111 lines
3.3 KiB
Java
111 lines
3.3 KiB
Java
/*
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* Copyright © 2010 Keith Packard <keithp@keithp.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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*/
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package org.altusmetrum.altoslib_14;
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import java.lang.Math;
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import java.io.*;
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public class AltosGreatCircle implements Cloneable {
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public double distance;
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public double bearing;
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public double range;
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public double elevation;
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double sqr(double a) { return a * a; }
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public static final double rad = Math.PI / 180;
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public static final double earth_radius = 6371.2 * 1000; /* in meters */
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public static final int BEARING_LONG = AltosConvert.BEARING_LONG;
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public static final int BEARING_SHORT = AltosConvert.BEARING_SHORT;
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public static final int BEARING_VOICE = AltosConvert.BEARING_VOICE;
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public String bearing_words(int length) {
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return AltosConvert.bearing_to_words(length, bearing);
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}
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public AltosGreatCircle (double start_lat, double start_lon, double start_alt,
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double end_lat, double end_lon, double end_alt) {
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double lat1 = rad * start_lat;
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double lon1 = rad * -start_lon;
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double lat2 = rad * end_lat;
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double lon2 = rad * -end_lon;
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double d_lon = lon2 - lon1;
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/* From http://en.wikipedia.org/wiki/Great-circle_distance */
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double vdn = Math.sqrt(sqr(Math.cos(lat2) * Math.sin(d_lon)) +
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sqr(Math.cos(lat1) * Math.sin(lat2) -
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Math.sin(lat1) * Math.cos(lat2) * Math.cos(d_lon)));
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double vdd = Math.sin(lat1) * Math.sin(lat2) + Math.cos(lat1) * Math.cos(lat2) * Math.cos(d_lon);
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double d = Math.atan2(vdn,vdd);
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double course;
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if (Math.cos(lat1) < 1e-20) {
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if (lat1 > 0)
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course = Math.PI;
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else
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course = -Math.PI;
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} else {
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if (d < 1e-10)
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course = 0;
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else
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course = Math.acos((Math.sin(lat2)-Math.sin(lat1)*Math.cos(d)) /
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(Math.sin(d)*Math.cos(lat1)));
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if (Math.sin(lon2-lon1) > 0)
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course = 2 * Math.PI-course;
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}
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distance = d * earth_radius;
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if (Double.isNaN(course) || Double.isInfinite(course))
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bearing = 0;
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else
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bearing = course * 180/Math.PI;
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double height_diff = end_alt - start_alt;
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range = Math.sqrt(distance * distance + height_diff * height_diff);
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elevation = Math.atan2(height_diff, distance) * 180 / Math.PI;
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}
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public AltosGreatCircle clone() {
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AltosGreatCircle n = new AltosGreatCircle();
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n.distance = distance;
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n.bearing = bearing;
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n.range = range;
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n.elevation = elevation;
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return n;
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}
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public AltosGreatCircle (double start_lat, double start_lon,
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double end_lat, double end_lon) {
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this(start_lat, start_lon, 0, end_lat, end_lon, 0);
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}
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public AltosGreatCircle(AltosGPS start, AltosGPS end) {
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this(start.lat, start.lon, start.alt, end.lat, end.lon, end.alt);
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}
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public AltosGreatCircle() {
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distance = 0;
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bearing = 0;
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range = 0;
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elevation = 0;
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}
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}
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