private void stop() {
   LOG.info("stop");
   playing = false;
   time = 0;
   app.setCameraEnabled(true);
   app.getGuiNode().setCullHint(Spatial.CullHint.Inherit);
   app.getNifty().gotoScreen(oldScreen);
   this.sceneNode.setCullHint(Spatial.CullHint.Inherit);
   if (recording) {
     recording = false;
     app.getStateManager().detach(app.getStateManager().getState(VideoRecorderAppState.class));
   }
 }
 public void play() {
   if (points.size() < 3) {
     LOG.warning("can only play when there are at least 3 points");
     return;
   }
   LOG.info("play");
   app.setCameraEnabled(false);
   playing = true;
   time = 0;
   stepLength = -1;
   currentStep = -1;
   app.getGuiNode().setCullHint(Spatial.CullHint.Always);
   oldScreen = app.getNifty().getCurrentScreen().getScreenId();
   app.getNifty().gotoScreen("Dummy");
 }