forked from bartvdbraak/blender
26bf230920
In scenes with many lights, some of them might have a very small contribution to some pixels, but the shadow rays are traced anyways. To avoid that, this patch adds probabilistic termination to light samples - if the contribution before checking for shadowing is below a user-defined threshold, the sample will be discarded with probability (1 - (contribution / threshold)) and otherwise kept, but weighted more to remain unbiased. This is the same approach that's also used in path termination based on length. Note that the rendering remains unbiased with this option, it just adds a bit of noise - but if the setting is used moderately, the speedup gained easily outweighs the additional noise. Reviewers: #cycles Subscribers: sergey, brecht Differential Revision: https://developer.blender.org/D2217
342 lines
11 KiB
C
342 lines
11 KiB
C
/*
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* Copyright 2011-2013 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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CCL_NAMESPACE_BEGIN
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/* Direction Emission */
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ccl_device_noinline float3 direct_emissive_eval(KernelGlobals *kg,
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ShaderData *emission_sd,
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LightSample *ls,
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ccl_addr_space PathState *state,
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float3 I,
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differential3 dI,
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float t,
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float time)
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{
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/* setup shading at emitter */
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float3 eval;
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int shader_flag = kernel_tex_fetch(__shader_flag, (ls->shader & SHADER_MASK)*SHADER_SIZE);
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#ifdef __BACKGROUND_MIS__
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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.t = 1.0f;
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# ifdef __OBJECT_MOTION__
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ray.time = time;
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# endif
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ray.dP = differential3_zero();
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ray.dD = dI;
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shader_setup_from_background(kg, emission_sd, &ray);
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path_state_modify_bounce(state, true);
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eval = shader_eval_background(kg, emission_sd, state, 0, SHADER_CONTEXT_EMISSION);
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path_state_modify_bounce(state, false);
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}
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else
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#endif
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if(shader_flag & SD_HAS_CONSTANT_EMISSION)
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{
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eval.x = __int_as_float(kernel_tex_fetch(__shader_flag, (ls->shader & SHADER_MASK)*SHADER_SIZE + 2));
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eval.y = __int_as_float(kernel_tex_fetch(__shader_flag, (ls->shader & SHADER_MASK)*SHADER_SIZE + 3));
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eval.z = __int_as_float(kernel_tex_fetch(__shader_flag, (ls->shader & SHADER_MASK)*SHADER_SIZE + 4));
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if((ls->prim != PRIM_NONE) && dot(ls->Ng, I) < 0.0f) {
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ls->Ng = -ls->Ng;
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}
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}
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else
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{
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shader_setup_from_sample(kg, emission_sd,
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ls->P, ls->Ng, I,
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ls->shader, ls->object, ls->prim,
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ls->u, ls->v, t, time, false, ls->lamp);
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ls->Ng = ccl_fetch(emission_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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path_state_modify_bounce(state, true);
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shader_eval_surface(kg, emission_sd, NULL, state, 0.0f, 0, SHADER_CONTEXT_EMISSION);
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path_state_modify_bounce(state, false);
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/* evaluate emissive closure */
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if(ccl_fetch(emission_sd, flag) & SD_EMISSION)
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eval = shader_emissive_eval(kg, emission_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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eval *= ls->eval_fac;
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return eval;
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}
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ccl_device_noinline bool direct_emission(KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *emission_sd,
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LightSample *ls,
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ccl_addr_space PathState *state,
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Ray *ray,
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BsdfEval *eval,
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bool *is_lamp,
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float rand_terminate)
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{
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if(ls->pdf == 0.0f)
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return false;
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/* todo: implement */
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differential3 dD = differential3_zero();
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/* evaluate closure */
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float3 light_eval = direct_emissive_eval(kg,
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emission_sd,
