Determine if a point reside inside a leaflet polygon - leaflet

Question

Suppose I Draw a polygan using leaflet like in the follow demo:
http://leaflet.github.io/Leaflet.draw/
My question is how I can determine if a given point reside inside the polygon or not.

Answer 1

Use the Ray Casting algorithm for checking if a point (marker) lies inside of a polygon:
function isMarkerInsidePolygon(marker, poly) {
var polyPoints = poly.getLatLngs();
var x = marker.getLatLng().lat, y = marker.getLatLng().lng;
var inside = false;
for (var i = 0, j = polyPoints.length - 1; i < polyPoints.length; j = i++) {
var xi = polyPoints[i].lat, yi = polyPoints[i].lng;
var xj = polyPoints[j].lat, yj = polyPoints[j].lng;
var intersect = ((yi > y) != (yj > y))
&& (x < (xj - xi) * (y - yi) / (yj - yi) + xi);
if (intersect) inside = !inside;
}
return inside;
};
See jsfiddle for example.
Original source for the code: https://github.com/substack/point-in-polygon/blob/master/index.js
See also 2014's similar answer, https://stackoverflow.com/a/41138512/287948

Answer 2

Here is the modified(with #Sumit hints) version of #gusper answer that worked for me:(i had donuts)
function isMarkerInsidePolygon(marker, poly) {
var inside = false;
var x = marker.getLatLng().lat, y = marker.getLatLng().lng;
for (var ii=0;ii<poly.getLatLngs().length;ii++){
var polyPoints = poly.getLatLngs()[ii];
for (var i = 0, j = polyPoints.length - 1; i < polyPoints.length; j = i++) {
var xi = polyPoints[i].lat, yi = polyPoints[i].lng;
var xj = polyPoints[j].lat, yj = polyPoints[j].lng;
var intersect = ((yi > y) != (yj > y))
&& (x < (xj - xi) * (y - yi) / (yj - yi) + xi);
if (intersect) inside = !inside;
}
}
return inside;
};

Answer 3

I found that none of the above answers worked for counting markers within non-contiguous polygons. Here's an example polygon where the above functions returned 0 markers inside:
For anyone who needs to do that, the Leaflet.PointInPolygon package worked for me: https://github.com/hayeswise/Leaflet.PointInPolygon
It's a bit slow, but it seems to be accurate.