Shader "DashGame/HighLight"
{
	Properties
	{
		[PerRendererData] _MainTex("Sprite Texture", 2D) = "white" {}
		_Scale("Scale", float) = 0.02
		_Color("Tint", Color) = (1,1,1,1)
		[MaterialToggle] PixelSnap("Pixel snap", Float) = 0
	}

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

		Cull Off
		Lighting Off
		ZWrite Off

		Pass
		{
			Blend SrcAlpha OneMinusSrcAlpha

			CGPROGRAM
				
			#pragma vertex vert
			#pragma fragment frag
				
			#pragma target 2.0
				
			#pragma multi_compile _ PIXELSNAP_ON
			#pragma multi_compile _ ETC1_EXTERNAL_ALPHA
				
			#include "UnityCG.cginc"

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

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

			float _Scale;
			fixed4 _Color;

			v2f vert(appdata_t IN)
			{
				v2f OUT;

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

				return OUT;
			}

			sampler2D _MainTex;

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

				return color;
			}

			fixed4 frag(v2f IN) : SV_Target
			{
				fixed4 c = SampleSpriteTexture(IN.texcoord) * IN.color;

				if (c.a == 0) 
				{
					fixed4 c1 = SampleSpriteTexture(IN.texcoord + float2(_Scale, 0));
					fixed4 c2 = SampleSpriteTexture(IN.texcoord + float2(-_Scale, 0));
					fixed4 c3 = SampleSpriteTexture(IN.texcoord + float2(0, _Scale));
					fixed4 c4 = SampleSpriteTexture(IN.texcoord + float2(0, -_Scale));
					fixed4 c5 = SampleSpriteTexture(IN.texcoord + float2(_Scale, _Scale));
					fixed4 c6 = SampleSpriteTexture(IN.texcoord + float2(_Scale, -_Scale));
					fixed4 c7 = SampleSpriteTexture(IN.texcoord + float2(-_Scale, _Scale));
					fixed4 c8 = SampleSpriteTexture(IN.texcoord + float2(-_Scale, -_Scale));

					if (c1.a > 0 || c2.a > 0 || c3.a > 0 || c4.a > 0 || c5.a > 0 || c6.a > 0 || c7.a > 0 || c8.a > 0)
					{
						c.rgba = 1;
					}
				}
				else if (c.a < 1)
				{
					c.rgba = 1;
				}

				return c;
			}
			ENDCG
		}
	}
}