TDataView_ui/scripts/vendor/map23dlib/draw/ext/PolygonUtil.js

/*
 * L.PolygonUtil contains different utility functions for Polygons.
 */

L.PolygonUtil = {
	// Ported from the OpenLayers implementation. See https://github.com/openlayers/openlayers/blob/master/lib/OpenLayers/Geometry/LinearRing.js#L270
	geodesicArea: function (latLngs) {
		var pointsCount = latLngs.length,
			area = 0.0,
			d2r = L.LatLng.DEG_TO_RAD,
			p1, p2;

		if (pointsCount > 2) {
			for (var i = 0; i < pointsCount; i++) {
				p1 = latLngs[i];
				p2 = latLngs[(i + 1) % pointsCount];
				area += ((p2.lng - p1.lng) * d2r) *
						(2 + Math.sin(p1.lat * d2r) + Math.sin(p2.lat * d2r));
			}
			area = area * 6378137.0 * 6378137.0 / 2.0;
		}

		return Math.abs(area);
	}
};