[UnityShader基础]08.UI-Default.shader

参考链接：

https://zhuanlan.zhihu.com/p/32561155

https://blog.csdn.net/WuShangLZ/article/details/80401441

https://www.jianshu.com/p/2d98fad196d2

内置shader下载方法：

https://jingyan.baidu.com/article/63acb44a1f598161fcc17efa.html

unity版本：2018.3.8f1

内置UI-Default.shader：

  1 // Unity built-in shader source. Copyright (c) 2016 Unity Technologies. MIT license (see license.txt)
  2 
  3 Shader "UI/Default"
  4 {
  5     Properties
  6     {
  7         [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
  8         _Color ("Tint", Color) = (1,1,1,1)
  9 
 10         _StencilComp ("Stencil Comparison", Float) = 8
 11         _Stencil ("Stencil ID", Float) = 0
 12         _StencilOp ("Stencil Operation", Float) = 0
 13         _StencilWriteMask ("Stencil Write Mask", Float) = 255
 14         _StencilReadMask ("Stencil Read Mask", Float) = 255
 15 
 16         _ColorMask ("Color Mask", Float) = 15
 17 
 18         [Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip ("Use Alpha Clip", Float) = 0
 19     }
 20 
 21     SubShader
 22     {
 23         Tags
 24         {
 25             "Queue"="Transparent"
 26             "IgnoreProjector"="True"
 27             "RenderType"="Transparent"
 28             "PreviewType"="Plane"
 29             "CanUseSpriteAtlas"="True"
 30         }
 31 
 32         Stencil
 33         {
 34             Ref [_Stencil]
 35             Comp [_StencilComp]
 36             Pass [_StencilOp]
 37             ReadMask [_StencilReadMask]
 38             WriteMask [_StencilWriteMask]
 39         }
 40 
 41         Cull Off
 42         Lighting Off
 43         ZWrite Off
 44         ZTest [unity_GUIZTestMode]
 45         Blend SrcAlpha OneMinusSrcAlpha
 46         ColorMask [_ColorMask]
 47 
 48         Pass
 49         {
 50             Name "Default"
 51         CGPROGRAM
 52             #pragma vertex vert
 53             #pragma fragment frag
 54             #pragma target 2.0
 55 
 56             #include "UnityCG.cginc"
 57             #include "UnityUI.cginc"
 58 
 59             #pragma multi_compile __ UNITY_UI_CLIP_RECT
 60             #pragma multi_compile __ UNITY_UI_ALPHACLIP
 61 
 62             struct appdata_t
 63             {
 64                 float4 vertex   : POSITION;
 65                 float4 color    : COLOR;
 66                 float2 texcoord : TEXCOORD0;
 67                 UNITY_VERTEX_INPUT_INSTANCE_ID
 68             };
 69 
 70             struct v2f
 71             {
 72                 float4 vertex   : SV_POSITION;
 73                 fixed4 color    : COLOR;
 74                 float2 texcoord  : TEXCOORD0;
 75                 float4 worldPosition : TEXCOORD1;
 76                 UNITY_VERTEX_OUTPUT_STEREO
 77             };
 78 
 79             sampler2D _MainTex;
 80             fixed4 _Color;
 81             fixed4 _TextureSampleAdd;
 82             float4 _ClipRect;
 83             float4 _MainTex_ST;
 84 
 85             v2f vert(appdata_t v)
 86             {
 87                 v2f OUT;
 88                 UNITY_SETUP_INSTANCE_ID(v);
 89                 UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
 90                 OUT.worldPosition = v.vertex;
 91                 OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
 92 
 93                 OUT.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
 94 
 95                 OUT.color = v.color * _Color;
 96                 return OUT;
 97             }
 98 
 99             fixed4 frag(v2f IN) : SV_Target
100             {
101                 half4 color = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;
102 
103                 #ifdef UNITY_UI_CLIP_RECT
104                 color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
105                 #endif
106 
107                 #ifdef UNITY_UI_ALPHACLIP
108                 clip (color.a - 0.001);
109                 #endif
110 
111                 return color;
112             }
113         ENDCG
114         }
115     }
116 }

1.模板测试

UnityGet2DClipping的定义在UnityUI.cginc中：

1 inline float UnityGet2DClipping (in float2 position, in float4 clipRect)
2 {
3     float2 inside = step(clipRect.xy, position.xy) * step(position.xy, clipRect.zw);
4     return inside.x * inside.y;
5 }

step(a, x)：如果a>x，返回0；否则，返回1

clipRect：左下角为xy，右上角为zw

因此，也就是说，如果点不在clipRect中，则返回0