Unity shader学习之屏幕后期处理效果之边缘检测

边缘检测的原理是利用一些边缘检测算子对图像进行卷积操作。

转载请注明出处：http://www.cnblogs.com/jietian331/p/7232707.html

例如：

代码如下：

 1 using UnityEngine;
 2 
 3 public class EdgeDetectRenderer : PostEffectRenderer
 4 {
 5     [SerializeField]
 6     Color m_edgeColor;
 7 
 8     protected override void OnRenderImage(RenderTexture src, RenderTexture dest)
 9     {
10         base.Mat.SetColor("_EdgeColor", m_edgeColor);
11         base.OnRenderImage(src, dest);
12     }
13 
14     protected override string ShaderName
15     {
16         get { return "Custom/Edge Detect"; }
17     }
18 }

EdgeDetectRenderer

shader如下：

 1 // Upgrade NOTE: replaced 'mul(UNITY_MATRIX_MVP,*)' with 'UnityObjectToClipPos(*)'
 2 
 3 Shader "Custom/Edge Detect"
 4 {
 5     Properties
 6     {
 7         _MainTex("Main Texture", 2D) = "white" {}
 8         _EdgeColor("Edge Color", Color) = (1,1,1,1)
 9     }
10 
11     SubShader
12     {
13         Pass
14         {
15             Cull Off
16             ZWrite Off
17             ZTest Always
18 
19             CGPROGRAM
20             #pragma vertex vert
21             #pragma fragment frag
22 
23             sampler2D _MainTex;
24             float4 _MainTex_TexelSize;
25             uniform fixed4 _EdgeColor;
26 
27             struct appdata
28             {
29                 float4 vertex : POSITION;
30                 float2 uv : TEXCOORD0;
31             };
32 
33             struct v2f
34             {
35                 float4 pos : SV_POSITION;
36                 half2 uv[9] : TEXCOORD0;
37             };
38 
39             v2f vert(appdata v)
40             {
41                 v2f o;
42                 o.pos = UnityObjectToClipPos(v.vertex);
43                 o.uv[0] = v.uv + _MainTex_TexelSize.xy * half2(-1, 1);
44                 o.uv[1] = v.uv + _MainTex_TexelSize.xy * half2(0, 1);
45                 o.uv[2] = v.uv + _MainTex_TexelSize.xy * half2(1, 1);
46                 o.uv[3] = v.uv + _MainTex_TexelSize.xy * half2(-1, 0);
47                 o.uv[4] = v.uv + _MainTex_TexelSize.xy * half2(0, 0);
48                 o.uv[5] = v.uv + _MainTex_TexelSize.xy * half2(1, 0);
49                 o.uv[6] = v.uv + _MainTex_TexelSize.xy * half2(-1, -1);
50                 o.uv[7] = v.uv + _MainTex_TexelSize.xy * half2(0, -1);
51                 o.uv[8] = v.uv + _MainTex_TexelSize.xy * half2(1, -1);
52                 return o;
53             }
54 
55             float luminance(float3 color)
56             {
57                 return dot(fixed3(0.2125, 0.7154, 0.0721), color);
58             }
59 
60             half sober(half2 uvs[9])
61             {
62                 half gx[9] = {    -1, 0, 1,
63                                 -2, 0, 2,
64                                 -1, 0, 1};
65                 half gy[9] = {    -1, -2, -1,
66                                 0, 0, 0,
67                                 1, 2, 1};
68 
69                 float edgeX = 0;
70                 float edgeY = 0;
71 
72                 for(int i = 0; i < 9; i++)
73                 {
74                     fixed3 c = tex2D(_MainTex, uvs[i]).rgb;
75                     float l = luminance(c);
76                     edgeX += l * gx[i];
77                     edgeY += l * gy[i];
78                 }
79 
80                 return abs(edgeX) + abs(edgeY);
81             }
82 
83             fixed4 frag(v2f i) : SV_TARGET
84             {
85                 half edge = sober(i.uv);
86                 fixed4 tex = tex2D(_MainTex, i.uv[4]);
87                 return lerp(tex, _EdgeColor, edge);
88             }
89             
90             ENDCG
91         }
92     }
93     
94     Fallback Off
95 }

View Code

效果如下：