NAME
    Random::PoissonDisc - distribute points aesthetically in R^n

SYNOPSIS
        my $points = Random::PoissonDisc->points(
            dimensions => [100,100],
            r => $r,
        );
        print join( ",", @$_),"\n"
            for @$points;

    This module allows relatively fast (linear in the number of points
    generated) generation of random points in *n*-dimensional space with a
    distance of at least `r' between each other. This distribution results
    in aesthetic so called "blue noise".

    The algorithm was adapted from a sketch by Robert Bridson in
    http://www.cs.ubc.ca/~rbridson/docs/bridson-siggraph07-poissondisk.pdf.

DATA REPRESENTATION
    All vectors (or points) are represented as anonymous arrays of numbers.
    All have the same dimension as the cardinality of the `dimensions' array
    passed in the `->points' method.

  USER INTERFACE
    `Random::PoissonDisc->points( %options )'
    Returns a reference to an array of points.

    Acceptable options are:

    *   ` r ' - minimum distance between points.

        Default is 10 units.

    *   ` dimensions ' - number of dimensions and respective value range as
        an arrayref.

        Default is

            [ 100, 100 ]

        meaning all points will be in R^2 , with each coordinate in the
        range [0, 100).

    *   ` candidates ' - Number of candidates to inspect before deciding
        that no ew neighbours can be placed around a point.

        Default is 30.

        This number may or may not need to be tweaked if you go further up
        in dimensionality beyond 3 dimensions. The more candidates you
        inspect the longer the algorithm will run for generating a number of
        points.

        In the algorithm description, this constant is named *k*.

  INTERNAL SUBROUTINES
    These subroutines are used for the algorithm. If you want to port this
    module to PDL or any other vector library, you will likely have to
    rewrite these.

    `rnd( $low, $high )'
        print rnd( 0, 1 );

    Returns a uniform distributed random number in `[ $low, $high )'.

    `grid_coords( $grid_size, $point )'
    Returns the string representing the coordinates of the grid cell in
    which `$point' falls.

    `norm( @vector )'
        print norm( 1,1 ); # 1.4142

    Returns the Euclidean length of the vector, passed in as array.

    `vdist( $l, $r )'
        print vdist( [1,0], [0,1] ); # 1.4142

    Returns the Euclidean distance between two points (or vectors)

    `neighbour_points( $size, $point, $grid )'
        my @neighbours = neighbour_points( $size, $p, \%grid )

    Returns the points from the grid that have a distance between 0 and 2r
    around `$point'. These points are the candidates to check when trying to
    insert a new random point into the space.

    `random_unit_vector( $dimensions )'
        print join ",", @{ random_unit_vector( 2 ) };

    Returns a vector of unit length pointing in a random uniform distributed
    *n*-dimensional direction angle and returns a unit vector pointing in
    that direction

    The algorithm used is outlined in Knuth, _The Art of Computer
    Programming_, vol. 2, 3rd. ed., section 3.4.1.E.6. but has not been
    verified formally or mathematically by the module author.

TODO
    The module does not use PDL or any other vector library.

REPOSITORY
    The public repository of this module is
    http://github.com/Corion/random-poissondisc.

SUPPORT
    The public support forum of this module is http://perlmonks.org/.

BUG TRACKER
    Please report bugs in this module via the RT CPAN bug queue at
    https://rt.cpan.org/Public/Dist/Display.html?Name=Random-PoissonDisc or
    via mail to random-poissondisc@rt.cpan.org.

AUTHOR
    Max Maischein `corion@cpan.org'

COPYRIGHT (c)
    Copyright 2011 by Max Maischein `corion@cpan.org'.

LICENSE
    This module is released under the same terms as Perl itself.