75a6d3abf7
This adds path guiding features into Cycles by integrating Intel's Open Path Guiding Library. It can be enabled in the Sampling > Path Guiding panel in the render properties. This feature helps reduce noise in scenes where finding a path to light is difficult for regular path tracing. The current implementation supports guiding directional sampling decisions on surfaces, when the material contains a least one diffuse component, and in volumes with isotropic and anisotropic Henyey-Greenstein phase functions. On surfaces, the guided sampling decision is proportional to the product of the incident radiance and the normal-oriented cosine lobe and in volumes it is proportional to the product of the incident radiance and the phase function. The incident radiance field of a scene is learned and updated during rendering after each per-frame rendering iteration/progression. At the moment, path guiding is only supported by the CPU backend. Support for GPU backends will be added in future versions of OpenPGL. Ref T92571 Differential Revision: https://developer.blender.org/D15286
222 lines
8.9 KiB
C
222 lines
8.9 KiB
C
/* SPDX-License-Identifier: Apache-2.0
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* Copyright 2011-2022 Blender Foundation */
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#pragma once
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#include "kernel/film/light_passes.h"
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#include "kernel/integrator/guiding.h"
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#include "kernel/integrator/surface_shader.h"
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#include "kernel/light/light.h"
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#include "kernel/light/sample.h"
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CCL_NAMESPACE_BEGIN
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ccl_device Spectrum integrator_eval_background_shader(KernelGlobals kg,
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IntegratorState state,
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ccl_global float *ccl_restrict render_buffer)
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{
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const int shader = kernel_data.background.surface_shader;
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const uint32_t path_flag = INTEGRATOR_STATE(state, path, flag);
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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) && (path_flag & PATH_RAY_DIFFUSE)) ||
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((shader & SHADER_EXCLUDE_GLOSSY) && ((path_flag & (PATH_RAY_GLOSSY | PATH_RAY_REFLECT)) ==
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(PATH_RAY_GLOSSY | PATH_RAY_REFLECT))) ||
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((shader & SHADER_EXCLUDE_TRANSMIT) && (path_flag & PATH_RAY_TRANSMIT)) ||
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((shader & SHADER_EXCLUDE_CAMERA) && (path_flag & PATH_RAY_CAMERA)) ||
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((shader & SHADER_EXCLUDE_SCATTER) && (path_flag & PATH_RAY_VOLUME_SCATTER)))
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return zero_spectrum();
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}
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/* Use fast constant background color if available. */
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Spectrum L = zero_spectrum();
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if (surface_shader_constant_emission(kg, shader, &L)) {
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return L;
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}
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/* Evaluate background shader. */
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/* TODO: does aliasing like this break automatic SoA in CUDA?
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* Should we instead store closures separate from ShaderData? */
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ShaderDataTinyStorage emission_sd_storage;
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ccl_private ShaderData *emission_sd = AS_SHADER_DATA(&emission_sd_storage);
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PROFILING_INIT_FOR_SHADER(kg, PROFILING_SHADE_LIGHT_SETUP);
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shader_setup_from_background(kg,
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emission_sd,
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INTEGRATOR_STATE(state, ray, P),
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INTEGRATOR_STATE(state, ray, D),
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INTEGRATOR_STATE(state, ray, time));
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PROFILING_SHADER(emission_sd->object, emission_sd->shader);
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PROFILING_EVENT(PROFILING_SHADE_LIGHT_EVAL);
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surface_shader_eval<KERNEL_FEATURE_NODE_MASK_SURFACE_BACKGROUND>(
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kg, state, emission_sd, render_buffer, path_flag | PATH_RAY_EMISSION);
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return surface_shader_background(emission_sd);
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}
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ccl_device_inline void integrate_background(KernelGlobals kg,
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IntegratorState state,
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ccl_global float *ccl_restrict render_buffer)
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{
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/* Accumulate transparency for transparent background. We can skip background
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* shader evaluation unless a background pass is used. */
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bool eval_background = true;
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float transparent = 0.0f;
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const bool is_transparent_background_ray = kernel_data.background.transparent &&
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(INTEGRATOR_STATE(state, path, flag) &
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PATH_RAY_TRANSPARENT_BACKGROUND);
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if (is_transparent_background_ray) {
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transparent = average(INTEGRATOR_STATE(state, path, throughput));
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#ifdef __PASSES__
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eval_background = (kernel_data.film.light_pass_flag & PASSMASK(BACKGROUND));
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#else
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eval_background = false;
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#endif
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}
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#ifdef __MNEE__
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if (INTEGRATOR_STATE(state, path, mnee) & PATH_MNEE_CULL_LIGHT_CONNECTION) {
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if (kernel_data.background.use_mis) {
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for (int lamp = 0; lamp < kernel_data.integrator.num_all_lights; lamp++) {
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/* This path should have been resolved with mnee, it will
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* generate a firefly for small lights since it is improbable. */
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const ccl_global KernelLight *klight = &kernel_data_fetch(lights, lamp);
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if (klight->type == LIGHT_BACKGROUND && klight->use_caustics) {
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eval_background = false;
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break;
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}
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}
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}
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}
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#endif /* __MNEE__ */
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/* Evaluate background shader. */
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Spectrum L = zero_spectrum();
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if (eval_background) {
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L = integrator_eval_background_shader(kg, state, render_buffer);
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/* When using the ao bounces approximation, adjust background
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* shader intensity with ao factor. */
