SensorRadius

Shader "Custom/SensorRadius" {
  Properties {
		_MainTex ("Main Texture", 2D) = "white" {}
		_RampTex ("Ramp Txture", 2D) = "white" {}
		_ScreenX ("Screen X", Float) = 0
		_ScreenY ("Screen Y", Float) = 0
		_Radius ("Cutoff Radius", Range(0, 1)) = 0.5
	}
	SubShader {
		Tags { "RenderType"="Transparent" "Queue"="Transparent"}
		LOD 200
		Pass {
		
//		Lighting Off
	    ZWrite On
	    Blend SrcAlpha OneMinusSrcAlpha
		
		CGPROGRAM
//		#pragma surface surf Lambert frag:frag vertex:vert_img
		#pragma fragment frag
		#pragma vertex vert_img
		#include "UnityCG.cginc"
		
		sampler2D _Mask;
		sampler2D _MainTex;
		sampler2D _RampTex;
		uniform float _Radius;
		uniform float _ScreenX;
		uniform float _ScreenY;
		
		half4 frag(v2f_img i) : COLOR {
			half4 color = tex2D(_MainTex, i.uv);
			//vector to the middle of the screen
        	half2 dir = 0.5 - i.uv;
        	half x = (0.5 - i.uv.x) * _ScreenX / _ScreenY;
        	dir.x = x;
			float dist = saturate(1 - dot(dir, dir));
//			dist = pow(dist, 1 / _Radius));
			//distance to center
//			half dist = sqrt(dir.x*dir.x + dir.y*dir.y);
//			half dist = sqrt(x * x + dir.y * dir.y);
			color.a = 1 - tex2D(_RampTex, float2(dist * _Radius, 0)).r;
			// for debugging
//			color.r = 1 - tex2D(_RampTex, float2(dist * _Radius, 0)).r;
			return color;
		}
		
//		struct Input {
//			float2 uv_MainTex;
//		};
//		
//		void surf (Input IN, inout SurfaceOutput o) {
//			fixed4 c = tex2D(_MainTex, IN.uv_MainTex);
//			o.Albedo = c.rgb;
//			o.Alpha = c.a;
//		}
		ENDCG
		}
	}
	
//	FallBack "Diffuse"
}