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=encoding utf8
=head1 NAME
Math::Polygon::Surface - Polygon with exclusions
=head1 SYNOPSIS
my $outer = Math::Polygon->new( [1,2], [2,4], [5,7], [1,2] );
my $surface = Math::Polygon::Surface->new($outer);
=head1 DESCRIPTION
A surface is one polygon which represents the outer bounds of an
array, plus optionally a list of polygons which represent exclusions
from that outer polygon.
=head1 METHODS
=head2 Constructors
=over 4
=item $any-E<gt>B<new>( [%options], [@polygons], %options )
You may merge C<%options> with C<@polygons>. You may also use
the "outer" and "inner" options.
Each polygon is a references to an ARRAY of points, each an ARRAY of X
and Y, but better pass L<Math::Polygon|Math::Polygon> objects.
-Option--Default
inner []
outer undef
=over 2
=item inner => \@polygons
The inner C<@polygons>, zero or more L<Math::Polygon|Math::Polygon> objects.
=item outer => $polygon
The outer C<$polygon>, a L<Math::Polygon|Math::Polygon>.
=back
=back
=head2 Attributes
=over 4
=item $obj-E<gt>B<inner>()
Returns a list (often empty) of inner polygons.
=item $obj-E<gt>B<outer>()
Returns the outer polygon.
=back
=head2 Simple calculations
=over 4
=item B<area>()
Returns the area enclosed by the outer polygon, minus the areas of the
inner polygons.
See method L<Math::Polygon::area()|Math::Polygon/"Geometry">.
=item $obj-E<gt>B<bbox>()
Returns a list with four elements: (xmin, ymin, xmax, ymax), which describe
the bounding box of the surface, which is the bbox of the outer polygon.
See method L<Math::Polygon::bbox()|Math::Polygon/"Geometry">.
=item $obj-E<gt>B<perimeter>()
The length of the border: sums outer and inner perimeters.
See method L<Math::Polygon::perimeter()|Math::Polygon/"Geometry">.
=back
=head2 Clipping
=over 4
=item $obj-E<gt>B<fillClip1>($box)
Clipping a polygon into rectangles can be done in various ways.
With this algorithm, the parts of the polygon which are outside
the C<$box> are mapped on the borders.
All polygons are treated separately.
=item $obj-E<gt>B<lineClip>($box)
Returned is a list of ARRAYS-OF-POINTS containing line pieces
from the input surface. Lines from outer and inner polygons are
undistinguishable.
See method L<Math::Polygon::lineClip()|Math::Polygon/"Clipping">.
=item $obj-E<gt>B<string>()
Translate the surface structure into some string. Use Geo::WKT if you
need a standardized format.
Returned is a single string possibly containing multiple lines. The first
line is the outer, the other lines represent the inner polygons.
=back
=head1 DIAGNOSTICS
=over 4
=item Error: surface requires outer polygon
Cast by new()
=back
=head1 SEE ALSO
This module is part of Math-Polygon version 2.00,
built on September 04, 2025. Website: F<http://perl.overmeer.net/CPAN/>
=head1 LICENSE
For contributors see file ChangeLog.
This software is copyright (c) 2004-2025 by Mark Overmeer.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
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