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

perl v5.12.4                                       2011-09-19                           Math::Polygon::Clip(3pm)