UE4 GBuffer DiffuseColor SpecularColor

DeferredShadingCommon.ush
 

GBuffer.DiffuseColor = GBuffer.BaseColor - GBuffer.BaseColor * GBuffer.Metallic;

GBuffer.SpecularColor = ComputeF0(GBuffer.Specular, GBuffer.BaseColor, GBuffer.Metallic);

ShadingCommon.ush

float DielectricSpecularToF0(float Specular)
{
    return 0.08f * Specular;
}

// [Burley, "Extending the Disney BRDF to a BSDF with Integrated Subsurface Scattering"]
float DielectricF0ToIor(float F0)
{
    return 2.0f / (1.0f - sqrt(F0)) - 1.0f;
}

float DielectricIorToF0(float Ior)
{
    const float F0Sqrt = (Ior-1)/(Ior+1);
    const float F0 = F0Sqrt*F0Sqrt;
    return F0;
}

float3 ComputeF0(float Specular, float3 BaseColor, float Metallic)
{
    return lerp(DielectricSpecularToF0(Specular).xxx, BaseColor, Metallic.xxx);
}