Time for action – adding the main loop

It's inside our main loop that we update our b2World object.

1. Start by updating the simulation as follows:

   void GameLayer::update(float dt) {
       
      if (!_running) return;
      if (_gameState == kGameOver) return;
       _world->Step(dt, 10, 10);

2. Next, we need to determine if the game has finished by checking on the number of balls currently in play. We use the following for that:

   //track invisible objects
   for (auto ball : _balls) {
      if (!ball->isVisible() && ball->getInPlay()) {
           ball->setInPlay(false);
           ball->hide();
           //count down balls
           _ballsInPlay--;
           SimpleAudioEngine::getInstance()->playEffect("drop.wav");
           if (_ballsInPlay == 0) {
               _gameState = kGameOver;
               _gameOver->setVisible(true);
           }
       } else {
           ball->update(dt);
       }
   }

3. Next, we continue to update the sprites as follows:

   if (!_cue->isVisible())  {
       _cue-&gt...