

 
Manual Reference Pages  MATH::POLYGON::TRANSFORM (3)
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NAME
Math::Polygon::Transform  Polygon transformation
CONTENTS
INHERITANCE
Math::Polygon::Transform
is a Exporter
SYNOPSIS
my @poly = ( [1,2], [2,4], [5,7], [1, 2] );
my $area = polygon_transform resize => 3.14, @poly;
DESCRIPTION
This package contains polygon transformation algorithms.
FUNCTIONS
<B>polygon_gridB>(%options, LISTof$points)

Snap the polygon points to grid points, where artifacts are removed.
OptionDefault
raster 1.0

raster => FLOAT

The raster size, which determines the points to round to. The origin
[0,0] is always on a gridpoint. When the raster value is zero,
no transformation will take place.



<B>polygon_mirrorB>(%options, LISTof$points)

Mirror the polygon in a line. Only one of the options can be provided.
Some programs call this flip or flop.
OptionDefault
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.



<B>polygon_moveB>(%options, LISTof$points)

Returns a list of points which are moved over the indicated distance
OptionDefault
dx 0
dy 0

dx => FLOAT

Displacement in the horizontal direction.

dy => FLOAT

Displacement in the vertical direction.



<B>polygon_resizeB>(%options, LISTof$points)

OptionDefault
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.



<B>polygon_rotateB>(%options, LISTof$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)



<B>polygon_simplifyB>(%options, LISTof$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.




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



SEE ALSO
This module is part of MathPolygon distribution version 1.03,
built on January 21, 2014. Website: http://perl.overmeer.net/geo/
LICENSE
Copyrights 2004,20062014 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 v5.20.3  MATH::POLYGON::TRANSFORM (3)  20140121 
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