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Merge pull request #45 from twpayne/initial-bearing-to

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Add OpenLayers.Spherical, including utility functions for calculations on the basis of a spherical earth, patch from @twpayne
This commit is contained in:
Éric Lemoine
2012-02-13 05:35:13 -08:00
parent 1f539470bb 8d6c9ef1ee
commit 16c30b8e6d
3 changed files with 66 additions and 1 deletions
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1
doc_config/Menu.txt
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@@ -458,6 +458,7 @@ Group: OpenLayers {
File: Tween (no auto-title, OpenLayers/Tween.js)
File: Util (no auto-title, OpenLayers/Util.js)
File: Spherical (no auto-title, OpenLayers/Spherical.js)
File: Deprecated (no auto-title, deprecated.js)
} # Group: OpenLayers

3
lib/OpenLayers.js
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@@ -348,7 +348,8 @@
"OpenLayers/Symbolizer/Text.js",
"OpenLayers/Symbolizer/Raster.js",
"OpenLayers/Lang.js",
"OpenLayers/Lang/en.js"
"OpenLayers/Lang/en.js",
"OpenLayers/Spherical.js"
]; // etc.
}

63
lib/OpenLayers/Spherical.js Normal file
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@@ -0,0 +1,63 @@
/* Copyright (c) 2006-2012 by OpenLayers Contributors (see authors.txt for
* full list of contributors). Published under the Clear BSD license.
* See http://svn.openlayers.org/trunk/openlayers/license.txt for the
* full text of the license. */
/**
* 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;
};