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