Time for action – handling touches

We need to implement onTouchBegan, onTouchMoved, and onTouchEnded.

1. Now in GameLayer.cpp, inside onTouchBegan, add the following lines:

   if (!_running) return true;
   Point tap = touch->getLocation();
   float dx = _rocket->getPositionX() - tap.x;
   float dy = _rocket->getPositionY() - tap.y;
   if (dx * dx + dy * dy <= pow(_rocket->getRadius(), 2) ) {
    _lineContainer->setLineType ( LINE_NONE );
    _rocket->setRotationOrientation ( ROTATE_NONE );
    _drawing = true;
   }
   
   return true;

   When a touch begins, we only need to determine whether it's touching the ship. If it is, we set our _drawing property to true. This will indicate we have a valid point (one that began by touching the _rocket sprite).

2. We clear any lines we may be currently drawing in _lineContainer by calling setLineType( LINE_NONE ), and we make sure _rocket will not rotate until we have a pivot point by releasing _rocket (setRotationOrientation ( ROTATE_NONE )), so it will continue to move...