52 lines
1.4 KiB
C
52 lines
1.4 KiB
C
/* SPDX-FileCopyrightText: 2011-2024 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 "kernel/types.h"
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#include "kernel/closure/volume_util.h"
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CCL_NAMESPACE_BEGIN
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/* RAYLEIGH CLOSURE */
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struct RayleighVolume {
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SHADER_CLOSURE_VOLUME_BASE;
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};
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static_assert(sizeof(ShaderVolumeClosure) >= sizeof(RayleighVolume),
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"RayleighVolume is too large!");
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ccl_device int volume_rayleigh_setup(ccl_private RayleighVolume *volume)
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{
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volume->type = CLOSURE_VOLUME_RAYLEIGH_ID;
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return SD_SCATTER;
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}
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ccl_device Spectrum volume_rayleigh_eval(const ccl_private ShaderData *sd,
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const float3 wo,
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ccl_private float *pdf)
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{
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/* note that wi points towards the viewer */
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const float cos_theta = dot(-sd->wi, wo);
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*pdf = phase_rayleigh(cos_theta);
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return make_spectrum(*pdf);
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}
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ccl_device int volume_rayleigh_sample(const ccl_private ShaderData *sd,
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const float2 rand,
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ccl_private Spectrum *eval,
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ccl_private float3 *wo,
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ccl_private float *pdf)
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{
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/* note that wi points towards the viewer and so is used negated */
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*wo = phase_rayleigh_sample(-sd->wi, rand, pdf);
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*eval = make_spectrum(*pdf); /* perfect importance sampling */
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return LABEL_VOLUME_SCATTER;
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}
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CCL_NAMESPACE_END
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