forked from bartvdbraak/blender
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
658 lines
21 KiB
C
658 lines
21 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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#ifdef __BRANCHED_PATH__
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ccl_device_inline void kernel_branched_path_ao(KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *emission_sd,
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PathRadiance *L,
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ccl_addr_space PathState *state,
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RNG *rng,
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float3 throughput)
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{
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int num_samples = kernel_data.integrator.ao_samples;
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float num_samples_inv = 1.0f/num_samples;
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float ao_factor = kernel_data.background.ao_factor;
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float3 ao_N;
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float3 ao_bsdf = shader_bsdf_ao(kg, sd, ao_factor, &ao_N);
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float3 ao_alpha = shader_bsdf_alpha(kg, sd);
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for(int j = 0; j < num_samples; j++) {
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float bsdf_u, bsdf_v;
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path_branched_rng_2D(kg, rng, state, j, num_samples, PRNG_BSDF_U, &bsdf_u, &bsdf_v);
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float3 ao_D;
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float ao_pdf;
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sample_cos_hemisphere(ao_N, bsdf_u, bsdf_v, &ao_D, &ao_pdf);
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if(dot(sd->Ng, ao_D) > 0.0f && ao_pdf != 0.0f) {
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Ray light_ray;
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float3 ao_shadow;
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light_ray.P = ray_offset(sd->P, sd->Ng);
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light_ray.D = ao_D;
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light_ray.t = kernel_data.background.ao_distance;
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#ifdef __OBJECT_MOTION__
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light_ray.time = sd->time;
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#endif /* __OBJECT_MOTION__ */
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light_ray.dP = sd->dP;
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light_ray.dD = differential3_zero();
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if(!shadow_blocked(kg, emission_sd, state, &light_ray, &ao_shadow)) {
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path_radiance_accum_ao(L, throughput*num_samples_inv, ao_alpha, ao_bsdf, ao_shadow, state->bounce);
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}
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else {
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path_radiance_accum_total_ao(L, throughput*num_samples_inv, ao_bsdf);
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}
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}
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}
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}
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#ifndef __SPLIT_KERNEL__
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/* bounce off surface and integrate indirect light */
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ccl_device_noinline void kernel_branched_path_surface_indirect_light(KernelGlobals *kg,
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RNG *rng, ShaderData *sd, ShaderData *indirect_sd, ShaderData *emission_sd,
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float3 throughput, float num_samples_adjust, PathState *state, PathRadiance *L)
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{
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for(int i = 0; i < sd->num_closure; i++) {
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const ShaderClosure *sc = &sd->closure[i];
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if(!CLOSURE_IS_BSDF(sc->type))
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continue;
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/* transparency is not handled here, but in outer loop */
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if(sc->type == CLOSURE_BSDF_TRANSPARENT_ID)
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continue;
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int num_samples;
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if(CLOSURE_IS_BSDF_DIFFUSE(sc->type))
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num_samples = kernel_data.integrator.diffuse_samples;
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else if(CLOSURE_IS_BSDF_BSSRDF(sc->type))
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num_samples = 1;
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else if(CLOSURE_IS_BSDF_GLOSSY(sc->type))
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num_samples = kernel_data.integrator.glossy_samples;
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else
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num_samples = kernel_data.integrator.transmission_samples;
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num_samples = ceil_to_int(num_samples_adjust*num_samples);
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float num_samples_inv = num_samples_adjust/num_samples;
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RNG bsdf_rng = cmj_hash(*rng, i);
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for(int j = 0; j < num_samples; j++) {
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PathState ps = *state;
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float3 tp = throughput;
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Ray bsdf_ray;
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if(!kernel_branched_path_surface_bounce(kg,
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&bsdf_rng,
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sd,
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sc,
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j,
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num_samples,
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&tp,
