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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License
*/
#ifndef __BSDF_OREN_NAYAR_H__
#define __BSDF_OREN_NAYAR_H__
CCL_NAMESPACE_BEGIN
ccl_device float3 bsdf_oren_nayar_get_intensity(const ShaderClosure *sc, float3 n, float3 v, float3 l)
{
float nl = max(dot(n, l), 0.0f);
float nv = max(dot(n, v), 0.0f);
float t = dot(l, v) - nl * nv;
if (t > 0.0f)
t /= max(nl, nv) + FLT_MIN;
float is = nl * (sc->data0 + sc->data1 * t);
return make_float3(is, is, is);
}
ccl_device int bsdf_oren_nayar_setup(ShaderClosure *sc)
{
float sigma = sc->data0;
sc->type = CLOSURE_BSDF_OREN_NAYAR_ID;
sigma = clamp(sigma, 0.0f, 1.0f);
float div = 1.0f / (M_PI_F + ((3.0f * M_PI_F - 4.0f) / 6.0f) * sigma);
sc->data0 = 1.0f * div;
sc->data1 = sigma * div;
return SD_BSDF | SD_BSDF_HAS_EVAL;
}
ccl_device void bsdf_oren_nayar_blur(ShaderClosure *sc, float roughness)
{
}
ccl_device float3 bsdf_oren_nayar_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
if (dot(sc->N, omega_in) > 0.0f) {
*pdf = 0.5f * M_1_PI_F;
return bsdf_oren_nayar_get_intensity(sc, sc->N, I, omega_in);
}
else {
*pdf = 0.0f;
return make_float3(0.0f, 0.0f, 0.0f);
}
}
ccl_device float3 bsdf_oren_nayar_eval_transmit(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
return make_float3(0.0f, 0.0f, 0.0f);
}
ccl_device int bsdf_oren_nayar_sample(const ShaderClosure *sc, float3 Ng, float3 I, float3 dIdx, float3 dIdy, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
{
sample_uniform_hemisphere(sc->N, randu, randv, omega_in, pdf);
if (dot(Ng, *omega_in) > 0.0f) {
*eval = bsdf_oren_nayar_get_intensity(sc, sc->N, I, *omega_in);
#ifdef __RAY_DIFFERENTIALS__
// TODO: find a better approximation for the bounce
*domega_in_dx = (2.0f * dot(sc->N, dIdx)) * sc->N - dIdx;
*domega_in_dy = (2.0f * dot(sc->N, dIdy)) * sc->N - dIdy;
#endif
}
else {
*pdf = 0.0f;
*eval = make_float3(0.0f, 0.0f, 0.0f);
}
return LABEL_REFLECT | LABEL_DIFFUSE;
}
CCL_NAMESPACE_END
#endif /* __BSDF_OREN_NAYAR_H__ */
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