HELP APPPOLYGON                                     David Young
                                                    April 1998

LIB * APPPOLYGON (note 3 "p"s as in appproperty) allows a procedure to
be applied to every integer-coordinate point (i.e. every pixel in image
processing terms) inside a polygon or on its boundary.

apppolygon(__x1, __y1, __x2, __y2, ... __xn, __yn, _n, ____proc)

        __x1, __y1, ... __xn, __yn are the coordinates of the vertices of the
        polygon, in order (clockwise or anticlockwise round the
        polygon). _n is the number of vertices, and so must be equal to
        half the number of preceding arguments.

        ____proc is a procedure of two arguments

                ____proc(_x, _y)

        which is called for every pair of integer coordinates inside the
        polygon or on its boundary.

        A point is inside the polygon if, to reach it from outside the
        polygon's bounding box, you have to cross an odd number of the
        polygon's edges.

For an example, see the commented-out code at the end of
LIB * APPPOLYGON.


--- __________________________$popvision/help/apppolygon
--- _________Copyright __________University __of ______Sussex _____1998. ___All ______rights _________reserved.