Error in ratio estimation on locateOnLine and interpolateOnLine

[alexroat]

I've found an inconsistency in the results if locateOnLine and interpolateOnline.

I've tried to compute the ratio of a point along a road of 320 km ca then convert the ratio to a latlon again. There is a variable misplacement, pretty high in my opinion, it could go above 1km.

I've fixed implementing my own version of the functions

interpolateOnLine = function (map, latLngs, ratio) {
    latLngs = (latLngs instanceof L.Polyline) ? latLngs.getLatLngs() : latLngs;
    var maxzoom = map.getMaxZoom();
    if (maxzoom === Infinity)
        maxzoom = map.getZoom();
    var pts = latLngs.map(function (x) {
        return map.project(x);
    });

    if (ratio <= 0)
        return latLngs[0];
    if (ratio >= 1)
        return latLngs[latLngs - 1];

    var dt = 0.;
    for (var i = 1; i < pts.length; i++)
        dt += pts[i - 1].distanceTo(pts[i]);

    var dp = dt * ratio;


    var dt = 0.;
    for (var i = 1; i < pts.length; i++)
    {
        var d = pts[i - 1].distanceTo(pts[i]);
        if (dt + d > dp)
        {
            //console.log((dp-dt)/d);
            var p = L.GeometryUtil.interpolateOnPointSegment(pts[i - 1], pts[i], (dp - dt) / d);
            return map.unproject(p);
        }
        dt += d;

    }

    return latLngs[latLngs - 1];
};


locateOnLine = function (map, polyline, latlng) {
    var maxzoom = map.getMaxZoom();
    if (maxzoom === Infinity)
        maxzoom = map.getZoom();
    var pts = polyline.getLatLngs().map(function (x) {
        return map.project(x);
    });
    var point = map.project(L.GeometryUtil.closest(map, polyline, latlng, false));


    var d = 0.;
    var dt = 0.;
    for (var i = 1; i < pts.length; i++)
    {
        var dd = pts[i - 1].distanceTo(pts[i]);
        if (L.GeometryUtil.belongsSegment(point, pts[i - 1], pts[i], 0.0001))
            d = dt + pts[i - 1].distanceTo(point);
        dt += dd;
    }
    return d / dt;
};

I've tested converting latlon to ratio to latlon to ratio .... till 10 times and now it seems to be very stable and consistent

PLEASE NOTE THAT interpolateOnLine here is not returning the precedent point , just the interpolated one

[leplatrem]

Could you please open a PR with the fixes? Thanks!