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Diffstat (limited to 'misc/openlayers/lib/OpenLayers/Spherical.js')
-rw-r--r-- | misc/openlayers/lib/OpenLayers/Spherical.js | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/misc/openlayers/lib/OpenLayers/Spherical.js b/misc/openlayers/lib/OpenLayers/Spherical.js new file mode 100644 index 0000000..74e14a8 --- /dev/null +++ b/misc/openlayers/lib/OpenLayers/Spherical.js @@ -0,0 +1,67 @@ +/* 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; +}; |