NAME¶
Math::Polygon::Clip - frame a polygon in a square
INHERITANCE¶
Math::Polygon::Clip
is a Exporter
SYNOPSIS¶
my @poly = ( [1,2], [2,4], [5,7], [1, 2] );
my @box = ( $xmin, $ymin, $xmax, $ymax );
my $boxed = polygon_clip \@box, @poly;
DESCRIPTION¶
Cut-off all parts of the polygon which are outside the box
FUNCTIONS¶
- polygon_fill_clip1(ARRAY-BOX, LIST-OF-POINTS)
- Clipping a polygon into rectangles can be done in various
ways. With this algorithm (which I designed myself, but may not be new),
the parts of the polygon which are outside the BOX are mapped on the
borders. The polygon stays in one piece.
Returned is one list of points, which is cleaned from double points, spikes
and superfluous intermediate points.
- polygon_fill_clip2(ARRAY-BOX, LIST-OF-POINTS)
- To be implemented. The polygon falls apart in fragments,
which are not connected: paths which are followed in two directions are
removed. This is required by some applications, like polygons used in
geographical context (country contours and such).
- polygon_fill_clip3(ARRAY-BOX, OUT-POLY,
[IN-POLYS])
- To be implemented. A surrounding polygon, with possible
inclussions.
- polygon_line_clip(ARRAY-BOX, LIST-OF-POINTS)
- Returned is a list of ARRAYS (possibly 0 long) containing
line pieces from the input polygon (or line).
example:
my @points = ( [1,2], [2,3], [2,0], [1,-1], [1,2] );
my @bbox = ( 0, -2, 2, 2 );
my @l = polygon_line_clip \@bbox, @points;
print scalar @l; # 1, only one piece found
my @first = @{$l[0]}; # first is [2,0], [1,-1], [1,2]
SEE ALSO¶
This module is part of Math-Polygon distribution version 1.02, built on
September 19, 2011. Website:
http://perl.overmeer.net/geo/
LICENSE¶
Copyrights 2004,2006-2011 by Mark Overmeer. For other contributors see
ChangeLog.
This program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself. See
http://www.perl.com/perl/misc/Artistic.html