Math::Polygon::Transform(3) Polygon transformation


   is a Exporter


my @poly = ( [1,2], [2,4], [5,7], [1, 2] );
my $area = polygon_transform resize => 3.14, @poly;


This package contains polygon transformation algorithms.


polygon_grid(%options, LIST-of-$points)
Snap the polygon points to grid points, where artifacts are removed.

  raster  1.0
raster => FLOAT
The raster size, which determines the points to round to. The origin "[0,0]" is always on a grid-point. When the raster value is zero, no transformation will take place.
polygon_mirror(%options, LIST-of-$points)
Mirror the polygon in a line. Only one of the options can be provided. Some programs call this ``flip'' or ``flop''.

  b       0
  line    <undef>
  rc      undef
  x       undef
  y       undef
b => FLOAT
Only used in combination with option "rc" to describe a line.
line => [POINT, POINT]
Alternative way to specify the mirror line. The "rc" and "b" are computed from the two points of the line.
rc => FLOAT
Description of the line which is used to mirror in. The line is "y= rc*x+b". The "rc" equals "-dy/dx", the firing angle. If "undef" is explicitly specified then "b" is used as constant x: it's a vertical mirror.
x => FLOAT
Mirror in the line "x=value", which means that "y" stays unchanged.
y => FLOAT
Mirror in the line "y=value", which means that "x" stays unchanged.
polygon_move(%options, LIST-of-$points)
Returns a list of points which are moved over the indicated distance

  dx      0
  dy      0
dx => FLOAT
Displacement in the horizontal direction.
dy => FLOAT
Displacement in the vertical direction.
polygon_resize(%options, LIST-of-$points)
  center  [0,0]
  scale   1.0
  xscale  <scale>
  yscale  <scale>
center => POINT
scale => FLOAT
Resize the polygon with the indicated factor. When the factor is larger than 1, the resulting polygon with grow, when small it will be reduced in size. The scale will be respective from the center.
xscale => FLOAT
Specific scaling factor in the horizontal direction.
yscale => FLOAT
Specific scaling factor in the vertical direction.
polygon_rotate(%options, LIST-of-$points)
 -Option --Default
  center   [0,0]
  degrees  0
  radians  0
center => POINT
degrees => FLOAT
specify rotation angle in degrees (between -180 and 360).
radians => FLOAT
specify rotation angle in rads (between -pi and 2*pi)
polygon_simplify(%options, LIST-of-$points)
 -Option    --Default
  max_points  undef
  same        0.0001
  slope       undef
max_points => INTEGER
First, "same" and "slope" reduce the number of points. Then, if there are still more than the specified number of points left, the points with the widest angles will be removed until the specified maximum number is reached.
same => FLOAT
The distance between two points to be considered ``the same'' point. The value is used as radius of the circle.
slope => FLOAT
With three points X(n),X(n+1),X(n+2), the point X(n+1) will be removed if the length of the path over all three points is less than "slope" longer than the direct path between X(n) and X(n+2).

The slope will not be removed around the starting point of the polygon. Removing points will change the area of the polygon.


Error: you need to specify 'x', 'y', 'rc', or 'line'


Copyrights 2004,2006-2014 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