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World Wind is a collection of components that interactively display 3D geographic information within Java applications or applets.
/*
* Copyright (C) 2012 United States Government as represented by the Administrator of the
* National Aeronautics and Space Administration.
* All Rights Reserved.
*/
package gov.nasa.worldwind.geom;
import gov.nasa.worldwind.util.*;
import java.util.*;
/**
* @author tag
* @version $Id: Position.java 1171 2013-02-11 21:45:02Z dcollins $
*/
public class Position extends LatLon
{
public static final Position ZERO = new Position(Angle.ZERO, Angle.ZERO, 0d);
public final double elevation;
public static Position fromRadians(double latitude, double longitude, double elevation)
{
return new Position(Angle.fromRadians(latitude), Angle.fromRadians(longitude), elevation);
}
public static Position fromDegrees(double latitude, double longitude, double elevation)
{
return new Position(Angle.fromDegrees(latitude), Angle.fromDegrees(longitude), elevation);
}
public static Position fromDegrees(double latitude, double longitude)
{
return new Position(Angle.fromDegrees(latitude), Angle.fromDegrees(longitude), 0);
}
public Position(Angle latitude, Angle longitude, double elevation)
{
super(latitude, longitude);
this.elevation = elevation;
}
public Position(LatLon latLon, double elevation)
{
super(latLon);
this.elevation = elevation;
}
// A class that makes it easier to pass around position lists.
public static class PositionList
{
public List list;
public PositionList(List list)
{
this.list = list;
}
}
/**
* Obtains the elevation of this position
*
* @return this position's elevation
*/
public double getElevation()
{
return this.elevation;
}
/**
* Obtains the elevation of this position
*
* @return this position's elevation
*/
public double getAltitude()
{
return this.elevation;
}
public Position add(Position that)
{
Angle lat = Angle.normalizedLatitude(this.latitude.add(that.latitude));
Angle lon = Angle.normalizedLongitude(this.longitude.add(that.longitude));
return new Position(lat, lon, this.elevation + that.elevation);
}
public Position subtract(Position that)
{
Angle lat = Angle.normalizedLatitude(this.latitude.subtract(that.latitude));
Angle lon = Angle.normalizedLongitude(this.longitude.subtract(that.longitude));
return new Position(lat, lon, this.elevation - that.elevation);
}
/**
* Returns the linear interpolation of value1 and value2, treating the geographic
* locations as simple 2D coordinate pairs, and treating the elevation values as 1D scalars.
*
* @param amount the interpolation factor
* @param value1 the first position.
* @param value2 the second position.
*
* @return the linear interpolation of value1 and value2.
*
* @throws IllegalArgumentException if either position is null.
*/
public static Position interpolate(double amount, Position value1, Position value2)
{
if (value1 == null || value2 == null)
{
String message = Logging.getMessage("nullValue.PositionIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
if (amount < 0)
return value1;
else if (amount > 1)
return value2;
LatLon latLon = LatLon.interpolate(amount, value1, value2);
// Elevation is independent of geographic interpolation method (i.e. rhumb, great-circle, linear), so we
// interpolate elevation linearly.
double elevation = WWMath.mix(amount, value1.getElevation(), value2.getElevation());
return new Position(latLon, elevation);
}
/**
* Returns the an interpolated location along the great-arc between value1 and value2. The
* position's elevation components are linearly interpolated as a simple 1D scalar value. The interpolation factor
* amount defines the weight given to each value, and is clamped to the range [0, 1]. If a
* is 0 or less, this returns value1. If amount is 1 or more, this returns
* value2. Otherwise, this returns the position on the great-arc between value1 and
* value2 with a linearly interpolated elevation component, and corresponding to the specified
* interpolation factor.
*
* @param amount the interpolation factor
* @param value1 the first position.
* @param value2 the second position.
*
* @return an interpolated position along the great-arc between value1 and value2, with a
* linearly interpolated elevation component.
*
* @throws IllegalArgumentException if either location is null.
