a7283fc1d5
The distance sampling is mostly based on weighted delta tracking from [Monte Carlo Methods for Volumetric Light Transport Simulation] (http://iliyan.com/publications/VolumeSTAR/VolumeSTAR_EG2018.pdf). The recursive Monte Carlo estimation of the Radiative Transfer Equation is \[\langle L \rangle=\frac{\bar T(x\rightarrow y)}{\bar p(x\rightarrow y)}(L_e+\sigma_s L_s + \sigma_n L).\] where \(\bar T(x\rightarrow y) = e^{-\bar\sigma\Vert x-y\Vert}\) is the majorant transmittance between points \(x\) and \(y\), \(p(x\rightarrow y) = \bar\sigma e^{-\bar\sigma\Vert x-y\Vert}\) is the probability of sampling point \(y\) from point \(x\) following exponential distribution. At each recursive step, we randomly pick one of the two events proportional to their weights: * If \(\xi < \frac{\sigma_s}{\sigma_s+\vert\sigma_n\vert}\), we sample scatter event and evaluate \(L_s\). * Otherwise, no real collision happens and we continue the recursive process. The emission \(L_e\) is evaluated at each step. This also removes some unused volume settings from the UI: * "Max Steps" is removed, because the step size is automatically specified by the volume octree. There is a hard-coded threshold `VOLUME_MAX_STEPS` to prevent numerical issues. * "Homogeneous" is automatically detected during density evaluation An option "Unbiased" is added to the UI. When enabled, densities above the majorant are clamped.
45 lines
867 B
C++
45 lines
867 B
C++
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
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*
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* SPDX-License-Identifier: Apache-2.0 */
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#pragma once
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#include "graph/node.h"
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#include "util/types.h"
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CCL_NAMESPACE_BEGIN
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class Device;
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class DeviceScene;
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class Scene;
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class Shader;
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class Background : public Node {
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public:
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NODE_DECLARE
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NODE_SOCKET_API(bool, use_shader)
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NODE_SOCKET_API(uint, visibility)
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NODE_SOCKET_API(Shader *, shader)
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NODE_SOCKET_API(bool, transparent)
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NODE_SOCKET_API(bool, transparent_glass)
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NODE_SOCKET_API(float, transparent_roughness_threshold)
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NODE_SOCKET_API(ustring, lightgroup)
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Background();
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~Background() override;
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void device_update(Device *device, DeviceScene *dscene, Scene *scene);
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void device_free(Device *device, DeviceScene *dscene);
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void tag_update(Scene *scene);
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Shader *get_shader(const Scene *scene);
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};
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CCL_NAMESPACE_END
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