HELP APPPOLYGON David Young
(Sussex University)
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.
--- $poplocal/local/help/apppolygon
--- Copyright University of Birmingham 1999. All rights reserved. ------