utils.js

//404 Motivation Not Found, 地球上の2地点間の距離を取得するアルゴリズム(ヒュベニ or 球面三角法)比較, https://tech-blog.s-yoshiki.com/2018/05/92/
function hubeny(lat1, lng1, lat2, lng2) {
    function rad(deg) {
        return deg * Math.PI / 180;
    }
    //degree to radian
    lat1 = rad(lat1);
    lng1 = rad(lng1);
    lat2 = rad(lat2);
    lng2 = rad(lng2);

    // 緯度差
    var latDiff = lat1 - lat2;
    // 経度差算
    var lngDiff = lng1 - lng2;
    // 平均緯度
    var latAvg = (lat1 + lat2) / 2.0;
    // 赤道半径
    var a = 6378137.0;
    // 極半径
    var b = 6356752.314140356;
    // 第一離心率^2
    var e2 = 0.00669438002301188;
    // 赤道上の子午線曲率半径
    var a1e2 = 6335439.32708317;

    var sinLat = Math.sin(latAvg);
    var W2 = 1.0 - e2 * (sinLat * sinLat);

    // 子午線曲率半径M
    var M = a1e2 / (Math.sqrt(W2) * W2);
    // 卯酉線曲率半径
    var N = a / Math.sqrt(W2);

    const t1 = M * latDiff;
    const t2 = N * Math.cos(latAvg) * lngDiff;
    return Math.sqrt((t1 * t1) + (t2 * t2));
}
function sphericalTrigonometry(lat1, lng1, lat2, lng2) {
    // 赤道半径
    var R = 6378137.0;

    function rad(deg) {
        return deg * Math.PI / 180;
    }

    return R *
        Math.acos(
            Math.cos(rad(lat1)) *
            Math.cos(rad(lat2)) *
            Math.cos(rad(lng2) - rad(lng1)) +
            Math.sin(rad(lat1)) *
            Math.sin(rad(lat2))
        );
}

//Andrei Sambra, Parsing a Link header in Javascript, https://coderwall.com/p/zrlulq/parsing-a-link-header-in-javascript
// Unquote string (utility)
function unquote(value) {
    if (value.charAt(0) == '"' && value.charAt(value.length - 1) == '"') return value.substring(1, value.length - 1);
    return value;
}

// Parse a Link header
function parseLinkHeader(header) {
    var linkexp = /<[^>]*>\s*(\s*;\s*[^\(\)<>@,;:"\/\[\]\?={} \t]+=(([^\(\)<>@,;:"\/\[\]\?={} \t]+)|("[^"]*")))*(,|$)/g;
    var paramexp = /[^\(\)<>@,;:"\/\[\]\?={} \t]+=(([^\(\)<>@,;:"\/\[\]\?={} \t]+)|("[^"]*"))/g;

    var matches = header.match(linkexp);
    var rels = new Object();
    for (i = 0; i < matches.length; i++) {
        var split = matches[i].split('>');
        var href = split[0].substring(1);
        var ps = split[1];
        var link = new Object();
        link.href = href;
        var s = ps.match(paramexp);
        for (j = 0; j < s.length; j++) {
            var p = s[j];
            var paramsplit = p.split('=');
            var name = paramsplit[0];
            link[name] = unquote(paramsplit[1]);
        }

        if (link.rel != undefined) {
            rels[link.rel] = link;
        }
    }

    return rels;
}
//-------------

//graphhopper, https://github.com/graphhopper/graphhopper/blob/d70b63660ac5200b03c38ba3406b8f93976628a6/web/src/main/webapp/js/ghrequest.js#L139
function decodePath(encoded, is3D) {
    var len = encoded.length;
    var index = 0;
    var array = [];
    var lat = 0;
    var lng = 0;
    var ele = 0;

    while (index < len) {
        var b;
        var shift = 0;
        var result = 0;
        do {
            b = encoded.charCodeAt(index++) - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        var deltaLat = ((result & 1) ? ~(result >> 1) : (result >> 1));
        lat += deltaLat;

        shift = 0;
        result = 0;
        do {
            b = encoded.charCodeAt(index++) - 63;
            result |= (b & 0x1f) << shift;
            shift += 5;
        } while (b >= 0x20);
        var deltaLon = ((result & 1) ? ~(result >> 1) : (result >> 1));
        lng += deltaLon;

        if (is3D) {
            // elevation
            shift = 0;
            result = 0;
            do {
                b = encoded.charCodeAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            var deltaEle = ((result & 1) ? ~(result >> 1) : (result >> 1));
            ele += deltaEle;
            array.push([lng * 1e-5, lat * 1e-5, ele / 100]);
        } else
            array.push([lng * 1e-5, lat * 1e-5]);
    }
    // var end = new Date().getTime();
    // console.log("decoded " + len + " coordinates in " + ((end - start) / 1000) + "s");
    return array;
};