I'm using MKMapView
and I send my php program the visible region (center lat, center lon, span lat, span lon). I need to determine if a coordinate is inside that region using php. I'm hoping there's a standard formula somewhere, but I haven't found one. I'll keep trying to come up with a formula, but it's surprisingly complicated (hopefully not as much as the haversine, which I don't believe I could have figured out myself).
Determine if coordinate is inside region (MKMapView, solve in PHP)
270 views Asked by Elliot Alderson At
4
There are 4 answers
0
On
I had worked a solution for my own problem before, but for decimal values of coordinates and it works. May be if you can convert deg to decimal it might work.
I have renamed the variable according to your problem.
Here's the logic.
if
(
(
($lat - $spanLat) < $centerLat &&
$centerLat < ($lat+ $spanLat)
) &&
(
($long - $spanLong) < $centerLong &&
$centerLong < ($long + $spanLong)
)
)
0
On
lets try this logic
$topRightLongitude = $centerLongitude + $spanLongitude/2;
if($topRightLongitude > 180 and ($pointLongitude < 0))
$topRightLongitude = $topRightLongitude - 360; // (180*2) - positive becomes negative
$bottomLeftLongitude = $centerLongitude - $spanLongitude/2;
if($bottomLeftLongitude< -180 and ($pointLongitude > 0))
$bottomLeftLongitude= 360 + $bottomLeftLongitude; // now is negative and will become positive
$topRightLatitude = $centerLatitude + $spanLatitude/2;
if($topRightLatitude > 90 and ($pointLatitude < 0))
$topRightLatitude = $topRightLatitude - 180; // (90*2) - positive becomes negative
$bottomLeftLatitude = $centerLatitude - $spanLatitude/2;
if($bottomLeftLatitude< -90 and ($pointLatitude > 0))
$bottomLeftLatitude= 180 + $bottomLeftLongitude; // now is negative and will become positive
if you have
$centerLongitude = 179;
$spanLongitude = 20;
$pointLongitude = -179;
results
$topRightLongitude = -171;
$bottomLeftLongitude = 169;
so your point is in if you test like this:
if($pointLongitude < $topRightLongitude &&
$pointLongitude > $bottomLeftLongitude &&
$pointLatitude < $topRightLatitude &&
$pointLatitude > $bottomLeftLatitude){
echo 'in';
}else{
echo 'out';
}
My Solution
This seems to work with
MKMapView
since the region latitudes are always between -90 and 90.