Completed
Push — leaflet-attribution ( 0121c0 )
by Peter
04:35
created

MapsGeoFunctions::findDestination()   B

Complexity

Conditions 1
Paths 1

Size

Total Lines 24
Code Lines 16

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
dl 0
loc 24
rs 8.9713
c 0
b 0
f 0
cc 1
eloc 16
nc 1
nop 3
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<?php
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// The approximate radius of the earth in meters, according to http://en.wikipedia.org/wiki/Earth_radius.
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use DataValues\Geo\Values\LatLongValue;
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define( 'Maps_EARTH_RADIUS', 6371000 );
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/**
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 * Static class containing geographical functions.
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 *
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 * @since 0.6
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 *
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 * @licence GNU GPL v2+
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 * @author Jeroen De Dauw < [email protected] >
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 * @author Pnelnik
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 * @author Matěj Grabovský
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 */
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final class MapsGeoFunctions {
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	/**
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	 * Returns the geographical distance between two coordinates.
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	 * See http://en.wikipedia.org/wiki/Geographical_distance
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	 *
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	 * @since 2.0
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	 *
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	 * @param LatLongValue $start
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	 * @param LatLongValue $end
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	 *
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	 * @return float Distance in m.
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	 */
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	public static function calculateDistance( LatLongValue $start, LatLongValue $end ) {
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		$northRad1 = deg2rad( $start->getLatitude() );
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		$eastRad1 = deg2rad( $start->getLongitude() );
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		$cosNorth1 = cos( $northRad1 );
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		$cosEast1 = cos( $eastRad1 );
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		$sinNorth1 = sin( $northRad1 );
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		$sinEast1 = sin( $eastRad1 );
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		$northRad2 = deg2rad( $end->getLatitude() );
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		$eastRad2 = deg2rad( $end->getLongitude() );
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		$cosNorth2 = cos( $northRad2 );
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		$cosEast2 = cos( $eastRad2 );
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		$sinNorth2 = sin( $northRad2 );
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		$sinEast2 = sin( $eastRad2 );
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		$term1 = $cosNorth1 * $sinEast1 - $cosNorth2 * $sinEast2;
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		$term2 = $cosNorth1 * $cosEast1 - $cosNorth2 * $cosEast2;
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		$term3 = $sinNorth1 - $sinNorth2;
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		$distThruSquared = $term1 * $term1 + $term2 * $term2 + $term3 * $term3;
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		$distance = 2 * Maps_EARTH_RADIUS * asin( sqrt( $distThruSquared ) / 2 );
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		assert( $distance >= 0 );
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		return $distance;
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	}
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	/**
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	 * Finds a destination given a starting location, bearing and distance.
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	 *
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	 * @since 2.0
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	 *
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	 * @param LatLongValue $startingCoordinates
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	 * @param float $bearing The initial bearing in degrees.
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	 * @param float $distance The distance to travel in km.
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	 *
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	 * @return array The destination coordinates, as non-directional floats in an array with lat and lon keys.
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	 */
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	public static function findDestination( LatLongValue $startingCoordinates, $bearing, $distance ) {
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		$startingCoordinates = [
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			'lat' => deg2rad( $startingCoordinates->getLatitude() ),
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			'lon' => deg2rad( $startingCoordinates->getLongitude() ),
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		];
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		$radBearing = deg2rad( (float)$bearing );
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		$angularDistance = $distance / Maps_EARTH_RADIUS;
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		$lat = asin(
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			sin( $startingCoordinates['lat'] ) * cos( $angularDistance ) + cos( $startingCoordinates['lat'] ) * sin(
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				$angularDistance
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			) * cos( $radBearing )
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		);
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		$lon = $startingCoordinates['lon'] + atan2(
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				sin( $radBearing ) * sin( $angularDistance ) * cos( $startingCoordinates['lat'] ),
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				cos( $angularDistance ) - sin( $startingCoordinates['lat'] ) * sin( $lat )
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			);
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		return [
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			'lat' => rad2deg( $lat ),
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			'lon' => rad2deg( $lon )
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		];
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	}
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}