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#ifndef __YUM_BRDF_INC
#define __YUM_BRDF_INC
#include "UnityCG.cginc"
#include "UnityStandardConfig.cginc"
#include "UnityLightingCommon.cginc"
#include "filamented.cginc"
#include "math.cginc"
#include "yum_pbr.cginc"
#include "yum_lighting.cginc"
#if defined(_MATERIAL_TYPE_CLOTH)
float D_Charlie(float roughness, float NoH) {
// Estevez and Kulla 2017, "Production Friendly Microfacet Sheen BRDF"
float invAlpha = 1.0 / roughness;
float cos2h = NoH * NoH;
float sin2h = max(1.0 - cos2h, 0.0078125); // 2^(-14/2), so sin2h^2 > 0 in fp16
return (2.0 + invAlpha) * pow(sin2h, invAlpha * 0.5) / (2.0 * PI);
}
#endif
// Cloth visibility term from Neubelt and Pettineo
float V_Cloth(float NoV, float NoL) {
return 1.0 / (4.0 * (NoL + NoV - NoL * NoV));
}
float3 specularLobe(YumPbr pbr, float f0,
float3 h, float LoH, float NoH, float NoV, float NoL)
{
#if defined(_MATERIAL_TYPE_CLOTH)
float D = D_Charlie(pbr.roughness, NoH);
float V = V_Cloth(NoV, NoL);
float3 F = _Cloth_Sheen_Color;
return (D * V) * F;
#else
// Fresnel
const float3 F = F_Schlick(f0, LoH);
// Normal distribution function
float D = D_GGX(pbr.roughness, NoH, h);
// Geometric shadowing
float V = V_SmithGGXCorrelated_Fast(pbr.roughness, NoV, NoL);
return (D * V) * F;
#endif
}
float4 YumBRDF(v2f i, const YumLighting light, YumPbr pbr) {
const float3 h = normalize(light.view_dir + light.dir);
const float LoH = saturate(dot(light.dir, h));
const float NoL = light.NoL;
#if defined(_WRAPPED_LIGHTING)
const float NoL_wrapped_s = light.NoL_wrapped_s;
const float NoL_wrapped_d = light.NoL_wrapped_d;
#else
const float NoL_wrapped_s = light.NoL;
const float NoL_wrapped_d = light.NoL;
#endif
const float NoV = max(1E-4, dot(pbr.normal, light.view_dir));
const float NoH = saturate(dot(pbr.normal, h));
const float VoL = saturate(dot(light.view_dir, light.dir));
const float f90 = 0.5 + 2 * pbr.roughness * LoH * LoH;
#if defined(_MATERIAL_TYPE_CLOTH)
// Cloth specific BRDF
float3 direct_cloth;
{
// Cloth diffuse BRDF - apply proper energy conservation
// Use a proper diffuse BRDF term instead of raw albedo
float3 Fd = pbr.albedo / PI;
Fd *= light.attenuation;
#if defined(_MATERIAL_TYPE_CLOTH_SUBSURFACE)
// Energy conservative wrap diffuse for subsurface scattering
float wrap_diffuse = saturate((NoL + 0.5) / 2.25);
Fd *= wrap_diffuse;
// Apply subsurface color
Fd *= saturate(_Cloth_Subsurface_Color + NoL);
#endif
// Cloth specular BRDF
float3 Fr = specularLobe(pbr, 0.04, h, LoH, NoH, NoV, NoL_wrapped_s);
#if defined(_MATERIAL_TYPE_CLOTH_SUBSURFACE)
// No need to multiply by NoL when using subsurface scattering
direct_cloth = (Fd + Fr * NoL) * light.direct * _Cloth_Direct_Multiplier;
#else
direct_cloth = (Fd + Fr) * NoL * light.direct * _Cloth_Direct_Multiplier;
#endif
}
#endif
float3 direct_standard;
{
// Typical values for different materials listed here:
// https://google.github.io/filament/Filament.html#toc4.8.3.2
// TODO expose an enum for different types of materials
const float reflectance = _reflectance;
// f0 = amount of light reflected back when viewing surface at a right angle
// Change to match the design document
const float3 f0 = lerp(0.16 * reflectance * reflectance, pbr.albedo, pbr.metallic);
const float3 dfg = PrefilteredDFG_LUT(pbr.roughness_perceptual, NoV);
const float3 E = specularDFG(dfg, f0);
const float3 energy_compensation = energyCompensation(dfg, f0);
float3 Fd = pbr.albedo / PI;
Fd *= (1.0 - pbr.metallic) * light.attenuation;
float3 Fr = specularLobe(pbr, f0, h, LoH, NoH, NoV, NoL_wrapped_s);
float3 color = Fd * NoL_wrapped_d + Fr * energy_compensation * NoL_wrapped_s;
direct_standard = color * light.direct;
}
#if defined(_MATERIAL_TYPE_CLOTH)
float3 indirect_cloth;
{
// Simple indirect lighting for cloth
// Add additional corrective term to account for the fact that vrchat map
// makers suck shit and don't use enough reflection probes.
float3 Fr = _Cloth_Sheen_Color * light.specular * light.diffuse_luminance;
float3 Fd = pbr.albedo * light.diffuse * pbr.ao;
#if defined(_MATERIAL_TYPE_CLOTH_SUBSURFACE)
// Apply subsurface color to indirect diffuse
Fd *= _Cloth_Subsurface_Color;
#endif
indirect_cloth = (Fr + Fd) * _Cloth_Indirect_Multiplier;
}
#endif
float3 indirect_standard;
{
const float reflectance = _reflectance;
const float3 f0 = reflectance * (1.0 - pbr.metallic) + pbr.albedo * pbr.metallic;
const float3 dfg = PrefilteredDFG_LUT(pbr.roughness_perceptual, NoV);
const float3 E = specularDFG(dfg, f0);
const float3 energy_compensation = energyCompensation(dfg, f0);
float3 Fr = E * light.specular * energy_compensation;
float3 Fd = pbr.albedo * light.diffuse * (1.0 - E) * (1.0 - pbr.metallic) * pbr.ao;
indirect_standard = Fr + Fd;
}
#if defined(_MATERIAL_TYPE_CLOTH)
float cloth_mask = _Cloth_Mask.Sample(linear_repeat_s, i.uv01.xy);
float3 direct = lerp(direct_standard, direct_cloth, cloth_mask);
float3 indirect = lerp(indirect_standard, indirect_cloth, cloth_mask);
#else
float3 direct = direct_standard;
float3 indirect = indirect_standard;
#endif
return float4(direct + indirect, pbr.albedo.a);
}
#endif // __YUM_BRDF_INC
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