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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.
*/
#include "stdcycles.h"
shader node_anisotropic_bsdf(color Color = 0.0,
string distribution = "GGX",
float Roughness = 0.0,
float Anisotropy = 0.0,
float Rotation = 0.0,
normal Normal = N,
normal Tangent = normalize(dPdu),
output closure color BSDF = 0)
{
/* rotate tangent around normal */
vector T = Tangent;
if (Rotation != 0.0)
T = rotate(T, Rotation * M_2PI, point(0.0, 0.0, 0.0), Normal);
/* compute roughness */
float roughness = Roughness * Roughness;
float roughness_u, roughness_v;
float aniso = clamp(Anisotropy, -0.99, 0.99);
if (aniso < 0.0) {
roughness_u = roughness / (1.0 + aniso);
roughness_v = roughness * (1.0 + aniso);
}
else {
roughness_u = roughness * (1.0 - aniso);
roughness_v = roughness / (1.0 - aniso);
}
if (distribution == "sharp")
BSDF = Color * reflection(Normal);
else if (distribution == "beckmann")
BSDF = Color * microfacet_beckmann_aniso(Normal, T, roughness_u, roughness_v);
else if (distribution == "GGX")
BSDF = Color * microfacet_ggx_aniso(Normal, T, roughness_u, roughness_v);
else if (distribution == "Multiscatter GGX")
BSDF = Color * microfacet_multi_ggx_aniso(Normal, T, roughness_u, roughness_v, Color);
else
BSDF = Color * ashikhmin_shirley(Normal, T, roughness_u, roughness_v);
}
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