e378bd70ed
There has been an attempt to reorganize this part, however, it seems that didn't compile on HIP, and is reverted in rBc2dc65dfa4ae60fa5d2c3b0cfe86f99dcb5bf16f. This is another attempt of refactoring. as I have no idea why some things don't work on HIP, it's best to check whether this compiles on other platforms. The main changes are creating a new struct named `MeshLight` that is shared between `KernelLightDistribution` and `KernelLightTreeEmitter`, and a bit of renaming, so that light sampling with or without light tree could call the same function. Also, I noticed a patch D16714 referring to HIP compilation error. Not sure if it's related, but browsing https://builder.blender.org/admin/#/builders/30/builds/7826/steps/7/logs/stdio, it didn't work on gfx1102, not gfx9*. Differential Revision: https://developer.blender.org/D16722
73 lines
2.6 KiB
C++
73 lines
2.6 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/light/light.h"
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#include "kernel/light/triangle.h"
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CCL_NAMESPACE_BEGIN
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/* Simple CDF based sampling over all lights in the scene, without taking into
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* account shading position or normal. */
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ccl_device int light_distribution_sample(KernelGlobals kg, ccl_private float *randu)
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{
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/* This is basically std::upper_bound as used by PBRT, to find a point light or
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* triangle to emit from, proportional to area. a good improvement would be to
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* also sample proportional to power, though it's not so well defined with
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* arbitrary shaders. */
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int first = 0;
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int len = kernel_data.integrator.num_distribution + 1;
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float r = *randu;
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do {
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int half_len = len >> 1;
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int middle = first + half_len;
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if (r < kernel_data_fetch(light_distribution, middle).totarea) {
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len = half_len;
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}
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else {
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first = middle + 1;
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len = len - half_len - 1;
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}
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} while (len > 0);
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/* Clamping should not be needed but float rounding errors seem to
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* make this fail on rare occasions. */
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int index = clamp(first - 1, 0, kernel_data.integrator.num_distribution - 1);
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/* Rescale to reuse random number. this helps the 2D samples within
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* each area light be stratified as well. */
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float distr_min = kernel_data_fetch(light_distribution, index).totarea;
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float distr_max = kernel_data_fetch(light_distribution, index + 1).totarea;
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*randu = (r - distr_min) / (distr_max - distr_min);
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return index;
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}
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template<bool in_volume_segment>
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ccl_device_noinline bool light_distribution_sample(KernelGlobals kg,
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float randu,
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const float randv,
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const float time,
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const float3 P,
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const int bounce,
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const uint32_t path_flag,
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ccl_private LightSample *ls)
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{
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/* Sample light index from distribution. */
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const int index = light_distribution_sample(kg, &randu);
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const float pdf_selection = kernel_data.integrator.distribution_pdf_lights;
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return light_sample<in_volume_segment>(
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kg, randu, randv, time, P, bounce, path_flag, index, pdf_selection, ls);
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}
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ccl_device_inline float light_distribution_pdf_lamp(KernelGlobals kg)
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{
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return kernel_data.integrator.distribution_pdf_lights;
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}
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CCL_NAMESPACE_END
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