Time for action – adding the main loop

Let's implement our main update method.

1. In GameLayer.cpp, inside the update method, add the following lines:

   if (!_running || _state != kGamePlay) return;
   if (_lineContainer->getLineType() != LINE_NONE) {
     _lineContainer->setTip (_rocket->getPosition() );
   }
   
   if (_rocket->collidedWithSides()) {
     _lineContainer->setLineType ( LINE_NONE );
   }
   _rocket->update(dt);
   
   //update jet particle so it follows rocket
   if (!_jet->isActive()) _jet->resetSystem();
   _jet->setRotation(_rocket->getRotation());
   _jet->setPosition(_rocket->getPosition());

   We check to see if we are not currently on pause. Then, if there is a line for our ship that we need to show in _lineContainer, we update the line's tip point with the _rocket current position.

   We run collision checks between _rocket and the screen sides, update the _rocket sprite, and position and rotate our _jet particle system to align it with the _rocket sprite.

2. Next we update _comet (its...