diffRecip, p);
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}
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/* Call-back to compute reciprocity over transmitted hemisphere */
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int
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transHemi(const SDData *bsdf, const FVECT v1, const RREAL *v0, void *p)
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{
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return sampBSDFhemi(bsdf, 1 - 2*(v1[2]>0), v1, &diffRecip, p);
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}
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/* Report reciprocity errors for the given directions */
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void
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checkReciprocity(const char *nm, const int side1, const int side2,
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const SDData *bsdf, const int fl)
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{
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SimpleStats myStats = SSinit;
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const SDSpectralDF *df = bsdf->tf;
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if (side1 == side2) {
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df = (side1 > 0) ? bsdf->rf : bsdf->rb;
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if (!df) goto nothing2do;
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} else if (!bsdf->tf | !bsdf->tb)
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goto nothing2do;
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if (fl & F_MATRIX) { /* special case for matrix BSDF */
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const SDMat *m = (const SDMat *)df->comp[0].dist;
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int i = m->ninc;
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double diffuseY;
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FVECT vin, vout;
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double fwdY;
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SDValue rev;
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if (side1 == side2)
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diffuseY = (side1 > 0) ? bsdf->rLambFront.cieY : bsdf->rLambBack.cieY;
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else
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diffuseY = (side1 > 0) ? bsdf->tLambFront.cieY : bsdf->tLambBack.cieY;
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diffuseY /= M_PI;
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while (i--) {
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int o = m->nout;
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if (!mBSDF_incvec(vin, m, i+.5))
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continue;
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while (o--) {
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if (!mBSDF_outvec(vout, m, o+.5))
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continue;
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fwdY = mBSDF_value(m, o, i) + diffuseY;
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if (fwdY <= 1e-4)
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continue;
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if (SDreportError( SDevalBSDF(&rev, vout, vin, bsdf), stderr))
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return;
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if (rev.cieY > 1e-4)
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addStat(&myStats, rdiff(fwdY, rev.cieY));
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}
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}
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} else if (fl & F_ISOTROPIC) { /* isotropic case */
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const double stepSize = sqrt(df->minProjSA/M_PI);
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FVECT vin;
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vin[1] = 0;
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for (vin[0] = 0.5*stepSize; vin[0] < 1; vin[0] += stepSize) {
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vin[2] = side1*sqrt(1. - vin[0]*vin[0]);
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if (!sampBSDFhemi(bsdf, side2, vin, &diffRecip, &myStats))
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return;
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}
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} else if (!sampBSDFhemi(bsdf, side1, NULL,
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(side1==side2) ? &reflHemi : &transHemi, &myStats))
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return;
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if (myStats.nvals) {
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printf("%s\t%5.1f\t%5.1f\t%5.1f\n", nm,
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100.*myStats.vmin,
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100.*myStats.vsum/(double)myStats.nvals,
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100.*myStats.vmax);
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return;
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}
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nothing2do:
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printf("%s\t 0\t 0\t 0\n", nm);
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}
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/* Report on the given BSDF XML file */
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int
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checkXML(char *fname)
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{
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int flags;
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SDData myBSDF;
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char *pth;
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puts("=====================================================");
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printf("File: '%s'\n", fname);
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SDclearBSDF(&myBSDF, fname);
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pth = getpath(fname, getrlibpath(), 0);
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if (!pth) {
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fprintf(stderr, "Cannot find file '%s'\n", fname);
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return 0;
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}
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if (SDreportError( SDloadFile(&myBSDF, pth), stderr))
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return 0;
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printf("Manufacturer: '%s'\n", myBSDF.makr);
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printf("BSDF Name: '%s'\n", myBSDF.matn);
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printf("Dimensions (W x H x Thickness): %g x %g x %g cm\n", 100.*myBSDF.dim[0],
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100.*myBSDF.dim[1], 100.*myBSDF.dim[2]);
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printf("Type: %s\n", getBSDFtype(&myBSDF, &flags));
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printf("Color: %d\n", (flags & F_IN_COLOR) != 0);
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printf("Has Geometry: %d\n", (myBSDF.mgf != NULL));
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puts("Component\tLambertian XYZ (%)\tMax. Tot. Dir\tMin. Angle");
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detailComponent("Interior Refl", &myBSDF.rLambFront, myBSDF.rf);
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detailComponent("Exterior Refl", &myBSDF.rLambBack, myBSDF.rb);
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detailComponent("Int->Ext Trans", &myBSDF.tLambFront, myBSDF.tf);
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detailComponent("Ext->Int Trans", &myBSDF.tLambBack, myBSDF.tb);
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puts("Component\tReciprocity Error (min avg max %)");
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checkReciprocity("Interior Refl", 1, 1, &myBSDF, flags);
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checkReciprocity("Exterior Refl", -1, -1, &myBSDF, flags);
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checkReciprocity("Transmission", -1, 1, &myBSDF, flags);
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SDfreeBSDF(&myBSDF);
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return 1;
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}
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int
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main(int argc, char *argv[])
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{
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int i;
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if (argc < 2) {
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fprintf(stderr, "Usage: %s bsdf.xml ..\n", argv[0]);
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return 1;
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}
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for (i = 1; i < argc; i++)
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if (!checkXML(argv[i]))
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return 1;
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return 0;
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}
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