// Copyright (c) 2016-2016 The Regents of the University of California.
// All rights reserved.
//
// Permission is hereby granted, without written agreement and without
// license or royalty fees, to use, copy, modify, and distribute this
// software and its documentation for any purpose, provided that the above
// copyright notice and the following two paragraphs appear in all copies
// of this software.
//
// IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
// ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
// THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//
// THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
// PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
// CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
// ENHANCEMENTS, OR MODIFICATIONS.
//
/** This accessor takes a WG-84 location (latitude, longitude, and altitude)
* and converts it to ECEF (Earth-Centered, Earth-Fixed) cartesian coordinates.
* Based on http://danceswithcode.net/engineeringnotes/geodetic_to_ecef/geodetic_to_ecef.html
*
* @accessor geodesy/Lla2Ecef
* @author Eloi T. Pereira (eloi@berkeley.edu)
* @version $$Id$$
* @input {double} lat latitude
* @input {double} lon longitude
* @input {double} alt altitude
* @output {double} x ecef x coordinate
* @output {double} y ecef y coordinate
* @output {double} z ecef z coordinate
*
*/
// Stop extra messages from jslint and jshint. Note that there should
// be no space between the / and the * and global. See
// https://chess.eecs.berkeley.edu/ptexternal/wiki/Main/JSHint */
/*globals addInputHandler, get, error, exports, extend, get, input, output, parameter, require, send */
/*jshint globalstrict: true*/
'use strict';
/** Set up the accessor by defining the inputs and outputs.
*/
exports.setup = function () {
this.input('lat');
this.input('lon');
this.input('alt');
this.output('x');
this.output('y');
this.output('z');
};
exports.initialize = function () {
// WGS-84 parameters
var a = 6378137.0; //WGS-84 semi-major axis (meters)
var e2 = 6.6943799901377997e-3; //WGS-84 first eccentricity squared
var self = this;
this.addInputHandler(function () {
var lat = this.get('lat') * Math.PI / 180;
var lon = this.get('lon') * Math.PI / 180;
var alt = this.get('alt');
var n = a / Math.sqrt(1 - e2 * Math.sin(lat) * Math.sin(lat));
var x = (n + alt) * Math.cos(lat) * Math.cos(lon);
var y = (n + alt) * Math.cos(lat) * Math.sin(lon);
var z = (n * (1 - e2) + alt) * Math.sin(lat);
self.send('x', x);
self.send('y', y);
self.send('z', z);
});
};