fixed4 frag(v2f IN) : SV_Target
           {
               fixed4 c = tex2D (_MainTex, IN.texcoord);
               clip(c.a-1);

               // Get the neighbouring four pixels.
               fixed4 pixelUp = tex2D(_MainTex, IN.texcoord + fixed2(0, _MainTex_TexelSize.y));
               fixed4 pixelDown = tex2D(_MainTex, IN.texcoord - fixed2(0, _MainTex_TexelSize.y));
               fixed4 pixelRight = tex2D(_MainTex, IN.texcoord + fixed2(_MainTex_TexelSize.x, 0));
               fixed4 pixelLeft = tex2D(_MainTex, IN.texcoord - fixed2(_MainTex_TexelSize.x, 0));

               fixed noAlpha = pixelUp.a * pixelDown.a * pixelRight.a * pixelLeft.a;
               fixed anyAlpha = 1 - noAlpha;
               c = c * IN.color.a + IN.color;
               return c * noAlpha + _Outline * anyAlpha;
           }