1Math::Polygon::Calc(3)User Contributed Perl DocumentationMath::Polygon::Calc(3)
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NAME

6       Math::Polygon::Calc - Simple polygon calculations
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INHERITANCE

9        Math::Polygon::Calc
10          is a Exporter
11

SYNOPSIS

13        my @poly = ( [1,2], [2,4], [5,7], [1, 2] );
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15        my ($xmin, $ymin, $xmax, $ymax) = polygon_bbox @poly;
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17        my $area = polygon_area @poly;
18        MY $L    = polygon_perimeter @poly;
19        if(polygon_is_clockwise @poly) { ... };
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21        my @rot  = polygon_start_minxy @poly;
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DESCRIPTION

24       This package contains a wide variaty of relatively easy polygon
25       calculations.  More complex calculations are put in separate packages.
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FUNCTIONS

28       polygon_area(@points)
29           Returns the area enclosed by the polygon.  The last point of the
30           list must be the same as the first to produce a correct result.
31
32           The algorithm was found at
33           <http://mathworld.wolfram.com/PolygonArea.html>, and sounds:
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35            A = abs( 1/2 * (x1y2-x2y1 + x2y3-x3y2 ...)
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37       polygon_bbox(@points)
38           Returns a list with four elements: (xmin, ymin, xmax, ymax), which
39           describe the bounding box of the polygon (all points of the polygon
40           are within that area.
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42       polygon_beautify( [\%options], @points )
43           Polygons, certainly after some computations, can have a lot of
44           horrible artifacts: points which are double, spikes, etc.  The
45           optional HASH contains the %options.
46
47            -Option       --Default
48             remove_spikes  <false>
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50           remove_spikes => BOOLEAN
51             Spikes contain of three successive points, where the first is on
52             the line between the second and the third.  The line goes from
53             first to second, but then back to get to the third point.
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55             At the moment, only pure horizontal and pure vertical spikes are
56             removed.
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58       polygon_centroid(@points)
59           Returns the centroid location of the polygon.  The last point of
60           the list must be the same as the first to produce a correct result.
61
62           The algorithm was found at
63           http://en.wikipedia.org/wiki/Centroid#Centroid_of_polygon
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65       polygon_clockwise(@points)
66           Be sure the polygon points are in clockwise order.
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68       polygon_contains_point($point, @points)
69           Returns true if the point is inside the closed polygon.  On an edge
70           will be flagged as 'inside'.  But be warned of rounding issues,
71           caused by the floating-point calculations used by this algorithm.
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73       polygon_counter_clockwise(@points)
74           Be sure the polygon points are in counter-clockwise order.
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76       polygon_distance($point, @polygon)
77           [1.05] calculate the shortest distance between a point and any
78           vertex of a closed polygon.
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80       polygon_equal( \@points1, \@points2, [$tolerance] )
81           Compare two polygons, on the level of points. When the polygons are
82           the same but rotated, this will return false. See polygon_same().
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84       polygon_format($format, @points)
85           [1.07] Map the $format over all @points, both the X and Y
86           coordinate.  This is especially useful to reduce the number of
87           digits in the stringification.  For instance, when you want
88           reproducible results in regression scripts.
89
90           The format is anything supported by printf(), for instance "%5.2f".
91           Or, you can pass a code reference which accepts a single value.
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93       polygon_is_clockwise(@points)
94       polygon_is_closed(@points)
95       polygon_perimeter(@points)
96           The length of the line of the polygon.  This can also be used to
97           compute the length of any line: of the last point is not equal to
98           the first, then a line is presumed; for a polygon they must match.
99
100           This is simply Pythagoras.
101
102            $l = sqrt((x1-x0)^2 + (y1-y0)^2) + sqrt((x2-x1)^2+(y2-y1)^2) + ...
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104       polygon_same( \@points1, \@points2, [$tolerance] )
105           Compare two polygons, where the polygons may be rotated wrt each
106           other. This is (much) slower than polygon_equal(), but some
107           algorithms will cause un unpredictable rotation in the result.
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109       polygon_start_minxy(@points)
110           Returns the polygon, where the point which is closest to the left-
111           bottom corner of the bounding box is made first.
112
113       polygon_string(@points)
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SEE ALSO

116       This module is part of Math-Polygon distribution version 1.10, built on
117       January 03, 2018. Website: http://perl.overmeer.net/CPAN/
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LICENSE

120       Copyrights 2004-2018 by [Mark Overmeer]. For other contributors see
121       ChangeLog.
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123       This program is free software; you can redistribute it and/or modify it
124       under the same terms as Perl itself.  See http://dev.perl.org/licenses/
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128perl v5.34.0                      2021-07-22            Math::Polygon::Calc(3)