141 lines
4.6 KiB
C
141 lines
4.6 KiB
C
/*
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* Copyright 2011-2017 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_PRINCIPLED_DIFFUSE_H__
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#define __BSDF_PRINCIPLED_DIFFUSE_H__
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/* DISNEY PRINCIPLED DIFFUSE BRDF
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*
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* Shading model by Brent Burley (Disney): "Physically Based Shading at Disney" (2012)
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*/
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CCL_NAMESPACE_BEGIN
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typedef ccl_addr_space struct PrincipledDiffuseBsdf {
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SHADER_CLOSURE_BASE;
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float roughness;
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} PrincipledDiffuseBsdf;
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static_assert(sizeof(ShaderClosure) >= sizeof(PrincipledDiffuseBsdf),
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"PrincipledDiffuseBsdf is too large!");
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ccl_device float3 calculate_principled_diffuse_brdf(
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const PrincipledDiffuseBsdf *bsdf, float3 N, float3 V, float3 L, float3 H, float *pdf)
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{
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float NdotL = max(dot(N, L), 0.0f);
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float NdotV = max(dot(N, V), 0.0f);
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if (NdotL < 0 || NdotV < 0) {
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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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float LdotH = dot(L, H);
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float FL = schlick_fresnel(NdotL), FV = schlick_fresnel(NdotV);
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const float Fd90 = 0.5f + 2.0f * LdotH * LdotH * bsdf->roughness;
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float Fd = (1.0f * (1.0f - FL) + Fd90 * FL) * (1.0f * (1.0f - FV) + Fd90 * FV);
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float value = M_1_PI_F * NdotL * Fd;
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return make_float3(value, value, value);
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}
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ccl_device int bsdf_principled_diffuse_setup(PrincipledDiffuseBsdf *bsdf)
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{
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bsdf->type = CLOSURE_BSDF_PRINCIPLED_DIFFUSE_ID;
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return SD_BSDF | SD_BSDF_HAS_EVAL;
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}
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ccl_device bool bsdf_principled_diffuse_merge(const ShaderClosure *a, const ShaderClosure *b)
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{
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const PrincipledDiffuseBsdf *bsdf_a = (const PrincipledDiffuseBsdf *)a;
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const PrincipledDiffuseBsdf *bsdf_b = (const PrincipledDiffuseBsdf *)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_principled_diffuse_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 PrincipledDiffuseBsdf *bsdf = (const PrincipledDiffuseBsdf *)sc;
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float3 N = bsdf->N;
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float3 V = I; // outgoing
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float3 L = omega_in; // incoming
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float3 H = normalize(L + V);
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if (dot(N, omega_in) > 0.0f) {
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*pdf = fmaxf(dot(N, omega_in), 0.0f) * M_1_PI_F;
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return calculate_principled_diffuse_brdf(bsdf, N, V, L, H, pdf);
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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_principled_diffuse_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_principled_diffuse_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 PrincipledDiffuseBsdf *bsdf = (const PrincipledDiffuseBsdf *)sc;
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float3 N = bsdf->N;
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sample_cos_hemisphere(N, randu, randv, omega_in, pdf);
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if (dot(Ng, *omega_in) > 0) {
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float3 H = normalize(I + *omega_in);
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*eval = calculate_principled_diffuse_brdf(bsdf, N, I, *omega_in, H, pdf);
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#ifdef __RAY_DIFFERENTIALS__
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// TODO: find a better approximation for the diffuse bounce
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*domega_in_dx = -((2 * dot(N, dIdx)) * N - dIdx);
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*domega_in_dy = -((2 * dot(N, dIdy)) * 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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}
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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_PRINCIPLED_DIFFUSE_H__ */
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