How to animate a custom Google Maps marker along a route?

Question

I have written a small application for a handheld device using JavaScript and Google Maps API's, now II need to move my marker icon anywhere on the map along a route using a timer function. I have a man icon and I need to move it automatically on the map. How can I do this?

Answer 1

A pretty cool example is here:

http://www.kmcgraphics.com/google/

Answer 2

Unfortunately, there is no automatic-marker-movement function in the official GMaps collection.

However, if you have a GRoute, that would mean you have a set of points. To loop through the route steps, you could use something like this:

for (var c = 0; c < yourroute.getNumSteps(); c++) { 
    yourmarker.setLatLng(yourroute.getStep(c).getLatLng());
}

Of course, you'll probably want to do this asynchronously using the timers:

function moveToStep(yourmarker,yourroute,c) {
    if {yourroute.getNumSteps() > c) {
        yourmarker.setLatLng(yourroute.getStep(c).getLatLng());
        window.setTimeout(function(){
            moveToStep(yourmarker,yourroute,c+1);
        },500);
    }
}

moveToStep(marker,route,0);

For even smoother movement, you could interpolate the points from those you already have.

Answer 3

Here is my solution that works with the v3 API. This animates the marker not with a fixed velocity, but based on the calculated route duration. There is a speed factor, so for example you can drive through the route 10x faster than in reality.

I've tried to do it as simple as possible. Feel free to use it.

var autoDriveSteps = new Array();
var speedFactor = 10; // 10x faster animated drive

function setAnimatedRoute(origin, destination, map) {
    // init routing services
    var directionsService = new google.maps.DirectionsService;
    var directionsRenderer = new google.maps.DirectionsRenderer({
        map: map
    });

    //calculate route
    directionsService.route({
            origin: origin,
            destination: destination,
            travelMode: google.maps.TravelMode.DRIVING
        },
        function(response, status) {
            if (status == google.maps.DirectionsStatus.OK) {
                // display the route
                directionsRenderer.setDirections(response);

                // calculate positions for the animation steps
                // the result is an array of LatLng, stored in autoDriveSteps
                autoDriveSteps = new Array();
                var remainingSeconds = 0;
                var leg = response.routes[0].legs[0]; // supporting single route, single legs currently
                leg.steps.forEach(function(step) {
                    var stepSeconds = step.duration.value;
                    var nextStopSeconds = speedFactor - remainingSeconds;
                    while (nextStopSeconds <= stepSeconds) {
                        var nextStopLatLng = getPointBetween(step.start_location, step.end_location, nextStopSeconds / stepSeconds);
                        autoDriveSteps.push(nextStopLatLng);
                        nextStopSeconds += speedFactor;
                    }
                    remainingSeconds = stepSeconds + speedFactor - nextStopSeconds;
                });
                if (remainingSeconds > 0) {
                    autoDriveSteps.push(leg.end_location);
                }
            } else {
                window.alert('Directions request failed due to ' + status);
            }
        });
}

// helper method to calculate a point between A and B at some ratio
function getPointBetween(a, b, ratio) {
    return new google.maps.LatLng(a.lat() + (b.lat() - a.lat()) * ratio, a.lng() + (b.lng() - a.lng()) * ratio);
}

// start the route simulation   
function startRouteAnimation(marker) {
    var autoDriveTimer = setInterval(function () {
            // stop the timer if the route is finished
            if (autoDriveSteps.length === 0) {
                clearInterval(autoDriveTimer);
            } else {
                // move marker to the next position (always the first in the array)
                marker.setPosition(autoDriveSteps[0]);
                // remove the processed position
                autoDriveSteps.shift();
            }
        },
        1000);
}

Usage:

setAnimatedRoute("source address or LatLng ...", "destination address or LatLng ...", map);
// start simulation on button click...
$("#simulateRouteButton").click(function() {
    startRouteAnimation(agentMarker);
});