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&ps,
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L,
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&bsdf_ray))
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{
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continue;
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}
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kernel_path_indirect(kg,
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indirect_sd,
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emission_sd,
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rng,
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&bsdf_ray,
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tp*num_samples_inv,
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num_samples,
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&ps,
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L);
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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(L);
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path_radiance_reset_indirect(L);
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}
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}
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}
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#ifdef __SUBSURFACE__
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ccl_device void kernel_branched_path_subsurface_scatter(KernelGlobals *kg,
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ShaderData *sd,
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ShaderData *indirect_sd,
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ShaderData *emission_sd,
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PathRadiance *L,
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PathState *state,
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RNG *rng,
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Ray *ray,
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float3 throughput)
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{
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for(int i = 0; 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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uint lcg_state = lcg_state_init(rng, state->rng_offset, state->sample, 0x68bc21eb);
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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 = 0; j < num_samples; j++) {
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SubsurfaceIntersection ss_isect;
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float bssrdf_u, bssrdf_v;
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path_branched_rng_2D(kg, &bssrdf_rng, state, j, num_samples, PRNG_BSDF_U, &bssrdf_u, &bssrdf_v);
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int num_hits = subsurface_scatter_multi_intersect(kg,
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&ss_isect,
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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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#ifdef __VOLUME__
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Ray volume_ray = *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 = 0; hit < num_hits; hit++) {
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ShaderData bssrdf_sd = *sd;
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subsurface_scatter_multi_setup(kg,
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&ss_isect,
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hit,
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&bssrdf_sd,
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state,
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state->flag,
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sc,
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true);
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PathState hit_state = *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,
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&volume_ray.t);
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kernel_volume_stack_update_for_subsurface(
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kg,
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emission_sd,
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&volume_ray,
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hit_state.volume_stack);
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}
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#endif /* __VOLUME__ */
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#ifdef __EMISSION__
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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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(state->flag & PATH_RAY_SHADOW_CATCHER);
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kernel_branched_path_surface_connect_light(
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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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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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#endif /* __EMISSION__ */
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/* indirect light */
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kernel_branched_path_surface_indirect_light(
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kg,
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rng,
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&bssrdf_sd,
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indirect_sd,
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emission_sd,
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throughput,
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num_samples_inv,
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&hit_state,
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L);
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}
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}
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}
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}
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#endif /* __SUBSURFACE__ */
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ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, int sample, Ray ray, ccl_global float *buffer)
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{
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/* initialize */
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PathRadiance L;
