Google maps como chegar

gistfile1.js

var maps;
var directionsService = new google.maps.DirectionsService();
var directionsDisplay = new google.maps.DirectionsRenderer();
var infoWindow = new google.maps.InfoWindow({maxWidth: 460});
var markerOffice = new google.maps.Marker({
    title: 'MARK_TITLE_HERE',
    //icon: 'site/images/icon-feed.gif', // icon
    position: new google.maps.LatLng('LAT_HERE', 'LONG_HERE')
});


function initialize() {
    var options = {
            zoom: 15,
            center: markerOffice.position,
            mapTypeId: google.maps.MapTypeId.ROADMAP
    };
 
    map = new google.maps.Map(document.getElementById("mapa"), options);
 
    markerOffice.setMap(map);

    google.maps.event.addListener(markerOffice, 'click', function() {
        infoWindow.setContent('HTML_MARK_CONTENT');
        infoWindow.open(map, markerOffice);
    });
}


$(function() {
    $('#form-endereco-rota').submit(function() {

        infoWindow.close();
        markerOffice.setMap(null);
        directionsDisplay.setMap(null);
        directionsDisplay = new google.maps.DirectionsRenderer();
 
        var request = {
                origin: $("#endereco").val(),
                destination: markerOffice.position,
                travelMode: google.maps.DirectionsTravelMode.DRIVING
        };
 
        directionsService.route(request, function(response, status) {
                if (status == google.maps.DirectionsStatus.OK) {
                    directionsDisplay.setDirections(response);
                    directionsDisplay.setMap(map);
                }
        });
 
        return false;
    });
    
    initialize();
});