Shader "Custom/NewSurfaceShader" 
{
	Properties
	{
		[PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
		_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     //关闭灯光
		ZWrite Off       //关闭Z缓冲
		Blend One OneMinusSrcAlpha     //混合源系数one(1)  目标系数OneMinusSrcAlpha(1-one=0)
 
		Pass
		{
		CGPROGRAM
			
			#pragma fragment frag
			#pragma multi_compile _ PIXELSNAP_ON       //告诉Unity编译不同版本的Shader,这里和后面vert中的PIXELSNAP_ON对应
			#include "UnityCG.cginc"
			sampler2D _MainTex;
			float4 _MainTex_TexelSize;
			
			fixed4 _Color;
			
			struct appdata_t                           //vert输入
			{
				float4 vertex   : POSITION;
				float4 color    : COLOR;
				float2 texcoord : TEXCOORD0;
			};
 
			struct v2f                                 //vert输出数据结构
			{
				float4 vertex   : SV_POSITION;
				fixed4 color    : COLOR;
				float2 texcoord  : TEXCOORD0;
			};
 
			v2f vert(appdata_t IN)
			{
				v2f OUT;
				OUT.vertex = UnityObjectToClipPos(IN.vertex);
				OUT.texcoord = IN.texcoord;
				OUT.color = IN.color * _Color;
				#ifdef PIXELSNAP_ON
				OUT.vertex = UnityPixelSnap (OUT.vertex);
				#endif
 
				return OUT;
			}
 
			fixed4 SampleSpriteTexture (float2 uv)
			{
				fixed4 color = tex2D (_MainTex, uv);
				return color;
			}
			

			fixed4 frag(v2f IN) : SV_Target
			{
				float _CheckRange = 1;
				float _CheckAccuracy = 0.5;
				fixed4 _OutlineColor = fixed4(1,1,1,1);
				float _LineWidth = 2;
			
				fixed4 c = SampleSpriteTexture (IN.texcoord) * IN.color;
				c.rgb *= c.a;
				float isOut = step(abs(1/_LineWidth),c.a);
				if(isOut != 0)
				{
					fixed4 pixelUp = tex2D(_MainTex, IN.texcoord + fixed2(0, _MainTex_TexelSize.y*_CheckRange));  
					fixed4 pixelDown = tex2D(_MainTex, IN.texcoord - fixed2(0, _MainTex_TexelSize.y*_CheckRange));  
					fixed4 pixelRight = tex2D(_MainTex, IN.texcoord + fixed2(_MainTex_TexelSize.x*_CheckRange, 0));  
					fixed4 pixelLeft = tex2D(_MainTex, IN.texcoord - fixed2(_MainTex_TexelSize.x*_CheckRange, 0));  
					float bOut = step((1-_CheckAccuracy),pixelUp.a*pixelDown.a*pixelRight.a*pixelLeft.a);
					c = lerp(_OutlineColor,c,bOut);
					return c;
				}
				return c;
				
			}
		ENDCG
		}
	}
}