JavascriptはGPS 2点の経緯度情報に基づいて距離を計算します.
3895 ワード
//
const EARTH_RADIUS = 6378137.0; // M
//PI
const PI = Math.PI;
function getRad(d) {
return d * PI / 180.0;
}
/**
* GPS
* @param {Number} latitude1 1 GPS
* @param {Number} longitude1 1 GPS
* @param {Number} latitude2 2 GPS
* @param {Number} longitude2 2 GPS
* @return {Number}
*/
function getFlatternDistance(latitude1, longitude1, latitude2, longitude2) {
if ((latitude1 === latitude2) && (longitude1 === longitude2)) {
return 0;
}
var lat1 = latitude1;
var lng1 = longitude1;
var lat2 = latitude2;
var lng2 = longitude2;
if (lat1 == null || lng1 == null ||
lat2 == null || lng2 == null) {
return Number.NaN;
}
var f = getRad((lat1 + lat2) / 2);
var g = getRad((lat1 - lat2) / 2);
var l = getRad((lng1 - lng2) / 2);
var sg = Math.sin(g);
var sl = Math.sin(l);
var sf = Math.sin(f);
var s, c, w, r, d, h1, h2;
var a = EARTH_RADIUS;
var fl = 1 / 298.257;
sg = sg * sg;
sl = sl * sl;
sf = sf * sf;
s = sg * (1 - sl) + (1 - sf) * sl;
c = (1 - sg) * (1 - sl) + sf * sl;
w = Math.atan(Math.sqrt(s / c));
r = Math.sqrt(s * c) / w;
d = 2 * w * a;
h1 = (3 * r - 1) / 2 / c;
h2 = (3 * r + 1) / 2 / s;
var tValue = d * (1 + fl * (h1 * sf * (1 - sg) - h2 * (1 - sf) * sg));
return tValue;
};