基本思路：Shader用兩個Pass，一個渲染描邊部分，一個渲染物體部分。

Pass1：剔除正面，渲染背面，把頂點延法線方向外圍擴充套件一定寬度，用來表現描邊的粗細，這部分用自己設定的顏色。

Pass2：剔除背面，渲染正面，正常渲染所看到的物體模型。

  1 // Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'mul(UNITY_MATRIX_MVP,*)'
  2 
  3 Shader "xj/ModelEffect/Outline" {
  4     Properties {
  5         _Color ("
 
模型顏色", Color) = (1,1,1,1)
  6         _OutlineColor ("描邊顏色", Color) = (1,0,0,1)
  7         _Outline ("描邊寬度", float) = 0.03
  8         _MainTex ("模型貼圖", 2D) = "white" {}
  9         _AlphaTex ("Alpha (A)", 2D) = "white" {}
 10         _intensity ("強度", float ) = 1.0
 11     }
 12  
 13     CGINCLUDE
 
 14         #include "UnityCG.cginc"
 15  
 16         struct appdata {
 17             float4 vertex : POSITION;
 18             float3 normal : NORMAL;
 19             half2 texcoord : TEXCOORD0;
 20         };
 21  
 22         struct v2f {
 23             float4 pos : SV_POSITION;
 24             fixed4 color : COLOR;
 
 25             half2 texcoord : TEXCOORD0;
 26         };
 27 
 28         struct basevt {
 29             float4 pos : SV_POSITION;
 30             half2 texcoord : TEXCOORD0;
 31         };
 32  
 33         sampler2D _MainTex;
 34         sampler2D _AlphaTex;
 35         uniform fixed _Outline;
 36         uniform fixed4 _OutlineColor;
 37         uniform fixed4 _Color;
 38         fixed _intensity;
 39  
 40         v2f outline_vert(appdata v) 
 41         {
 42             //在vertex階段，每個頂點按照法線的方向偏移一部分，不過這種會造成近大遠小的透視問題
 43             //正確的做法是轉換到投影空間下做偏移
 44             //v.vertex.xyz += v.normal * _Outline;
 45 
 46             v2f o;
 47             o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
 48             float3 norm = mul ((float3x3)UNITY_MATRIX_IT_MV, v.normal);
 49             float2 offset = TransformViewToProjection(norm.xy);
 50             o.pos.xy += offset * _Outline;
 51             o.color = _OutlineColor;
 52             o.texcoord = v.texcoord;
 53             return o;
 54         }
 55 
 56         fixed4 outline_frag(v2f i): SV_Target
 57         {
 58             fixed4 color = i.color;
 59             color.a = tex2D(_AlphaTex, i.texcoord).a;
 60             return color;
 61         }
 62 
 63         basevt base_vert(appdata v)
 64         {
 65             basevt o;
 66             o.pos = mul(UNITY_MATRIX_MVP,v.vertex);
 67             o.texcoord = v.texcoord;
 68             return o;
 69         }
 70 
 71         fixed4 base_frag(basevt i): SV_Target
 72         {
 73             fixed4 col = tex2D(_MainTex, i.texcoord) * _Color * _intensity;
 74             col.a = tex2D(_AlphaTex, i.texcoord).a * _Color.a;
 75             return col;
 76         }    
 77     ENDCG
 78  
 79     SubShader {
 80         Tags { "Queue" = "Transparent" "IgnoreProjector"="True" "RenderType"="Transparent"}
 81         Fog {Mode Off}
 82 
 83         Pass 
 84         {
 85             Name "OUTLINE"
 86             Cull Front //剔除正面
 87             CGPROGRAM
 88 
 89             #pragma vertex outline_vert
 90             #pragma fragment outline_frag
 91             #pragma fragmentoption ARB_precision_hint_fastest
 92          
 93             ENDCG
 94         }
 95  
 96         Pass 
 97         {
 98             Name "BASE"
 99             Cull Back //剔除背面
100             CGPROGRAM
101 
102             #pragma vertex base_vert
103             #pragma fragment base_frag
104             #pragma fragmentoption ARB_precision_hint_fastest
105          
106             ENDCG
107         }
108     }
109     FallBack "xj/Default"
110 }