float PlasticBsdf::pdf(const SurfaceScatterEvent &event) const
{
if (event.wi.z() <= 0.0f || event.wo.z() <= 0.0f)
return 0.0f;
bool sampleR = event.requestedLobe.test(BsdfLobes::SpecularReflectionLobe);
bool sampleT = event.requestedLobe.test(BsdfLobes::DiffuseReflectionLobe);
if (sampleR && sampleT) {
float Fi = Fresnel::dielectricReflectance(1.0f/_ior, event.wi.z());
float substrateWeight = _avgTransmittance*(1.0f - Fi);
float specularWeight = Fi;
float specularProbability = specularWeight/(specularWeight + substrateWeight);
if (checkReflectionConstraint(event.wi, event.wo))
return specularProbability;
else
return SampleWarp::cosineHemispherePdf(event.wo)*(1.0f - specularProbability);
} else if (sampleT) {
return SampleWarp::cosineHemispherePdf(event.wo);
} else if (sampleR) {
return checkReflectionConstraint(event.wi, event.wo) ? 1.0f : 0.0f;
} else {
return 0.0f;
}
}
Vec3f PlasticBsdf::eval(const SurfaceScatterEvent &event) const
{
if (event.wi.z() <= 0.0f || event.wo.z() <= 0.0f)
return Vec3f(0.0f);
bool evalR = event.requestedLobe.test(BsdfLobes::SpecularReflectionLobe);
bool evalT = event.requestedLobe.test(BsdfLobes::DiffuseReflectionLobe);
float eta = 1.0f/_ior;
float Fi = Fresnel::dielectricReflectance(eta, event.wi.z());
float Fo = Fresnel::dielectricReflectance(eta, event.wo.z());
if (evalR && checkReflectionConstraint(event.wi, event.wo)) {
return Vec3f(Fi);
} else if (evalT) {
Vec3f diffuseAlbedo = albedo(event.info);
Vec3f brdf = ((1.0f - Fi)*(1.0f - Fo)*eta*eta*event.wo.z()*INV_PI)*
(diffuseAlbedo/(1.0f - diffuseAlbedo*_diffuseFresnel));
if (_scaledSigmaA.max() > 0.0f)
brdf *= std::exp(_scaledSigmaA*(-1.0f/event.wo.z() - 1.0f/event.wi.z()));
return brdf;
} else {
return Vec3f(0.0f);
}
}
float ThinSheetBsdf::pdf(const SurfaceScatterEvent &event) const
{
bool sampleR = event.requestedLobe.test(BsdfLobes::SpecularReflectionLobe);
if (sampleR && checkReflectionConstraint(event.wi, event.wo))
return 1.0f;
else
return 0.0f;
}
Vec3f ConductorBsdf::eval(const SurfaceScatterEvent &event) const
{
bool evalR = event.requestedLobe.test(BsdfLobes::SpecularReflectionLobe);
if (evalR && checkReflectionConstraint(event.wi, event.wo))
return albedo(event.info)*Fresnel::conductorReflectance(_eta, _k, event.wi.z());
else
return Vec3f(0.0f);
}
bool ThinSheetBsdf::invert(WritablePathSampleGenerator &/*sampler*/, const SurfaceScatterEvent &event) const
{
bool sampleR = event.requestedLobe.test(BsdfLobes::SpecularReflectionLobe);
return sampleR && checkReflectionConstraint(event.wi, event.wo);
}
bool ConductorBsdf::invert(WritablePathSampleGenerator &/*sampler*/, const SurfaceScatterEvent &event) const
{
return checkReflectionConstraint(event.wi, event.wo);
}
