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/*
* Adapted from Open Shading Language with this license:
*
* Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
* All Rights Reserved.
*
* Modifications Copyright 2011, Blender Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Sony Pictures Imageworks nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef __BSDF_WESTIN_H__
#define __BSDF_WESTIN_H__
CCL_NAMESPACE_BEGIN
/* WESTIN BACKSCATTER */
typedef struct BsdfWestinBackscatterClosure {
//float3 m_N;
float m_invroughness;
} BsdfWestinBackscatterClosure;
__device void bsdf_westin_backscatter_setup(ShaderData *sd, ShaderClosure *sc, float roughness)
{
roughness = clamp(roughness, 1e-5f, 1.0f);
float m_invroughness = 1.0f/roughness;
sc->type = CLOSURE_BSDF_WESTIN_BACKSCATTER_ID;
sd->flag |= SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
sc->data0 = m_invroughness;
}
__device void bsdf_westin_backscatter_blur(ShaderClosure *sc, float roughness)
{
float m_invroughness = sc->data0;
m_invroughness = min(1.0f/roughness, m_invroughness);
sc->data0 = m_invroughness;
}
__device float3 bsdf_westin_backscatter_eval_reflect(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
float m_invroughness = sc->data0;
float3 m_N = sd->N;
// pdf is implicitly 0 (no indirect sampling)
float cosNO = dot(m_N, I);
float cosNI = dot(m_N, omega_in);
if(cosNO > 0 && cosNI > 0) {
float cosine = dot(I, omega_in);
*pdf = cosine > 0 ? (m_invroughness + 1) * powf(cosine, m_invroughness) : 0;
*pdf *= 0.5f * M_1_PI_F;
return make_float3 (*pdf, *pdf, *pdf);
}
return make_float3 (0, 0, 0);
}
__device float3 bsdf_westin_backscatter_eval_transmit(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
return make_float3(0.0f, 0.0f, 0.0f);
}
__device float bsdf_westin_backscatter_albedo(const ShaderData *sd, const ShaderClosure *sc, const float3 I)
{
return 1.0f;
}
__device int bsdf_westin_backscatter_sample(const ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
{
float m_invroughness = sc->data0;
float3 m_N = sd->N;
float cosNO = dot(m_N, sd->I);
if(cosNO > 0) {
#ifdef __RAY_DIFFERENTIALS__
*domega_in_dx = sd->dI.dx;
*domega_in_dy = sd->dI.dy;
#endif
float3 T, B;
make_orthonormals (sd->I, &T, &B);
float phi = 2 * M_PI_F * randu;
float cosTheta = powf(randv, 1 / (m_invroughness + 1));
float sinTheta2 = 1 - cosTheta * cosTheta;
float sinTheta = sinTheta2 > 0 ? sqrtf(sinTheta2) : 0;
*omega_in = (cosf(phi) * sinTheta) * T +
(sinf(phi) * sinTheta) * B +
(cosTheta) * sd->I;
if(dot(sd->Ng, *omega_in) > 0)
{
// common terms for pdf and eval
float cosNI = dot(m_N, *omega_in);
// make sure the direction we chose is still in the right hemisphere
if(cosNI > 0)
{
*pdf = 0.5f * M_1_PI_F * powf(cosTheta, m_invroughness);
*pdf = (m_invroughness + 1) * (*pdf);
*eval = make_float3(*pdf, *pdf, *pdf);
#ifdef __RAY_DIFFERENTIALS__
// Since there is some blur to this reflection, make the
// derivatives a bit bigger. In theory this varies with the
// exponent but the exact relationship is complex and
// requires more ops than are practical.
*domega_in_dx *= 10.0f;
*domega_in_dy *= 10.0f;
#endif
}
}
}
return LABEL_REFLECT|LABEL_GLOSSY;
}
/* WESTIN SHEEN */
typedef struct BsdfWestinSheenClosure {
//float3 m_N;
float m_edginess;
} BsdfWestinSheenClosure;
__device void bsdf_westin_sheen_setup(ShaderData *sd, ShaderClosure *sc, float edginess)
{
sc->type = CLOSURE_BSDF_WESTIN_SHEEN_ID;
sd->flag |= SD_BSDF|SD_BSDF_HAS_EVAL|SD_BSDF_GLOSSY;
sc->data0 = edginess;
}
__device void bsdf_westin_sheen_blur(ShaderClosure *sc, float roughness)
{
}
__device float3 bsdf_westin_sheen_eval_reflect(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
float m_edginess = sc->data0;
float3 m_N = sd->N;
// pdf is implicitly 0 (no indirect sampling)
float cosNO = dot(m_N, I);
float cosNI = dot(m_N, omega_in);
if(cosNO > 0 && cosNI > 0) {
float sinNO2 = 1 - cosNO * cosNO;
*pdf = cosNI * M_1_PI_F;
float westin = sinNO2 > 0 ? powf(sinNO2, 0.5f * m_edginess) * (*pdf) : 0;
return make_float3 (westin, westin, westin);
}
return make_float3 (0, 0, 0);
}
__device float3 bsdf_westin_sheen_eval_transmit(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
return make_float3(0.0f, 0.0f, 0.0f);
}
__device float bsdf_westin_sheen_albedo(const ShaderData *sd, const ShaderClosure *sc, const float3 I)
{
return 1.0f;
}
__device int bsdf_westin_sheen_sample(const ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
{
float m_edginess = sc->data0;
float3 m_N = sd->N;
// we are viewing the surface from the right side - send a ray out with cosine
// distribution over the hemisphere
sample_cos_hemisphere(m_N, randu, randv, omega_in, pdf);
if(dot(sd->Ng, *omega_in) > 0) {
// TODO: account for sheen when sampling
float cosNO = dot(m_N, sd->I);
float sinNO2 = 1 - cosNO * cosNO;
float westin = sinNO2 > 0 ? powf(sinNO2, 0.5f * m_edginess) * (*pdf) : 0;
*eval = make_float3(westin, westin, westin);
#ifdef __RAY_DIFFERENTIALS__
// TODO: find a better approximation for the diffuse bounce
*domega_in_dx = (2 * dot(m_N, sd->dI.dx)) * m_N - sd->dI.dx;
*domega_in_dy = (2 * dot(m_N, sd->dI.dy)) * m_N - sd->dI.dy;
*domega_in_dx *= 125.0f;
*domega_in_dy *= 125.0f;
#endif
}
else {
pdf = 0;
}
return LABEL_REFLECT|LABEL_DIFFUSE;
}
CCL_NAMESPACE_END
#endif /* __BSDF_WESTIN_H__ */
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