Mai Lavelle
6238214159
Unlike regular path tracing, branched path tracing is usually used with lower sample counts, at least for primary rays. This means that are less samples for the GPU to work on in parallel and rendering is slower. As there is less work overall there is also more inactive threads during rendering with BPT. This patch makes use of those inactive rays to render branched samples in parallel with other samples. Each thread that is preparing for a branched sample will attempt to find an inactive thread and if one is found the state for the sample is copied to that thread. Potentially, if there are enough inactive threads, 100s of branched samples could be generated from the same originating thread and ran in parallel giving large speed ups. Gives 70% faster render for pavillion midday scene. 20-60% faster on BMW with car paint replaced with SSS/volumes.
111 lines
3.5 KiB
C++
111 lines
3.5 KiB
C++
/*
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* Copyright 2011-2015 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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/* Shadow ray cast for direct visible light. */
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ccl_device void kernel_shadow_blocked_dl(KernelGlobals *kg)
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{
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unsigned int dl_queue_length = kernel_split_params.queue_index[QUEUE_SHADOW_RAY_CAST_DL_RAYS];
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ccl_barrier(CCL_LOCAL_MEM_FENCE);
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int ray_index = QUEUE_EMPTY_SLOT;
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int thread_index = ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0);
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if(thread_index < dl_queue_length) {
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ray_index = get_ray_index(kg, thread_index, QUEUE_SHADOW_RAY_CAST_DL_RAYS,
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kernel_split_state.queue_data, kernel_split_params.queue_size, 1);
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}
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#ifdef __BRANCHED_PATH__
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/* TODO(mai): move this somewhere else? */
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if(thread_index == 0) {
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/* Clear QUEUE_INACTIVE_RAYS before next kernel. */
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kernel_split_params.queue_index[QUEUE_INACTIVE_RAYS] = 0;
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}
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#endif /* __BRANCHED_PATH__ */
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if(ray_index == QUEUE_EMPTY_SLOT)
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return;
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ccl_global PathState *state = &kernel_split_state.path_state[ray_index];
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Ray ray = kernel_split_state.light_ray[ray_index];
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PathRadiance *L = &kernel_split_state.path_radiance[ray_index];
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ShaderData *sd = &kernel_split_state.sd[ray_index];
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float3 throughput = kernel_split_state.throughput[ray_index];
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RNG rng = kernel_split_state.rng[ray_index];
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BsdfEval L_light = kernel_split_state.bsdf_eval[ray_index];
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ShaderData *emission_sd = &kernel_split_state.sd_DL_shadow[ray_index];
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bool is_lamp = kernel_split_state.is_lamp[ray_index];
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# if defined(__BRANCHED_PATH__) || defined(__SHADOW_TRICKS__)
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bool use_branched = false;
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int all = 0;
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if(state->flag & PATH_RAY_SHADOW_CATCHER) {
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use_branched = true;
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all = 1;
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}
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# if defined(__BRANCHED_PATH__)
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else if(kernel_data.integrator.branched) {
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use_branched = true;
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if(IS_FLAG(kernel_split_state.ray_state, ray_index, RAY_BRANCHED_INDIRECT)) {
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all = (kernel_data.integrator.sample_all_lights_indirect);
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}
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else
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{
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all = (kernel_data.integrator.sample_all_lights_direct);
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}
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}
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# endif /* __BRANCHED_PATH__ */
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if(use_branched) {
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kernel_branched_path_surface_connect_light(kg,
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&rng,
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sd,
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emission_sd,
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state,
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throughput,
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1.0f,
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L,
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all);
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}
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else
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# endif /* defined(__BRANCHED_PATH__) || defined(__SHADOW_TRICKS__)*/
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{
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/* trace shadow ray */
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float3 shadow;
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if(!shadow_blocked(kg,
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emission_sd,
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state,
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&ray,
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&shadow))
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{
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/* accumulate */
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path_radiance_accum_light(L, state, throughput, &L_light, shadow, 1.0f, is_lamp);
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}
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else {
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path_radiance_accum_total_light(L, state, throughput, &L_light);
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}
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}
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kernel_split_state.rng[ray_index] = rng;
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}
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CCL_NAMESPACE_END
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