gistfile1.php

<?php 
function intersectPoint($line1start, $line1end, $line2start, $line2end)
{

    bcscale(20);
    $x1 = (double) $line1start['lat'];
    $y1 = (double) $line1start['lng'];
    $x2 = (double) $line1end['lat'];
    $y2 = (double) $line1end['lng'];
    $x3 = (double) $line2start['lat'];
    $y3 = (double) $line2start['lng'];
    $x4 = (double) $line2end['lat'];
    $y4 = (double) $line2end['lng'];
    AppCommUtility::echof("===============\n".'Checking intersect' . print_r(func_get_args(),true));
    $den =
        bcsub(
            bcmul(bcsub($y4,$y3), bcsub($x2,$x1)),
            bcmul(bcsub($x4,$x3), bcsub($y2,$y1))
        );
    if((double) $den == 0)
    {
        AppCommUtility::echof("den == 0");
        return null;
    }
    $ua1 = bcmul(bcsub($x4, $x3), bcsub($y1, $y3));
    $ua2 = bcmul(bcsub($y4, $y3), bcsub($x1, $x3));
    $num_ua =
        bcsub(
            $ua1,
            $ua2
        );
    if((double) $num_ua == 0)
    {
        AppCommUtility::echof("num_ua == 0");
    }
    $ua =
        bcdiv(
            $num_ua,
            $den
        );
    $ub1 = bcmul(bcsub($x2,$x1), bcsub($y1, $y3));
    $ub2 = bcmul(bcsub($y2, $y1), bcsub($x1, $x3));
    $num_ub =
        bcsub(
            $ub1,
            $ub2
        );
    if((double) $num_ub == 0)
    {
        AppCommUtility::echof("num_ub == 0");
    }
    $ub =
        bcdiv(
            $num_ub,
            $den
        );
    AppCommUtility::echof("ua $ua <ua1 $ua1, ua2 $ua2> ub $ub <ub1 $ub1, ub2 $ub2> div $den");
    if($ua >= 0 && $ua <= 1 && $ub >= 0 && $ub <= 1)
    {
        return array(
            'lat' => (double) bcadd($x1, bcmul($ua, bcsub($x2, $x1))),
            'lng' => (double) bcadd($y1, bcmul($ua, bcsub($y2, $y1)))
        );
    }
    return null;
}