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.
97 lines
2.7 KiB
C++
97 lines
2.7 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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#include "kernel/sample/mapping.h"
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#include "kernel/util/color.h"
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CCL_NAMESPACE_BEGIN
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#ifdef __OSL__
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typedef struct DiffuseRampBsdf {
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SHADER_CLOSURE_BASE;
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ccl_private float3 *colors;
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} DiffuseRampBsdf;
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static_assert(sizeof(ShaderClosure) >= sizeof(DiffuseRampBsdf), "DiffuseRampBsdf is too large!");
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ccl_device float3 bsdf_diffuse_ramp_get_color(const float3 colors[8], float pos)
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{
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int MAXCOLORS = 8;
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float npos = pos * (float)(MAXCOLORS - 1);
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int ipos = float_to_int(npos);
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if (ipos < 0)
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return colors[0];
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if (ipos >= (MAXCOLORS - 1))
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return colors[MAXCOLORS - 1];
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float offset = npos - (float)ipos;
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return colors[ipos] * (1.0f - offset) + colors[ipos + 1] * offset;
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}
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ccl_device int bsdf_diffuse_ramp_setup(DiffuseRampBsdf *bsdf)
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{
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bsdf->type = CLOSURE_BSDF_DIFFUSE_RAMP_ID;
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return SD_BSDF | SD_BSDF_HAS_EVAL;
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}
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ccl_device void bsdf_diffuse_ramp_blur(ccl_private ShaderClosure *sc, float roughness)
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{
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}
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ccl_device Spectrum bsdf_diffuse_ramp_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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const DiffuseRampBsdf *bsdf = (const DiffuseRampBsdf *)sc;
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float3 N = bsdf->N;
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float cosNO = fmaxf(dot(N, wo), 0.0f);
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if (cosNO >= 0.0f) {
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*pdf = cosNO * M_1_PI_F;
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return rgb_to_spectrum(bsdf_diffuse_ramp_get_color(bsdf->colors, cosNO) * M_1_PI_F);
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}
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else {
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*pdf = 0.0f;
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return zero_spectrum();
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}
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}
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ccl_device int bsdf_diffuse_ramp_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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const DiffuseRampBsdf *bsdf = (const DiffuseRampBsdf *)sc;
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float3 N = bsdf->N;
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// distribution over the hemisphere
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sample_cos_hemisphere(N, randu, randv, wo, pdf);
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if (dot(Ng, *wo) > 0.0f) {
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*eval = rgb_to_spectrum(bsdf_diffuse_ramp_get_color(bsdf->colors, *pdf * M_PI_F) * M_1_PI_F);
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}
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else {
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*pdf = 0.0f;
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*eval = zero_spectrum();
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}
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return LABEL_REFLECT | LABEL_DIFFUSE;
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}
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#endif /* __OSL__ */
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CCL_NAMESPACE_END
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