*/
public static Position interpolateGreatCircle(double amount, Position value1, Position value2)
{
if (value1 == null || value2 == null)
{
String message = Logging.getMessage("nullValue.PositionIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
LatLon latLon = LatLon.interpolateGreatCircle(amount, value1, value2);
// Elevation is independent of geographic interpolation method (i.e. rhumb, great-circle, linear), so we
// interpolate elevation linearly.
double elevation = WWMath.mix(amount, value1.getElevation(), value2.getElevation());
return new Position(latLon, elevation);
}
/**
* Returns the an interpolated location along the rhumb line between value1 and value2.
* The position's elevation components are linearly interpolated as a simple 1D scalar value. The interpolation
* factor amount defines the weight given to each value, and is clamped to the range [0, 1]. If
* a is 0 or less, this returns value1. If amount is 1 or more, this returns
* value2. Otherwise, this returns the position on the rhumb line between value1 and
* value2 with a linearly interpolated elevation component, and corresponding to the specified
* interpolation factor.
*
* @param amount the interpolation factor
* @param value1 the first position.
* @param value2 the second position.
*
* @return an interpolated position along the great-arc between value1 and value2, with a
* linearly interpolated elevation component.
*
* @throws IllegalArgumentException if either location is null.
*/
public static Position interpolateRhumb(double amount, Position value1, Position value2)
{
if (value1 == null || value2 == null)
{
String message = Logging.getMessage("nullValue.PositionIsNull");
Logging.logger().severe(message);
throw new IllegalArgumentException(message);
}
LatLon latLon = LatLon.interpolateRhumb(amount, value1, value2);
// Elevation is independent of geographic interpolation method (i.e. rhumb, great-circle, linear), so we
// interpolate elevation linearly.
double elevation = WWMath.mix(amount, value1.getElevation(), value2.getElevation());
return new Position(latLon, elevation);
}
public static boolean positionsCrossDateLine(Iterable positions)
{
if (positions == null)
{
String msg = Logging.getMessage("nullValue.PositionsListIsNull");
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
Position pos = null;
for (Position posNext : positions)
{
if (pos != null)
{
// A segment cross the line if end pos have different longitude signs
// and are more than 180 degress longitude apart
if (Math.signum(pos.getLongitude().degrees) != Math.signum(posNext.getLongitude().degrees))
{
double delta = Math.abs(pos.getLongitude().degrees - posNext.getLongitude().degrees);
if (delta > 180 && delta < 360)
return true;
}
}
pos = posNext;
}
return false;
}
/**
* Computes a new set of positions translated from a specified reference position to a new reference position.
*
* @param oldPosition the original reference position.
* @param newPosition the new reference position.
* @param positions the positions to translate.
*
* @return the translated positions, or null if the positions could not be translated.
*
* @throws IllegalArgumentException if any argument is null.
*/
public static List computeShiftedPositions(Position oldPosition, Position newPosition,
Iterable positions)
{
// TODO: Account for dateline spanning
if (oldPosition == null || newPosition == null)
{
String msg = Logging.getMessage("nullValue.PositionIsNull");
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
if (positions == null)
{
String msg = Logging.getMessage("nullValue.PositionsListIsNull");
Logging.logger().severe(msg);
throw new IllegalArgumentException(msg);
}
ArrayList newPositions = new ArrayList();
double elevDelta = newPosition.getElevation() - oldPosition.getElevation();
for (Position pos : positions)
{
Angle distance = LatLon.greatCircleDistance(oldPosition, pos);
Angle azimuth = LatLon.greatCircleAzimuth(oldPosition, pos);
LatLon newLocation = LatLon.greatCircleEndPosition(newPosition, azimuth, distance);
double newElev = pos.getElevation() + elevDelta;
newPositions.add(new Position(newLocation, newElev));
}
return newPositions;
}
@Override
public boolean equals(Object o)
{
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
if (!super.equals(o))
return false;
Position position = (Position) o;
//noinspection RedundantIfStatement
if (Double.compare(position.elevation, elevation) != 0)
return false;
return true;
}
@Override
public int hashCode()
{
int result = super.hashCode();
long temp;
temp = elevation != +0.0d ? Double.doubleToLongBits(elevation) : 0L;
result = 31 * result + (int) (temp ^ (temp >>> 32));
return result;
}
public String toString()
{
return "(" + this.latitude.toString() + ", " + this.longitude.toString() + ", " + this.elevation + ")";
}
}