00001 /*************************************************************************** 00002 * Copyright (C) 1998-2009 by authors (see AUTHORS.txt ) * 00003 * * 00004 * This file is part of LuxRender. * 00005 * * 00006 * Lux Renderer is free software; you can redistribute it and/or modify * 00007 * it under the terms of the GNU General Public License as published by * 00008 * the Free Software Foundation; either version 3 of the License, or * 00009 * (at your option) any later version. * 00010 * * 00011 * Lux Renderer is distributed in the hope that it will be useful, * 00012 * but WITHOUT ANY WARRANTY; without even the implied warranty of * 00013 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * 00014 * GNU General Public License for more details. * 00015 * * 00016 * You should have received a copy of the GNU General Public License * 00017 * along with this program. If not, see <http://www.gnu.org/licenses/>. * 00018 * * 00019 * This project is based on PBRT ; see http://www.pbrt.org * 00020 * Lux Renderer website : http://www.luxrender.net * 00021 ***************************************************************************/ 00022 00023 // orennayar.cpp* 00024 #include "orennayar.h" 00025 #include "spectrum.h" 00026 #include "mc.h" 00027 00028 using namespace lux; 00029 00030 void OrenNayar::f(const TsPack *tspack, const Vector &wo, 00031 const Vector &wi, SWCSpectrum *const f_) const 00032 { 00033 float sinthetai = SinTheta(wi); 00034 float sinthetao = SinTheta(wo); 00035 // Compute cosine term of Oren--Nayar model 00036 float maxcos = 0.f; 00037 if (sinthetai > 1e-4f && sinthetao > 1e-4f) { 00038 float sinphii = SinPhi(wi), cosphii = CosPhi(wi); 00039 float sinphio = SinPhi(wo), cosphio = CosPhi(wo); 00040 float dcos = cosphii * cosphio + sinphii * sinphio; 00041 maxcos = max(0.f, dcos); 00042 } 00043 // Compute sine and tangent terms of Oren--Nayar model 00044 float sinalpha, tanbeta; 00045 if (fabsf(CosTheta(wi)) > fabsf(CosTheta(wo))) { 00046 sinalpha = sinthetao; 00047 tanbeta = sinthetai / fabsf(CosTheta(wi)); 00048 } else { 00049 sinalpha = sinthetai; 00050 tanbeta = sinthetao / fabsf(CosTheta(wo)); 00051 } 00052 f_->AddWeighted(INV_PI * (A + B * maxcos * sinalpha * tanbeta), R); 00053 } 00054