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ls,
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state,
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-ls->D,
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dD,
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ls->t,
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ccl_fetch(sd, time));
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if(is_zero(light_eval))
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return false;
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/* evaluate BSDF at shading point */
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#ifdef __VOLUME__
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if(ccl_fetch(sd, prim) != PRIM_NONE)
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shader_bsdf_eval(kg, sd, ls->D, eval, ls->pdf, ls->shader & SHADER_USE_MIS);
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else {
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float bsdf_pdf;
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shader_volume_phase_eval(kg, sd, ls->D, eval, &bsdf_pdf);
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if(ls->shader & SHADER_USE_MIS) {
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/* Multiple importance sampling. */
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float mis_weight = power_heuristic(ls->pdf, bsdf_pdf);
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light_eval *= mis_weight;
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}
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}
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#else
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shader_bsdf_eval(kg, sd, ls->D, eval, ls->pdf, ls->shader & SHADER_USE_MIS);
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#endif
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bsdf_eval_mul3(eval, light_eval/ls->pdf);
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#ifdef __PASSES__
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/* use visibility flag to skip lights */
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if(ls->shader & SHADER_EXCLUDE_ANY) {
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if(ls->shader & SHADER_EXCLUDE_DIFFUSE) {
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eval->diffuse = make_float3(0.0f, 0.0f, 0.0f);
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eval->subsurface = make_float3(0.0f, 0.0f, 0.0f);
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}
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if(ls->shader & SHADER_EXCLUDE_GLOSSY)
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eval->glossy = make_float3(0.0f, 0.0f, 0.0f);
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if(ls->shader & SHADER_EXCLUDE_TRANSMIT)
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eval->transmission = make_float3(0.0f, 0.0f, 0.0f);
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if(ls->shader & SHADER_EXCLUDE_SCATTER)
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eval->scatter = make_float3(0.0f, 0.0f, 0.0f);
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}
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#endif
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if(bsdf_eval_is_zero(eval))
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return false;
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if(kernel_data.integrator.light_inv_rr_threshold > 0.0f) {
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float probability = max3(bsdf_eval_sum(eval)) * kernel_data.integrator.light_inv_rr_threshold;
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if(probability < 1.0f) {
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if(rand_terminate >= probability) {
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return false;
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}
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bsdf_eval_mul(eval, 1.0f / probability);
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}
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}
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if(ls->shader & SHADER_CAST_SHADOW) {
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/* setup ray */
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bool transmit = (dot(ccl_fetch(sd, Ng), ls->D) < 0.0f);
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ray->P = ray_offset(ccl_fetch(sd, P), (transmit)? -ccl_fetch(sd, Ng): ccl_fetch(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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ray->dP = ccl_fetch(sd, dP);
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ray->dD = differential3_zero();
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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 if it's a lamp for shadow pass */
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*is_lamp = (ls->prim == PRIM_NONE && ls->type != LIGHT_BACKGROUND);
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return true;
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}
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/* Indirect Primitive Emission */
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ccl_device_noinline float3 indirect_primitive_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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#ifdef __HAIR__
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if(!(path_flag & PATH_RAY_MIS_SKIP) && (ccl_fetch(sd, flag) & SD_USE_MIS) && (ccl_fetch(sd, type) & PRIMITIVE_ALL_TRIANGLE))
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#else
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if(!(path_flag & PATH_RAY_MIS_SKIP) && (ccl_fetch(sd, flag) & SD_USE_MIS))
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#endif
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{
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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, ccl_fetch(sd, Ng), ccl_fetch(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 Lamp Emission */
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ccl_device_noinline bool indirect_lamp_emission(KernelGlobals *kg,
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ShaderData *emission_sd,
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ccl_addr_space PathState *state,
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Ray *ray,
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float3 *emission)
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{
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bool hit_lamp = false;
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*emission = make_float3(0.0f, 0.0f, 0.0f);
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for(int lamp = 0; lamp < kernel_data.integrator.num_all_lights; lamp++) {
