blender/intern/cycles/kernel/svm/bsdf_microfacet.h
2012-04-06 16:08:14 +00:00

509 lines
19 KiB
C

/*
* Adapted from Open Shading Language with this license:
*
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
* All Rights Reserved.
*
* Modifications Copyright 2011, Blender Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Sony Pictures Imageworks nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __BSDF_MICROFACET_H__
#define __BSDF_MICROFACET_H__
CCL_NAMESPACE_BEGIN
/* GGX */
typedef struct BsdfMicrofacetGGXClosure {
//float3 m_N;
float m_ag;
float m_eta;
} BsdfMicrofacetGGXClosure;
__device_inline float safe_sqrtf(float f)
{
return sqrtf(max(f, 0.0f));
}
__device void bsdf_microfacet_ggx_setup(ShaderData *sd, ShaderClosure *sc, float ag, float eta, bool refractive)
{
float m_ag = clamp(ag, 1e-4f, 1.0f);
float m_eta = eta;
sc->data0 = m_ag;
sc->data1 = m_eta;
if(refractive)
sc->type = CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID;
else
sc->type = CLOSURE_BSDF_MICROFACET_GGX_ID;
sd->flag |= SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
}
__device void bsdf_microfacet_ggx_blur(ShaderClosure *sc, float roughness)
{
float m_ag = sc->data0;
m_ag = fmaxf(roughness, m_ag);
sc->data0 = m_ag;
}
__device float3 bsdf_microfacet_ggx_eval_reflect(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
float m_ag = sc->data0;
//float m_eta = sc->data1;
int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID;
float3 m_N = sd->N;
if(m_refractive) return make_float3 (0, 0, 0);
float cosNO = dot(m_N, I);
float cosNI = dot(m_N, omega_in);
if(cosNI > 0 && cosNO > 0) {
// get half vector
float3 Hr = normalize(omega_in + I);
// eq. 20: (F*G*D)/(4*in*on)
// eq. 33: first we calculate D(m) with m=Hr:
float alpha2 = m_ag * m_ag;
float cosThetaM = dot(m_N, Hr);
float cosThetaM2 = cosThetaM * cosThetaM;
float tanThetaM2 = (1 - cosThetaM2) / cosThetaM2;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
// eq. 34: now calculate G1(i,m) and G1(o,m)
float G1o = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNO * cosNO) / (cosNO * cosNO)));
float G1i = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNI * cosNI) / (cosNI * cosNI)));
float G = G1o * G1i;
float out = (G * D) * 0.25f / cosNO;
// eq. 24
float pm = D * cosThetaM;
// convert into pdf of the sampled direction
// eq. 38 - but see also:
// eq. 17 in http://www.graphics.cornell.edu/~bjw/wardnotes.pdf
*pdf = pm * 0.25f / dot(Hr, I);
return make_float3 (out, out, out);
}
return make_float3 (0, 0, 0);
}
__device float3 bsdf_microfacet_ggx_eval_transmit(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
float m_ag = sc->data0;
float m_eta = sc->data1;
int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID;
float3 m_N = sd->N;
if(!m_refractive) return make_float3 (0, 0, 0);
float cosNO = dot(m_N, I);
float cosNI = dot(m_N, omega_in);
if(cosNO <= 0 || cosNI >= 0)
return make_float3 (0, 0, 0); // vectors on same side -- not possible
// compute half-vector of the refraction (eq. 16)
float3 ht = -(m_eta * omega_in + I);
