Rim 边缘光

边缘光：计算眼睛和模型顶点法线的点积，结果作为强度，和材质输出；顶点和法线平行时，强度最大，垂直时，强度最小。因此将他取反，即同一方向时，强度最小，垂直时，强度最大。

float rim= -dot(normalize(viewDirection),normalDirection);

源代码：

 Shader "JQM/Rim_1"
 {
     Properties
     {
         _Color("Color", color) = (1.0,1.0,1.0,1.0)
         _SpecColor("Specular Color", color) = (1.0,1.0,1.0,1.0)
         _Shininess("Shininess",float) =
         _RimColor("Rim Coloe Color", color) = (1.0,1.0,1.0,1.0)
         _RimPower("Rim Power",Range(0.1,10.0)) = 3.0

     }
     SubShader{
         Pass{

             Tags { "LightMode" = "ForwardBase"}

             CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag

             //使用自定义变量
             uniform float4 _Color;
             uniform float4 _SpecColor;
             uniform float4 _RimColor;
             uniform float _Shininess;
             uniform float _RimPower;

             //使用Unity定义的变量
             uniform float4 _LightColor0;

             struct vertexInput{
                 float4 vertex:POSITION;
                 float3 normal:NORMAL;
             };

             struct vertexOutput{
                 float4 pos:SV_POSITION;
                 float4 posWorld:TEXCOORD0;
                 float3 normalDir:TEXCOORD1;
             };

             //顶点程序
             vertexOutput vert(vertexInput v)
             {
                 vertexOutput o;
                 o.posWorld = mul(_Object2World, v.vertex);
                 o.normalDir =  normalize( mul(float4(v.normal,0.0),_World2Object).xyz);
                 o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
                 return o;
             }

             //片段程序
             float4 frag(vertexOutput i):COLOR
             {
                 float3 normalDirection = i.normalDir;
                 float3 viewDirection = normalize(_WorldSpaceCameraPos.xyz- i.posWorld.xyz);

                 float rim= -dot(normalize(viewDirection),normalDirection);
                 return float4(rim*_Color.xyz,1.0);
             }

             ENDCG
         }
     }

 }