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/*
* Copyright 2011-2021 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include "kernel/kernel_accumulate.h"
#include "kernel/kernel_emission.h"
#include "kernel/kernel_light.h"
#include "kernel/kernel_shader.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);
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 beyond light. */
/* TODO: can we make this more numerically robust to avoid reintersecting the
* same light in some cases? */
const float3 new_ray_P = ray_offset(ray_P + ray_D * isect.t, ray_D);
INTEGRATOR_STATE_WRITE(state, ray, P) = new_ray_P;
INTEGRATOR_STATE_WRITE(state, ray, t) -= isect.t;
/* Set position to where the BSDF was sampled, for correct MIS PDF. */
const float mis_ray_t = INTEGRATOR_STATE(state, path, mis_ray_t);
ray_P -= ray_D * mis_ray_t;
isect.t += mis_ray_t;
INTEGRATOR_STATE_WRITE(state, path, mis_ray_t) = mis_ray_t + 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);
float3 light_eval = light_sample_shader_eval(kg, state, emission_sd, &ls, ray_time);
if (is_zero(light_eval)) {
return;
}
/* MIS weighting. */
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);
const float mis_weight = power_heuristic(mis_ray_pdf, ls.pdf);
light_eval *= mis_weight;
}
/* Write to render buffer. */
const float3 throughput = INTEGRATOR_STATE(state, path, throughput);
kernel_accum_emission(kg, state, throughput, light_eval, render_buffer);
}
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(DEVICE_KERNEL_INTEGRATOR_SHADE_LIGHT);
return;
}
else {
INTEGRATOR_PATH_NEXT(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
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