Finding all the markers inside a given radius
Here is a working example. Click map to draw a radius with selected radius and it would display all the markers from all_locations example array which fall inside the radius. Click on a marker to see the distance in meters from the radius center. (Click somewhere around New York's Second Street to see the example markers - map is already centered to that location)
var map = null;
var radius_circle = null;
var markers_on_map = [];
//all_locations is just a sample, you will probably load those from database
var all_locations = [
{type: "Restaurant", name: "Restaurant 1", lat: 40.723080, lng: -73.984340},
{type: "School", name: "School 1", lat: 40.724705, lng: -73.986611},
{type: "School", name: "School 2", lat: 40.724165, lng: -73.983883},
{type: "Restaurant", name: "Restaurant 2", lat: 40.721819, lng: -73.991358},
{type: "School", name: "School 3", lat: 40.732056, lng: -73.998683}
];
//initialize map on document ready
$(document).ready(function(){
var latlng = new google.maps.LatLng(40.723080, -73.984340); //you can use any location as center on map startup
var myOptions = {
zoom: 14,
center: latlng,
mapTypeControl: true,
mapTypeControlOptions: {style: google.maps.MapTypeControlStyle.DROPDOWN_MENU},
navigationControl: true,
mapTypeId: google.maps.MapTypeId.ROADMAP
};
map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
google.maps.event.addListener(map, 'click', showCloseLocations);
});
function showCloseLocations(e) {
var i;
var radius_km = $('#radius_km').val();
var address = $('#address').val();
//remove all radii and markers from map before displaying new ones
if (radius_circle) {
radius_circle.setMap(null);
radius_circle = null;
}
for (i = 0; i < markers_on_map.length; i++) {
if (markers_on_map[i]) {
markers_on_map[i].setMap(null);
markers_on_map[i] = null;
}
}
var address_lat_lng = e.latLng;
radius_circle = new google.maps.Circle({
center: address_lat_lng,
radius: radius_km * 1000,
clickable: false,
map: map
});
if(radius_circle) map.fitBounds(radius_circle.getBounds());
for (var j = 0; j < all_locations.length; j++) {
(function (location) {
var marker_lat_lng = new google.maps.LatLng(location.lat, location.lng);
var distance_from_location = google.maps.geometry.spherical.computeDistanceBetween(address_lat_lng, marker_lat_lng); //distance in meters between your location and the marker
if (distance_from_location <= radius_km * 1000) {
var new_marker = new google.maps.Marker({
position: marker_lat_lng,
map: map,
title: location.name
});
google.maps.event.addListener(new_marker, 'click', function () {
alert(location.name + " is " + distance_from_location + " meters from my location");
});
markers_on_map.push(new_marker);
}
})(all_locations[j]);
}
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script type="text/javascript" src="http://www.google.com/jsapi"></script>
<script type="text/javascript">
google.load("maps", "3",{other_params:"sensor=false&libraries=geometry"});
</script>
<body style="margin:0px; padding:0px;" >
<select id="radius_km">
<option value=1>1km</option>
<option value=2>2km</option>
<option value=5>5km</option>
<option value=30>30km</option>
</select>
<div id="map_canvas" style="width:500px; height:300px;">
</body>Just iterate all the markers you have and use the following function to get the distance from the specific co-ordinate to the marker: computeDistanceBetween():
To compute this distance, call computeDistanceBetween(), passing it two LatLng objects.
I found it over here. Then just filter out all the markers that turn out to be close enough.
var targetLat=marker.getPosition().lat();
var targetLng=marker.getPosition().lng();
var targetLoc = new GLatLng(targetLat,targetLng);
var center= new GLatLng(centerLat, centerLng);
var distanceInkm=center.distanceFrom(targetLoc) / 1000;
if(distanceInkm < radius){
// To add the marker to the map, call setMap();
marker.setMap(map);
}