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if (path_state_ao_bounce(kg, state)) {
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L *= kernel_data.integrator.ao_bounces_factor;
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}
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/* Background MIS weights. */
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float mis_weight = 1.0f;
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/* Check if background light exists or if we should skip pdf. */
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if (!(INTEGRATOR_STATE(state, path, flag) & PATH_RAY_MIS_SKIP) &&
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kernel_data.background.use_mis) {
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const float3 ray_P = INTEGRATOR_STATE(state, ray, P);
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const float3 ray_D = INTEGRATOR_STATE(state, ray, D);
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const float mis_ray_pdf = INTEGRATOR_STATE(state, path, mis_ray_pdf);
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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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const float pdf = background_light_pdf(kg, ray_P, ray_D);
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mis_weight = light_sample_mis_weight_forward(kg, mis_ray_pdf, pdf);
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}
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guiding_record_background(kg, state, L, mis_weight);
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L *= mis_weight;
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}
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/* Write to render buffer. */
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film_write_background(kg, state, L, transparent, is_transparent_background_ray, render_buffer);
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}
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ccl_device_inline void integrate_distant_lights(KernelGlobals kg,
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IntegratorState state,
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ccl_global float *ccl_restrict render_buffer)
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{
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const float3 ray_D = INTEGRATOR_STATE(state, ray, D);
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const float ray_time = INTEGRATOR_STATE(state, ray, time);
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LightSample ls ccl_optional_struct_init;
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for (int lamp = 0; lamp < kernel_data.integrator.num_all_lights; lamp++) {
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if (light_sample_from_distant_ray(kg, ray_D, lamp, &ls)) {
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/* Use visibility flag to skip lights. */
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#ifdef __PASSES__
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const uint32_t path_flag = INTEGRATOR_STATE(state, path, flag);
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if (ls.shader & SHADER_EXCLUDE_ANY) {
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if (((ls.shader & SHADER_EXCLUDE_DIFFUSE) && (path_flag & PATH_RAY_DIFFUSE)) ||
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((ls.shader & SHADER_EXCLUDE_GLOSSY) &&
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((path_flag & (PATH_RAY_GLOSSY | PATH_RAY_REFLECT)) ==
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(PATH_RAY_GLOSSY | PATH_RAY_REFLECT))) ||
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((ls.shader & SHADER_EXCLUDE_TRANSMIT) && (path_flag & PATH_RAY_TRANSMIT)) ||
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((ls.shader & SHADER_EXCLUDE_CAMERA) && (path_flag & PATH_RAY_CAMERA)) ||
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((ls.shader & SHADER_EXCLUDE_SCATTER) && (path_flag & PATH_RAY_VOLUME_SCATTER)))
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return;
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}
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#endif
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#ifdef __MNEE__
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if (INTEGRATOR_STATE(state, path, mnee) & PATH_MNEE_CULL_LIGHT_CONNECTION) {
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/* This path should have been resolved with mnee, it will
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* generate a firefly for small lights since it is improbable. */
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const ccl_global KernelLight *klight = &kernel_data_fetch(lights, lamp);
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if (klight->use_caustics)
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return;
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}
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#endif /* __MNEE__ */
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/* Evaluate light shader. */
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/* TODO: does aliasing like this break automatic SoA in CUDA? */
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ShaderDataTinyStorage emission_sd_storage;
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ccl_private ShaderData *emission_sd = AS_SHADER_DATA(&emission_sd_storage);
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Spectrum light_eval = light_sample_shader_eval(kg, state, emission_sd, &ls, ray_time);
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if (is_zero(light_eval)) {
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return;
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}
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/* MIS weighting. */
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float mis_weight = 1.0f;
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if (!(path_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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const float mis_ray_pdf = INTEGRATOR_STATE(state, path, mis_ray_pdf);
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mis_weight = light_sample_mis_weight_forward(kg, mis_ray_pdf, ls.pdf);
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}
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/* Write to render buffer. */
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guiding_record_background(kg, state, light_eval, mis_weight);
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film_write_surface_emission(
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kg, state, light_eval, mis_weight, render_buffer, kernel_data.background.lightgroup);
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}
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}
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}
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ccl_device void integrator_shade_background(KernelGlobals kg,
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IntegratorState state,
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ccl_global float *ccl_restrict render_buffer)
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{
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PROFILING_INIT(kg, PROFILING_SHADE_LIGHT_SETUP);
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/* TODO: unify these in a single loop to only have a single shader evaluation call. */
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integrate_distant_lights(kg, state, render_buffer);
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integrate_background(kg, state, render_buffer);
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#ifdef __SHADOW_CATCHER__
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if (INTEGRATOR_STATE(state, path, flag) & PATH_RAY_SHADOW_CATCHER_BACKGROUND) {
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/* Special case for shadow catcher where we want to fill the background pass
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* behind the shadow catcher but also continue tracing the path. */
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INTEGRATOR_STATE_WRITE(state, path, flag) &= ~PATH_RAY_SHADOW_CATCHER_BACKGROUND;
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integrator_intersect_next_kernel_after_shadow_catcher_background<
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DEVICE_KERNEL_INTEGRATOR_SHADE_BACKGROUND>(kg, state);
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return;
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}
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#endif
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integrator_path_terminate(kg, state, DEVICE_KERNEL_INTEGRATOR_SHADE_BACKGROUND);
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}
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CCL_NAMESPACE_END
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