Spectrum KajiyaKay::f(const Vector3f &wo, const Vector3f &wi) const {
Spectrum diffuse(0.f), specular(0.f);
if (!Ks.IsBlack()) {
// Compute specular Kajiya-Kay term
Vector3f wh = wi + wo;
if (!(wh.x == 0 && wh.y == 0 && wh.z == 0)) {
wh = Normalize(wh);
#if 0
Float cosThetaH = Dot(wo, wh);
Float sinThetaH = std::sqrt(std::max((Float)0, (Float)1 - cosThetaH * cosThetaH));
Float cosThetaO = CosTheta(wo), sinThetaO = SinTheta(wo);
Float spec = std::pow(cosThetao * cosThetah + sinThetaO * sinThetaH,
exponent);
#else
Float tdoth = wh.x;
Float spec = std::pow(
std::sqrt(std::max((Float)0, (Float)1 - tdoth * tdoth)),
exponent);
#endif
specular = spec * Ks;
}
}
// Compute diffuse Kajiya-Kay term
diffuse = Kd * std::sqrt(std::max((Float)0., (Float)1. - wi.x * wi.x));
return (InvPi / AbsCosTheta(wi)) * (diffuse + specular);
}
// commented, dpl 10 august 2005
Spectrum OrenNayar::f(const Vector &wo,
const Vector &wi) const {
float sinthetai = SinTheta(wi);
float sinthetao = SinTheta(wo);
// Compute cosine term of Oren--Nayar model
float sinphii = SinPhi(wi), cosphii = CosPhi(wi);
float sinphio = SinPhi(wo), cosphio = CosPhi(wo);
float dcos = cosphii * cosphio + sinphii * sinphio;
float maxcos = max(0.f, dcos);
// Compute sine and tangent terms of Oren--Nayar model
float sinalpha, tanbeta;
if (fabsf(CosTheta(wi)) > fabsf(CosTheta(wo))) {
sinalpha = sinthetao;
tanbeta = sinthetai / fabsf(CosTheta(wi));
}
else {
sinalpha = sinthetai;
tanbeta = sinthetao / fabsf(CosTheta(wo));
}
return R * INV_PI *
(A + B * maxcos * sinalpha * tanbeta);
}
Spectrum OrenNayar::f(const Vector3f &wo, const Vector3f &wi) const {
Float sinThetaI = SinTheta(wi);
Float sinThetaO = SinTheta(wo);
// Compute cosine term of Oren-Nayar model
Float maxCos = 0;
if (sinThetaI > 1e-4 && sinThetaO > 1e-4) {
Float sinPhiI = SinPhi(wi), cosPhiI = CosPhi(wi);
Float sinPhiO = SinPhi(wo), cosPhiO = CosPhi(wo);
Float dCos = cosPhiI * cosPhiO + sinPhiI * sinPhiO;
maxCos = std::max((Float)0, dCos);
}
// Compute sine and tangent terms of Oren-Nayar model
Float sinAlpha, tanBeta;
if (AbsCosTheta(wi) > AbsCosTheta(wo)) {
sinAlpha = sinThetaO;
tanBeta = sinThetaI / AbsCosTheta(wi);
} else {
sinAlpha = sinThetaI;
tanBeta = sinThetaO / AbsCosTheta(wo);
}
return R * InvPi * (A + B * maxCos * sinAlpha * tanBeta);
}
inline typename scalar_type<V>::type SinPhi(const V &w) {
return w.y() / SinTheta(w);
}
