Shader "Hidden/OutlineShader"
{
    Properties
    {
        _OutlineColor ("Outline Color", Color) = (1,1,1,1)
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" "Queue"="Transparent" }
        Pass
        {
            Name "Outline"
            Cull Off
            Blend SrcAlpha OneMinusSrcAlpha
            ZWrite Off
            ZTest Always

            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #include "UnityCG.cginc"

            float4 _OutlineColor;

            struct appdata
            {
                float4 vertex : POSITION;
            };

            struct v2f
            {
                float4 vertex : SV_POSITION;
            };

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

            fixed4 frag (v2f i) : SV_Target
            {
                return _OutlineColor;
            }
            ENDHLSL
        }
    }
}