Unity Shader实现描边OutLine效果

Shader "Custom/OutlineShader" {
 Properties {
 _MainTex ("Albedo (RGB)", 2D) = "white" {}
 _OutLineWidth("width", float) = 1.2//定义一个变量
 }
 SubShader {
 
 Pass
 {
 CGPROGRAM 
 #pragma vertex vert
 #pragma fragment frag
 #include "UnityCG.cginc"
 
 struct appdata {
 float4 vertex:POSITION;
 float2 uv:TEXCOORD0;
 };
 
 struct v2f
 {
 float2 uv :TEXCOORD0;
 float4 vertex:SV_POSITION;
 };
 
 
 float _OutLineWidth;//设置变量
 v2f vert(appdata v)
 {
 v2f o;
 //设置一下xy
 //v.vertex.xy *= 1.1;
 v.vertex.xy *= _OutLineWidth;//乘上变量
 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
 o.uv = v.uv;
 return o;
 }
 
 sampler2D _MainTex;
 
 fixed4 frag(v2f i) :SV_Target
 {
 fixed4 col = tex2D(_MainTex, i.uv);
 //return col;
 return fixed4(0, 0, 1, 1);
 }
 ENDCG
 }
 
 
 Pass
 {
 ZTest Always
 CGPROGRAM
 #pragma vertex vert
 #pragma fragment frag
 #include "UnityCG.cginc"
 
 struct appdata {
 float4 vertex:POSITION;
 float2 uv:TEXCOORD0;
 };
 
 struct v2f
 {
 float2 uv :TEXCOORD0;
 float4 vertex:SV_POSITION;
 };
 
 
 v2f vert(appdata v)
 {
 v2f o;
 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
 o.uv = v.uv;
 return o;
 }
 
 sampler2D _MainTex;
 
 fixed4 frag(v2f i) :SV_Target
 {
 fixed4 col = tex2D(_MainTex, i.uv);
 //return fixed4(0, 0, 1, 1);//返回蓝色，因为再次渲染会把第一个颜色覆盖掉
 return col;
 }
 ENDCG
 }
 } 
 FallBack "Diffuse"
}