diff options
Diffstat (limited to 'leaflet-geodesy.js')
| -rw-r--r-- | leaflet-geodesy.js | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/leaflet-geodesy.js b/leaflet-geodesy.js new file mode 100644 index 0000000..359b4ab --- /dev/null +++ b/leaflet-geodesy.js @@ -0,0 +1,198 @@ +!function(e){"object"==typeof exports?module.exports=e():"function"==typeof define&&define.amd?define(e):"undefined"!=typeof window?window.LGeo=e():"undefined"!=typeof global?global.LGeo=e():"undefined"!=typeof self&&(self.LGeo=e())}(function(){var define,module,exports;return (function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);throw new Error("Cannot find module '"+o+"'")}var f=n[o]={exports:{}};t[o][0].call(f.exports,function(e){var n=t[o][1][e];return s(n?n:e)},f,f.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){ +var spherical = require('spherical'), + geojsonArea = require('geojson-area'), + wgs84 = require('wgs84'); + +module.exports.circle = function(center, radius, opt) { + center = L.latLng(center); + opt = opt || {}; + var parts = opt.parts || 20; + + function generate(center) { + var lls = []; + var angularRadius = radius / wgs84.RADIUS * 180 / Math.PI; + + for (var i = 0; i < parts + 1; i++) { + lls.push(spherical.radial( + [center.lng, center.lat], + (i / parts) * 360, radius).reverse()); + } + + if (angularRadius > (90 - center.lat)) { + lls.push([lls[0][0], center.lng + 180], + [90, center.lng + 180], + [90, center.lng - 180], + [lls[0][0], center.lng - 180]); + } + + if (angularRadius > (90 + center.lat)) { + lls.splice((parts >> 1) + 1, 0, + [lls[(parts>>1)][0], center.lng-180 ], + [-90, center.lng-180], + [-90, center.lng+180], + [lls[(parts >> 1)][0], center.lng+180 ]); + } + + return lls; + } + + var poly = L.polygon(generate(center), opt); + + poly.setLatLng = function(_) { + center = _; + poly.setLatLngs(generate(center)); + return poly; + }; + + poly.getRadius = function(_) { + return radius; + }; + + poly.setRadius = function(_) { + radius = _; + poly.setLatLngs(generate(center)); + return poly; + }; + + return poly; +}; + +module.exports.area = function(layer) { + var gj = layer.toGeoJSON(); + return geojsonArea(gj.geometry); +}; + +},{"geojson-area":2,"spherical":4,"wgs84":6}],2:[function(require,module,exports){ +var wgs84 = require('wgs84'); + +module.exports = function(_) { + if (_.type === 'Polygon') return polygonArea(_.coordinates); + else if (_.type === 'MultiPolygon') { + var area = 0; + for (var i = 0; i < _.coordinates.length; i++) { + area += polygonArea(_.coordinates[i]); + } + return area; + } else { + return null; + } +}; + +function polygonArea(coords) { + var area = 0; + if (coords && coords.length > 0) { + area += Math.abs(ringArea(coords[0])); + for (var i = 1; i < coords.length; i++) { + area -= Math.abs(ringArea(coords[i])); + } + } + return area; +} + +/** + * Calculate the approximate area of the polygon were it projected onto + * the earth. Note that this area will be positive if ring is oriented + * clockwise, otherwise it will be negative. + * + * Reference: + * Robert. G. Chamberlain and William H. Duquette, "Some Algorithms for + * Polygons on a Sphere", JPL Publication 07-03, Jet Propulsion + * Laboratory, Pasadena, CA, June 2007 http://trs-new.jpl.nasa.gov/dspace/handle/2014/40409 + * + * Returns: + * {float} The approximate signed geodesic area of the polygon in square + * meters. + */ +function ringArea(coords) { + var area = 0; + + if (coords.length > 2) { + var p1, p2; + for (var i = 0; i < coords.length - 1; i++) { + p1 = coords[i]; + p2 = coords[i + 1]; + area += rad(p2[0] - p1[0]) * (2 + Math.sin(rad(p1[1])) + Math.sin(rad(p2[1]))); + } + + area = area * wgs84.RADIUS * wgs84.RADIUS / 2; + } + + return area; +} + +function rad(_) { + return _ * Math.PI / 180; +} + +},{"wgs84":3}],3:[function(require,module,exports){ +module.exports.RADIUS = 6378137; +module.exports.FLATTENING = 1/298.257223563; +module.exports.POLAR_RADIUS = 6356752.3142; + +},{}],4:[function(require,module,exports){ +var wgs84 = require('wgs84'); + +module.exports.heading = function(from, to) { + var y = Math.sin(Math.PI * (from[0] - to[0]) / 180) * Math.cos(Math.PI * to[1] / 180); + var x = Math.cos(Math.PI * from[1] / 180) * Math.sin(Math.PI * to[1] / 180) - + Math.sin(Math.PI * from[1] / 180) * Math.cos(Math.PI * to[1] / 180) * Math.cos(Math.PI * (from[0] - to[0]) / 180); + return 180 * Math.atan2(y, x) / Math.PI; +}; + +module.exports.distance = function(from, to) { + var sinHalfDeltaLon = Math.sin(Math.PI * (to[0] - from[0]) / 360); + var sinHalfDeltaLat = Math.sin(Math.PI * (to[1] - from[1]) / 360); + var a = sinHalfDeltaLat * sinHalfDeltaLat + + sinHalfDeltaLon * sinHalfDeltaLon * Math.cos(Math.PI * from[1] / 180) * Math.cos(Math.PI * to[1] / 180); + return 2 * wgs84.RADIUS * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a)); +}; + +module.exports.radial = function(from, tc_deg, d_m, wrap) { + var tc = rad(tc_deg); + var d = d_m / wgs84.RADIUS; + + var lon1 = rad(from[0]), + lat1 = rad(from[1]); + + var lat = Math.asin( + Math.sin(lat1) * + Math.cos(d) + + Math.cos(lat1) * + Math.sin(d) * + Math.cos(tc)); + + var dlon = Math.atan2( + Math.sin(tc) * + Math.sin(d) * + Math.cos(lat1), + Math.cos(d) - + Math.sin(lat1) * + Math.sin(lat)); + + var lon; + if (wrap) { + lon = (lon1 - dlon + Math.PI) % + (2 * Math.PI) - Math.PI; + } else { + lon = (lon1 - dlon + Math.PI) - Math.PI; + } + + return [deg(lon), deg(lat)]; +}; + +function rad(_) { + return _ * (Math.PI / 180); +} + +function deg(_) { + return _ * (180 / Math.PI); +} + +},{"wgs84":5}],5:[function(require,module,exports){ +module.exports=require(3) +},{}],6:[function(require,module,exports){ +module.exports=require(3) +},{}]},{},[1]) +(1) +}); +;
\ No newline at end of file |