ctrlpoints : Array [0..3, 0..3, 0..2] of GLFloat =
 (
    (
        (2, -2, 0),
        (3, -1, 0),
        (3, 1, 0),
        (2, 2, 0)),
     (
        (1, -3, 0),
        (2, -3, 5),
        (2, 3, 5),
        (1, 3, 0)),
    (
        (-1, -3, 0),
        (-2, -3, 5),
        (-2, 3, 5),
        (-1, 3, 0)),
    (
        (-2, -2, 0),
        (-3, -1, 0),
        (-3, 1, 0),
        (-2, 2, 0))
 );