NAME

       Math::Polygon::Transform - Polygon transformation

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

       polygon_grid(OPTIONS, LIST-OF-POINTS)
           Snap the polygon points to grid points, where artifacts are removed.

            -Option--Default
             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".

            -Option--Default
             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

            -Option--Default
             dx      0
             dy      0

           dx => FLOAT
             Displacement in the horizontal direction.

           dy => FLOAT
             Displacement in the vertical direction.

       polygon_resize(OPTIONS, LIST-OF-POINTS)
            -Option--Default
             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.

DIAGNOSTICS

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

SEE ALSO

       This module is part of Math-Polygon distribution version 1.02, built on September 19,
       2011. Website: http://perl.overmeer.net/geo/

LICENSE

       Copyrights 2004,2006-2011 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