Newell's algorithm

Newell's Algorithm is a 3D computer graphics procedure for elimination of polygon cycles in the depth sorting required in hidden surface removal.

It was proposed in 1972 by brothers Martin Newell and Dick Newell, and Tom Sancha, while all three were working at CADCentre.

In the depth sorting phase of hidden surface removal, if two polygons have no overlapping extents or extreme minimum and maximum values in the x, y, and z directions, then they can be easily sorted.

If two polygons, Q and P, do have overlapping extents in the Z direction, then it is possible that cutting is necessary.

If the tests are all false, then switch the order of P and Q in the sort, record having done so, and try again.