场景设计

Assets/OtherPlugins/ChocDino/UIFX/Runtime/Shaders/Resources/Composite.shader

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+Shader "Hidden/ChocDino/UIFX/Composite"
+{
+	Properties
+	{
+		[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
+	}
+
+	CGINCLUDE
+	
+	#include "UnityCG.cginc"
+	#include "UnityUI.cginc"
+	#include "ColorUtils.cginc"
+
+	struct appdata
+	{
+		float4 vertex : POSITION;
+		float2 uv : TEXCOORD0;
+	};
+
+	struct v2f
+	{
+		float4 vertex : SV_POSITION;
+		float2 uv : TEXCOORD0;
+	};
+
+	sampler2D _MainTex;
+	float4 _MainTex_ST;
+
+	v2f vert (appdata v)
+	{
+		v2f o;
+		o.vertex = UnityObjectToClipPos(v.vertex);
+		o.uv = TRANSFORM_TEX(v.uv, _MainTex);
+		return o;
+	}
+
+	float4 frag(v2f i) : SV_Target
+	{
+		// NOTE: Since the UI element was rendered to a black target, the RGB values are now effectively pre-multiplied by alpha
+		float4 col = tex2D(_MainTex, i.uv);
+
+		// NOTE: We have to sqrt the alpha channel to reverse the effects of alpha blending because alpha blending causes the written to a zero dst alpha channel to be squared.
+		// Luckily this is only an issue before Unity 2020.1.0 where they changed UI rendering to use premultiplied alpha.
+		// However still not sure how this would play with custom UI rendering if other blend modes are used.
+		col.a = sqrt(col.a);
+
+		return col;
+	}
+
+	ENDCG
+
+	SubShader
+	{
+		Tags
+		{
+			"Queue"="Transparent"
+			"IgnoreProjector"="True"
+			"RenderType"="Transparent"
+			"PreviewType"="Plane"
+			"CanUseSpriteAtlas"="True"
+			"OutputsPremultipliedAlpha"="True"
+		}
+
+		Cull Off
+		ZWrite Off
+		ZTest Always
+		Blend One OneMinusSrcAlpha // Premultiplied transparency
+
+		Pass
+		{
+			Name "Composite-FromAlphaBlended-ToPremultiplied"
+			CGPROGRAM
+			#pragma vertex vert
+			#pragma fragment frag
+			ENDCG
+		}
+	}
+}