shader outline test

Shader "Custom/Outline"
{
    Properties{
     _Color("Main Color", Color) = (0.5,0.5,0.5,1)
     _MainTex("Texture", 2D) = "White" {}
     _OutlineColor("Outline color", color) = (0,0,0,1)
     _OutlineWidth("Outline width", Range(1.0,5.0)) = 1.01
         _X("X",float) = 0 // shape center x
         _Y("Y",float) = 0 // shape center y
    }


        SubShader{

         Pass{ //render the outline
          ZWrite off

          CGPROGRAM
          #pragma vertex vert
          #pragma fragment frag


         //starthere
         struct appdata {
            float4 vertex : POSITION;
            float3 normal : NORMAL;
          };

        struct v2f {
             float4 pos : POSITION;
             float3 normal : NORMAL;
             float2 uvs : TEXCOORD0;
        };

        float _OutlineWidth;
        float4 _OutlineColor;
        float _X;
        float _Y;

        v2f vert(appdata v)
        {
            float xStartPos = v.vertex.x;
            float yStartPos= v.vertex.y;

            float xOriginDiff = 0 - xStartPos;
            float yOriginDiff = 0 - yStartPos;

            v.vertex.xyz *= _OutlineWidth;

            float xMultipliedOriginDiff = 0 - v.vertex.x;
            float yMultipliedOriginDiff = 0 - v.vertex.y;

            float xDiff = abs(xMultipliedOriginDiff - xOriginDiff);
            float yDiff = abs(yMultipliedOriginDiff - yOriginDiff);


            // offset?
            v.vertex.x += xDiff;
            v.vertex.y += yDiff;
            //

             v2f o;
             o.pos = UnityObjectToClipPos(v.vertex);
             return o;
        };
        //endhere

        half4 frag(v2f i) : COLOR
        {
            return _OutlineColor;
        }
        ENDCG
       }


       Pass
       {
        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        // make fog work
        #pragma multi_compile_fog

        #include "UnityCG.cginc"

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

        struct v2f
        {
         float2 uv : TEXCOORD0;
         UNITY_FOG_COORDS(1)
         float4 vertex : SV_POSITION;
        };

        sampler2D _MainTex;
        float4 _MainTex_ST;

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

        fixed4 frag(v2f i) : SV_Target
        {
            // sample the texture
            fixed4 col = tex2D(_MainTex, i.uv);
        // apply fog
        UNITY_APPLY_FOG(i.fogCoord, col);
        return col;
       }
       ENDCG
      }
     }

}