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<?php
namespace Maps;
use DataValues\Geo\Values\LatLongValue;
/**
* Static class containing geographical functions.
*
* @licence GNU GPL v2+
* @author Jeroen De Dauw < jeroendedauw@gmail.com >
* @author Pnelnik
* @author Matěj Grabovský
*/
final class GeoFunctions {
// The approximate radius of the earth in meters, according to http://en.wikipedia.org/wiki/Earth_radius.
private const EARTH_RADIUS = 6371000;
/**
* Returns the geographical distance between two coordinates.
* See http://en.wikipedia.org/wiki/Geographical_distance
*
* @since 2.0
*
* @param LatLongValue $start
* @param LatLongValue $end
*
* @return float Distance in m.
*/
public static function calculateDistance( LatLongValue $start, LatLongValue $end ) {
$northRad1 = deg2rad( $start->getLatitude() );
$eastRad1 = deg2rad( $start->getLongitude() );
$cosNorth1 = cos( $northRad1 );
$cosEast1 = cos( $eastRad1 );
$sinNorth1 = sin( $northRad1 );
$sinEast1 = sin( $eastRad1 );
$northRad2 = deg2rad( $end->getLatitude() );
$eastRad2 = deg2rad( $end->getLongitude() );
$cosNorth2 = cos( $northRad2 );
$cosEast2 = cos( $eastRad2 );
$sinNorth2 = sin( $northRad2 );
$sinEast2 = sin( $eastRad2 );
$term1 = $cosNorth1 * $sinEast1 - $cosNorth2 * $sinEast2;
$term2 = $cosNorth1 * $cosEast1 - $cosNorth2 * $cosEast2;
$term3 = $sinNorth1 - $sinNorth2;
$distThruSquared = $term1 * $term1 + $term2 * $term2 + $term3 * $term3;
$distance = 2 * self::EARTH_RADIUS * asin( sqrt( $distThruSquared ) / 2 );
assert( $distance >= 0 );
return $distance;
}
/**
* Finds a destination given a starting location, bearing and distance.
*
* @since 2.0
*
* @param LatLongValue $startingCoordinates
* @param float $bearing The initial bearing in degrees.
* @param float $distance The distance to travel in km.
*
* @return array The destination coordinates, as non-directional floats in an array with lat and lon keys.
*/
public static function findDestination( LatLongValue $startingCoordinates, $bearing, $distance ) {
$startingCoordinates = [
'lat' => deg2rad( $startingCoordinates->getLatitude() ),
'lon' => deg2rad( $startingCoordinates->getLongitude() ),
];
$radBearing = deg2rad( (float)$bearing );
$angularDistance = $distance / self::EARTH_RADIUS;
$lat = asin(
sin( $startingCoordinates['lat'] ) * cos( $angularDistance ) + cos( $startingCoordinates['lat'] ) * sin(
$angularDistance
) * cos( $radBearing )
);
$lon = $startingCoordinates['lon'] + atan2(
sin( $radBearing ) * sin( $angularDistance ) * cos( $startingCoordinates['lat'] ),
cos( $angularDistance ) - sin( $startingCoordinates['lat'] ) * sin( $lat )
);
return [
'lat' => rad2deg( $lat ),
'lon' => rad2deg( $lon )
];
}
}
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