float3 Ht = normalize(ht);
float cosHO = dot(Ht, I);
float cosHI = dot(Ht, omega_in);
// eq. 33: first we calculate D(m) with m=Ht:
float alpha2 = m_ag * m_ag;
float cosThetaM = dot(m_N, Ht);
float cosThetaM2 = cosThetaM * cosThetaM;
float tanThetaM2 = (1 - cosThetaM2) / cosThetaM2;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
// eq. 34: now calculate G1(i,m) and G1(o,m)
float G1o = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNO * cosNO) / (cosNO * cosNO)));
float G1i = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNI * cosNI) / (cosNI * cosNI)));
float G = G1o * G1i;
// probability
float invHt2 = 1 / dot(ht, ht);
*pdf = D * fabsf(cosThetaM) * (fabsf(cosHI) * (m_eta * m_eta)) * invHt2;
float out = (fabsf(cosHI * cosHO) * (m_eta * m_eta) * (G * D) * invHt2) / cosNO;
return make_float3 (out, out, out);
}
__device float bsdf_microfacet_ggx_albedo(const ShaderData *sd, const ShaderClosure *sc, const float3 I)
{
return 1.0f;
}
__device int bsdf_microfacet_ggx_sample(const ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
{
float m_ag = sc->data0;
float m_eta = sc->data1;
int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID;
float3 m_N = sd->N;
float cosNO = dot(m_N, sd->I);
if(cosNO > 0) {
float3 X, Y, Z = m_N;
make_orthonormals(Z, &X, &Y);
// generate a random microfacet normal m
// eq. 35,36:
// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
//tttt and sin(atan(x)) == x/sqrt(1+x^2)
float alpha2 = m_ag * m_ag;
float tanThetaM2 = alpha2 * randu / (1 - randu);
float cosThetaM = 1 / safe_sqrtf(1 + tanThetaM2);
float sinThetaM = cosThetaM * safe_sqrtf(tanThetaM2);
float phiM = 2 * M_PI_F * randv;
float3 m = (cosf(phiM) * sinThetaM) * X +
(sinf(phiM) * sinThetaM) * Y +
cosThetaM * Z;
if(!m_refractive) {
float cosMO = dot(m, sd->I);
if(cosMO > 0) {
// eq. 39 - compute actual reflected direction
*omega_in = 2 * cosMO * m - sd->I;
if(dot(sd->Ng, *omega_in) > 0) {
// microfacet normal is visible to this ray
// eq. 33
float cosThetaM2 = cosThetaM * cosThetaM;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
// eq. 24
float pm = D * cosThetaM;
// convert into pdf of the sampled direction
// eq. 38 - but see also:
// eq. 17 in http://www.graphics.cornell.edu/~bjw/wardnotes.pdf
*pdf = pm * 0.25f / cosMO;
// eval BRDF*cosNI
float cosNI = dot(m_N, *omega_in);
// eq. 34: now calculate G1(i,m) and G1(o,m)
float G1o = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNO * cosNO) / (cosNO * cosNO)));
float G1i = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNI * cosNI) / (cosNI * cosNI)));
float G = G1o * G1i;
// eq. 20: (F*G*D)/(4*in*on)
float out = (G * D) * 0.25f / cosNO;
*eval = make_float3(out, out, out);
#ifdef __RAY_DIFFERENTIALS__
*domega_in_dx = (2 * dot(m, sd->dI.dx)) * m - sd->dI.dx;
*domega_in_dy = (2 * dot(m, sd->dI.dy)) * m - sd->dI.dy;
// Since there is some blur to this reflection, make the
// derivatives a bit bigger. In theory this varies with the
// roughness but the exact relationship is complex and
// requires more ops than are practical.
