forked from bartvdbraak/blender
132 lines
4.1 KiB
C
132 lines
4.1 KiB
C
/*
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* Copyright 2011-2013 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef __BSDF_OREN_NAYAR_H__
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#define __BSDF_OREN_NAYAR_H__
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CCL_NAMESPACE_BEGIN
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typedef ccl_addr_space struct OrenNayarBsdf {
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SHADER_CLOSURE_BASE;
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float roughness;
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float a;
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float b;
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} OrenNayarBsdf;
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static_assert(sizeof(ShaderClosure) >= sizeof(OrenNayarBsdf), "OrenNayarBsdf is too large!");
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ccl_device float3 bsdf_oren_nayar_get_intensity(const ShaderClosure *sc,
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float3 n,
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float3 v,
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float3 l)
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{
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const OrenNayarBsdf *bsdf = (const OrenNayarBsdf *)sc;
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float nl = max(dot(n, l), 0.0f);
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float nv = max(dot(n, v), 0.0f);
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float t = dot(l, v) - nl * nv;
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if (t > 0.0f)
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t /= max(nl, nv) + FLT_MIN;
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float is = nl * (bsdf->a + bsdf->b * t);
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return make_float3(is, is, is);
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}
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ccl_device int bsdf_oren_nayar_setup(OrenNayarBsdf *bsdf)
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{
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float sigma = bsdf->roughness;
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bsdf->type = CLOSURE_BSDF_OREN_NAYAR_ID;
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sigma = saturate(sigma);
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float div = 1.0f / (M_PI_F + ((3.0f * M_PI_F - 4.0f) / 6.0f) * sigma);
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bsdf->a = 1.0f * div;
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bsdf->b = sigma * div;
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return SD_BSDF | SD_BSDF_HAS_EVAL;
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}
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ccl_device bool bsdf_oren_nayar_merge(const ShaderClosure *a, const ShaderClosure *b)
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{
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const OrenNayarBsdf *bsdf_a = (const OrenNayarBsdf *)a;
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const OrenNayarBsdf *bsdf_b = (const OrenNayarBsdf *)b;
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return (isequal_float3(bsdf_a->N, bsdf_b->N)) && (bsdf_a->roughness == bsdf_b->roughness);
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}
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ccl_device float3 bsdf_oren_nayar_eval_reflect(const ShaderClosure *sc,
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const float3 I,
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const float3 omega_in,
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float *pdf)
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{
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const OrenNayarBsdf *bsdf = (const OrenNayarBsdf *)sc;
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if (dot(bsdf->N, omega_in) > 0.0f) {
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*pdf = 0.5f * M_1_PI_F;
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return bsdf_oren_nayar_get_intensity(sc, bsdf->N, I, omega_in);
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}
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else {
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*pdf = 0.0f;
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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}
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ccl_device float3 bsdf_oren_nayar_eval_transmit(const ShaderClosure *sc,
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const float3 I,
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const float3 omega_in,
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float *pdf)
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{
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return make_float3(0.0f, 0.0f, 0.0f);
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}
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ccl_device int bsdf_oren_nayar_sample(const ShaderClosure *sc,
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float3 Ng,
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float3 I,
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float3 dIdx,
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float3 dIdy,
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float randu,
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float randv,
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float3 *eval,
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float3 *omega_in,
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float3 *domega_in_dx,
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float3 *domega_in_dy,
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float *pdf)
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{
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const OrenNayarBsdf *bsdf = (const OrenNayarBsdf *)sc;
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sample_uniform_hemisphere(bsdf->N, randu, randv, omega_in, pdf);
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if (dot(Ng, *omega_in) > 0.0f) {
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*eval = bsdf_oren_nayar_get_intensity(sc, bsdf->N, I, *omega_in);
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#ifdef __RAY_DIFFERENTIALS__
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// TODO: find a better approximation for the bounce
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*domega_in_dx = (2.0f * dot(bsdf->N, dIdx)) * bsdf->N - dIdx;
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*domega_in_dy = (2.0f * dot(bsdf->N, dIdy)) * bsdf->N - dIdy;
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#endif
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}
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else {
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*pdf = 0.0f;
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*eval = make_float3(0.0f, 0.0f, 0.0f);
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}
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return LABEL_REFLECT | LABEL_DIFFUSE;
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}
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CCL_NAMESPACE_END
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#endif /* __BSDF_OREN_NAYAR_H__ */
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