Math::Polygon::Calc - Simple polygon calculations
Math::Polygon::Calc
is a Exporter
my @poly = ( [1,2], [2,4], [5,7], [1, 2] );
my ($xmin, $ymin, $xmax, $ymax) = polygon_bbox @poly;
my $area = polygon_area @poly;
MY $L = polygon_perimeter @poly;
if(polygon_is_clockwise @poly) { ... };
my @rot = polygon_start_minxy @poly;
This package contains a wide variaty of relatively easy polygon calculations.
More complex calculations are put in separate packages.
- polygon_area(@points)
- Returns the area enclosed by the polygon. The last point of the list must
be the same as the first to produce a correct result.
The algorithm was found at
<http://mathworld.wolfram.com/PolygonArea.html>, and sounds:
A = abs( 1/2 * (x1y2-x2y1 + x2y3-x3y2 ...)
- polygon_bbox(@points)
- Returns a list with four elements: (xmin, ymin, xmax, ymax), which
describe the bounding box of the polygon (all points of the polygon are
within that area.
- polygon_beautify( [\%options], @points )
- Polygons, certainly after some computations, can have a lot of horrible
artifacts: points which are double, spikes, etc. The optional HASH
contains the %options.
-Option --Default
remove_spikes <false>
- remove_spikes => BOOLEAN
- Spikes contain of three successive points, where the first is on the line
between the second and the third. The line goes from first to second, but
then back to get to the third point.
At the moment, only pure horizontal and pure vertical spikes are
removed.
- polygon_centroid(@points)
- Returns the centroid location of the polygon. The last point of the list
must be the same as the first to produce a correct result.
The algorithm was found at
http://en.wikipedia.org/wiki/Centroid#Centroid_of_polygon
- polygon_clockwise(@points)
- Be sure the polygon points are in clockwise order.
- polygon_contains_point($point, @points)
- Returns true if the point is inside the closed polygon. On an edge will be
flagged as 'inside'. But be warned of rounding issues, caused by the
floating-point calculations used by this algorithm.
- polygon_counter_clockwise(@points)
- Be sure the polygon points are in counter-clockwise order.
- polygon_distance($point, @polygon)
- [1.05] calculate the shortest distance between a point and any vertex of a
closed polygon.
- polygon_equal( \@points1, \@points2, [$tolerance] )
- Compare two polygons, on the level of points. When the polygons are the
same but rotated, this will return false. See polygon_same().
- polygon_format($format, @points)
- [1.07] Map the $format over all @points, both the X and Y coordinate. This
is especially useful to reduce the number of digits in the
stringification. For instance, when you want reproducible results in
regression scripts.
The format is anything supported by printf(), for instance
"%5.2f". Or, you can pass a code reference which accepts a
single value.
- polygon_is_clockwise(@points)
- polygon_is_closed(@points)
- polygon_perimeter(@points)
- The length of the line of the polygon. This can also be used to compute
the length of any line: of the last point is not equal to the first, then
a line is presumed; for a polygon they must match.
This is simply Pythagoras.
$l = sqrt((x1-x0)^2 + (y1-y0)^2) + sqrt((x2-x1)^2+(y2-y1)^2) + ...
- polygon_same( \@points1, \@points2, [$tolerance] )
- Compare two polygons, where the polygons may be rotated wrt each other.
This is (much) slower than polygon_equal(), but some algorithms
will cause un unpredictable rotation in the result.
- polygon_start_minxy(@points)
- Returns the polygon, where the point which is closest to the left-bottom
corner of the bounding box is made first.
- polygon_string(@points)
This module is part of Math-Polygon distribution version 1.10, built on January
03, 2018. Website:
http://perl.overmeer.net/CPAN/
Copyrights 2004-2018 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://dev.perl.org/licenses/