*domega_in_dx *= 10.0f;
*domega_in_dy *= 10.0f;
#endif
}
}
} else {
// CAUTION: the i and o variables are inverted relative to the paper
// eq. 39 - compute actual refractive direction
float3 R, T;
#ifdef __RAY_DIFFERENTIALS__
float3 dRdx, dRdy, dTdx, dTdy;
#endif
bool inside;
fresnel_dielectric(m_eta, m, sd->I, &R, &T,
#ifdef __RAY_DIFFERENTIALS__
sd->dI.dx, sd->dI.dy, &dRdx, &dRdy, &dTdx, &dTdy,
#endif
&inside);
if(!inside) {
*omega_in = T;
#ifdef __RAY_DIFFERENTIALS__
*domega_in_dx = dTdx;
*domega_in_dy = dTdy;
#endif
// eq. 33
float cosThetaM2 = cosThetaM * cosThetaM;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = alpha2 / (M_PI_F * cosThetaM4 * (alpha2 + tanThetaM2) * (alpha2 + tanThetaM2));
// eq. 24
float pm = D * cosThetaM;
// eval BRDF*cosNI
float cosNI = dot(m_N, *omega_in);
// eq. 34: now calculate G1(i,m) and G1(o,m)
float G1o = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNO * cosNO) / (cosNO * cosNO)));
float G1i = 2 / (1 + safe_sqrtf(1 + alpha2 * (1 - cosNI * cosNI) / (cosNI * cosNI)));
float G = G1o * G1i;
// eq. 21
float cosHI = dot(m, *omega_in);
float cosHO = dot(m, sd->I);
float Ht2 = m_eta * cosHI + cosHO;
Ht2 *= Ht2;
float out = (fabsf(cosHI * cosHO) * (m_eta * m_eta) * (G * D)) / (cosNO * Ht2);
// eq. 38 and eq. 17
*pdf = pm * (m_eta * m_eta) * fabsf(cosHI) / Ht2;
*eval = make_float3(out, out, out);
#ifdef __RAY_DIFFERENTIALS__
// Since there is some blur to this refraction, make the
// derivatives a bit bigger. In theory this varies with the
// roughness but the exact relationship is complex and
// requires more ops than are practical.
*domega_in_dx *= 10.0f;
*domega_in_dy *= 10.0f;
#endif
}
}
}
return (m_refractive) ? LABEL_TRANSMIT|LABEL_GLOSSY : LABEL_REFLECT|LABEL_GLOSSY;
}
/* BECKMANN */
typedef struct BsdfMicrofacetBeckmannClosure {
//float3 m_N;
float m_ab;
float m_eta;
} BsdfMicrofacetBeckmannClosure;
__device void bsdf_microfacet_beckmann_setup(ShaderData *sd, ShaderClosure *sc, float ab, float eta, bool refractive)
{
float m_ab = clamp(ab, 1e-4f, 1.0f);
float m_eta = eta;
sc->data0 = m_ab;
sc->data1 = m_eta;
if(refractive)
sc->type = CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID;
else
sc->type = CLOSURE_BSDF_MICROFACET_BECKMANN_ID;
sd->flag |= SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
}
__device void bsdf_microfacet_beckmann_blur(ShaderClosure *sc, float roughness)
{
float m_ab = sc->data0;
m_ab = fmaxf(roughness, m_ab);
sc->data0 = m_ab;
}
__device float3 bsdf_microfacet_beckmann_eval_reflect(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
float m_ab = sc->data0;
//float m_eta = sc->data1;
int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID;
float3 m_N = sd->N;
if(m_refractive) return make_float3 (0, 0, 0);
float cosNO = dot(m_N, I);
float cosNI = dot(m_N, omega_in);
if(cosNO > 0 && cosNI > 0) {
// get half vector
float3 Hr = normalize(omega_in + I);
// eq. 20: (F*G*D)/(4*in*on)
// eq. 25: first we calculate D(m) with m=Hr:
float alpha2 = m_ab * m_ab;
float cosThetaM = dot(m_N, Hr);
float cosThetaM2 = cosThetaM * cosThetaM;
float tanThetaM2 = (1 - cosThetaM2) / cosThetaM2;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = expf(-tanThetaM2 / alpha2) / (M_PI_F * alpha2 * cosThetaM4);
// eq. 26, 27: now calculate G1(i,m) and G1(o,m)
float ao = 1 / (m_ab * safe_sqrtf((1 - cosNO * cosNO) / (cosNO * cosNO)));
float ai = 1 / (m_ab * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI)));
float G1o = ao < 1.6f ? (3.535f * ao + 2.181f * ao * ao) / (1 + 2.276f * ao + 2.577f * ao * ao) : 1.0f;
float G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f;
float G = G1o * G1i;
float out = (G * D) * 0.25f / cosNO;
// eq. 24
float pm = D * cosThetaM;
// convert into pdf of the sampled direction
// eq. 38 - but see also:
// eq. 17 in http://www.graphics.cornell.edu/~bjw/wardnotes.pdf
*pdf = pm * 0.25f / dot(Hr, I);
return make_float3 (out, out, out);
}
return make_float3 (0, 0, 0);
}
