forked from bartvdbraak/blender
140 lines
3.5 KiB
C
140 lines
3.5 KiB
C
/*
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* Copyright 2011, Blender Foundation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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CCL_NAMESPACE_BEGIN
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/* Direction Emission */
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__device float3 direct_emissive_eval(KernelGlobals *kg, float rando,
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LightSample *ls, float u, float v, float3 I)
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{
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/* setup shading at emitter */
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ShaderData sd;
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shader_setup_from_sample(kg, &sd, ls->P, ls->Ng, I, ls->shader, ls->object, ls->prim, u, v);
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ls->Ng = sd.Ng;
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/* no path flag, we're evaluating this for all closures. that's weak but
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we'd have to do multiple evaluations otherwise */
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shader_eval_surface(kg, &sd, rando, 0);
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float3 eval;
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/* evaluate emissive closure */
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if(sd.flag & SD_EMISSION)
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eval = shader_emissive_eval(kg, &sd);
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else
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eval = make_float3(0.0f, 0.0f, 0.0f);
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shader_release(kg, &sd);
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return eval;
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}
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__device bool direct_emission(KernelGlobals *kg, ShaderData *sd, int lindex,
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float randt, float rando, float randu, float randv, Ray *ray, float3 *eval)
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{
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LightSample ls;
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#ifdef __MULTI_LIGHT__
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if(lindex != -1) {
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/* sample position on a specified light */
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light_select(kg, lindex, randu, randv, sd->P, &ls);
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}
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else
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#endif
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{
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/* sample a light and position on int */
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light_sample(kg, randt, randu, randv, sd->P, &ls);
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}
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/* compute pdf */
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float pdf = light_sample_pdf(kg, &ls, -ls.D, ls.t);
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/* evaluate closure */
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*eval = direct_emissive_eval(kg, rando, &ls, randu, randv, -ls.D);
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if(is_zero(*eval) || pdf == 0.0f)
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return false;
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/* todo: use visbility flag to skip lights */
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/* evaluate BSDF at shading point */
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float bsdf_pdf;
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float3 bsdf_eval = shader_bsdf_eval(kg, sd, ls.D, &bsdf_pdf);
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*eval *= bsdf_eval/pdf;
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if(is_zero(*eval))
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return false;
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if(ls.prim != ~0) {
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/* multiple importance sampling */
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float mis_weight = power_heuristic(pdf, bsdf_pdf);
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*eval *= mis_weight;
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}
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/* todo: clean up these weights */
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else if(ls.shader & SHADER_AREA_LIGHT)
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*eval *= 0.25f; /* area lamp */
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else if(ls.t != FLT_MAX)
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*eval *= 0.25f*M_1_PI_F; /* point lamp */
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if(ls.shader & SHADER_CAST_SHADOW) {
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/* setup ray */
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ray->P = ray_offset(sd->P, sd->Ng);
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if(ls.t == FLT_MAX) {
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/* distant light */
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ray->D = ls.D;
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ray->t = ls.t;
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}
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else {
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/* other lights, avoid self-intersection */
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ray->D = ray_offset(ls.P, ls.Ng) - ray->P;
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ray->D = normalize_len(ray->D, &ray->t);
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}
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}
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else {
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/* signal to not cast shadow ray */
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ray->t = 0.0f;
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}
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return true;
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}
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/* Indirect Emission */
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__device float3 indirect_emission(KernelGlobals *kg, ShaderData *sd, float t, int path_flag, float bsdf_pdf)
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{
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/* evaluate emissive closure */
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float3 L = shader_emissive_eval(kg, sd);
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if(!(path_flag & PATH_RAY_MIS_SKIP) && (sd->flag & SD_SAMPLE_AS_LIGHT)) {
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/* multiple importance sampling */
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float pdf = triangle_light_pdf(kg, sd->Ng, sd->I, t);
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float mis_weight = power_heuristic(bsdf_pdf, pdf);
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return L*mis_weight;
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}
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return L;
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}
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CCL_NAMESPACE_END
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