Shader "UI/Greyscale"
{
	Properties
	{
		[PerRendererData] _MainTex("Sprite 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

		_EffectAmount("Effect Amount", Range(0, 1)) = 1.0
		_BrightnessAmount("Brightness Amount", Range(0.0, 3)) = 1.0

		_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"
				#include "UnityUI.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;
					float4 worldPosition : TEXCOORD1;
				};

				fixed4 _Color;
				fixed4 _TextureSampleAdd;

				bool _UseClipRect;
				float4 _ClipRect;

				bool _UseAlphaClip;
				uniform float _EffectAmount;
				uniform float _BrightnessAmount;

				v2f vert(appdata_t IN)
				{
					v2f OUT;
					OUT.worldPosition = IN.vertex;
					OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);

					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;

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

					if (_UseClipRect)
						color *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);

					if (_UseAlphaClip)
						clip(color.a - 0.001);

					float3 brtColor = color.rgb * _BrightnessAmount;
					color.rgb = lerp(brtColor, dot(brtColor, float3(0.3, 0.59, 0.11)), _EffectAmount);
					return color;
				}
			ENDCG
			}
		}
			FallBack "UI/Default"
}