/**
* Find a location a distance and bearing from this one
*
* @param Number $distance distance to other point
* @param Number $bearing initial bearing to other point
* @param String $unit The unit the distance is in
*
* @return Point
*/
public function getRelativePoint($distance, $bearing, $unit = 'km')
{
$rad = Location::getEllipsoid()->radius($unit);
$lat1 = $this->latitudeToRad();
$lon1 = $this->longitudeToRad();
$bearing = deg2rad($bearing);
$lat2 = sin($lat1) * cos($distance / $rad) + cos($lat1) * sin($distance / $rad) * cos($bearing);
$lat2 = asin($lat2);
$lon2y = sin($bearing) * sin($distance / $rad) * cos($lat1);
$lon2x = cos($distance / $rad) - sin($lat1) * sin($lat2);
$lon2 = $lon1 + atan2($lon2y, $lon2x);
return new self(rad2deg($lat2), rad2deg($lon2));
}
/**
* @param Point $point the centre of the bounding box
* @param number $radius minimum radius from $point
* @param string $unit unit of the radius (default is kilometres)
*
* @return Polygon the BBox
*/
public static function getBBoxByRadius(Point $point, $radius, $unit = 'km')
{
$north = $point->getRelativePoint($radius, 0, $unit);
$south = $point->getRelativePoint($radius, 180, $unit);
$limits['n'] = $north->getLatitude();
$limits['s'] = $south->getLatitude();
$radDist = $radius / Location::getEllipsoid()->radius($unit);
// $minLat = deg2rad( $limits['s'] );
// $maxLat = deg2rad( $limits['n'] );
$radLon = $point->longitudeToRad();
//if ($minLat > deg2rad(-90) && $maxLat < deg2rad(90)) {
$deltaLon = asin(sin($radDist) / cos($point->latitudeToRad()));
$minLon = $radLon - $deltaLon;
if ($minLon < deg2rad(-180)) {
$minLon += 2 * pi();
}
$maxLon = $radLon + $deltaLon;
if ($maxLon > deg2rad(180)) {
$maxLon -= 2 * pi();
}
//}
$limits['w'] = rad2deg($minLon);
$limits['e'] = rad2deg($maxLon);
$nw = new Point($limits['n'], $limits['w']);
$ne = new Point($limits['n'], $limits['e']);
$sw = new Point($limits['s'], $limits['w']);
$se = new Point($limits['s'], $limits['e']);
$polygon = new Polygon([[$nw, $ne, $se, $sw]]);
return $polygon;
}
