Hi Guys,I was trying to transform Disney BRDF into Unity shader.
It is obvious some error in my shader, you can test with one directional light.
But I can’t fix it.Could anyone help me?
Direct implementation, but still requires improvements:
Shader "Disney"
{
Properties
{
metallic ("Metallic", Range (0.0,1.0)) = 0.0
subsurface ("Subsurface", Range (0.0,1.0)) = 0.0
_specular ("Specular", Range (0.0,1.0)) = 0.0
roughness ("Roughness", Range (0.0,1.0)) = 0.5
specularTint ("SpecularTint", Range (0.0,1.0)) = 0.0
anisotropic ("Anisotropic", Range (0.0,1.0)) = 0.0
sheen ("Sheen", Range (0.0,1.0)) = 0.0
sheenTint ("SheenTint", Range (0.0,1.0)) = 0.5
clearcoat ("Clearcoat", Range (0.0,1.0)) = 0.0
clearcoatGloss ("ClearcoatGloss", Range (0.0,1.0)) = 1.0
}
SubShader
{
Pass
{
CGPROGRAM
#pragma vertex VSMain
#pragma fragment PSMain
static const float3 baseColor = float3(1,1,1);
float metallic, subsurface, _specular, roughness, specularTint, anisotropic, sheen,
sheenTint, clearcoat, clearcoatGloss;
static const float PI = 3.14159265358979323846;
float sqr(float x) { return x*x; }
float SchlickFresnel(float u)
{
float m = clamp(1-u, 0, 1);
float m2 = m*m;
return m2*m2*m; // pow(m,5)
}
float GTR1(float NdotH, float a)
{
if (a >= 1) return 1/PI;
float a2 = a*a;
float t = 1 + (a2-1)*NdotH*NdotH;
return (a2-1) / (PI*log(a2)*t);
}
float GTR2(float NdotH, float a)
{
float a2 = a*a;
float t = 1 + (a2-1)*NdotH*NdotH;
return a2 / (PI * t*t);
}
float GTR2_aniso(float NdotH, float HdotX, float HdotY, float ax, float ay)
{
return 1 / (PI * ax*ay * sqr( sqr(HdotX/ax) + sqr(HdotY/ay) + NdotH*NdotH ));
}
float smithG_GGX(float NdotV, float alphaG)
{
float a = alphaG*alphaG;
float b = NdotV*NdotV;
return 1 / (NdotV + sqrt(a + b - a*b));
}
float smithG_GGX_aniso(float NdotV, float VdotX, float VdotY, float ax, float ay)
{
return 1 / (NdotV + sqrt( sqr(VdotX*ax) + sqr(VdotY*ay) + sqr(NdotV) ));
}
float3 mon2lin(float3 x)
{
return float3(pow(x[0], 2.2), pow(x[1], 2.2), pow(x[2], 2.2));
}
float3 BRDF( float3 L, float3 V, float3 N, float3 X, float3 Y )
{
float NdotL = max(dot(N,L),0.0);
float NdotV = max(dot(N,V),0.0);
float3 H = normalize(L+V);
float NdotH = max(dot(N,H),0.0);
float LdotH = max(dot(L,H),0.0);
float3 Cdlin = mon2lin(baseColor);
float Cdlum = .3*Cdlin[0] + .6*Cdlin[1] + .1*Cdlin[2]; // luminance approx.
float3 Ctint = Cdlum > 0 ? Cdlin/Cdlum : float3(1,1,1); // normalize lum. to isolate hue+sat
float3 Cspec0 = lerp(_specular*.08*lerp(float3(1,1,1), Ctint, specularTint), Cdlin, metallic);
float3 Csheen = lerp(float3(1,1,1), Ctint, sheenTint);
// Diffuse fresnel - go from 1 at normal incidence to .5 at grazing
// and lerp in diffuse retro-reflection based on roughness
float FL = SchlickFresnel(NdotL), FV = SchlickFresnel(NdotV);
float Fd90 = 0.5 + 2 * LdotH*LdotH * roughness;
float Fd = lerp(1.0, Fd90, FL) * lerp(1.0, Fd90, FV);
// Based on Hanrahan-Krueger brdf approximation of isotropic bssrdf
// 1.25 scale is used to (roughly) preserve albedo
// Fss90 used to "flatten" retroreflection based on roughness
float Fss90 = LdotH*LdotH*roughness;
float Fss = lerp(1.0, Fss90, FL) * lerp(1.0, Fss90, FV);
float ss = 1.25 * (Fss * (1 / (NdotL + NdotV) - .5) + .5);
// specular
float aspect = sqrt(1-anisotropic*.9);
float ax = max(.001, sqr(roughness)/aspect);
float ay = max(.001, sqr(roughness)*aspect);
float Ds = GTR2_aniso(NdotH, dot(H, X), dot(H, Y), ax, ay);
float FH = SchlickFresnel(LdotH);
float3 Fs = lerp(Cspec0, float3(1,1,1), FH);
float Gs = smithG_GGX_aniso(NdotL, dot(L, X), dot(L, Y), ax, ay);
Gs *= smithG_GGX_aniso(NdotV, dot(V, X), dot(V, Y), ax, ay);
// sheen
float3 Fsheen = FH * sheen * Csheen;
// clearcoat (ior = 1.5 -> F0 = 0.04)
float Dr = GTR1(NdotH, lerp(.1,.001,clearcoatGloss));
float Fr = lerp(.04, 1.0, FH);
float Gr = smithG_GGX(NdotL, .25) * smithG_GGX(NdotV, .25);
return ((1/PI) * lerp(Fd, ss, subsurface)*Cdlin + Fsheen) * (1-metallic) + Gs*Fs*Ds + .25*clearcoat*Gr*Fr*Dr;
}
void VSMain (inout float4 vertex:POSITION, inout float2 uv:TEXCOORD0, inout float3 normal:NORMAL, inout float4 tangent:TANGENT, out float3 world:TEXCOORD1)
{
world = mul(unity_ObjectToWorld, vertex).xyz;
vertex = UnityObjectToClipPos(vertex);
}
float4 PSMain (float4 vertex:POSITION, float2 uv:TEXCOORD0, float3 normal:NORMAL, float4 tangent:TANGENT, float3 world:TEXCOORD1) : SV_TARGET
{
float3 LightDirection = normalize(lerp(_WorldSpaceLightPos0.xyz, _WorldSpaceLightPos0.xyz - world,_WorldSpaceLightPos0.w));
float3 NormalDirection = normalize(mul((float3x3)unity_ObjectToWorld,normal));
float3 ViewDirection = normalize( _WorldSpaceCameraPos.xyz - world);
float3 WorldTangent = mul((float3x3)unity_ObjectToWorld,tangent.xyz);
float3 WorldBinormal = cross(NormalDirection,WorldTangent)*tangent.w;
return float4(BRDF( LightDirection, ViewDirection, NormalDirection, WorldTangent, WorldBinormal ), 1.0);
}
ENDCG
}
}
}
@[Przemyslaw_Zaworski]( Disney Principled BRDF shader members/przemyslaw_zaworski.1409771/),Thank you.it very helpful.I should check my code according to it