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.
118 lines
3.7 KiB
C++
118 lines
3.7 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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/* This kernel takes care of scene_intersect function.
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*
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* This kernel changes the ray_state of RAY_REGENERATED rays to RAY_ACTIVE.
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* This kernel processes rays of ray state RAY_ACTIVE
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* This kernel determines the rays that have hit the background and changes
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* their ray state to RAY_HIT_BACKGROUND.
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*/
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ccl_device void kernel_scene_intersect(KernelGlobals *kg)
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{
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/* Fetch use_queues_flag */
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char local_use_queues_flag = *kernel_split_params.use_queues_flag;
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ccl_barrier(CCL_LOCAL_MEM_FENCE);
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int ray_index = ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0);
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if(local_use_queues_flag) {
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ray_index = get_ray_index(kg, ray_index,
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QUEUE_ACTIVE_AND_REGENERATED_RAYS,
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kernel_split_state.queue_data,
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kernel_split_params.queue_size,
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0);
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if(ray_index == QUEUE_EMPTY_SLOT) {
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return;
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}
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}
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/* All regenerated rays become active here */
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if(IS_STATE(kernel_split_state.ray_state, ray_index, RAY_REGENERATED)) {
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#ifdef __BRANCHED_PATH__
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if(kernel_split_state.branched_state[ray_index].waiting_on_shared_samples) {
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kernel_split_path_end(kg, ray_index);
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}
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else
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#endif /* __BRANCHED_PATH__ */
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{
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ASSIGN_RAY_STATE(kernel_split_state.ray_state, ray_index, RAY_ACTIVE);
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}
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}
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if(!IS_STATE(kernel_split_state.ray_state, ray_index, RAY_ACTIVE)) {
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return;
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}
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#ifdef __KERNEL_DEBUG__
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DebugData *debug_data = &kernel_split_state.debug_data[ray_index];
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#endif
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Intersection isect;
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PathState state = kernel_split_state.path_state[ray_index];
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Ray ray = kernel_split_state.ray[ray_index];
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/* intersect scene */
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uint visibility = path_state_ray_visibility(kg, &state);
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if(state.bounce > kernel_data.integrator.ao_bounces) {
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visibility = PATH_RAY_SHADOW;
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ray.t = kernel_data.background.ao_distance;
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}
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#ifdef __HAIR__
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float difl = 0.0f, extmax = 0.0f;
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uint lcg_state = 0;
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RNG rng = kernel_split_state.rng[ray_index];
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if(kernel_data.bvh.have_curves) {
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if((kernel_data.cam.resolution == 1) && (state.flag & PATH_RAY_CAMERA)) {
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float3 pixdiff = ray.dD.dx + ray.dD.dy;
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/*pixdiff = pixdiff - dot(pixdiff, ray.D)*ray.D;*/
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difl = kernel_data.curve.minimum_width * len(pixdiff) * 0.5f;
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}
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extmax = kernel_data.curve.maximum_width;
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lcg_state = lcg_state_init(&rng, state.rng_offset, state.sample, 0x51633e2d);
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}
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bool hit = scene_intersect(kg, ray, visibility, &isect, &lcg_state, difl, extmax);
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#else
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bool hit = scene_intersect(kg, ray, visibility, &isect, NULL, 0.0f, 0.0f);
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#endif
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kernel_split_state.isect[ray_index] = isect;
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#ifdef __KERNEL_DEBUG__
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if(state.flag & PATH_RAY_CAMERA) {
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debug_data->num_bvh_traversed_nodes += isect.num_traversed_nodes;
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debug_data->num_bvh_traversed_instances += isect.num_traversed_instances;
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debug_data->num_bvh_intersections += isect.num_intersections;
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}
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debug_data->num_ray_bounces++;
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#endif
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if(!hit) {
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/* Change the state of rays that hit the background;
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* These rays undergo special processing in the
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* background_bufferUpdate kernel.
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*/
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ASSIGN_RAY_STATE(kernel_split_state.ray_state, ray_index, RAY_HIT_BACKGROUND);
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}
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}
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CCL_NAMESPACE_END
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