// Author: Blastom
// 仅用于摄像机拍摄UI面板的RenderTexture
// 该材质会向颜色Buffer中写入Alpha值，因此不会在没有背景时被剔除
Shader "Zhanyou/Particles/AlphaBlendMask" 
{
Properties {
	_TintColor ("Tint Color", Color) = (0.5,0.5,0.5,0.5)
	_MainTex ("Particle Texture", 2D) = "white" {}
	_MaskTex ("Mask Texture", 2D) = "white" {}
}

Category {
	Tags { "Queue"="Transparent" "IgnoreProjector"="True" "RenderType"="Transparent" "PreviewType"="Plane" }
	Blend one OneMinusSrcAlpha

	Cull Off
	Lighting Off
	ZWrite Off

	SubShader {
		Pass {
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			#pragma target 2.0
			#pragma multi_compile_fog
			
			#include "UnityCG.cginc"
            #include "UnityUI.cginc"
			
			uniform fixed4 _TintColor;
			uniform sampler2D _MainTex;
			uniform float4 _MainTex_ST;
			uniform sampler2D _MaskTex;
			uniform float4 _MaskTex_ST;
			
			struct appdata_t
			{
				float4 vertex : POSITION;
				fixed4 color : COLOR;
				float2 texcoord : TEXCOORD0;
			};

			struct v2f
			{
				float4 vertex : SV_POSITION;
				fixed4 color : COLOR;
				float2 uv0 : TEXCOORD0;
				float2 uv1 : TEXCOORD1;
				UNITY_FOG_COORDS(2)
			};

			v2f vert (appdata_t v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.color = v.color;
				o.uv0 = TRANSFORM_TEX(v.texcoord, _MainTex);
				o.uv1 = TRANSFORM_TEX(v.texcoord, _MaskTex);
				UNITY_TRANSFER_FOG(o, o.vertex);
				return o;
			}

			fixed4 frag (v2f i) : SV_Target
			{
				fixed4 maskCol = tex2D(_MaskTex, i.uv1);
				fixed4 col = i.color * _TintColor * fixed4(tex2D(_MainTex, i.uv0).rgb,maskCol.a) * 2.0;
				col.a = clamp(col.a, 0, 1);
				UNITY_APPLY_FOG(i.fogCoord, col);
				col.rgb *= col.a;
				return col;
			}
			ENDCG 
		}
	}	
}
}