Shader "MoleGame/Particles/Overlay"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_TintColor("Tint Color", Color) = (0.5,0.5,0.5,0.5)
		_Threshold("Threshold", Range(0.0,0.99)) = 0.5

		_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"}

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

		ZTest[unity_GUIZTestMode]
		ColorMask[_ColorMask]

		Blend SrcAlpha One
		Cull Off Lighting Off ZWrite Off
		
		LOD 100

		Pass
		{
			CGPROGRAM
			#pragma vertex vert
			#pragma fragment frag
			 #pragma target 2.0
			
			#include "UnityCG.cginc"
			#include "UnityUI.cginc"

			#pragma multi_compile __ UNITY_UI_CLIP_RECT
			#pragma multi_compile __ UNITY_UI_ALPHACLIP

			struct appdata
			{
				float4 vertex : POSITION;
				fixed4 color : COLOR;
				float2 uv : TEXCOORD0;
				UNITY_VERTEX_INPUT_INSTANCE_ID
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				fixed4 color : COLOR;
				float4 vertex : SV_POSITION;
				float4 worldPosition : TEXCOORD1;
				UNITY_VERTEX_OUTPUT_STEREO
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			half4 _TintColor;
			half _Threshold;
			float4 _ClipRect;

			v2f vert (appdata v)
			{
				v2f o;
				UNITY_SETUP_INSTANCE_ID(v);
				UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(o);
				o.worldPosition = v.vertex;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.color = v.color;
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				// sample the texture
				fixed4 col = tex2D(_MainTex, i.uv) * i.color;
				float a = col.a * i.color.a;
				col = 2*lerp(col*_TintColor, col, (col.r - _Threshold)/ (1-_Threshold));
				col.a = a;

				#ifdef UNITY_UI_CLIP_RECT
				col.a *= UnityGet2DClipping(i.worldPosition.xy, _ClipRect);
				#endif
				#ifdef UNITY_UI_ALPHACLIP
				clip(col.a - 0.001);
				#endif
				return col;
			}
			ENDCG
		}
	}
}