forked from bartvdbraak/blender
145 lines
4.5 KiB
C
145 lines
4.5 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_UTIL_H__
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#define __BSDF_UTIL_H__
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CCL_NAMESPACE_BEGIN
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ccl_device float fresnel_dielectric(
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float eta, const float3 N,
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const float3 I, float3 *R, float3 *T,
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#ifdef __RAY_DIFFERENTIALS__
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const float3 dIdx, const float3 dIdy,
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float3 *dRdx, float3 *dRdy,
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float3 *dTdx, float3 *dTdy,
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#endif
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bool *is_inside)
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{
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float cos = dot(N, I), neta;
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float3 Nn;
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// check which side of the surface we are on
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if(cos > 0) {
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// we are on the outside of the surface, going in
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neta = 1 / eta;
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Nn = N;
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*is_inside = false;
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}
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else {
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// we are inside the surface
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cos = -cos;
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neta = eta;
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Nn = -N;
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*is_inside = true;
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}
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// compute reflection
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*R = (2 * cos)* Nn - I;
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#ifdef __RAY_DIFFERENTIALS__
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*dRdx = (2 * dot(Nn, dIdx)) * Nn - dIdx;
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*dRdy = (2 * dot(Nn, dIdy)) * Nn - dIdy;
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#endif
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float arg = 1 -(neta * neta *(1 -(cos * cos)));
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if(arg < 0) {
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*T = make_float3(0.0f, 0.0f, 0.0f);
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#ifdef __RAY_DIFFERENTIALS__
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*dTdx = make_float3(0.0f, 0.0f, 0.0f);
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*dTdy = make_float3(0.0f, 0.0f, 0.0f);
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#endif
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return 1; // total internal reflection
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}
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else {
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float dnp = sqrtf(arg);
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float nK = (neta * cos)- dnp;
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*T = -(neta * I)+(nK * Nn);
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#ifdef __RAY_DIFFERENTIALS__
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*dTdx = -(neta * dIdx) + ((neta - neta * neta * cos / dnp) * dot(dIdx, Nn)) * Nn;
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*dTdy = -(neta * dIdy) + ((neta - neta * neta * cos / dnp) * dot(dIdy, Nn)) * Nn;
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#endif
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// compute Fresnel terms
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float cosTheta1 = cos; // N.R
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float cosTheta2 = -dot(Nn, *T);
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float pPara = (cosTheta1 - eta * cosTheta2)/(cosTheta1 + eta * cosTheta2);
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float pPerp = (eta * cosTheta1 - cosTheta2)/(eta * cosTheta1 + cosTheta2);
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return 0.5f * (pPara * pPara + pPerp * pPerp);
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}
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}
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ccl_device float fresnel_dielectric_cos(float cosi, float eta)
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{
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// compute fresnel reflectance without explicitly computing
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// the refracted direction
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float c = fabsf(cosi);
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float g = eta * eta - 1 + c * c;
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if(g > 0) {
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g = sqrtf(g);
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float A = (g - c)/(g + c);
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float B = (c *(g + c)- 1)/(c *(g - c)+ 1);
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return 0.5f * A * A *(1 + B * B);
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}
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return 1.0f; // TIR(no refracted component)
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}
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#if 0
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ccl_device float3 fresnel_conductor(float cosi, const float3 eta, const float3 k)
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{
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float3 cosi2 = make_float3(cosi*cosi);
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float3 one = make_float3(1.0f, 1.0f, 1.0f);
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float3 tmp_f = eta * eta + k * k;
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float3 tmp = tmp_f * cosi2;
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float3 Rparl2 = (tmp - (2.0f * eta * cosi) + one) /
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(tmp + (2.0f * eta * cosi) + one);
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float3 Rperp2 = (tmp_f - (2.0f * eta * cosi) + cosi2) /
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(tmp_f + (2.0f * eta * cosi) + cosi2);
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return(Rparl2 + Rperp2) * 0.5f;
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}
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#endif
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ccl_device float smooth_step(float edge0, float edge1, float x)
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{
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float result;
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if(x < edge0) result = 0.0f;
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else if(x >= edge1) result = 1.0f;
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else {
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float t = (x - edge0)/(edge1 - edge0);
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result = (3.0f-2.0f*t)*(t*t);
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}
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return result;
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}
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CCL_NAMESPACE_END
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#endif /* __BSDF_UTIL_H__ */
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