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fixed the Phong & Ashikhmin-Shirley shadowing-masking term

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Wenzel Jakob 2011-07-07 21:57:35 +02:00
parent de4fe46aff
commit ff62ccea31
1 changed files with 28 additions and 28 deletions
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50
src/bsdfs/microfacet.h
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@ -35,10 +35,10 @@ public:
enum EType { enum EType {
/// Beckmann distribution derived from Gaussian random surfaces /// Beckmann distribution derived from Gaussian random surfaces
EBeckmann = 0, EBeckmann = 0,
/// Classical Phong distribution
EPhong = 1,
/// Long-tailed distribution proposed by Walter et al. /// Long-tailed distribution proposed by Walter et al.
EGGX = 2, EGGX = 1,
/// Classical Phong distribution
EPhong = 2,
/// Anisotropic distribution by Ashikhmin and Shirley /// Anisotropic distribution by Ashikhmin and Shirley
EAshikhminShirley = 3 EAshikhminShirley = 3
}; };
@ -104,13 +104,6 @@ public:
} }
break; break;
case EPhong: {
/* Phong distribution function */
result = (alphaU + 2) * INV_TWOPI
* std::pow(Frame::cosTheta(m), alphaU);
}
break;
case EGGX: { case EGGX: {
/* Empirical GGX distribution function for rough surfaces */ /* Empirical GGX distribution function for rough surfaces */
const Float tanTheta = Frame::tanTheta(m), const Float tanTheta = Frame::tanTheta(m),
@ -123,6 +116,13 @@ public:
} }
break; break;
case EPhong: {
/* Phong distribution function */
result = (alphaU + 2) * INV_TWOPI
* std::pow(Frame::cosTheta(m), alphaU);
}
break;
case EAshikhminShirley: { case EAshikhminShirley: {
const Float cosTheta = Frame::cosTheta(m); const Float cosTheta = Frame::cosTheta(m);
const Float ds = 1 - cosTheta * cosTheta; const Float ds = 1 - cosTheta * cosTheta;
@ -208,16 +208,16 @@ public:
std::log(1.0f - sample.x))); std::log(1.0f - sample.x)));
break; break;
case EPhong:
thetaM = std::acos(std::pow(sample.x, (Float) 1 /
(alphaU + 2)));
break;
case EGGX: case EGGX:
thetaM = std::atan(alphaU * std::sqrt(sample.x) / thetaM = std::atan(alphaU * std::sqrt(sample.x) /
std::sqrt(1.0f - sample.x)); std::sqrt(1.0f - sample.x));
break; break;
case EPhong:
thetaM = std::acos(std::pow(sample.x, (Float) 1 /
(alphaU + 2)));
break;
case EAshikhminShirley: { case EAshikhminShirley: {
/* Sampling method based on code from PBRT */ /* Sampling method based on code from PBRT */
Float phi, cosTheta; Float phi, cosTheta;
@ -273,24 +273,24 @@ public:
return 0.0f; return 0.0f;
switch (m_type) { switch (m_type) {
case EAshikhminShirley:
case EPhong: case EPhong:
case EAshikhminShirley:
case EBeckmann: {
Float a;
/* Approximation recommended by Bruce Walter: Use /* Approximation recommended by Bruce Walter: Use
the Beckmann shadowing-masking function with the Beckmann shadowing-masking function with
specially chosen roughness value */ specially chosen roughness value */
cout << alpha << endl; if (m_type != EBeckmann)
alpha = std::sqrt(0.5f * alpha + 1) / tanTheta; a = std::sqrt(0.5f * alpha + 1) / tanTheta;
cout << " becomes " << alpha << endl; else
a = 1.0f / (alpha * tanTheta);
case EBeckmann: {
/* Use a fast and accurate (<0.35% rel. error) rational
approximation to the shadowing-masking function */
const Float a = 1.0f / (alpha * tanTheta);
const Float aSqr = a * a;
if (a >= 1.6f) if (a >= 1.6f)
return 1.0f; return 1.0f;
/* Use a fast and accurate (<0.35% rel. error) rational
approximation to the shadowing-masking function */
const Float aSqr = a * a;
return (3.535f * a + 2.181f * aSqr) return (3.535f * a + 2.181f * aSqr)
/ (1.0f + 2.276f * a + 2.577f * aSqr); / (1.0f + 2.276f * a + 2.577f * aSqr);
} }