__device float3 bsdf_microfacet_beckmann_eval_transmit(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
float m_ab = sc->data0;
float m_eta = sc->data1;
int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID;
float3 m_N = sd->N;
if(!m_refractive) return make_float3 (0, 0, 0);
float cosNO = dot(m_N, I);
float cosNI = dot(m_N, omega_in);
if(cosNO <= 0 || cosNI >= 0)
return make_float3 (0, 0, 0);
// compute half-vector of the refraction (eq. 16)
float3 ht = -(m_eta * omega_in + I);
float3 Ht = normalize(ht);
float cosHO = dot(Ht, I);
float cosHI = dot(Ht, omega_in);
// eq. 33: first we calculate D(m) with m=Ht:
float alpha2 = m_ab * m_ab;
float cosThetaM = dot(m_N, Ht);
float cosThetaM2 = cosThetaM * cosThetaM;
float tanThetaM2 = (1 - cosThetaM2) / cosThetaM2;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = expf(-tanThetaM2 / alpha2) / (M_PI_F * alpha2 * cosThetaM4);
// eq. 26, 27: now calculate G1(i,m) and G1(o,m)
float ao = 1 / (m_ab * safe_sqrtf((1 - cosNO * cosNO) / (cosNO * cosNO)));
float ai = 1 / (m_ab * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI)));
float G1o = ao < 1.6f ? (3.535f * ao + 2.181f * ao * ao) / (1 + 2.276f * ao + 2.577f * ao * ao) : 1.0f;
float G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f;
float G = G1o * G1i;
// probability
float invHt2 = 1 / dot(ht, ht);
*pdf = D * fabsf(cosThetaM) * (fabsf(cosHI) * (m_eta * m_eta)) * invHt2;
float out = (fabsf(cosHI * cosHO) * (m_eta * m_eta) * (G * D) * invHt2) / cosNO;
return make_float3 (out, out, out);
}
__device float bsdf_microfacet_beckmann_albedo(const ShaderData *sd, const ShaderClosure *sc, const float3 I)
{
return 1.0f;
}
__device int bsdf_microfacet_beckmann_sample(const ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
{
float m_ab = sc->data0;
float m_eta = sc->data1;
int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID;
float3 m_N = sd->N;
float cosNO = dot(m_N, sd->I);
if(cosNO > 0) {
float3 X, Y, Z = m_N;
make_orthonormals(Z, &X, &Y);
// generate a random microfacet normal m
// eq. 35,36:
// we take advantage of cos(atan(x)) == 1/sqrt(1+x^2)
//tttt and sin(atan(x)) == x/sqrt(1+x^2)
float alpha2 = m_ab * m_ab;
float tanThetaM = safe_sqrtf(-alpha2 * logf(1 - randu));
float cosThetaM = 1 / safe_sqrtf(1 + tanThetaM * tanThetaM);
float sinThetaM = cosThetaM * tanThetaM;
float phiM = 2 * M_PI_F * randv;
float3 m = (cosf(phiM) * sinThetaM) * X +
(sinf(phiM) * sinThetaM) * Y +
cosThetaM * Z;
if(!m_refractive) {
float cosMO = dot(m, sd->I);
if(cosMO > 0) {
// eq. 39 - compute actual reflected direction
*omega_in = 2 * cosMO * m - sd->I;
if(dot(sd->Ng, *omega_in) > 0) {
// microfacet normal is visible to this ray
// eq. 25
float cosThetaM2 = cosThetaM * cosThetaM;
float tanThetaM2 = tanThetaM * tanThetaM;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = expf(-tanThetaM2 / alpha2) / (M_PI_F * alpha2 * cosThetaM4);
// eq. 24
float pm = D * cosThetaM;
// convert into pdf of the sampled direction
// eq. 38 - but see also:
// eq. 17 in http://www.graphics.cornell.edu/~bjw/wardnotes.pdf
*pdf = pm * 0.25f / cosMO;
// Eval BRDF*cosNI
float cosNI = dot(m_N, *omega_in);
// eq. 26, 27: now calculate G1(i,m) and G1(o,m)
float ao = 1 / (m_ab * safe_sqrtf((1 - cosNO * cosNO) / (cosNO * cosNO)));
float ai = 1 / (m_ab * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI)));
float G1o = ao < 1.6f ? (3.535f * ao + 2.181f * ao * ao) / (1 + 2.276f * ao + 2.577f * ao * ao) : 1.0f;
float G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f;
float G = G1o * G1i;
// eq. 20: (F*G*D)/(4*in*on)
float out = (G * D) * 0.25f / cosNO;
*eval = make_float3(out, out, out);
#ifdef __RAY_DIFFERENTIALS__
*domega_in_dx = (2 * dot(m, sd->dI.dx)) * m - sd->dI.dx;
*domega_in_dy = (2 * dot(m, sd->dI.dy)) * m - sd->dI.dy;
// Since there is some blur to this reflection, make the
// derivatives a bit bigger. In theory this varies with the
// roughness but the exact relationship is complex and
// requires more ops than are practical.
