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
110 lines
4.0 KiB
C
110 lines
4.0 KiB
C
/* SPDX-License-Identifier: Apache-2.0
|
|
* Copyright 2011-2022 Blender Foundation */
|
|
|
|
#pragma once
|
|
|
|
#include "kernel/film/light_passes.h"
|
|
#include "kernel/integrator/surface_shader.h"
|
|
#include "kernel/light/light.h"
|
|
#include "kernel/light/sample.h"
|
|
|
|
CCL_NAMESPACE_BEGIN
|
|
|
|
ccl_device_inline void integrate_light(KernelGlobals kg,
|
|
IntegratorState state,
|
|
ccl_global float *ccl_restrict render_buffer)
|
|
{
|
|
/* Setup light sample. */
|
|
Intersection isect ccl_optional_struct_init;
|
|
integrator_state_read_isect(kg, state, &isect);
|
|
|
|
guiding_record_light_surface_segment(kg, state, &isect);
|
|
|
|
float3 ray_P = INTEGRATOR_STATE(state, ray, P);
|
|
const float3 ray_D = INTEGRATOR_STATE(state, ray, D);
|
|
const float ray_time = INTEGRATOR_STATE(state, ray, time);
|
|
|
|
/* Advance ray to new start distance. */
|
|
INTEGRATOR_STATE_WRITE(state, ray, tmin) = intersection_t_offset(isect.t);
|
|
|
|
LightSample ls ccl_optional_struct_init;
|
|
const bool use_light_sample = light_sample_from_intersection(kg, &isect, ray_P, ray_D, &ls);
|
|
|
|
if (!use_light_sample) {
|
|
return;
|
|
}
|
|
|
|
/* Use visibility flag to skip lights. */
|
|
#ifdef __PASSES__
|
|
const uint32_t path_flag = INTEGRATOR_STATE(state, path, flag);
|
|
|
|
if (ls.shader & SHADER_EXCLUDE_ANY) {
|
|
if (((ls.shader & SHADER_EXCLUDE_DIFFUSE) && (path_flag & PATH_RAY_DIFFUSE)) ||
|
|
((ls.shader & SHADER_EXCLUDE_GLOSSY) &&
|
|
((path_flag & (PATH_RAY_GLOSSY | PATH_RAY_REFLECT)) ==
|
|
(PATH_RAY_GLOSSY | PATH_RAY_REFLECT))) ||
|
|
((ls.shader & SHADER_EXCLUDE_TRANSMIT) && (path_flag & PATH_RAY_TRANSMIT)) ||
|
|
((ls.shader & SHADER_EXCLUDE_SCATTER) && (path_flag & PATH_RAY_VOLUME_SCATTER)))
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
/* Evaluate light shader. */
|
|
/* TODO: does aliasing like this break automatic SoA in CUDA? */
|
|
ShaderDataTinyStorage emission_sd_storage;
|
|
ccl_private ShaderData *emission_sd = AS_SHADER_DATA(&emission_sd_storage);
|
|
Spectrum light_eval = light_sample_shader_eval(kg, state, emission_sd, &ls, ray_time);
|
|
if (is_zero(light_eval)) {
|
|
return;
|
|
}
|
|
|
|
/* MIS weighting. */
|
|
float mis_weight = 1.0f;
|
|
if (!(path_flag & PATH_RAY_MIS_SKIP)) {
|
|
/* multiple importance sampling, get regular light pdf,
|
|
* and compute weight with respect to BSDF pdf */
|
|
const float mis_ray_pdf = INTEGRATOR_STATE(state, path, mis_ray_pdf);
|
|
mis_weight = light_sample_mis_weight_forward(kg, mis_ray_pdf, ls.pdf);
|
|
}
|
|
|
|
/* Write to render buffer. */
|
|
guiding_record_surface_emission(kg, state, light_eval, mis_weight);
|
|
film_write_surface_emission(kg, state, light_eval, mis_weight, render_buffer, ls.group);
|
|
}
|
|
|
|
ccl_device void integrator_shade_light(KernelGlobals kg,
|
|
IntegratorState state,
|
|
ccl_global float *ccl_restrict render_buffer)
|
|
{
|
|
PROFILING_INIT(kg, PROFILING_SHADE_LIGHT_SETUP);
|
|
|
|
integrate_light(kg, state, render_buffer);
|
|
|
|
/* TODO: we could get stuck in an infinite loop if there are precision issues
|
|
* and the same light is hit again.
|
|
*
|
|
* As a workaround count this as a transparent bounce. It makes some sense
|
|
* to interpret lights as transparent surfaces (and support making them opaque),
|
|
* but this needs to be revisited. */
|
|
uint32_t transparent_bounce = INTEGRATOR_STATE(state, path, transparent_bounce) + 1;
|
|
INTEGRATOR_STATE_WRITE(state, path, transparent_bounce) = transparent_bounce;
|
|
|
|
if (transparent_bounce >= kernel_data.integrator.transparent_max_bounce) {
|
|
integrator_path_terminate(kg, state, DEVICE_KERNEL_INTEGRATOR_SHADE_LIGHT);
|
|
return;
|
|
}
|
|
else {
|
|
integrator_path_next(kg,
|
|
state,
|
|
DEVICE_KERNEL_INTEGRATOR_SHADE_LIGHT,
|
|
DEVICE_KERNEL_INTEGRATOR_INTERSECT_CLOSEST);
|
|
return;
|
|
}
|
|
|
|
/* TODO: in some cases we could continue directly to SHADE_BACKGROUND, but
|
|
* probably that optimization is probably not practical if we add lights to
|
|
* scene geometry. */
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|