Created
August 14, 2010 04:13
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<?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; | |
} |
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