// KdSubsurfaceMaterial Method Definitions
void KdSubsurfaceMaterial::ComputeScatteringFunctions(
SurfaceInteraction *si, MemoryArena &arena, TransportMode mode,
bool allowMultipleLobes) const {
// Perform bump mapping with _bumpMap_, if present
if (bumpMap) Bump(bumpMap, si);
si->bsdf = ARENA_ALLOC(arena, BSDF)(*si, eta);
Spectrum R = Kr->Evaluate(*si).Clamp();
Spectrum T = Kt->Evaluate(*si).Clamp();
if (allowMultipleLobes && (!R.IsBlack() || !T.IsBlack()))
si->bsdf->Add(
ARENA_ALLOC(arena, FresnelSpecular)(1., 1., 1.f, eta, mode));
else {
if (!R.IsBlack())
si->bsdf->Add(ARENA_ALLOC(arena, SpecularReflection)(
R, ARENA_ALLOC(arena, FresnelDielectric)(1.f, eta)));
if (!T.IsBlack())
si->bsdf->Add(
ARENA_ALLOC(arena, SpecularTransmission)(T, 1.f, eta, mode));
}
Spectrum sig_t = scale * sigma_t->Evaluate(*si).Clamp();
Spectrum kd = Kd->Evaluate(*si).Clamp();
Spectrum sig_a, sig_s;
SubsurfaceFromDiffuse(table, kd, sig_t, &sig_a, &sig_s);
si->bssrdf = ARENA_ALLOC(arena, TabulatedBSSRDF)(*si, this, mode, eta,
sig_a, sig_s, table);
}
BSSRDF *KdSubsurfaceMaterial::GetBSSRDF(const DifferentialGeometry &dgGeom,
const DifferentialGeometry &dgShading,
MemoryArena &arena) const {
float ior = index->Evaluate(dgShading);
float mfp = meanfreepath->Evaluate(dgShading);
Spectrum kd = Kd->Evaluate(dgShading).Clamp();
Spectrum sigma_a, sigma_prime_s;
SubsurfaceFromDiffuse(kd, mfp, ior, &sigma_a, &sigma_prime_s);
return BSDF_ALLOC(arena, BSSRDF)(sigma_a, sigma_prime_s, ior);
}
// KdSubsurfaceMaterial Method Definitions
void KdSubsurfaceMaterial::ComputeScatteringFunctions(
SurfaceInteraction *si, MemoryArena &arena, TransportMode mode,
bool allowMultipleLobes) const {
// Perform bump mapping with _bumpMap_, if present
if (bumpMap) Bump(bumpMap, si);
Spectrum R = Kr->Evaluate(*si).Clamp();
Spectrum T = Kt->Evaluate(*si).Clamp();
Float urough = uRoughness->Evaluate(*si);
Float vrough = vRoughness->Evaluate(*si);
// Initialize _bsdf_ for smooth or rough dielectric
si->bsdf = ARENA_ALLOC(arena, BSDF)(*si, eta);
if (R.IsBlack() && T.IsBlack()) return;
bool isSpecular = urough == 0 && vrough == 0;
if (isSpecular && allowMultipleLobes) {
si->bsdf->Add(
ARENA_ALLOC(arena, FresnelSpecular)(R, T, 1.f, eta, mode));
} else {
if (remapRoughness) {
urough = TrowbridgeReitzDistribution::RoughnessToAlpha(urough);
vrough = TrowbridgeReitzDistribution::RoughnessToAlpha(vrough);
}
MicrofacetDistribution *distrib =
isSpecular ? nullptr
: ARENA_ALLOC(arena, TrowbridgeReitzDistribution)(
urough, vrough);
if (!R.IsBlack()) {
Fresnel *fresnel = ARENA_ALLOC(arena, FresnelDielectric)(1.f, eta);
if (isSpecular)
si->bsdf->Add(
ARENA_ALLOC(arena, SpecularReflection)(R, fresnel));
else
si->bsdf->Add(ARENA_ALLOC(arena, MicrofacetReflection)(
R, distrib, fresnel));
}
if (!T.IsBlack()) {
if (isSpecular)
si->bsdf->Add(ARENA_ALLOC(arena, SpecularTransmission)(
T, 1.f, eta, mode));
else
si->bsdf->Add(ARENA_ALLOC(arena, MicrofacetTransmission)(
T, distrib, 1.f, eta, mode));
}
}
Spectrum mfree = scale * mfp->Evaluate(*si).Clamp();
Spectrum kd = Kd->Evaluate(*si).Clamp();
Spectrum sig_a, sig_s;
SubsurfaceFromDiffuse(table, kd, Spectrum(1.f) / mfree, &sig_a, &sig_s);
si->bssrdf = ARENA_ALLOC(arena, TabulatedBSSRDF)(*si, this, mode, eta,
sig_a, sig_s, table);
}
