b0cc8e8dde
The first two dimensions of scrambled, shuffled Sobol and shuffled PMJ02 are equivalent, so this makes no real difference for the first two dimensions. But Sobol allows us to naturally extend to more dimensions. Pretabulated Sobol is now always used, and the sampling pattern settings is now only available as a debug option. This in turn allows the following two things (also implemented): * Use proper 3D samples for combined lens + motion blur sampling. This notably reduces the noise on objects that are simultaneously out-of-focus and motion blurred. * Use proper 3D samples for combined light selection + light sampling. Cycles was already doing something clever here with 2D samples, but using 3D samples is more straightforward and avoids overloading one of the dimensions. In the future this will also allow for proper sampling of e.g. volumetric light sources and other things that may need three or four dimensions. Differential Revision: https://developer.blender.org/D16443
68 lines
2.3 KiB
C++
68 lines
2.3 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, const float randn)
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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 = randn;
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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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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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const float randn,
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const 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, randn);
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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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