Unity surface shader with round corners

Round Rect.shader

Shader "Custom/Round Rect" {
	Properties {
		_Color ("Color", Color) = (1,1,1,1)
		_Pos("Position", Vector) = (0,0,0,0)
		_Width("Width", float) = 0.0
		_Height ("Height", float) = 0.0
		_Radius ("Radius", float) = 0.5
	}
 
	SubShader {
		Tags { "RenderType"="Transparent" "Queue"="Transparent" "AllowProjectors"="False" }
 
		blend SrcAlpha OneMinusSrcAlpha
 
		CGPROGRAM
		#pragma surface surf NoLighting alpha
 
		fixed4 LightingNoLighting(SurfaceOutput s, fixed3 lightDir, fixed atten)
		{
			return fixed4(0,0,0, s.Alpha);
		}
 
		sampler2D _MainTex;
 
		struct Input
		{
			float4 color : COLOR;
			float3 worldPos;
		};
 
		float4 _Color;
		float4 _Pos;
		float _Radius;
		float _Width;
		float _Height;
		void surf (Input IN, inout SurfaceOutput o) {
			float4 rectCenter = fixed4(_Pos.x - _Width/2.0 + _Radius, _Pos.y + _Height/2.0 - _Radius,IN.worldPos.z,0);
			
			if(IN.worldPos.x < rectCenter.x && IN.worldPos.y > rectCenter.y && distance(IN.worldPos, rectCenter) > _Radius){
				o.Alpha = 0;
			} else {
				rectCenter = fixed4(_Pos.x + _Width/2.0 - _Radius, _Pos.y + _Height/2.0 - _Radius,IN.worldPos.z,0);
				if(IN.worldPos.x > rectCenter.x && IN.worldPos.y > rectCenter.y && distance(IN.worldPos, rectCenter) > _Radius){
					o.Alpha = 0;
				} else {
					rectCenter = fixed4(_Pos.x + _Width/2.0 - _Radius, _Pos.y - _Height/2.0 + _Radius,IN.worldPos.z,0);
					if(IN.worldPos.x > rectCenter.x && IN.worldPos.y < rectCenter.y && distance(IN.worldPos, rectCenter) > _Radius){
						o.Alpha = 0;
					} else {
						rectCenter = fixed4(_Pos.x - _Width/2.0 + _Radius, _Pos.y - _Height/2.0 + _Radius,IN.worldPos.z,0);
						if(IN.worldPos.x < rectCenter.x && IN.worldPos.y < rectCenter.y && distance(IN.worldPos, rectCenter) > _Radius){
							o.Alpha = 0;
						} else {
							o.Alpha = 1;
						}
					}
				}
			}

			o.Emission = _Color.rgb;
		}
		ENDCG
	} 
	FallBack "Diffuse"
}