javascript - Google map API v.3 find nearest point from one point to point on polyline

Question

I`ve got a map with a polyline. The server will responds me with a LatLng point on a map. I need to check if the point from the server situated on a polyline edge. If not, i need to find the nearest point on the polyline and place a marker on the nearest point on the polyline. For example, if the server responds me with a point A, i need to place a marker to a point B.

I find a good library http://wtp2.appspot.com/cSnapToRouteDemo.html, but this library is for Google API ver. 2, and i'm using Google API ver. 3. Is there any alternative for Google API ver. 3 ? Thank's.

Answer 1

Found an easier solution.Using turf.js.Just use your polyline coordinates to create turf line and marker position for creating turf point.

then;

var line = turf.lineString(Your polyline coordinates in GeoJson array);
var pt = turf.point([Marker_Lon, Marker_Lat]);
var snapped = turf.pointOnLine(line, pt);
var pstnOnLine = { lat: snapped.geometry.coordinates[1], lng: snapped.geometry.coordinates[0] };
var distToLine = snapped.properties.dist

This way you can calculate the distance and coordinates on your polyline easily.

You can find out more from Turf website.