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/* SPDX-License-Identifier: BSD-3-Clause
*
* Adapted from Open Shading Language
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
* All Rights Reserved.
*
* Modifications Copyright 2011-2022 Blender Foundation. */
#pragma once
#include "kernel/sample/mapping.h"
CCL_NAMESPACE_BEGIN
typedef struct DiffuseBsdf {
SHADER_CLOSURE_BASE;
} DiffuseBsdf;
static_assert(sizeof(ShaderClosure) >= sizeof(DiffuseBsdf), "DiffuseBsdf is too large!");
/* DIFFUSE */
ccl_device int bsdf_diffuse_setup(ccl_private DiffuseBsdf *bsdf)
{
bsdf->type = CLOSURE_BSDF_DIFFUSE_ID;
return SD_BSDF | SD_BSDF_HAS_EVAL;
}
ccl_device float3 bsdf_diffuse_eval_reflect(ccl_private const ShaderClosure *sc,
const float3 I,
const float3 omega_in,
ccl_private float *pdf)
{
ccl_private const DiffuseBsdf *bsdf = (ccl_private const DiffuseBsdf *)sc;
float3 N = bsdf->N;
float cos_pi = fmaxf(dot(N, omega_in), 0.0f) * M_1_PI_F;
*pdf = cos_pi;
return make_float3(cos_pi, cos_pi, cos_pi);
}
ccl_device float3 bsdf_diffuse_eval_transmit(ccl_private const ShaderClosure *sc,
const float3 I,
const float3 omega_in,
ccl_private float *pdf)
{
*pdf = 0.0f;
return make_float3(0.0f, 0.0f, 0.0f);
}
ccl_device int bsdf_diffuse_sample(ccl_private const ShaderClosure *sc,
float3 Ng,
float3 I,
float3 dIdx,
float3 dIdy,
float randu,
float randv,
ccl_private float3 *eval,
ccl_private float3 *omega_in,
ccl_private float3 *domega_in_dx,
ccl_private float3 *domega_in_dy,
ccl_private float *pdf)
{
ccl_private const DiffuseBsdf *bsdf = (ccl_private const DiffuseBsdf *)sc;
float3 N = bsdf->N;
// distribution over the hemisphere
sample_cos_hemisphere(N, randu, randv, omega_in, pdf);
if (dot(Ng, *omega_in) > 0.0f) {
*eval = make_float3(*pdf, *pdf, *pdf);
#ifdef __RAY_DIFFERENTIALS__
// TODO: find a better approximation for the diffuse bounce
*domega_in_dx = (2 * dot(N, dIdx)) * N - dIdx;
*domega_in_dy = (2 * dot(N, dIdy)) * N - dIdy;
#endif
}
else {
*pdf = 0.0f;
*eval = make_float3(0.0f, 0.0f, 0.0f);
}
return LABEL_REFLECT | LABEL_DIFFUSE;
}
/* TRANSLUCENT */
ccl_device int bsdf_translucent_setup(ccl_private DiffuseBsdf *bsdf)
{
bsdf->type = CLOSURE_BSDF_TRANSLUCENT_ID;
return SD_BSDF | SD_BSDF_HAS_EVAL;
}
ccl_device float3 bsdf_translucent_eval_reflect(ccl_private const ShaderClosure *sc,
const float3 I,
const float3 omega_in,
ccl_private float *pdf)
{
*pdf = 0.0f;
return make_float3(0.0f, 0.0f, 0.0f);
}
ccl_device float3 bsdf_translucent_eval_transmit(ccl_private const ShaderClosure *sc,
const float3 I,
const float3 omega_in,
ccl_private float *pdf)
{
ccl_private const DiffuseBsdf *bsdf = (ccl_private const DiffuseBsdf *)sc;
float3 N = bsdf->N;
float cos_pi = fmaxf(-dot(N, omega_in), 0.0f) * M_1_PI_F;
*pdf = cos_pi;
return make_float3(cos_pi, cos_pi, cos_pi);
}
ccl_device int bsdf_translucent_sample(ccl_private const ShaderClosure *sc,
float3 Ng,
float3 I,
float3 dIdx,
float3 dIdy,
float randu,
float randv,
ccl_private float3 *eval,
ccl_private float3 *omega_in,
ccl_private float3 *domega_in_dx,
ccl_private float3 *domega_in_dy,
ccl_private float *pdf)
{
ccl_private const DiffuseBsdf *bsdf = (ccl_private const DiffuseBsdf *)sc;
float3 N = bsdf->N;
// we are viewing the surface from the right side - send a ray out with cosine
// distribution over the hemisphere
sample_cos_hemisphere(-N, randu, randv, omega_in, pdf);
if (dot(Ng, *omega_in) < 0) {
*eval = make_float3(*pdf, *pdf, *pdf);
#ifdef __RAY_DIFFERENTIALS__
// TODO: find a better approximation for the diffuse bounce
*domega_in_dx = -((2 * dot(N, dIdx)) * N - dIdx);
*domega_in_dy = -((2 * dot(N, dIdy)) * N - dIdy);
#endif
}
else {
*pdf = 0;
*eval = make_float3(0.0f, 0.0f, 0.0f);
}
return LABEL_TRANSMIT | LABEL_DIFFUSE;
}
CCL_NAMESPACE_END
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