CG之菲涅尔效果简单实现

 1 Shader "Custom/Test"
 2 {
 3     Properties
 4     {
 5         _Cube("Cube", Cube) = "white" {}
 6         _EtaRatio("Eta ratio", float) = 0.8
 7         _FresnelPower("Fresnel power", float) = 2
 8         _FresnelScale("Fresnel scale", float) = 1
 9         _FresnelBias("Fresnel bias", float) = 0
10     }
11 
12     SubShader
13     {
14         Tags
15         {
16             "RenderType" = "Opaque"
17         }
18 
19         Pass
20         {
21             CGPROGRAM
22             #pragma vertex Vert
23             #pragma fragment Frag
24 
25             uniform samplerCUBE _Cube;
26             uniform float _EtaRatio;
27             uniform float _FresnelPower;
28             uniform float _FresnelScale;
29             uniform float _FresnelBias;
30 
31             struct AppData
32             {
33                 float4 pos : POSITION;
34                 float3 nor : NORMAL;
35             };
36 
37             struct V2F
38             {
39                 float4 pos : SV_POSITION;
40                 float reflectionFactor : Color;
41                 float3 r : TEXCOORD0;
42                 float3 t : TEXCOORD1;
43             };
44 
45             V2F Vert(AppData vi)
46             {
47                 V2F fi;
48                 fi.pos = mul(UNITY_MATRIX_MVP, vi.pos);
49 
50                 float3 worldPos = mul(_Object2World, vi.pos.xyz);
51                 float3 n = mul(_Object2World, vi.nor);
52                 float3 i = worldPos - _WorldSpaceCameraPos.xyz;
53                 fi.r = reflect(i, n);
54 
55                 i = normalize(i);
56                 n = normalize(n);
57                 fi.t = refract(i, n, _EtaRatio);
58 
59                 fi.reflectionFactor = _FresnelBias + _FresnelScale * pow(1 + dot(i, n), _FresnelPower);
60 
61                 return fi;
62             }
63 
64             float4 Frag(V2F fi) : Color
65             {
66                 float4 reflectC = texCUBE(_Cube, fi.r);
67                 float4 refractC = texCUBE(_Cube, fi.t);
68                 return lerp(refractC, reflectC, fi.reflectionFactor);
69             }
70 
71             ENDCG
72         }
73     }
74 }