Shader "BetterUI/Grayscale"
{
	Properties
	{
		[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
		_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

		SrcBlendMode("SrcBlendMode", Float) = 5
		DstBlendMode("DstBlendMode", Float) = 10

		[Toggle(COMBINE_ALPHA)] CombineAlpha("Combine Alpha", Float) = 0
		[Toggle(FORCE_CLIP)] ForceClip("Force Clip", Float) = 0
		ClipThreshold("Alpha Clip Threshold", Float) = 0.5
	}

	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[SrcBlendMode][DstBlendMode]
		ColorMask[_ColorMask]

		Pass
		{
			Name "Grayscale"
			CGPROGRAM

	#pragma vertex vert
	#pragma fragment frag
	#pragma target 2.0
	#include "UnityCG.cginc"
	#include "UnityUI.cginc"
	#pragma multi_compile __ UNITY_UI_ALPHACLIP
	#pragma multi_compile __ COMBINE_ALPHA
	#pragma multi_compile __ FORCE_CLIP

		struct appdata_t
		{
			float4 vertex   : POSITION;
			float4 color    : COLOR;
			float2 texcoord : TEXCOORD0;
			float2 uv1      : TEXCOORD1; 
#if UNITY_VERSION >= 550
				UNITY_VERTEX_INPUT_INSTANCE_ID
#endif
		};
		
		struct v2f
		{
			float4 vertex   : SV_POSITION;
			fixed4 color : COLOR;
			float2 texcoord  : TEXCOORD0;
			float4 worldPosition	: TEXCOORD1;
			float2 amount      : TEXCOORD2;
#if UNITY_VERSION >= 550
			UNITY_VERTEX_OUTPUT_STEREO
#endif
		};
		
		fixed4 _TextureSampleAdd;
		float4 _ClipRect;
#if UNITY_VERSION < 550
		bool _UseClipRect;
		bool _UseAlphaClip;
		bool CombineAlpha;
		bool ForceClip;

#endif
		
		// VERTEX SHADER
		v2f vert(appdata_t IN)
		{
			v2f OUT;
	#if UNITY_VERSION >= 550
			UNITY_SETUP_INSTANCE_ID(IN);
			UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
	#endif
			OUT.worldPosition = IN.vertex;
#if UNITY_VERSION >= 550
			OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
#else
			OUT.vertex = UnityObjectToClipPos(OUT.worldPosition);
#ifdef UNITY_HALF_TEXEL_OFFSET
			OUT.vertex.xy += (_ScreenParams.zw - 1.0) * float2(-1, 1);
#endif
#endif
			OUT.texcoord = IN.texcoord;
			OUT.color = IN.color;
			OUT.amount = IN.uv1;
			return OUT;
		}
		
		sampler2D _MainTex;
		float ClipThreshold;

		// FRAGMENT SHADER
		fixed4 frag(v2f IN) : SV_Target
		{
			half4 origColor = (tex2D(_MainTex, IN.texcoord) + _TextureSampleAdd) * IN.color;
			half4 greyColor = dot(origColor.rgb, float3(0.3, 0.59, 0.11));
			half4 color = lerp(origColor, greyColor, IN.amount.x);
			color.a = origColor.a;

#if UNITY_VERSION >= 550
	#ifdef COMBINE_ALPHA
			color.rgb *= color.a;
	#endif
	#ifdef FORCE_CLIP
			clip(color.a - ClipThreshold);
	#endif
#else
			if (CombineAlpha)
				color.rgb *= color.a;

			if (ForceClip)
				clip(color.a - ClipThreshold);
#endif

#if UNITY_VERSION >= 550
			color.a *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);
	#ifdef UNITY_UI_ALPHACLIP
			clip(color.a - 0.001);
	#endif
#else
			if (_UseClipRect)
				color *= UnityGet2DClipping(IN.worldPosition.xy, _ClipRect);		if (_UseAlphaClip)
				clip(color.a - 0.001);

#endif
			return color;
		}
		ENDCG
		}
	}
}