public int GetTotalNumVertices()
    {
        int numverts = 0;

        if (Top != null)
        {
            numverts += Top.GetNumVertices();
        }
        if (Bottom != null)
        {
            numverts += Bottom.GetNumVertices();
        }
        if (Left != null)
        {
            numverts += Left.GetNumVertices();
        }
        if (Right != null)
        {
            numverts += Right.GetNumVertices();
        }
        if (Front != null)
        {
            numverts += Front.GetNumVertices();
        }
        if (Back != null)
        {
            numverts += Back.GetNumVertices();
        }
        return(numverts);
    }