private static void LoadSinglePolygon(XmlTextReader xmlReader, NavMesh navMesh)
        {
            ConvexPolygon polygon = new ConvexPolygon();

            xmlReader.MoveToContent();
            while (xmlReader.Read())
            {
                if ("point" == xmlReader.Name)
                {
                    float x = float.Parse(xmlReader.GetAttribute("x"));
                    float y = float.Parse(xmlReader.GetAttribute("y"));
                    polygon.Vertices.Add(new Point(x, y));
                }
                else if ("polygon" == xmlReader.Name)
                {
                    polygon.GenerateEdges();
                    navMesh.AddPolygon(polygon);
                    return;
                }
            }
        }