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float3 throughput = make_float3(1.0f, 1.0f, 1.0f);
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float L_transparent = 0.0f;
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path_radiance_init(&L, kernel_data.film.use_light_pass);
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/* shader data memory used for both volumes and surfaces, saves stack space */
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ShaderData sd;
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/* shader data used by emission, shadows, volume stacks, indirect path */
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ShaderData emission_sd, indirect_sd;
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PathState state;
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path_state_init(kg, &emission_sd, &state, rng, sample, &ray);
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#ifdef __KERNEL_DEBUG__
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DebugData debug_data;
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debug_data_init(&debug_data);
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#endif /* __KERNEL_DEBUG__ */
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/* Main Loop
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* Here we only handle transparency intersections from the camera ray.
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* Indirect bounces are handled in kernel_branched_path_surface_indirect_light().
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*/
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for(;;) {
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/* intersect scene */
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Intersection isect;
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uint visibility = path_state_ray_visibility(kg, &state);
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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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if(kernel_data.bvh.have_curves) {
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if(kernel_data.cam.resolution == 1) {
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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 /* __HAIR__ */
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#ifdef __KERNEL_DEBUG__
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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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debug_data.num_ray_bounces++;
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#endif /* __KERNEL_DEBUG__ */
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#ifdef __VOLUME__
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/* Sanitize volume stack. */
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if(!hit) {
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kernel_volume_clean_stack(kg, state.volume_stack);
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}
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/* volume attenuation, emission, scatter */
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if(state.volume_stack[0].shader != SHADER_NONE) {
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Ray volume_ray = ray;
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volume_ray.t = (hit)? isect.t: FLT_MAX;
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bool heterogeneous = volume_stack_is_heterogeneous(kg, state.volume_stack);
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#ifdef __VOLUME_DECOUPLED__
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/* decoupled ray marching only supported on CPU */
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/* cache steps along volume for repeated sampling */
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VolumeSegment volume_segment;
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shader_setup_from_volume(kg, &sd, &volume_ray);
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kernel_volume_decoupled_record(kg, &state,
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&volume_ray, &sd, &volume_segment, heterogeneous);
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/* direct light sampling */
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if(volume_segment.closure_flag & SD_SCATTER) {
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volume_segment.sampling_method = volume_stack_sampling_method(kg, state.volume_stack);
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int all = kernel_data.integrator.sample_all_lights_direct;
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kernel_branched_path_volume_connect_light(kg, rng, &sd,
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&emission_sd, throughput, &state, &L, all,
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&volume_ray, &volume_segment);
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/* indirect light sampling */
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int num_samples = kernel_data.integrator.volume_samples;
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float num_samples_inv = 1.0f/num_samples;
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for(int j = 0; j < num_samples; j++) {
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PathState ps = state;
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Ray pray = ray;
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float3 tp = throughput;
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/* branch RNG state */
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path_state_branch(&ps, j, num_samples);
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/* scatter sample. if we use distance sampling and take just one
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* sample for direct and indirect light, we could share this
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* computation, but makes code a bit complex */
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float rphase = path_state_rng_1D_for_decision(kg, rng, &ps, PRNG_PHASE);
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float rscatter = path_state_rng_1D_for_decision(kg, rng, &ps, PRNG_SCATTER_DISTANCE);
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VolumeIntegrateResult result = kernel_volume_decoupled_scatter(kg,
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&ps, &pray, &sd, &tp, rphase, rscatter, &volume_segment, NULL, false);
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(void)result;
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kernel_assert(result == VOLUME_PATH_SCATTERED);
