forked from bartvdbraak/blender
5873301257
By default lighting from the world is computed solely with indirect light sampling. However for more complex environment maps this can be too noisy, as sampling the BSDF may not easily find the highlights in the environment map image. By enabling this option, the world background will be sampled as a lamp, with lighter parts automatically given more samples. Map Resolution specifies the size of the importance map (res x res). Before rendering starts, an importance map is generated by "baking" a grayscale image from the world shader. This will then be used to determine which parts of the background are light and so should receive more samples than darker parts. Higher resolutions will result in more accurate sampling but take more setup time and memory. Patch by Mike Farnsworth, thanks!
186 lines
4.7 KiB
C
186 lines
4.7 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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float3 eval;
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if(ls->type == LIGHT_BACKGROUND) {
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Ray ray;
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ray.D = ls->D;
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ray.P = ls->P;
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ray.dP.dx = make_float3(0.0f, 0.0f, 0.0f);
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ray.dP.dy = make_float3(0.0f, 0.0f, 0.0f);
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shader_setup_from_background(kg, &sd, &ray);
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eval = shader_eval_background(kg, &sd, 0);
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}
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else {
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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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/* 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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}
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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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float pdf = -1.0f;
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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, &pdf);
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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, &pdf);
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}
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/* compute pdf */
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if(pdf < 0.0f)
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pdf = light_sample_pdf(kg, &ls, -ls.D, ls.t);
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if(pdf == 0.0f)
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return false;
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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))
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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 || ls.type == LIGHT_BACKGROUND) {
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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, get triangle light pdf,
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and compute weight with respect to BSDF pdf */
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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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/* Indirect Background */
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__device float3 indirect_background(KernelGlobals *kg, Ray *ray, int path_flag, float bsdf_pdf)
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{
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#ifdef __BACKGROUND__
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/* evaluate background closure */
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ShaderData sd;
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shader_setup_from_background(kg, &sd, ray);
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float3 L = shader_eval_background(kg, &sd, path_flag);
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shader_release(kg, &sd);
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/* check if background light exists or if we should skip pdf */
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int res = kernel_data.integrator.pdf_background_res;
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if(!(path_flag & PATH_RAY_MIS_SKIP) && res) {
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/* multiple importance sampling, get background light pdf for ray
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direction, and compute weight with respect to BSDF pdf */
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float pdf = background_light_pdf(kg, ray->D);
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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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#else
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return make_float3(0.8f, 0.8f, 0.8f);
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#endif
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}
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CCL_NAMESPACE_END
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