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/* SPDX-License-Identifier: Apache-2.0
* Copyright 2011-2022 Blender Foundation */
#include "node_fresnel.h"
#include "stdcycles.h"
shader node_principled_bsdf(string distribution = "Multiscatter GGX",
string subsurface_method = "random_walk",
color BaseColor = color(0.8, 0.8, 0.8),
float Subsurface = 0.0,
vector SubsurfaceRadius = vector(1.0, 1.0, 1.0),
color SubsurfaceColor = color(0.7, 0.1, 0.1),
float SubsurfaceIOR = 1.4,
float SubsurfaceAnisotropy = 0.0,
float Metallic = 0.0,
float Specular = 0.5,
float SpecularTint = 0.0,
float Roughness = 0.5,
float Anisotropic = 0.0,
float AnisotropicRotation = 0.0,
float Sheen = 0.0,
float SheenTint = 0.5,
float Clearcoat = 0.0,
float ClearcoatRoughness = 0.03,
float IOR = 1.45,
float Transmission = 0.0,
float TransmissionRoughness = 0.0,
normal Normal = N,
normal ClearcoatNormal = N,
normal Tangent = normalize(dPdu),
output closure color BSDF = 0)
{
float f = max(IOR, 1e-5);
float diffuse_weight = (1.0 - clamp(Metallic, 0.0, 1.0)) * (1.0 - clamp(Transmission, 0.0, 1.0));
float final_transmission = clamp(Transmission, 0.0, 1.0) * (1.0 - clamp(Metallic, 0.0, 1.0));
float specular_weight = (1.0 - final_transmission);
vector T = Tangent;
float m_cdlum = luminance(BaseColor);
color m_ctint = m_cdlum > 0.0 ? BaseColor / m_cdlum :
color(1.0, 1.0, 1.0); // normalize lum. to isolate hue+sat
/* rotate tangent */
if (AnisotropicRotation != 0.0)
T = rotate(T, AnisotropicRotation * M_2PI, point(0.0, 0.0, 0.0), Normal);
if (diffuse_weight > 1e-5) {
if (Subsurface > 1e-5) {
color mixed_ss_base_color = SubsurfaceColor * Subsurface + BaseColor * (1.0 - Subsurface);
BSDF = mixed_ss_base_color * bssrdf(subsurface_method,
Normal,
Subsurface * SubsurfaceRadius,
mixed_ss_base_color,
"roughness",
Roughness,
"ior",
SubsurfaceIOR,
"anisotropy",
SubsurfaceAnisotropy);
}
else {
BSDF = BaseColor * principled_diffuse(Normal, Roughness);
}
if (Sheen > 1e-5) {
color sheen_color = color(1.0, 1.0, 1.0) * (1.0 - SheenTint) + m_ctint * SheenTint;
BSDF = BSDF + sheen_color * Sheen * principled_sheen(Normal);
}
BSDF = BSDF * diffuse_weight;
}
if (specular_weight > 1e-5) {
float aspect = sqrt(1.0 - Anisotropic * 0.9);
float r2 = Roughness * Roughness;
float alpha_x = r2 / aspect;
float alpha_y = r2 * aspect;
color tmp_col = color(1.0, 1.0, 1.0) * (1.0 - SpecularTint) + m_ctint * SpecularTint;
color Cspec0 = (Specular * 0.08 * tmp_col) * (1.0 - Metallic) + BaseColor * Metallic;
if (distribution == "GGX" || Roughness <= 0.075) {
BSDF = BSDF + specular_weight *
microfacet_ggx_aniso_fresnel(Normal,
T,
alpha_x,
alpha_y,
(2.0 / (1.0 - sqrt(0.08 * Specular))) - 1.0,
BaseColor,
Cspec0);
}
else {
BSDF = BSDF + specular_weight * microfacet_multi_ggx_aniso_fresnel(
Normal,
T,
alpha_x,
alpha_y,
(2.0 / (1.0 - sqrt(0.08 * Specular))) - 1.0,
BaseColor,
Cspec0);
}
}
if (final_transmission > 1e-5) {
color Cspec0 = BaseColor * SpecularTint + color(1.0, 1.0, 1.0) * (1.0 - SpecularTint);
float eta = backfacing() ? 1.0 / f : f;
if (distribution == "GGX" || Roughness <= 5e-2) {
float cosNO = dot(Normal, I);
float Fr = fresnel_dielectric_cos(cosNO, eta);
float refl_roughness = Roughness;
if (Roughness <= 1e-2)
refl_roughness = 0.0;
float transmission_roughness = refl_roughness;
if (distribution == "GGX")
transmission_roughness = 1.0 - (1.0 - refl_roughness) * (1.0 - TransmissionRoughness);
BSDF = BSDF +
final_transmission *
(Fr * microfacet_ggx_fresnel(
Normal, refl_roughness * refl_roughness, eta, BaseColor, Cspec0) +
(1.0 - Fr) * BaseColor *
microfacet_ggx_refraction(
Normal, transmission_roughness * transmission_roughness, eta));
}
else {
BSDF = BSDF +
final_transmission * microfacet_multi_ggx_glass_fresnel(
Normal, Roughness * Roughness, eta, BaseColor, Cspec0);
}
}
if (Clearcoat > 1e-5) {
BSDF = BSDF + principled_clearcoat(
ClearcoatNormal, Clearcoat, ClearcoatRoughness * ClearcoatRoughness);
}
}
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