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LightSample ls;
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if(!lamp_light_eval(kg, lamp, ray->P, ray->D, ray->t, &ls))
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continue;
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#ifdef __PASSES__
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/* use visibility flag to skip lights */
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if(ls.shader & SHADER_EXCLUDE_ANY) {
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if(((ls.shader & SHADER_EXCLUDE_DIFFUSE) && (state->flag & PATH_RAY_DIFFUSE)) ||
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((ls.shader & SHADER_EXCLUDE_GLOSSY) &&
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((state->flag & (PATH_RAY_GLOSSY|PATH_RAY_REFLECT)) == (PATH_RAY_GLOSSY|PATH_RAY_REFLECT))) ||
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((ls.shader & SHADER_EXCLUDE_TRANSMIT) && (state->flag & PATH_RAY_TRANSMIT)) ||
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((ls.shader & SHADER_EXCLUDE_SCATTER) && (state->flag & PATH_RAY_VOLUME_SCATTER)))
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continue;
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}
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#endif
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float3 L = direct_emissive_eval(kg,
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emission_sd,
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&ls,
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state,
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-ray->D,
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ray->dD,
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ls.t,
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ray->time);
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#ifdef __VOLUME__
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if(state->volume_stack[0].shader != SHADER_NONE) {
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/* shadow attenuation */
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Ray volume_ray = *ray;
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volume_ray.t = ls.t;
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float3 volume_tp = make_float3(1.0f, 1.0f, 1.0f);
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kernel_volume_shadow(kg, emission_sd, state, &volume_ray, &volume_tp);
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L *= volume_tp;
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}
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#endif
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if(!(state->flag & PATH_RAY_MIS_SKIP)) {
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/* multiple importance sampling, get regular light pdf,
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* and compute weight with respect to BSDF pdf */
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float mis_weight = power_heuristic(state->ray_pdf, ls.pdf);
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L *= mis_weight;
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}
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*emission += L;
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hit_lamp = true;
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}
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return hit_lamp;
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}
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/* Indirect Background */
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ccl_device_noinline float3 indirect_background(KernelGlobals *kg,
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ShaderData *emission_sd,
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ccl_addr_space PathState *state,
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ccl_addr_space Ray *ray)
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{
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#ifdef __BACKGROUND__
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int shader = kernel_data.background.surface_shader;
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/* use visibility flag to skip lights */
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if(shader & SHADER_EXCLUDE_ANY) {
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if(((shader & SHADER_EXCLUDE_DIFFUSE) && (state->flag & PATH_RAY_DIFFUSE)) ||
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((shader & SHADER_EXCLUDE_GLOSSY) &&
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((state->flag & (PATH_RAY_GLOSSY|PATH_RAY_REFLECT)) == (PATH_RAY_GLOSSY|PATH_RAY_REFLECT))) ||
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((shader & SHADER_EXCLUDE_TRANSMIT) && (state->flag & PATH_RAY_TRANSMIT)) ||
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((shader & SHADER_EXCLUDE_CAMERA) && (state->flag & PATH_RAY_CAMERA)) ||
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((shader & SHADER_EXCLUDE_SCATTER) && (state->flag & PATH_RAY_VOLUME_SCATTER)))
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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/* evaluate background closure */
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# ifdef __SPLIT_KERNEL__
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Ray priv_ray = *ray;
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shader_setup_from_background(kg, emission_sd, &priv_ray);
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# else
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shader_setup_from_background(kg, emission_sd, ray);
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# endif
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path_state_modify_bounce(state, true);
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float3 L = shader_eval_background(kg, emission_sd, state, state->flag, SHADER_CONTEXT_EMISSION);
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path_state_modify_bounce(state, false);
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#ifdef __BACKGROUND_MIS__
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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(!(state->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->P, ray->D);
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float mis_weight = power_heuristic(state->ray_pdf, pdf);
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return L*mis_weight;
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}
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#endif
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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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