Weizhen Huang
543bf28fb1
wi is the viewing direction, and wo is the illumination direction. Under this notation, BSDF sampling always samples from wi and outputs wo, which is consistent with most of the papers and mitsuba. This order is reversed compared with PBRT, although PBRT also traces from the camera.
88 lines
2.6 KiB
C++
88 lines
2.6 KiB
C++
/* SPDX-License-Identifier: BSD-3-Clause
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*
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* Adapted from Open Shading Language
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* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
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* All Rights Reserved.
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*
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* Modifications Copyright 2011-2022 Blender Foundation. */
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#pragma once
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CCL_NAMESPACE_BEGIN
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ccl_device void bsdf_transparent_setup(ccl_private ShaderData *sd,
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const Spectrum weight,
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uint32_t path_flag)
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{
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/* Check cutoff weight. */
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float sample_weight = fabsf(average(weight));
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if (!(sample_weight >= CLOSURE_WEIGHT_CUTOFF)) {
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return;
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}
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if (sd->flag & SD_TRANSPARENT) {
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sd->closure_transparent_extinction += weight;
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/* Add weight to existing transparent BSDF. */
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for (int i = 0; i < sd->num_closure; i++) {
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ccl_private ShaderClosure *sc = &sd->closure[i];
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if (sc->type == CLOSURE_BSDF_TRANSPARENT_ID) {
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sc->weight += weight;
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sc->sample_weight += sample_weight;
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break;
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}
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}
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}
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else {
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sd->flag |= SD_BSDF | SD_TRANSPARENT;
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sd->closure_transparent_extinction = weight;
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if (path_flag & PATH_RAY_TERMINATE) {
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/* In this case the number of closures is set to zero to disable
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* all others, but we still want to get transparency so increase
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* the number just for this. */
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sd->num_closure_left = 1;
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}
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/* Create new transparent BSDF. */
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ccl_private ShaderClosure *bsdf = closure_alloc(
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sd, sizeof(ShaderClosure), CLOSURE_BSDF_TRANSPARENT_ID, weight);
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if (bsdf) {
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bsdf->sample_weight = sample_weight;
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bsdf->N = sd->N;
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}
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else if (path_flag & PATH_RAY_TERMINATE) {
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sd->num_closure_left = 0;
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}
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}
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}
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ccl_device Spectrum bsdf_transparent_eval(ccl_private const ShaderClosure *sc,
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const float3 wi,
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const float3 wo,
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ccl_private float *pdf)
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{
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*pdf = 0.0f;
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return zero_spectrum();
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}
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ccl_device int bsdf_transparent_sample(ccl_private const ShaderClosure *sc,
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float3 Ng,
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float3 wi,
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float randu,
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float randv,
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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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// only one direction is possible
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*wo = -wi;
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*pdf = 1;
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*eval = one_spectrum();
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return LABEL_TRANSMIT | LABEL_TRANSPARENT;
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}
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CCL_NAMESPACE_END
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