This is it. The tutorial you’ve all been waiting for. The tutorial that will bring everything together. The tutorial which will make you cry out in joy– OK, maybe not, I’m getting a little too excited… but seriously this is a good one.
If you haven’t read the whole series yet, I recommend starting at the beginning.
Let’s get started.
So far, we’ve got the ball to move and bounce off walls. We’ve made the playerPaddle be controllable by the mouse. And we’ve told the cpuPaddle to move up or down depending upon the position of the ball. It’s time to turn this into a “real” game by letting the ball be blocked by the paddles.
The way Flash handles collisions between two objects on the stage is called hit testing. The way it works is that Flash keeps track of invisible bounding boxes around every object on the screen. These bounding boxes are the smallest possible rectangle that your object can fit inside. So for our paddles, the bounding box is exactly the same shape. But for the ball, instead of using the circular 30px by 30px shape we drew, Flash uses a 30px by 30px square.