*domega_in_dx *= 10.0f;
*domega_in_dy *= 10.0f;
#endif
}
}
} else {
// CAUTION: the i and o variables are inverted relative to the paper
// eq. 39 - compute actual refractive direction
float3 R, T;
#ifdef __RAY_DIFFERENTIALS__
float3 dRdx, dRdy, dTdx, dTdy;
#endif
bool inside;
fresnel_dielectric(m_eta, m, sd->I, &R, &T,
#ifdef __RAY_DIFFERENTIALS__
sd->dI.dx, sd->dI.dy, &dRdx, &dRdy, &dTdx, &dTdy,
#endif
&inside);
if(!inside) {
*omega_in = T;
#ifdef __RAY_DIFFERENTIALS__
*domega_in_dx = dTdx;
*domega_in_dy = dTdy;
#endif
// eq. 33
float cosThetaM2 = cosThetaM * cosThetaM;
float tanThetaM2 = tanThetaM * tanThetaM;
float cosThetaM4 = cosThetaM2 * cosThetaM2;
float D = expf(-tanThetaM2 / alpha2) / (M_PI_F * alpha2 * cosThetaM4);
// eq. 24
float pm = D * cosThetaM;
// eval BRDF*cosNI
float cosNI = dot(m_N, *omega_in);
// eq. 26, 27: now calculate G1(i,m) and G1(o,m)
float ao = 1 / (m_ab * safe_sqrtf((1 - cosNO * cosNO) / (cosNO * cosNO)));
float ai = 1 / (m_ab * safe_sqrtf((1 - cosNI * cosNI) / (cosNI * cosNI)));
float G1o = ao < 1.6f ? (3.535f * ao + 2.181f * ao * ao) / (1 + 2.276f * ao + 2.577f * ao * ao) : 1.0f;
float G1i = ai < 1.6f ? (3.535f * ai + 2.181f * ai * ai) / (1 + 2.276f * ai + 2.577f * ai * ai) : 1.0f;
float G = G1o * G1i;
// eq. 21
float cosHI = dot(m, *omega_in);
float cosHO = dot(m, sd->I);
float Ht2 = m_eta * cosHI + cosHO;
Ht2 *= Ht2;
float out = (fabsf(cosHI * cosHO) * (m_eta * m_eta) * (G * D)) / (cosNO * Ht2);
// eq. 38 and eq. 17
*pdf = pm * (m_eta * m_eta) * fabsf(cosHI) / Ht2;
*eval = make_float3(out, out, out);
#ifdef __RAY_DIFFERENTIALS__
// Since there is some blur to this refraction, make the
// derivatives a bit bigger. In theory this varies with the
// roughness but the exact relationship is complex and
// requires more ops than are practical.
*domega_in_dx *= 10.0f;
*domega_in_dy *= 10.0f;
#endif
}
}
}
return (m_refractive) ? LABEL_TRANSMIT|LABEL_GLOSSY : LABEL_REFLECT|LABEL_GLOSSY;
}
CCL_NAMESPACE_END
#endif /* __BSDF_MICROFACET_H__ */