915766f42d
This implements branched path tracing for the split kernel. General approach is to store the ray state at a branch point, trace the branched ray as normal, then restore the state as necessary before iterating to the next part of the path. A state machine is used to advance the indirect loop state, which avoids the need to add any new kernels. Each iteration the state machine recreates as much state as possible from the stored ray to keep overall storage down. Its kind of hard to keep all the different integration loops in sync, so this needs lots of testing to make sure everything is working correctly. We should probably start trying to deduplicate the integration loops more now. Nonbranched BMW is ~2% slower, while classroom is ~2% faster, other scenes could use more testing still. Reviewers: sergey, nirved Reviewed By: nirved Subscribers: Blendify, bliblubli Differential Revision: https://developer.blender.org/D2611
316 lines
12 KiB
C
316 lines
12 KiB
C
/*
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* Copyright 2011-2017 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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#if defined(__BRANCHED_PATH__) && defined(__SUBSURFACE__)
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ccl_device_inline void kernel_split_branched_path_subsurface_indirect_light_init(KernelGlobals *kg, int ray_index)
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{
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kernel_split_branched_path_indirect_loop_init(kg, ray_index);
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SplitBranchedState *branched_state = &kernel_split_state.branched_state[ray_index];
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branched_state->ss_next_closure = 0;
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branched_state->ss_next_sample = 0;
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branched_state->num_hits = 0;
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branched_state->next_hit = 0;
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ADD_RAY_FLAG(kernel_split_state.ray_state, ray_index, RAY_BRANCHED_SUBSURFACE_INDIRECT);
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}
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ccl_device_noinline bool kernel_split_branched_path_subsurface_indirect_light_iter(KernelGlobals *kg, int ray_index)
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{
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SplitBranchedState *branched_state = &kernel_split_state.branched_state[ray_index];
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ShaderData *sd = &branched_state->sd;
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RNG rng = kernel_split_state.rng[ray_index];
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PathRadiance *L = &kernel_split_state.path_radiance[ray_index];
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ShaderData *emission_sd = &kernel_split_state.sd_DL_shadow[ray_index];
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for(int i = branched_state->ss_next_closure; i < sd->num_closure; i++) {
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ShaderClosure *sc = &sd->closure[i];
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if(!CLOSURE_IS_BSSRDF(sc->type))
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continue;
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/* set up random number generator */
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if(branched_state->ss_next_sample == 0 && branched_state->next_hit == 0 &&
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branched_state->next_closure == 0 && branched_state->next_sample == 0)
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{
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branched_state->lcg_state = lcg_state_init(&rng,
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branched_state->path_state.rng_offset,
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branched_state->path_state.sample,
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0x68bc21eb);
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}
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int num_samples = kernel_data.integrator.subsurface_samples;
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float num_samples_inv = 1.0f/num_samples;
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RNG bssrdf_rng = cmj_hash(rng, i);
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/* do subsurface scatter step with copy of shader data, this will
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* replace the BSSRDF with a diffuse BSDF closure */
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for(int j = branched_state->ss_next_sample; j < num_samples; j++) {
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ccl_global SubsurfaceIntersection *ss_isect = &branched_state->ss_isect;
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float bssrdf_u, bssrdf_v;
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path_branched_rng_2D(kg,
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&bssrdf_rng,
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&branched_state->path_state,
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j,
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num_samples,
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PRNG_BSDF_U,
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&bssrdf_u,
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&bssrdf_v);
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/* intersection is expensive so avoid doing multiple times for the same input */
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if(branched_state->next_hit == 0 && branched_state->next_closure == 0 && branched_state->next_sample == 0) {
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RNG lcg_state = branched_state->lcg_state;
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SubsurfaceIntersection ss_isect_private;
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branched_state->num_hits = subsurface_scatter_multi_intersect(kg,
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&ss_isect_private,
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sd,
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sc,
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&lcg_state,
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bssrdf_u, bssrdf_v,
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true);
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branched_state->lcg_state = lcg_state;
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*ss_isect = ss_isect_private;
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}
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#ifdef __VOLUME__
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Ray volume_ray = branched_state->ray;
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bool need_update_volume_stack =
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kernel_data.integrator.use_volumes &&
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sd->object_flag & SD_OBJECT_INTERSECTS_VOLUME;
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#endif /* __VOLUME__ */
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/* compute lighting with the BSDF closure */
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for(int hit = branched_state->next_hit; hit < branched_state->num_hits; hit++) {
