Google Maps Custom Markers in an Area [duplicate] - google-maps

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Calculate “as the crow flies” distance php
I am trying to develop a GoogleMaps page where I can get the user location and show custom marker points from an XML file that fells within the calculated area around the user.
To make things more clear :
I have a radius parameter from WebConfig file, say 5000 (in meters)
I've found the user location on map,
Using the xml list that I own (xml has the Lat-Long values of
each store) I want to put custom markers on map which fell within
the 5 km^2 area range with the user's location as center.
Is there a way to achieve this goal?
How do I calculate a point's Lat & Long values by only passing user's location coordinates and a distance parameter (say 5000 in my case)?
Edit :
My XML doc is kinda huge including whitegoods stores all around the
country. My main problem is to filter these rows of data (long,latt)
using user's current location.
I need something like:
func distanceCale(int long, int latt, int radius)
to return me some values that can help me filter my XML data.
I guess my question was not clear enough at the firs place. :)

Answer 1

You can achieve this using the Haversine formula. This formula has been used in a Demo from an XML file showing markers within a given radius.
For your application the javascript code is used to generate markers from XML file.
function deg2rad(degrees){
radians = degrees * (Math.PI/180);
//document.write(radians);
return radians;
}
function Haversine(lat1,lon1,lat2,lon2) {
deltaLat = lat2 - lat1 ;
deltaLon = lon2 - lon1 ;
earthRadius = 3959; // in miles 6371 in meters.
alpha = deltaLat/2;
beta = deltaLon/2;
a = Math.sin(deg2rad(alpha)) * Math.sin(deg2rad(alpha)) + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.sin(deg2rad(beta)) * Math.sin(deg2rad(beta)) ;
c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
distance = earthRadius * c;
return distance.toFixed(2);
}
The Haversine function is used when parsing XML
var radius = document.getElementById('radiusSelect').value;
for (var i = 0; i < markerNodes.length; i++) {
var lat = parseFloat(markerNodes[i].getAttribute("lat"));
var lng = parseFloat(markerNodes[i].getAttribute("lng"));
var latlng = new google.maps.LatLng(
lat,
lng);
var distance = Haversine(center.lat(),center.lng(),lat,lng);
if(distance<=radius) {
createOption(name, distance, i);
createMarker(latlng, name, distance);
bounds.extend(latlng);
}