/*

* Copyright (C) 2008 Google Inc.

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

import java.util.ArrayList;

import java.util.List;

import com.google.android.maps.GeoPoint;

/**

* Library for some use useful latitude/longitude math

*/

public class GeoUtils {

private static int EARTH_RADIUS_KM = 6371;

public static double MILLION = 1000000;

/**

* Computes the bearing in degrees between two points on Earth.

*

* @param lat1 Latitude of the first point

* @param lon1 Longitude of the first point

* @param lat2 Latitude of the second point

* @param lon2 Longitude of the second point

* @return Bearing between the two points in degrees. A value of 0 means due

* north.

*/

public static double bearing(double lat1, double lon1, double lat2, double lon2) {

double lat1Rad = Math.toRadians(lat1);

double lat2Rad = Math.toRadians(lat2);

double deltaLonRad = Math.toRadians(lon2 - lon1);

double y = Math.sin(deltaLonRad) * Math.cos(lat2Rad);

double x = Math.cos(lat1Rad) * Math.sin(lat2Rad) - Math.sin(lat1Rad) * Math.cos(lat2Rad)

* Math.cos(deltaLonRad);

return radToBearing(Math.atan2(y, x));

}

/**

* Computes the bearing in degrees between two points on Earth.

*

* @param p1 First point

* @param p2 Second point

* @return Bearing between the two points in degrees. A value of 0 means due

* north.

*/

public static double bearing(GeoPoint p1, GeoPoint p2) {

double lat1 = p1.getLatitudeE6() / MILLION;

double lon1 = p1.getLongitudeE6() / MILLION;

double lat2 = p2.getLatitudeE6() / MILLION;

double lon2 = p2.getLongitudeE6() / MILLION;

return bearing(lat1, lon1, lat2, lon2);

}

/**

* Converts an angle in radians to degrees

*/

public static double radToBearing(double rad) {

return (Math.toDegrees(rad) + 360) % 360;

}

}