Make a working pong game by completing the updateGameState in the Pong game code. Make sure to to read the comments in the pong game code for some details.

Note (2/23/09): if the GUI "Up", "Down", "Quit" buttons don't work reasonably well on your system, you may do your work in the"no-GUI" version here. The paddle doesn't move but at least it should work well on any machine and you should be able to get all the bouncing code working correctly.

Completing this project is in many ways just a generalization of HW4's scrolling program. Scrolling was one dimensional - you had to detect when the word reached the left and/or right ends of the window. Igoring the paddle (which you should until you get everything else working), pong is very similar exept that it's two dimensional - you simply need to detect when the "ball" (really, a small square) reaches the left, right, top, or bottom of the game area.

You don't need to understand the main game code at all. Ignore the graphical interface buttons, the drawing of the ball and paddle, etc. My code handles all that. You simply need to do one thing. At each "frame" of the game, you must compute a new position and movement direction for the ball. You will do this in the updateGameState function. That function takes 11 arguments, which contain all the information you need to determine the ball's next position. The arguments are:

• window: this is a picture object representing the game area. You'll need to use its width and height in your computation.
• ballX and ballY: the current position of the ball
• ballSize: the width and height of the "ball" in pixels
• ballSpeed
• ballXDir and ballYDir: use these however you wish to maintain information about the travel direction of the ball
• paddleX and paddleY: current position of the paddle
• paddleWidth and paddleHeight: paddle dimensions in pixels

NOTE: If you get a strange error in JES when trying to run "playPong" again after you've already run it at least once, click the "Load Program" button and try "playPong" again. I don't know why this happens but re-loading the code seems to get rid of the problem.