Shader "Custom/JoystickCircle" {
Properties{
    _Color ("Main Color", Color) = (1,1,1,1)
    _Falloff ("Falloff", Float) = 0.025
}
SubShader {
	Tags
        {
            "Queue" = "Transparent"
            "IgnoreProjector" = "True"
            "RenderType" = "Transparent"
            "PreviewType"="Plane"
        }
	Pass {
	 	Blend SrcAlpha OneMinusSrcAlpha
	 	Cull Off
        Lighting Off
        ZWrite Off
        ZTest Always
        Fog { Mode Off }
        
		CGPROGRAM
		#pragma vertex vert
		#pragma fragment frag
		#include "UnityCG.cginc"
		
		float _Falloff;
		float4 _Color;

		struct v2f {
			float4 pos : SV_POSITION;
			float3 color : COLOR0;
			float2 uv : TEXCOORD0;
		};

		v2f vert (appdata_base v){
			v2f o;
			o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
			o.color = v.normal * 0.5 + 0.5;
			o.uv = v.texcoord.xy;
			return o;
		}

		half4 frag (v2f i) : COLOR{
			float radius = length(i.uv - 0.5f) * 2.0f;
			//clip(1.0f - radius);
			
			float falloffRadius = 1.0f - clamp(radius, 1.0f - _Falloff, 1.0f);
			
			float falloff = pow(falloffRadius / _Falloff, 1.0f / 2);
			
			float3 color = falloff;
			return half4 (_Color.rgb, _Color.a * falloff);
		}
		ENDCG
	}
}
Fallback "VertexLit"
}