Shader "DashGame/Mask"
{
	Properties
	{
		_Color("Tint", Color) = (1,1,1,1)

		[MaterialToggle] PixelSnap("Pixel snap", Float) = 0
		[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
	}

	SubShader
	{
		Tags
		{
			"Queue" = "Transparent"
			"RenderType" = "Transparent"
			"PreviewType" = "Plane"
			"IgnoreProjector" = "True"
			"CanUseSpriteAtlas" = "True"
		}

		Cull Off
		ZWrite Off
		Lighting Off

		Pass
		{
			Blend SrcAlpha OneMinusSrcAlpha

			CGPROGRAM

			#pragma vertex vert
			#pragma fragment frag

			#pragma multi_compile _ PIXELSNAP_ON
			#pragma multi_compile _ ETC1_EXTERNAL_ALPHA

			#include "UnityCG.cginc"

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

			struct v2f
			{
				fixed4 color : COLOR;
				float4 vertex   : SV_POSITION;
				float2 texcoord  : TEXCOORD0;
				float4 screenPos   : TEXCOORD1;
			};

			float _Angle;
			float _RadiusX;
			float _RadiusY;
			float2 _Center;
			fixed4 _Color;
			sampler2D _MainTex;
			
			v2f vert(appdata_t IN)
			{
				v2f OUT;

				OUT.color = IN.color * _Color;
				OUT.vertex = UnityObjectToClipPos(IN.vertex);
				OUT.texcoord = IN.texcoord;
				OUT.screenPos = ComputeScreenPos(OUT.vertex);

				return OUT;
			}


			fixed4 SampleSpriteTexture(float2 uv)
			{
				fixed4 color = tex2D(_MainTex, uv);

				return color;
			}

			fixed4 frag(v2f i) : SV_Target
			{
				fixed4 col = SampleSpriteTexture(i.texcoord) * i.color;

				_Angle = _RadiusY / 4;

				float x = i.screenPos.x - _Center.x;
				float y = i.screenPos.y - _Center.y;

				if (abs(x) < _RadiusX && abs(y) < _RadiusY)
				{
					float2 ulo = _Center + float2(-_RadiusX, _RadiusY);
					float2 uli = ulo + float2(_Angle, -_Angle / (_ScreenParams.y / _ScreenParams.x));

					float2 uro = _Center + float2(_RadiusX, _RadiusY);
					float2 uri = uro + float2(-_Angle, -_Angle / (_ScreenParams.y / _ScreenParams.x));

					float2 lro = _Center + float2(_RadiusX, -_RadiusY);
					float2 lri = lro + float2(-_Angle, _Angle / (_ScreenParams.y / _ScreenParams.x));

					float2 llo = _Center + float2(-_RadiusX, -_RadiusY);
					float2 lli = llo + float2(_Angle, _Angle / (_ScreenParams.y / _ScreenParams.x));

					float urox = uro.x - i.screenPos.x;
					float urix = i.screenPos.x - uri.x;
					float uroy = uro.y - i.screenPos.y;
					float uriy = i.screenPos.y - uri.y;

					float ulox = i.screenPos.x - ulo.x;
					float ulix = uli.x - i.screenPos.x;
					float uloy = ulo.y - i.screenPos.y;
					float uliy = i.screenPos.y - uli.y;

					float lrox = lro.x - i.screenPos.x;
					float lrix = i.screenPos.x - lri.x;
					float lroy = i.screenPos.y - lro.y;
					float lriy = lri.y - i.screenPos.y;

					float llox = i.screenPos.x - llo.x;
					float llix = lli.x - i.screenPos.x;
					float lloy = i.screenPos.y - llo.y;
					float lliy = lli.y - i.screenPos.y;

					if (ulox > 0 && ulix  > 0 && uloy > 0 && uliy > 0)
					{
						float2 vec = uli - i.screenPos;
						vec.y *= _ScreenParams.y / _ScreenParams.x;

						if (length(vec) < _Angle)
						{
							col.a = 0;
						}
					}
					else if (urox > 0 && urix  > 0 && uroy > 0 && uriy > 0)
					{
						float2 vec = uri - i.screenPos;
						vec.y *= _ScreenParams.y / _ScreenParams.x;

						if (length(vec) < _Angle)
						{
							col.a = 0;
						}
					}
					else if (lrox > 0 && lrix > 0 && lroy > 0 && lriy > 0)
					{
						float2 vec = lri - i.screenPos;
						vec.y *= _ScreenParams.y / _ScreenParams.x;

						if (length(vec) < _Angle)
						{
							col.a = 0;
						}
					}
					else if (llox > 0 && llix  > 0 && lloy > 0 && lliy > 0)
					{
						float2 vec = lli - i.screenPos;
						vec.y *= _ScreenParams.y / _ScreenParams.x;

						if (length(vec) < _Angle)
						{
							col.a = 0;
						}
					}
					else
					{
						col.a = 0;
					}
				}

				return col;
			}
			ENDCG
		}
	}
}