This is a php version implemention of the Kamada-Kawai algorithm for force directed graph layout.
Does not respect filter calls, and sometimes crashes when the view changes to it.

see "Tomihisa Kamada and Satoru Kawai: An algorithm for drawing general indirect graphs. Information Processing Letters 31(1):7-15, 1989" 
see "Tomihisa Kamada: On visualization of abstract objects and relations. Ph.D. dissertation, Dept. of Information Science, Univ. of Tokyo, Dec. 1988."

author ggsonic

*the getDistance function needs to be hacked. For now, it is just a very simple strategy to get the weight of distance

code sample to use:
<?php

$nodes = array();

/* Create 11 random nodes */ 
for($i=0;$i<=10;$i++)
{
    $Connections = ""; $RandCx1 = rand(0,1);
    for($j=0;$j<=$RandCx1;$j++)
    {
        $RandCx2 = rand(0,10);
        if ( $RandCx2 != $j )
        { $Connections[] = $RandCx2; }
    }
    $nodes[$i] = array('idx' => $i, "conn" => $Connections);
}
$kklayout = new KKLayout ( $nodes );
$kklayout->initialize ();
while ( ! $kklayout->done () ) {
    $kklayout->step ();
}
//var_dump($kklayout->xydata);exit;
?>