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

	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"

			struct appdata_t
			{
				float4 vertex   : POSITION;
				float4 color    : COLOR;
				float2 texcoord : TEXCOORD0;
			};

			struct v2f
			{
				float4 vertex   : SV_POSITION;
				fixed4 color : COLOR;
				half2 texcoord  : TEXCOORD0;
			};

			fixed4 _Color;


			v2f vert(appdata_t IN)
			{
				v2f OUT;
				OUT.vertex = mul(UNITY_MATRIX_MVP, IN.vertex);
				OUT.texcoord = IN.texcoord;
		#ifdef UNITY_HALF_TEXEL_OFFSET
				OUT.vertex.xy += (_ScreenParams.zw - 1.0)*float2(-1,1);
		#endif
				OUT.color = IN.color * _Color;
				return OUT;
			}

			sampler2D _MainTex;
			sampler2D _MaskTex;

			fixed4 frag(v2f IN) : SV_Target
			{
				half4 color = tex2D(_MainTex, IN.texcoord) * IN.color;
				half4 mask = tex2D(_MaskTex, IN.texcoord);

				color.a *= mask.r;
				clip(color.a - 0.01);
				return color;
			}

		ENDCG
		}
	}
}