Shader "Outline2D" {
    Properties {
        _Color ("Main Tint", Color) = (1,1,1,1)
        _OutlineColor ("Outline Color", Color) = (1,1,1,1)
        _MainTex ("Albedo (RGB)", 2D) = "white" {}
        _Cutoff ("Main Alpha Cutoff", Range(0,1)) = 0.5
        _OutlineCutoff ("Outline Alpha Cutoff", Range(0,1)) = 0.25
        _LineOffset ("Outline Depth Offset", Range(0,-10000)) = -1000
    }

    SubShader {

        //Standard Pass
        Tags { "RenderType"="Opaque" }
        LOD 200

        Offset -3, [_LineOffset]
        Cull Off

        CGPROGRAM
        // Physically based Standard lighting model, and enable shadows on all light types
        #pragma surface surf Standard
        #pragma target 3.0

        sampler2D _MainTex;

        struct Input {
            float2 uv_MainTex;
        };

        fixed4 _Color;
        half _Cutoff;

        void surf (Input IN, inout SurfaceOutputStandard o) {
            fixed4 albedo = tex2D (_MainTex, IN.uv_MainTex) * _Color;
            clip (albedo.a - _Cutoff);
            o.Albedo = albedo.rgb;
            o.Alpha = albedo.a;
        }
        ENDCG


        //Outline Pass
        Tags { "RenderType"="Opaque" }
        LOD 200

        Offset 0, 0
        Cull Off

        CGPROGRAM
        // Physically based Standard lighting model, and enable shadows on all light types
        #pragma surface surf Standard addshadow
        #pragma target 3.0

        sampler2D _MainTex;

        struct Input {
            float2 uv_MainTex;
        };

        fixed4 _OutlineColor;
        half _OutlineCutoff;

        void surf (Input IN, inout SurfaceOutputStandard o) {
            fixed4 albedo = tex2D (_MainTex, IN.uv_MainTex);
            clip (albedo.a - _OutlineCutoff);
            o.Albedo = _OutlineColor.rgb;
            o.Alpha = albedo.a;
        }
        ENDCG
    }
}