72 lines
1.7 KiB
HLSL
72 lines
1.7 KiB
HLSL
static const float PI = 3.141592653589793;
|
|
|
|
float3 FresnelSchlick(float cosTheta, float3 F0)
|
|
{
|
|
return F0 + (1.0 - F0) * pow(1.0 - cosTheta, 5.0);
|
|
}
|
|
|
|
float DistributionGGX(float3 N, float3 H, float roughness)
|
|
{
|
|
float a = roughness * roughness;
|
|
float a2 = a * a;
|
|
float NdotH = max(dot(N, H), 0.0);
|
|
float NdotH2 = NdotH * NdotH;
|
|
|
|
float num = a2;
|
|
float denom = (NdotH2 * (a2 - 1.0) + 1.0);
|
|
denom = PI * denom * denom;
|
|
|
|
return num / denom;
|
|
}
|
|
|
|
float GeometrySchlickGGX(float NdotV, float roughness)
|
|
{
|
|
float r = (roughness + 1.0);
|
|
float k = (r * r) / 8.0;
|
|
|
|
float num = NdotV;
|
|
float denom = NdotV * (1.0 - k) + k;
|
|
|
|
return num / denom;
|
|
}
|
|
|
|
float GeometrySmith(float3 N, float3 V, float3 L, float roughness)
|
|
{
|
|
float NdotV = max(dot(N, V), 0.0);
|
|
float NdotL = max(dot(N, L), 0.0);
|
|
float ggx2 = GeometrySchlickGGX(NdotV, roughness);
|
|
float ggx1 = GeometrySchlickGGX(NdotL, roughness);
|
|
|
|
return ggx1 * ggx2;
|
|
}
|
|
|
|
float3 ComputeLight(
|
|
float3 L,
|
|
float3 radiance,
|
|
float3 F0,
|
|
float3 V,
|
|
float3 N,
|
|
float3 albedo,
|
|
float metallic,
|
|
float roughness,
|
|
float shadow
|
|
) {
|
|
float3 H = normalize(V + L);
|
|
|
|
float NDF = DistributionGGX(N, H, roughness);
|
|
float G = GeometrySmith(N, V, L, roughness);
|
|
float3 F = FresnelSchlick(max(dot(H, V), 0.0), F0);
|
|
|
|
float3 numerator = NDF * G * F;
|
|
float denominator = 4.0 * max(dot(N, V), 0.0) * max(dot(N, L), 0.0);
|
|
float3 specular = numerator / max(denominator, 0.001);
|
|
|
|
float3 kS = F;
|
|
float3 kD = float3(1.0, 1.0, 1.0) - kS;
|
|
|
|
kD *= 1.0 - metallic;
|
|
|
|
float NdotL = max(dot(N, L), 0.0);
|
|
return (kD * albedo / PI + specular) * radiance * NdotL * shadow;
|
|
}
|