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ShaderData *bssrdf_sd = &kernel_split_state.sd[ray_index];
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*bssrdf_sd = *sd; /* note: copy happens each iteration of inner loop, this is
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* important as the indirect path will write into bssrdf_sd */
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SubsurfaceIntersection ss_isect_private = *ss_isect;
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subsurface_scatter_multi_setup(kg,
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&ss_isect_private,
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hit,
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bssrdf_sd,
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&branched_state->path_state,
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branched_state->path_state.flag,
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sc,
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true);
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*ss_isect = ss_isect_private;
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ccl_global PathState *hit_state = &kernel_split_state.path_state[ray_index];
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*hit_state = branched_state->path_state;
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path_state_branch(hit_state, j, num_samples);
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#ifdef __VOLUME__
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if(need_update_volume_stack) {
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/* Setup ray from previous surface point to the new one. */
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float3 P = ray_offset(bssrdf_sd->P, -bssrdf_sd->Ng);
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volume_ray.D = normalize_len(P - volume_ray.P, &volume_ray.t);
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/* this next part is expensive as it does scene intersection so only do once */
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if(branched_state->next_closure == 0 && branched_state->next_sample == 0) {
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for(int k = 0; k < VOLUME_STACK_SIZE; k++) {
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branched_state->volume_stack[k] = hit_state->volume_stack[k];
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}
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kernel_volume_stack_update_for_subsurface(kg,
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emission_sd,
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&volume_ray,
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branched_state->volume_stack);
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}
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for(int k = 0; k < VOLUME_STACK_SIZE; k++) {
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hit_state->volume_stack[k] = branched_state->volume_stack[k];
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}
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}
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#endif /* __VOLUME__ */
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#ifdef __EMISSION__
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if(branched_state->next_closure == 0 && branched_state->next_sample == 0) {
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/* direct light */
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if(kernel_data.integrator.use_direct_light) {
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int all = (kernel_data.integrator.sample_all_lights_direct) ||
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(branched_state->path_state.flag & PATH_RAY_SHADOW_CATCHER);
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kernel_branched_path_surface_connect_light(kg,
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&rng,
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bssrdf_sd,
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emission_sd,
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hit_state,
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branched_state->throughput,
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num_samples_inv,
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L,
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all);
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}
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}
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#endif /* __EMISSION__ */
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/* indirect light */
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if(kernel_split_branched_path_surface_indirect_light_iter(kg,
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ray_index,
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num_samples_inv,
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bssrdf_sd,
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false))
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{
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branched_state->ss_next_closure = i;
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branched_state->ss_next_sample = j;
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branched_state->next_hit = hit;
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return true;
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}
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branched_state->next_closure = 0;
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}
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branched_state->next_hit = 0;
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}
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branched_state->ss_next_sample = 0;
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}
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kernel_split_branched_path_indirect_loop_end(kg, ray_index);
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return false;
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}
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#endif /* __BRANCHED_PATH__ && __SUBSURFACE__ */
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ccl_device void kernel_subsurface_scatter(KernelGlobals *kg)
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{
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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 == 0) {
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/* We will empty both queues in this kernel. */
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kernel_split_params.queue_index[QUEUE_ACTIVE_AND_REGENERATED_RAYS] = 0;
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kernel_split_params.queue_index[QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS] = 0;
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}
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int ray_index = ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0);
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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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1);
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get_ray_index(kg, thread_index,
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QUEUE_HITBG_BUFF_UPDATE_TOREGEN_RAYS,