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if(kernel_path_volume_bounce(kg,
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rng,
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&sd,
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&tp,
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&ps,
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&L,
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&pray))
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{
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kernel_path_indirect(kg,
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&indirect_sd,
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&emission_sd,
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rng,
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&pray,
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tp*num_samples_inv,
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num_samples,
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&ps,
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&L);
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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(&L);
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path_radiance_reset_indirect(&L);
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}
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}
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}
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/* emission and transmittance */
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if(volume_segment.closure_flag & SD_EMISSION)
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path_radiance_accum_emission(&L, throughput, volume_segment.accum_emission, state.bounce);
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throughput *= volume_segment.accum_transmittance;
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/* free cached steps */
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kernel_volume_decoupled_free(kg, &volume_segment);
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#else
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/* GPU: no decoupled ray marching, scatter probalistically */
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int num_samples = kernel_data.integrator.volume_samples;
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float num_samples_inv = 1.0f/num_samples;
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/* todo: we should cache the shader evaluations from stepping
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* through the volume, for now we redo them multiple times */
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for(int j = 0; j < num_samples; j++) {
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PathState ps = state;
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Ray pray = ray;
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float3 tp = throughput * num_samples_inv;
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/* branch RNG state */
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path_state_branch(&ps, j, num_samples);
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VolumeIntegrateResult result = kernel_volume_integrate(
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kg, &ps, &sd, &volume_ray, &L, &tp, rng, heterogeneous);
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#ifdef __VOLUME_SCATTER__
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if(result == VOLUME_PATH_SCATTERED) {
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/* todo: support equiangular, MIS and all light sampling.
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* alternatively get decoupled ray marching working on the GPU */
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kernel_path_volume_connect_light(kg, rng, &sd, &emission_sd, tp, &state, &L);
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if(kernel_path_volume_bounce(kg,
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rng,
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&sd,
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&tp,
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&ps,
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&L,
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&pray))
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{
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kernel_path_indirect(kg,
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&indirect_sd,
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&emission_sd,
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rng,
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&pray,
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tp,
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num_samples,
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&ps,
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&L);
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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(&L);
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path_radiance_reset_indirect(&L);
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}
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}
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#endif /* __VOLUME_SCATTER__ */
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}
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/* todo: avoid this calculation using decoupled ray marching */
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kernel_volume_shadow(kg, &emission_sd, &state, &volume_ray, &throughput);
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#endif /* __VOLUME_DECOUPLED__ */
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}
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#endif /* __VOLUME__ */
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if(!hit) {
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/* eval background shader if nothing hit */
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if(kernel_data.background.transparent) {
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L_transparent += average(throughput);
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#ifdef __PASSES__
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if(!(kernel_data.film.pass_flag & PASS_BACKGROUND))
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#endif /* __PASSES__ */
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break;
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}
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#ifdef __BACKGROUND__
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/* sample background shader */
