Snippet

Snippet so7945210
Multiple Points Along Line between two known Geo Coords?


<!DOCTYPE html>
<!-- http://stackoverflow.com/a/7945210 -->
<!-- Author Jiri @ http://stackoverflow.com/users/805681/jiri -->
<!-- Created 03-Nov-2011 -->
<html>
<head>
<script type="text/javascript"
    src="http://maps.googleapis.com/maps/api/js?libraries=geometry&sensor=false">
</script>

<script type="text/javascript">
    var map;
    
    function initialize() {
        var myOptions = {
                zoom: 7,
              center: new google.maps.LatLng(47.9, 5.0),
              mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        map = new google.maps.Map(document.getElementById("map_canvas"),
            myOptions);
       
        var p1 = new google.maps.LatLng(47.362, 8.571);
        var p2 = new google.maps.LatLng(48.858, 2.331);
        var m1 = createMarker(map, p1, "point 1");
        var m2 = createMarker(map, p2, "point 2");
        
        divide(p1, p2, 6);
      }
  
      function bearing(lat1, lng1, lat2, lng2) {
          var dLon = lng2 - lng1;
          var cos_2 = Math.cos(lat2);
          var y = Math.sin(dLon) * cos_2;
        var x = Math.cos(lat1)*Math.sin(lat2) -
            Math.sin(lat1)*cos_2*Math.cos(dLon);
        var theta = Math.atan2(y, x);
        return theta;
    }

    function distance(lat1, lng1, lat2, lng2) {
        var R = 6371000; // meters
        var dLat = lat2 - lat1;
        var dLon = lng2 - lng1;
        var sinLat = Math.sin(dLat/2);
        var sinLng = Math.sin(dLon/2);
        var a = sinLat * sinLat +
                sinLng * sinLng * Math.cos(lat1) * Math.cos(lat2);
        var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
        var d = R * c;
        return d;
    }

    function offset(lat1, lng1, bearing, distance) {
        var R = 6371000; // meters
        var d = distance/R;
        var cos_d = Math.cos(d);
        var sin_d = Math.sin(d);
        var sin_1 = Math.sin(lat1);
        var cos_1 = Math.cos(lat1);
        var lat2 = Math.asin(sin_1*cos_d + cos_1*sin_d*Math.cos(bearing));
        var sin_2 = Math.sin(lat2);
        var lng2 = lng1 +
            Math.atan2(Math.sin(bearing)*sin_d*cos_1, cos_d-sin_1*sin_2);
        return {lat: lat2, lng: lng2};
    }
                                  
    function createMarker(map, point, title) {
         return new google.maps.Marker({
            map: map,
            position: point,
            title: title
        });
    }
    
    function divide(p1, p2, n) {
        var lat1 = p1.lat() * Math.PI / 180;
        var lng1 = p1.lng() * Math.PI / 180;
        var lat2 = p2.lat() * Math.PI / 180;
        var lng2 = p2.lng() * Math.PI / 180;
        var heading = bearing(lat1, lng1, lat2, lng2);
        var D = distance(lat1, lng1, lat2, lng2);
        
        for (var i = 1; i < n; ++i) {
            var p = offset(lat1, lng1, heading, i * D/n);
            
            var lat = p.lat * 180 / Math.PI;
            var lng = p.lng * 180 / Math.PI;           
            var latLng = new google.maps.LatLng(lat, lng);
            var mc = createMarker(map, latLng, "div " + i);
        }
    }       
    
</script>
</head>

<body onload="initialize()">
<div id="map_canvas" style="width: 800px; height: 500px"></div>
</body>

</html>