forked from bartvdbraak/blender
149 lines
4.9 KiB
C
149 lines
4.9 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_ASHIKHMIN_VELVET_H__
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#define __BSDF_ASHIKHMIN_VELVET_H__
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CCL_NAMESPACE_BEGIN
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__device int bsdf_ashikhmin_velvet_setup(ShaderClosure *sc)
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{
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float sigma = fmaxf(sc->data0, 0.01f);
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sc->data0 = 1.0f/(sigma * sigma); /* m_invsigma2 */
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sc->type = CLOSURE_BSDF_ASHIKHMIN_VELVET_ID;
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return SD_BSDF|SD_BSDF_HAS_EVAL;
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}
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__device void bsdf_ashikhmin_velvet_blur(ShaderClosure *sc, float roughness)
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{
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}
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__device float3 bsdf_ashikhmin_velvet_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
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{
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float m_invsigma2 = sc->data0;
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float3 N = sc->N;
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float cosNO = dot(N, I);
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float cosNI = dot(N, omega_in);
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if(cosNO > 0 && cosNI > 0) {
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float3 H = normalize(omega_in + I);
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float cosNH = dot(N, H);
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float cosHO = fabsf(dot(I, H));
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if(!(fabsf(cosNH) < 1.0f-1e-5f && cosHO > 1e-5f))
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return make_float3(0, 0, 0);
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float cosNHdivHO = cosNH / cosHO;
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cosNHdivHO = fmaxf(cosNHdivHO, 1e-5f);
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float fac1 = 2 * fabsf(cosNHdivHO * cosNO);
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float fac2 = 2 * fabsf(cosNHdivHO * cosNI);
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float sinNH2 = 1 - cosNH * cosNH;
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float sinNH4 = sinNH2 * sinNH2;
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float cotangent2 = (cosNH * cosNH) / sinNH2;
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float D = expf(-cotangent2 * m_invsigma2) * m_invsigma2 * M_1_PI_F / sinNH4;
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float G = min(1.0f, min(fac1, fac2)); // TODO: derive G from D analytically
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float out = 0.25f * (D * G) / cosNO;
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*pdf = 0.5f * M_1_PI_F;
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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_ashikhmin_velvet_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
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{
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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__device int bsdf_ashikhmin_velvet_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)
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{
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float m_invsigma2 = sc->data0;
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float3 N = sc->N;
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// we are viewing the surface from above - send a ray out with uniform
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// distribution over the hemisphere
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sample_uniform_hemisphere(N, randu, randv, omega_in, pdf);
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if(dot(Ng, *omega_in) > 0) {
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float3 H = normalize(*omega_in + I);
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float cosNI = dot(N, *omega_in);
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float cosNO = dot(N, I);
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float cosNH = dot(N, H);
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float cosHO = fabsf(dot(I, H));
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if(fabsf(cosNO) > 1e-5f && fabsf(cosNH) < 1.0f-1e-5f && cosHO > 1e-5f) {
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float cosNHdivHO = cosNH / cosHO;
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cosNHdivHO = fmaxf(cosNHdivHO, 1e-5f);
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float fac1 = 2 * fabsf(cosNHdivHO * cosNO);
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float fac2 = 2 * fabsf(cosNHdivHO * cosNI);
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float sinNH2 = 1 - cosNH * cosNH;
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float sinNH4 = sinNH2 * sinNH2;
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float cotangent2 = (cosNH * cosNH) / sinNH2;
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float D = expf(-cotangent2 * m_invsigma2) * m_invsigma2 * M_1_PI_F / sinNH4;
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float G = min(1.0f, min(fac1, fac2)); // TODO: derive G from D analytically
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float power = 0.25f * (D * G) / cosNO;
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*eval = make_float3(power, power, power);
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#ifdef __RAY_DIFFERENTIALS__
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// TODO: find a better approximation for the retroreflective bounce
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*domega_in_dx = (2 * dot(N, dIdx)) * N - dIdx;
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*domega_in_dy = (2 * dot(N, dIdy)) * N - dIdy;
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#endif
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}
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else
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*pdf = 0.0f;
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}
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else
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*pdf = 0.0f;
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return LABEL_REFLECT|LABEL_DIFFUSE;
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}
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CCL_NAMESPACE_END
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#endif /* __BSDF_ASHIKHMIN_VELVET_H__ */
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