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float3 L_background = indirect_background(kg, &emission_sd, &state, &ray);
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path_radiance_accum_background(&L, &state, throughput, L_background);
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#endif /* __BACKGROUND__ */
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break;
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}
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/* setup shading */
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shader_setup_from_ray(kg, &sd, &isect, &ray);
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shader_eval_surface(kg, &sd, rng, &state, 0.0f, state.flag, SHADER_CONTEXT_MAIN);
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shader_merge_closures(&sd);
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#ifdef __SHADOW_TRICKS__
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if((sd.object_flag & SD_OBJECT_SHADOW_CATCHER)) {
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if(state.flag & PATH_RAY_CAMERA) {
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state.flag |= (PATH_RAY_SHADOW_CATCHER | PATH_RAY_SHADOW_CATCHER_ONLY);
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state.catcher_object = sd.object;
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if(!kernel_data.background.transparent) {
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L.shadow_color = indirect_background(kg, &emission_sd, &state, &ray);
|
|
}
|
|
}
|
|
}
|
|
else {
|
|
state.flag &= ~PATH_RAY_SHADOW_CATCHER_ONLY;
|
|
}
|
|
#endif /* __SHADOW_TRICKS__ */
|
|
|
|
/* holdout */
|
|
#ifdef __HOLDOUT__
|
|
if((sd.flag & SD_HOLDOUT) || (sd.object_flag & SD_OBJECT_HOLDOUT_MASK)) {
|
|
if(kernel_data.background.transparent) {
|
|
float3 holdout_weight;
|
|
if(sd.object_flag & SD_OBJECT_HOLDOUT_MASK) {
|
|
holdout_weight = make_float3(1.0f, 1.0f, 1.0f);
|
|
}
|
|
else {
|
|
holdout_weight = shader_holdout_eval(kg, &sd);
|
|
}
|
|
/* any throughput is ok, should all be identical here */
|
|
L_transparent += average(holdout_weight*throughput);
|
|
}
|
|
if(sd.object_flag & SD_OBJECT_HOLDOUT_MASK) {
|
|
break;
|
|
}
|
|
}
|
|
#endif /* __HOLDOUT__ */
|
|
|
|
/* holdout mask objects do not write data passes */
|
|
kernel_write_data_passes(kg, buffer, &L, &sd, sample, &state, throughput);
|
|
|
|
#ifdef __EMISSION__
|
|
/* emission */
|
|
if(sd.flag & SD_EMISSION) {
|
|
float3 emission = indirect_primitive_emission(kg, &sd, isect.t, state.flag, state.ray_pdf);
|
|
path_radiance_accum_emission(&L, throughput, emission, state.bounce);
|
|
}
|
|
#endif /* __EMISSION__ */
|
|
|
|
/* transparency termination */
|
|
if(state.flag & PATH_RAY_TRANSPARENT) {
|
|
/* path termination. this is a strange place to put the termination, it's
|
|
* mainly due to the mixed in MIS that we use. gives too many unneeded
|
|
* shader evaluations, only need emission if we are going to terminate */
|
|
float probability = path_state_terminate_probability(kg, &state, throughput);
|
|
|
|
if(probability == 0.0f) {
|
|
break;
|
|
}
|
|
else if(probability != 1.0f) {
|
|
float terminate = path_state_rng_1D_for_decision(kg, rng, &state, PRNG_TERMINATE);
|
|
|
|
if(terminate >= probability)
|
|
break;
|
|
|
|
throughput /= probability;
|
|
}
|
|
}
|
|
|
|
#ifdef __AO__
|
|
/* ambient occlusion */
|
|
if(kernel_data.integrator.use_ambient_occlusion || (sd.flag & SD_AO)) {
|
|
kernel_branched_path_ao(kg, &sd, &emission_sd, &L, &state, rng, throughput);
|
|
}
|
|
#endif /* __AO__ */
|
|
|
|
#ifdef __SUBSURFACE__
|
|
/* bssrdf scatter to a different location on the same object */
|
|
if(sd.flag & SD_BSSRDF) {
|
|
kernel_branched_path_subsurface_scatter(kg, &sd, &indirect_sd, &emission_sd,
|
|
&L, &state, rng, &ray, throughput);
|
|
}
|
|
#endif /* __SUBSURFACE__ */
|
|
|
|
if(!(sd.flag & SD_HAS_ONLY_VOLUME)) {
|
|
PathState hit_state = state;
|
|
|
|
#ifdef __EMISSION__
|
|
/* direct light */
|
|
if(kernel_data.integrator.use_direct_light) {
|
|
int all = (kernel_data.integrator.sample_all_lights_direct) ||
|
|
(state.flag & PATH_RAY_SHADOW_CATCHER);
|
|
kernel_branched_path_surface_connect_light(kg, rng,
|
|
&sd, &emission_sd, &hit_state, throughput, 1.0f, &L, all);
|
|
}
|
|
#endif /* __EMISSION__ */
|
|
|
|
/* indirect light */
|
|
kernel_branched_path_surface_indirect_light(kg, rng,
|
|
&sd, &indirect_sd, &emission_sd, throughput, 1.0f, &hit_state, &L);
|
|
|
|
/* continue in case of transparency */
|
|
throughput *= shader_bsdf_transparency(kg, &sd);
|
|
|
|
if(is_zero(throughput))
|
|
break;
|
|
}
|
|
|
|
/* Update Path State */
|
|
state.flag |= PATH_RAY_TRANSPARENT;
|
|
state.transparent_bounce++;
|
|
|
|
ray.P = ray_offset(sd.P, -sd.Ng);
|
|
ray.t -= sd.ray_length; /* clipping works through transparent */
|
|
|
|
|
|
#ifdef __RAY_DIFFERENTIALS__
|
|
ray.dP = sd.dP;
|
|
ray.dD.dx = -sd.dI.dx;
|
|
ray.dD.dy = -sd.dI.dy;
|
|
#endif /* __RAY_DIFFERENTIALS__ */
|
|
|
|
#ifdef __VOLUME__
|
|
/* enter/exit volume */
|
|
kernel_volume_stack_enter_exit(kg, &sd, state.volume_stack);
|
|
#endif /* __VOLUME__ */
|
|
}
|
|
|
|
float3 L_sum;
|
|
#ifdef __SHADOW_TRICKS__
|
|
if(state.flag & PATH_RAY_SHADOW_CATCHER) {
|
|
L_sum = path_radiance_sum_shadowcatcher(kg, &L, &L_transparent);
|
|
}
|
|
else
|
|
#endif /* __SHADOW_TRICKS__ */
|
|
{
|
|
L_sum = path_radiance_clamp_and_sum(kg, &L);
|
|
}
|
|
|
|
kernel_write_light_passes(kg, buffer, &L, sample);
|
|
|
|
#ifdef __KERNEL_DEBUG__
|
|
kernel_write_debug_passes(kg, buffer, &state, &debug_data, sample);
|
|
#endif /* __KERNEL_DEBUG__ */
|
|
|
|
return make_float4(L_sum.x, L_sum.y, L_sum.z, 1.0f - L_transparent);
|
|
}
|
|
|
|
ccl_device void kernel_branched_path_trace(KernelGlobals *kg,
|
|
ccl_global float *buffer, ccl_global uint *rng_state,
|
|
int sample, int x, int y, int offset, int stride)
|
|
{
|
|
/* buffer offset */
|
|
int index = offset + x + y*stride;
|
|
int pass_stride = kernel_data.film.pass_stride;
|
|
|
|
rng_state += index;
|
|
buffer += index*pass_stride;
|
|
|
|
/* initialize random numbers and ray */
|
|
RNG rng;
|
|
Ray ray;
|
|
|
|
kernel_path_trace_setup(kg, rng_state, sample, x, y, &rng, &ray);
|
|
|
|
/* integrate */
|
|
float4 L;
|
|
|
|
if(ray.t != 0.0f)
|
|
L = kernel_branched_path_integrate(kg, &rng, sample, ray, buffer);
|
|
else
|
|
L = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
|
|
|
|
/* accumulate result in output buffer */
|
|
kernel_write_pass_float4(buffer, sample, L);
|
|
|
|
path_rng_end(kg, rng_state, rng);
|
|
}
|
|
|
|
#endif /* __SPLIT_KERNEL__ */
|
|
|
|
#endif /* __BRANCHED_PATH__ */
|
|
|
|
CCL_NAMESPACE_END
|
|
|