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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/util/color.h"
CCL_NAMESPACE_BEGIN
#ifdef __OSL__
typedef struct PhongRampBsdf {
SHADER_CLOSURE_BASE;
float exponent;
ccl_private float3 *colors;
} PhongRampBsdf;
static_assert(sizeof(ShaderClosure) >= sizeof(PhongRampBsdf), "PhongRampBsdf is too large!");
ccl_device float3 bsdf_phong_ramp_get_color(const float3 colors[8], float pos)
{
int MAXCOLORS = 8;
float npos = pos * (float)(MAXCOLORS - 1);
int ipos = float_to_int(npos);
if (ipos < 0)
return colors[0];
if (ipos >= (MAXCOLORS - 1))
return colors[MAXCOLORS - 1];
float offset = npos - (float)ipos;
return colors[ipos] * (1.0f - offset) + colors[ipos + 1] * offset;
}
ccl_device int bsdf_phong_ramp_setup(ccl_private PhongRampBsdf *bsdf)
{
bsdf->type = CLOSURE_BSDF_PHONG_RAMP_ID;
bsdf->exponent = max(bsdf->exponent, 0.0f);
return SD_BSDF | SD_BSDF_HAS_EVAL;
}
ccl_device Spectrum bsdf_phong_ramp_eval(ccl_private const ShaderClosure *sc,
const float3 I,
const float3 omega_in,
ccl_private float *pdf)
{
ccl_private const PhongRampBsdf *bsdf = (ccl_private const PhongRampBsdf *)sc;
float m_exponent = bsdf->exponent;
float cosNI = dot(bsdf->N, omega_in);
float cosNO = dot(bsdf->N, I);
if (cosNI > 0 && cosNO > 0) {
// reflect the view vector
float3 R = (2 * cosNO) * bsdf->N - I;
float cosRI = dot(R, omega_in);
if (cosRI > 0) {
float cosp = powf(cosRI, m_exponent);
float common = 0.5f * M_1_PI_F * cosp;
float out = cosNI * (m_exponent + 2) * common;
*pdf = (m_exponent + 1) * common;
return rgb_to_spectrum(bsdf_phong_ramp_get_color(bsdf->colors, cosp) * out);
}
}
*pdf = 0.0f;
return zero_spectrum();
}
ccl_device_inline float phong_ramp_exponent_to_roughness(float exponent)
{
return sqrt(1.0f / ((exponent + 2.0f) / 2.0f));
}
ccl_device int bsdf_phong_ramp_sample(ccl_private const ShaderClosure *sc,
float3 Ng,
float3 I,
float randu,
float randv,
ccl_private Spectrum *eval,
ccl_private float3 *omega_in,
ccl_private float *pdf,
ccl_private float2 *sampled_roughness)
{
ccl_private const PhongRampBsdf *bsdf = (ccl_private const PhongRampBsdf *)sc;
float cosNO = dot(bsdf->N, I);
float m_exponent = bsdf->exponent;
const float m_roughness = phong_ramp_exponent_to_roughness(m_exponent);
*sampled_roughness = make_float2(m_roughness, m_roughness);
if (cosNO > 0) {
// reflect the view vector
float3 R = (2 * cosNO) * bsdf->N - I;
float3 T, B;
make_orthonormals(R, &T, &B);
float phi = M_2PI_F * randu;
float cosTheta = powf(randv, 1 / (m_exponent + 1));
float sinTheta2 = 1 - cosTheta * cosTheta;
float sinTheta = sinTheta2 > 0 ? sqrtf(sinTheta2) : 0;
*omega_in = (cosf(phi) * sinTheta) * T + (sinf(phi) * sinTheta) * B + (cosTheta)*R;
if (dot(Ng, *omega_in) > 0.0f) {
// common terms for pdf and eval
float cosNI = dot(bsdf->N, *omega_in);
// make sure the direction we chose is still in the right hemisphere
if (cosNI > 0) {
float cosp = powf(cosTheta, m_exponent);
float common = 0.5f * M_1_PI_F * cosp;
*pdf = (m_exponent + 1) * common;
float out = cosNI * (m_exponent + 2) * common;
*eval = rgb_to_spectrum(bsdf_phong_ramp_get_color(bsdf->colors, cosp) * out);
}
}
}
else {
*eval = zero_spectrum();
*pdf = 0.0f;
}
return LABEL_REFLECT | LABEL_GLOSSY;
}
#endif /* __OSL__ */
CCL_NAMESPACE_END
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