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