Shader "Umawerse/BorderCircle"
{
    Properties
    {
        _Color("Color",Color)=(0.5,0.5,0.5,1)
        _Thickness("Thickness",Range(0,1)) = 0.1
        _Border("Border",Color)=(1,1,1,1)
        [Enum(UnityEngine.Rendering.CompareFunction)]_ZTest("ZTest",int) = 0
    }
    SubShader
    {
        Tags { "RenderType"="Transparent" "Queue"="Overlay" "PreviewType"="Plane"}
        ZTest[_ZTest]
        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

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

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            fixed4 _Color;
            fixed _Thickness;
            fixed4 _Border;
            

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            fixed4 frag (v2f i) : SV_Target
            {
                // sample the texture
                fixed4 col = _Color;
                const fixed r = 0.5;
                const fixed ir = r*(1-_Thickness);
                const fixed x = i.uv.x - r;
                const fixed y = i.uv.y - r;
                
                if(x*x+y*y>ir*ir) col = _Border;
                clip(r*r-x*x-y*y);
                return col;
            }
            ENDCG
        }
    }
}