Android Open Source - pink-ponies Location

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License

The source code is released under:

Software License Agreement (BSD License) Copyright (c) 2013, Pink Ponies Team All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted prov...

Java Source Code

/**
 * Copyright (c) 2013 Alexander Konovalov, Andrey Konovalov, Sergey Voronov, Vitaly Malyshev. All
 * rights reserved. Use of this source code is governed by a BSD-style license that can be found in
 * the LICENSE file.//from  w  w w  . j av a  2  s . com
 */

package ru.pinkponies.protocol;

import java.util.Random;

import org.msgpack.annotation.Message;

// Location class.
// @see http://www.movable-type.co.uk/scripts/latlong.html
@Message
public final class Location {
  // The average radius of the Earth in meters.
  private static final double EARTH_AVERAGE_RADIUS = 6371000;

  public double longitude;
  public double latitude;
  public double altitude;

  public Location() {
    this.longitude = 0;
    this.latitude = 0;
    this.altitude = 0;
  }

  public Location(final double longitude, final double latitude, final double altitude) {
    this.longitude = longitude;
    this.latitude = latitude;
    this.altitude = altitude;
  }

  // Finds the distance between this point and some other point on the globe.
  public double distanceTo(final Location that) {
    double latitudeDifference = this.latitude - that.latitude;
    double longitudeDifference = this.longitude - that.longitude;

    double a = Math.sin(latitudeDifference / 2) * Math.sin(latitudeDifference / 2)
        + Math.sin(longitudeDifference / 2) * Math.sin(longitudeDifference / 2) * Math.cos(this.latitude)
        * Math.cos(that.latitude);
    double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
    double d = EARTH_AVERAGE_RADIUS * c;

    return d;
  }

  // Finds the initial bearing (forward azimuth) to some other point.
  public double bearingTo(final Location that) {
    double longitudeDifference = this.longitude - that.longitude;

    double y = Math.sin(longitudeDifference) * Math.cos(that.latitude);
    double x = Math.cos(this.latitude) * Math.sin(that.latitude) - Math.sin(this.latitude)
        * Math.cos(that.latitude) * Math.cos(longitudeDifference);
    return Math.atan2(y, x);
  }

  // Calculate a point that is the specified distance and bearing away from this point.
  public Location moveBy(final double distanceInMeters, final double bearingInRadians) {
    // Convert distance to angular distance.
    double distance = distanceInMeters / EARTH_AVERAGE_RADIUS;

    double newLatitude = Math.asin(Math.sin(this.latitude) * Math.cos(distance) + Math.cos(this.latitude)
        * Math.sin(distance) * Math.cos(bearingInRadians));
    double newLongitude = this.longitude
        + Math.atan2(Math.sin(bearingInRadians) * Math.sin(distance) * Math.cos(this.latitude),
            Math.cos(distance) - Math.sin(this.latitude) * Math.sin(newLatitude));
    newLongitude = (newLongitude + 3 * Math.PI) % (2 * Math.PI) - Math.PI; // normalise to
                                        // -180..+180

    return new Location(newLongitude, newLatitude, this.altitude);
  }

  public Location randomLocationInCircle(final Random random, final double radiusInMeters) {
    double radius = radiusInMeters / EARTH_AVERAGE_RADIUS;

    if (radius >= Math.PI) {
      throw new IllegalArgumentException("Radius has to be smaller than half the circumference of the Earth.");
    }

    double distanceInMeters = Math.acos(1 - (1 - Math.cos(radius)) * random.nextDouble()) * EARTH_AVERAGE_RADIUS;
    double bearingInDegrees = random.nextDouble() * 2 * Math.PI;
    return this.moveBy(distanceInMeters, bearingInDegrees);
  }

  @Override
  public String toString() {
    return "Location [longitude=" + this.longitude + ", latitude=" + this.latitude + ", altitude=" + this.altitude
        + "]";
  }
}

Java Source Code List

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