本例適用於 UGUI

一般專案中會有一些圖示，當你擁有該圖示顯示為彩色圖示，一般專案中最佔資源的就是圖片，不允許新增一張彩色圖片，一張灰色圖片，必須通過一些方法將彩色圖示的顏色去掉，獲取圖示的灰色值。

UGUI 自帶了一個Shader， Sprites/Default, 預設給了一個新增該Shader 的材質球

 1 Shader "UISprites/DefaultGray"
 2 {
 3     Properties
 4     {
 5         [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
 6         _Color ("
 
Tint", Color) = (1,1,1,1)
 7         [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
 8 
 9         //---Add---
10         // Change the brightness of the Sprite
11         _GrayScale ("GrayScale", Float) = 1
12         //---Add---
13     }
14 
15     SubShader
16     {
17         Tags
18         { 
19
 
             "Queue"="Transparent" 
20             "IgnoreProjector"="True" 
21             "RenderType"="Transparent" 
22             "PreviewType"="Plane"
23             "CanUseSpriteAtlas"="True"
24         }
25 
26         Cull Off
27         Lighting Off
28         ZWrite Off
29         Blend One OneMinusSrcAlpha
 
30 
31         Pass
32         {
33         CGPROGRAM
34             #pragma vertex vert
35             #pragma fragment frag
36             #pragma multi_compile _ PIXELSNAP_ON
37             #include "UnityCG.cginc"
38 
39             struct appdata_t
40             {
41                 float4 vertex   : POSITION;
42                 float4 color    : COLOR;
43                 float2 texcoord : TEXCOORD0;
44             };
45 
46             struct v2f
47             {
48                 float4 vertex   : SV_POSITION;
49                 fixed4 color    : COLOR;
50                 half2 texcoord  : TEXCOORD0;
51             };
52 
53             fixed4 _Color;
54 
55             v2f vert(appdata_t IN)
56             {
57                 v2f OUT;
58                 OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
59                 OUT.texcoord = IN.texcoord;
60                 OUT.color = IN.color * _Color;
61                 #ifdef PIXELSNAP_ON
62                 OUT.vertex = UnityPixelSnap (OUT.vertex);
63                 #endif
64 
65                 return OUT;
66             }
67 
68             sampler2D _MainTex;
69             float _GrayScale;
70 
71             fixed4 frag(v2f IN) : SV_Target
72             {
73                 fixed4 c = tex2D(_MainTex, IN.texcoord) * IN.color;
74 
75                 //---Add--
76                 float cc = (c.r * 0.299 + c.g * 0.518 + c.b * 0.184);
77                 cc *= _GrayScale;
78                 c.r = c.g = c.b = cc;
79                 //---Add--
80 
81                 c.rgb *= c.a;
82                 return c;
83             }
84         ENDCG
85         }
86     }
87 }