public void OnAddGrid()
    {
        GridRows    = EditorGUILayout.IntField("Number of Rows: ", GridRows);
        GridColumns = EditorGUILayout.IntField("Number of Nodes Per Row: ", GridColumns);
        GridOffset  = EditorGUILayout.IntSlider("Node Offset", GridOffset, 1, 10);

        List <Node> gridNodes = new List <Node>();

        if (GUILayout.Button("Add Grid"))
        {
            gridNodes = map.AddNodeGrid(GridColumns, GridRows, map.transform.position, GridOffset);
        }

        map.UpdateEdges(gridNodes, true);
    }