Shader "Unlit/TestCrossShader"
{
	Properties
	{
		_MainTex ("Texture", 2D) = "white" {}
		_AlphaData("Alpha Data",float)=1.0
		_IntersectPower("Intersect Power",float)= 1.0
		_ScanValue("Scan Value",float)= 1.0
		_ScanLineWidth("Scan Line Width",float)= 1.0
		_ScanLineColor("Scan Line Color",COLOR)=(1,1,1,1)
	}
	SubShader
	{
		Tags { "RenderType"="Opaque" "Queue"="Transparent" }
		LOD 100

		Pass
		{
			ZWrite Off //ZTest Always
			Blend SrcAlpha OneMinusSrcAlpha

			CGPROGRAM
			
			#pragma vertex vert
			#pragma fragment frag
			// make fog work
			#pragma multi_compile_fog
			
			#include "UnityCG.cginc"
			

			struct appdata
			{
				float4 vertex : POSITION;
				float3 normal : NORMAL;
				float2 uv : TEXCOORD0;
			};

			struct v2f
			{
				float2 uv : TEXCOORD0;
				UNITY_FOG_COORDS(1)
				float4 vertex : SV_POSITION;
				float4 scrPos : TEXCOORD1;
				float3 worldNormal : TEXCOORD2;
			};

			sampler2D _MainTex;
			float4 _MainTex_ST;
			float _AlphaData;
			sampler2D _CameraDepthTexture;
			float _ScanValue;
			float _ScanLineWidth;
			fixed4 _ScanLineColor;
			float _IntersectPower;

			
			v2f vert (appdata v)
			{
				v2f o;
				o.vertex = UnityObjectToClipPos(v.vertex);
				o.uv = TRANSFORM_TEX(v.uv, _MainTex);
				o.scrPos = ComputeScreenPos(o.vertex);
				o.worldNormal = UnityObjectToWorldNormal(v.normal);
				COMPUTE_EYEDEPTH(o.scrPos.z);
				return o;
			}
			
			fixed4 frag (v2f i) : SV_Target
			{
				// sample the texture
				fixed4 col = tex2D(_MainTex, i.uv);
				fixed4 refrCol = tex2D(_CameraDepthTexture, i.scrPos.xy/i.scrPos.w);
				//float d = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture,i.uv);
				//float d = SAMPLE_DEPTH_TEXTURE_PROJ(_CameraDepthTexture,UNITY_PROJ_COORD(i.scrPos));
				//float depth = tex2D(_CameraDepthTexture, i.uv).r;
				float depth = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, i.uv);
				float linearDepth = LinearEyeDepth(refrCol.r);
				float partZ = i.scrPos.z;
				// 两者相减就是深度的差异diff，再用1 - diff就得到了一个“相交程度”。
				float diff = linearDepth - partZ; // 两个值都在同一空间下, 就可以做比较了
				float intersect = (1 - diff) * _IntersectPower;
				col = float4(0,0, intersect*_AlphaData, 1 );
				//col = fixed4(i.worldNormal,col.a*_AlphaData);
				// apply fog
				// UNITY_APPLY_FOG(i.fogCoord, col);
				return col;
				/*float depth = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, i.uv);
				float lnr01Depth = Linear01Depth(depth);
				fixed4 screenTexture = tex2D(_MainTex, i.uv);
				float near = smoothstep(_ScanValue, lnr01Depth, _ScanValue - _ScanLineWidth); // _ScanValue 就是 控制值, 在 [0, 1] 区间
				float far = smoothstep(_ScanValue, lnr01Depth, _ScanValue + _ScanLineWidth);
				fixed4 emissionClr = _ScanLineColor * (near + far);
				return screenTexture + emissionClr;*/
			}
			ENDCG
		}
	}
}