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/* Copyright (c) 2006-2013 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the 2-clause BSD license.
* See license.txt in the OpenLayers distribution or repository for the
* full text of the license. */
/**
* @requires OpenLayers/SingleFile.js
*/
/**
* Namespace: Spherical
* The OpenLayers.Spherical namespace includes utility functions for
* calculations on the basis of a spherical earth (ignoring ellipsoidal
* effects), which is accurate enough for most purposes.
*
* Relevant links:
* * http://www.movable-type.co.uk/scripts/latlong.html
* * http://code.google.com/apis/maps/documentation/javascript/reference.html#spherical
*/
OpenLayers.Spherical = OpenLayers.Spherical || {};
OpenLayers.Spherical.DEFAULT_RADIUS = 6378137;
/**
* APIFunction: computeDistanceBetween
* Computes the distance between two LonLats.
*
* Parameters:
* from - {<OpenLayers.LonLat>} or {Object} Starting point. A LonLat or
* a JavaScript literal with lon lat properties.
* to - {<OpenLayers.LonLat>} or {Object} Ending point. A LonLat or a
* JavaScript literal with lon lat properties.
* radius - {Float} The radius. Optional. Defaults to 6378137 meters.
*
* Returns:
* {Float} The distance in meters.
*/
OpenLayers.Spherical.computeDistanceBetween = function(from, to, radius) {
var R = radius || OpenLayers.Spherical.DEFAULT_RADIUS;
var sinHalfDeltaLon = Math.sin(Math.PI * (to.lon - from.lon) / 360);
var sinHalfDeltaLat = Math.sin(Math.PI * (to.lat - from.lat) / 360);
var a = sinHalfDeltaLat * sinHalfDeltaLat +
sinHalfDeltaLon * sinHalfDeltaLon * Math.cos(Math.PI * from.lat / 180) * Math.cos(Math.PI * to.lat / 180);
return 2 * R * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
};
/**
* APIFunction: computeHeading
* Computes the heading from one LonLat to another LonLat.
*
* Parameters:
* from - {<OpenLayers.LonLat>} or {Object} Starting point. A LonLat or
* a JavaScript literal with lon lat properties.
* to - {<OpenLayers.LonLat>} or {Object} Ending point. A LonLat or a
* JavaScript literal with lon lat properties.
*
* Returns:
* {Float} The heading in degrees.
*/
OpenLayers.Spherical.computeHeading = function(from, to) {
var y = Math.sin(Math.PI * (from.lon - to.lon) / 180) * Math.cos(Math.PI * to.lat / 180);
var x = Math.cos(Math.PI * from.lat / 180) * Math.sin(Math.PI * to.lat / 180) -
Math.sin(Math.PI * from.lat / 180) * Math.cos(Math.PI * to.lat / 180) * Math.cos(Math.PI * (from.lon - to.lon) / 180);
return 180 * Math.atan2(y, x) / Math.PI;
};
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