Unity通过Shader遮罩实现边缘羽化和异形视频播放

使用SpriteRenderer播放视频时，自定制遮罩形状，实现羽化边缘，异形视频效果，并可跟随SpriteRenderer修改颜色和透明度

Shader "Custom/VideoMask_SpriteRenderer"
{
	Properties
	{
		[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
		_Mask("Mask(RGB)", 2D) = "white" {}

		_Color("Tint", Color) = (1,1,1,1)
		_StencilComp("Stencil Comparison", Float) = 8
		_Stencil("Stencil ID", Float) = 0
		_StencilOp("Stencil Operation", Float) = 0
		_StencilWriteMask("Stencil Write Mask", Float) = 255
		_StencilReadMask("Stencil Read Mask", Float) = 255
		_ColorMask("Color Mask", Float) = 15
		[Toggle(UNITY_UI_ALPHACLIP)] _UseUIAlphaClip("Use Alpha Clip", Float) = 0
	}

	SubShader
	{
		Tags
		{
			"Queue" = "Transparent"
			"IgnoreProjector" = "True"
			"RenderType" = "Transparent"
			"PreviewType" = "Plane"
			"CanUseSpriteAtlas" = "True"
		}

		Stencil
		{
			Ref[_Stencil]
			Comp[_StencilComp]
			Pass[_StencilOp]
			ReadMask[_StencilReadMask]
			WriteMask[_StencilWriteMask]
		}

		Cull Off
		Lighting Off
		ZWrite Off
		ZTest[unity_GUIZTestMode]
		Blend SrcAlpha OneMinusSrcAlpha
		ColorMask[_ColorMask]

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag

			#include "UnityCG.cginc"
			#include "UnityUI.cginc"

			#pragma multi_compile __ UNITY_UI_ALPHACLIP

			struct a2v
			{
				fixed2 uv : TEXCOORD0;
				half4 vertex : POSITION;
				float4 color    : COLOR;
			};

			fixed4 _Color;

			struct v2f
			{
				fixed2 uv : TEXCOORD0;
				half4 vertex : SV_POSITION;
				float4 color    : COLOR;
			};

			sampler2D _MainTex;
			sampler2D _Mask;

			v2f vert(a2v i)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(i.vertex);
				o.uv = i.uv;

				o.color = i.color * _Color;
				return o;
			}

			fixed4 frag(v2f i) : COLOR
			{
				half4 color = tex2D(_MainTex, i.uv) * i.color;
				half4 mask = tex2D(_Mask, i.uv);
				color.a *= mask.a;
				return color;
			}
			ENDCG
		}
	}
}