// BSDF Method Definitions
Spectrum BSDF::Sample_f(const Vector &wo, Vector *wi, BxDFType flags,
BxDFType *sampledType) const {
float pdf;
Spectrum f = Sample_f(wo, wi, RandomFloat(), RandomFloat(),
RandomFloat(), &pdf, flags, sampledType);
if (!f.Black() && pdf > 0.) f /= pdf;
return f;
}
Spectrum BxDF::rho(const Vector3f &w, int nSamples, const Point2f *u) const {
Spectrum r(0.);
for (int i = 0; i < nSamples; ++i) {
// Estimate one term of $\rho_\roman{hd}$
Vector3f wi;
Float pdf = 0;
Spectrum f = Sample_f(w, &wi, u[i], &pdf);
if (pdf > 0) r += f * AbsCosTheta(wi) / pdf;
}
return r / nSamples;
}
Spectrum BxDF::rho(int nSamples, const Point2f *u1, const Point2f *u2) const {
Spectrum r(0.f);
for (int i = 0; i < nSamples; ++i) {
// Estimate one term of $\rho_\roman{hh}$
Vector3f wo, wi;
wo = UniformSampleHemisphere(u1[i]);
Float pdfo = UniformHemispherePdf(), pdfi = 0;
Spectrum f = Sample_f(wo, &wi, u2[i], &pdfi);
if (pdfi > 0)
r += f * AbsCosTheta(wi) * AbsCosTheta(wo) / (pdfo * pdfi);
}
return r / (Pi * nSamples);
}
Spectrum BxDF::rho(const Vector &w, int nSamples,
float *samples) const {
if (!samples) {
samples =
(float *)alloca(2 * nSamples * sizeof(float));
LatinHypercube(samples, nSamples, 2);
}
Spectrum r = 0.;
for (int i = 0; i < nSamples; ++i) {
// Estimate one term of $\rho_{dh}$
Vector wi;
float pdf = 0.f;
Spectrum f =
Sample_f(w, &wi, samples[2*i], samples[2*i+1], &pdf);
if (pdf > 0.) r += f * fabsf(wi.z) / pdf;
}
return r / nSamples;
}
Spectrum BxDF::rho(int nSamples, float *samples) const {
if (!samples) {
samples =
(float *)alloca(4 * nSamples * sizeof(float));
LatinHypercube(samples, nSamples, 4);
}
Spectrum r = 0.;
for (int i = 0; i < nSamples; ++i) {
// Estimate one term of $\rho_{hh}$
Vector wo, wi;
wo = UniformSampleHemisphere(samples[4*i], samples[4*i+1]);
float pdf_o = INV_TWOPI, pdf_i = 0.f;
Spectrum f =
Sample_f(wo, &wi, samples[4*i+2], samples[4*i+3],
&pdf_i);
if (pdf_i > 0.)
r += f * fabsf(wi.z * wo.z) / (pdf_o * pdf_i);
}
return r / (M_PI*nSamples);
}