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kernel_split_state.queue_data,
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kernel_split_params.queue_size,
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1);
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#ifdef __SUBSURFACE__
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ccl_global char *ray_state = kernel_split_state.ray_state;
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ccl_global PathState *state = &kernel_split_state.path_state[ray_index];
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PathRadiance *L = &kernel_split_state.path_radiance[ray_index];
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RNG rng = kernel_split_state.rng[ray_index];
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ccl_global Ray *ray = &kernel_split_state.ray[ray_index];
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ccl_global float3 *throughput = &kernel_split_state.throughput[ray_index];
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ccl_global SubsurfaceIndirectRays *ss_indirect = &kernel_split_state.ss_rays[ray_index];
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ShaderData *sd = &kernel_split_state.sd[ray_index];
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ShaderData *emission_sd = &kernel_split_state.sd_DL_shadow[ray_index];
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if(IS_STATE(ray_state, ray_index, RAY_ACTIVE)) {
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if(sd->flag & SD_BSSRDF) {
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#ifdef __BRANCHED_PATH__
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if(!kernel_data.integrator.branched) {
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#endif
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if(kernel_path_subsurface_scatter(kg,
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sd,
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emission_sd,
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L,
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state,
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&rng,
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ray,
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throughput,
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ss_indirect)) {
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kernel_split_path_end(kg, ray_index);
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}
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#ifdef __BRANCHED_PATH__
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}
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else if(IS_FLAG(ray_state, ray_index, RAY_BRANCHED_INDIRECT)) {
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float bssrdf_probability;
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ShaderClosure *sc = subsurface_scatter_pick_closure(kg, sd, &bssrdf_probability);
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/* modify throughput for picking bssrdf or bsdf */
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*throughput *= bssrdf_probability;
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/* do bssrdf scatter step if we picked a bssrdf closure */
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if(sc) {
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uint lcg_state = lcg_state_init(&rng, state->rng_offset, state->sample, 0x68bc21eb);
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float bssrdf_u, bssrdf_v;
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path_state_rng_2D(kg,
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&rng,
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state,
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PRNG_BSDF_U,
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&bssrdf_u, &bssrdf_v);
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subsurface_scatter_step(kg,
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sd,
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state,
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state->flag,
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sc,
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&lcg_state,
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bssrdf_u, bssrdf_v,
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false);
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}
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}
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else {
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kernel_split_branched_path_subsurface_indirect_light_init(kg, ray_index);
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if(kernel_split_branched_path_subsurface_indirect_light_iter(kg, ray_index)) {
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ASSIGN_RAY_STATE(ray_state, ray_index, RAY_REGENERATED);
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}
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}
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#endif
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}
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kernel_split_state.rng[ray_index] = rng;
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}
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# ifdef __BRANCHED_PATH__
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if(ccl_global_id(0) == 0 && ccl_global_id(1) == 0) {
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kernel_split_params.queue_index[QUEUE_SUBSURFACE_INDIRECT_ITER] = 0;
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}
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/* iter loop */
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ray_index = get_ray_index(kg, ccl_global_id(1) * ccl_global_size(0) + ccl_global_id(0),
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QUEUE_SUBSURFACE_INDIRECT_ITER,
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kernel_split_state.queue_data,
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kernel_split_params.queue_size,
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1);
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if(IS_STATE(ray_state, ray_index, RAY_SUBSURFACE_INDIRECT_NEXT_ITER)) {
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/* for render passes, sum and reset indirect light pass variables
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* for the next samples */
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path_radiance_sum_indirect(&kernel_split_state.path_radiance[ray_index]);
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path_radiance_reset_indirect(&kernel_split_state.path_radiance[ray_index]);
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if(kernel_split_branched_path_subsurface_indirect_light_iter(kg, ray_index)) {
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ASSIGN_RAY_STATE(ray_state, ray_index, RAY_REGENERATED);
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}
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}
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# endif /* __BRANCHED_PATH__ */
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#endif /* __SUBSURFACE__ */
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}
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CCL_NAMESPACE_END
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