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Diffstat (limited to 'intern/cycles/kernel/closure/bsdf_microfacet.h')
| -rw-r--r-- | intern/cycles/kernel/closure/bsdf_microfacet.h | 506 |
1 files changed, 506 insertions, 0 deletions
diff --git a/intern/cycles/kernel/closure/bsdf_microfacet.h b/intern/cycles/kernel/closure/bsdf_microfacet.h new file mode 100644 index 00000000000..a564b99e759 --- /dev/null +++ b/intern/cycles/kernel/closure/bsdf_microfacet.h @@ -0,0 +1,506 @@ +/* + * 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 */ + +__device_inline float safe_sqrtf(float f) +{ + return sqrtf(max(f, 0.0f)); +} + +__device int bsdf_microfacet_ggx_setup(ShaderClosure *sc) +{ + float ag = sc->data0; + + float m_ag = clamp(ag, 1e-4f, 1.0f); + + sc->data0 = m_ag; + sc->type = CLOSURE_BSDF_MICROFACET_GGX_ID; + + return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY; +} + +__device int bsdf_microfacet_ggx_refraction_setup(ShaderClosure *sc) +{ + float ag = sc->data0; + float eta = sc->data1; + + float m_ag = clamp(ag, 1e-4f, 1.0f); + float m_eta = eta; + + sc->data0 = m_ag; + sc->data1 = m_eta; + sc->type = CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID; + + return 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 ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf) +{ + float m_ag = sc->data0; + int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID; + float3 N = sc->N; + + if(m_refractive) return make_float3 (0, 0, 0); + float cosNO = dot(N, I); + float cosNI = dot(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(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 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 N = sc->N; + + if(!m_refractive) return make_float3 (0, 0, 0); + float cosNO = dot(N, I); + float cosNI = dot(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(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 int bsdf_microfacet_ggx_sample(const ShaderClosure *sc, float3 Ng, float3 I, float3 dIdx, float3 dIdy, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf) +{ + float m_ag = sc->data0; + int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID; + float3 N = sc->N; + + float cosNO = dot(N, I); + if(cosNO > 0) { + float3 X, Y, Z = 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, I); + if(cosMO > 0) { + // eq. 39 - compute actual reflected direction + *omega_in = 2 * cosMO * m - I; + if(dot(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(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, dIdx)) * m - dIdx; + *domega_in_dy = (2 * dot(m, dIdy)) * m - dIdy; + // 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 + float m_eta = sc->data1; + bool inside; + fresnel_dielectric(m_eta, m, I, &R, &T, +#ifdef __RAY_DIFFERENTIALS__ + dIdx, dIdy, &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(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, 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 */ + +__device int bsdf_microfacet_beckmann_setup(ShaderClosure *sc) +{ + float ab = sc->data0; + float m_ab = clamp(ab, 1e-4f, 1.0f); + + sc->data0 = m_ab; + + sc->type = CLOSURE_BSDF_MICROFACET_BECKMANN_ID; + return SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY; +} + +__device int bsdf_microfacet_beckmann_refraction_setup(ShaderClosure *sc) +{ + float ab = sc->data0; + float eta = sc->data1; + float m_ab = clamp(ab, 1e-4f, 1.0f); + float m_eta = eta; + + sc->data0 = m_ab; + sc->data1 = m_eta; + + sc->type = CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID; + return 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 ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf) +{ + float m_ab = sc->data0; + int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID; + float3 N = sc->N; + + if(m_refractive) return make_float3 (0, 0, 0); + float cosNO = dot(N, I); + float cosNI = dot(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(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 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 N = sc->N; + + if(!m_refractive) return make_float3 (0, 0, 0); + float cosNO = dot(N, I); + float cosNI = dot(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(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 int bsdf_microfacet_beckmann_sample(const ShaderClosure *sc, float3 Ng, float3 I, float3 dIdx, float3 dIdy, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf) +{ + float m_ab = sc->data0; + int m_refractive = sc->type == CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID; + float3 N = sc->N; + + float cosNO = dot(N, I); + if(cosNO > 0) { + float3 X, Y, Z = 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, I); + if(cosMO > 0) { + // eq. 39 - compute actual reflected direction + *omega_in = 2 * cosMO * m - I; + if(dot(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(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, dIdx)) * m - dIdx; + *domega_in_dy = (2 * dot(m, dIdy)) * m - dIdy; + // 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 + float m_eta = sc->data1; + bool inside; + fresnel_dielectric(m_eta, m, I, &R, &T, +#ifdef __RAY_DIFFERENTIALS__ + dIdx, dIdy, &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(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, 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__ */ + |