public void OnTrackableStateChanged(TrackableBehaviour.Status previousStatus, TrackableBehaviour.Status newStatus)
{
Debug.Log ("OnTrackableStateChanged = " + newStatus.ToString ());
if (newStatus == TrackableBehaviour.Status.DETECTED ||
newStatus == TrackableBehaviour.Status.TRACKED) {
OnTrackingFound ();
} else {
OnTrackingLost ();
}
}