Unity Shader: Cook-Torrance

// 原公式来自于 GPU 编程与CG 语言之阳春白雪下里巴人 的 114页的（10-11）。公式中的分母少了个 （N·L），具体看 113 页的公式（10-3）。

 1 Shader "Custom/Cook-Torrance" {
    Properties {
        _MainTex("Main Tex", 2D) = "white" {}
        _AmbiColor ("Main Color", Color) = (1, 1, 1, 1)
        _Ak ("Ambient Coef", float) = 1
        _DiffColor ("Diff Color", Color) = (1, 1, 1, 1)
        _Dk ("Diff Coef", float) = 1
        _SpecColor ("Spec Color", Color) = (1, 1, 1, 1)
        _Sk ("Sk", float) = 1
        // _Sp ("Sp", Range(0, 5)) = 1
        _m ("m", Range(0, 1)) = 0.1
        _f0 ("f0", Range(0, 1)) = 0.5
    }

    SubShader {
        Tags { "RenderType"="Opaque" }
        LOD 200
        Pass {
            CGPROGRAM
            #include "UnityCG.cginc"
            #pragma vertex vert
            #pragma fragment frag

            float4 _AmbiColor;
            float _Ak;
            float4 _DiffColor;
            float _Dk;
            float4 _SpecColor;
            float _Sk;
            // float _Sp;
            float _m;
            float _f0;

            sampler2D _MainTex;

            struct v2f {
                float4 pos : POSITION;
                float2 uv : TEXCOORD0;
                float3 light : TEXCOORD1;
                float3 view : TEXCOORD2;
                float3 normal : TEXCOORD3;
            };

            v2f vert(appdata_base v) {
                v2f o;
                o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                o.normal = v.normal;
                o.light = ObjSpaceLightDir(v.vertex);
                o.view = ObjSpaceViewDir(v.vertex);
                o.uv = v.texcoord;

                return o;
            }

            float4 frag(v2f i) : COLOR {
                float3 l = normalize(i.light);
                float3 v = normalize(i.view);
                float3 n = normalize(i.normal);
                float3 h = normalize(l + v);

                float vh = dot(v, h);
                float nh = dot(n, h);
                float nl = dot(n, l);
                float nv = dot(n, v);

                float4 t = tex2D(_MainTex, i.uv);

                float4 ambi = _AmbiColor * _Ak;
                float4 diff = _DiffColor * _Dk * saturate(nl);

                if (nh <= 0 || nl <= 0)
                    return t * ambi + diff;

                float F = _f0 + (1 - _f0) * (1 - pow(vh, 5));
                float D = exp((nh * nh - 1) / (_m * _m * nh * nh)) / (_m * _m * pow(nh, 4));
                float G = min(1, min(2 * nh * nl / vh, 2 * nh * nv / vh));

                float R = F * D * G / (nv * nl);

                float spec = _SpecColor * _Sk * R * nl;

                return t * ambi + diff + spec;
            }

            ENDCG
        }
    } 
88     FallBack "Diffuse"
89 }

 效果如下：