确定坐标是否在区域内（MKMapView，用PHP解决）

Question

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).

Answer 1

My Solution

$top = $c_lat + ($d_lat / 2.0);
$bottom = $c_lat - ($d_lat / 2.0);
$left = $c_lon - ($d_lon / 2.0);
$right = $c_lon + ($d_lon / 2.0);
if($left < -180)
{
    $second_left = $left + 360.0;
    $second_right = 180.0;
    $left = -180;
}
elseif($right > 180)
{
    $second_right = $right - 360.0;
    $second_left = -180.0;
    $right = 180.0;
}
$inside = false;
if($t_lat > $bottom && $t_lat < $top && $t_lon > $left && $t_lon < $right)
    $inside = true;
else if($second_right && $second_left)
{
    if($t_lat > $bottom && $t_lat < $top && $t_lon > $second_left && $t_lon < $second_right)
        $inside = true;
}

if($inside)
{

}

This seems to work with MKMapView since the region latitudes are always between -90 and 90.