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