Computer Science 120
Introduction to Programming
Spring 2011, Siena College
Pong Demo
A working demo of Pong will appear below. Click inside the applet to interact with it.
Pong BlueJ Project
Click here to download a BlueJ project for Pong.
Pong Source Code
The Java source code for Pong is below. Click on a file name to download it.
import objectdraw.*; import java.awt.*; /* * Example Pong: a still-simple but playable "Pong" game that features * a paddle and a falling ball that can now bounce off the sides and * interact with the paddle. * * Jim Teresco, Siena College, CSIS 120, Spring 2011 * Based on similar example from CSCI 134, Williams College * * $Id: LessPatheticPong.java 1549 2011-02-22 04:01:53Z terescoj $ */ public class Pong extends WindowController { // position and dimensions of the court private static final int COURT_LEFT = 50; private static final int COURT_TOP = 50; private static final int COURT_HEIGHT = 300; private static final int COURT_WIDTH = 300; private static final int COURT_RIGHT = COURT_LEFT + COURT_WIDTH; // dimensions of the paddle private static final int PADDLE_WIDTH = 50; private static final int PADDLE_HEIGHT = 20; private static final int PADDLE_Y = COURT_TOP + COURT_HEIGHT - PADDLE_HEIGHT - 1; private FilledRect paddle; private FramedRect boundary; // the boundary of the playing area. public void begin() { // make the playing area boundary = new FramedRect(COURT_LEFT, COURT_TOP, COURT_WIDTH, COURT_HEIGHT, canvas); // make the paddle paddle = new FilledRect(COURT_LEFT + (COURT_WIDTH-PADDLE_WIDTH)/2, COURT_TOP + COURT_HEIGHT - PADDLE_HEIGHT -1, PADDLE_WIDTH, PADDLE_HEIGHT, canvas); } // create a new falling ball public void onMouseClick(Location point) { // create the ball at the top of the playing area // at the mouse point's x coordinate if (boundary.contains(point)) { new PongBall(paddle, boundary, canvas); } } // move the paddle to follow the mouse's x coordinate public void onMouseMove(Location point) { if (point.getX() < COURT_LEFT) { // place paddle at left edge of the court paddle.moveTo(COURT_LEFT, PADDLE_Y); } else if (point.getX() + PADDLE_WIDTH > COURT_RIGHT) { // place paddle at right edge of the court paddle.moveTo(COURT_RIGHT - PADDLE_WIDTH, PADDLE_Y); } else { // keep the edge of the paddle lined up with the mouse paddle.moveTo(point.getX(), PADDLE_Y); } } }
import objectdraw.*; import java.awt.*; /* * * A simple active object that controls a ball that bounces around the * canvas and interacts with a boundary and a pong paddle * * Jim Teresco, Siena College, CSIS 120, Spring 2011 * * $Id: SimplePongBall.java 1549 2011-02-22 04:01:53Z terescoj $ */ public class PongBall extends ActiveObject { // size and speed of falling balls private static final int BALLSIZE = 30; private static final double MIN_SPEED = 3; private static final double MAX_SPEED = 10; private static final int DELAY_TIME = 33; // the ball controlled by this instance private FilledOval ball; // the paddle with which we will interact private FilledRect paddle; // how far to fall before stopping and disappearing? private double yMax; // how far up to go before bouncing off the ceiling? private double yMin; // and what about the walls? private double xMin, xMax; // Draw a ball and start it falling. public PongBall(FilledRect paddle, FramedRect boundary, DrawingCanvas aCanvas) { // compute/remember our boundaries (of the upper left corner of a ball) yMax = boundary.getY()+boundary.getHeight(); yMin = boundary.getY(); xMin = boundary.getX(); xMax = boundary.getX() + boundary.getWidth() - BALLSIZE; // random generator for the x-coordinate RandomDoubleGenerator posGen = new RandomDoubleGenerator(xMin, xMax); // draw the ball at its initial position, which is at the // top of the playing area, at a randomly-selected position ball = new FilledOval(posGen.nextValue(), yMin+1, BALLSIZE, BALLSIZE, aCanvas); // remember the paddle this.paddle = paddle; // activate! start(); } // move the ball repeatedly until it falls off screen, bouncing // off the paddle and walls along the way public void run() { double xSpeed, ySpeed; // start by moving downward and some amount to the left or right RandomDoubleGenerator speedGen = new RandomDoubleGenerator(MIN_SPEED, MAX_SPEED); xSpeed = speedGen.nextValue(); double initYSpeed = speedGen.nextValue(); ySpeed = initYSpeed; // keep moving as long as we haven't fallen off the bottom of // the screen while (ball.getY() <= yMax) { // if we are above the top line, start moving down if (ball.getY() < yMin) { ySpeed = initYSpeed; } // if we are in contact with the paddle, start moving up if (ball.overlaps(paddle)) { ySpeed = -initYSpeed; } // bounce off side walls if (ball.getX() < xMin || ball.getX() > xMax) { xSpeed = -xSpeed; } // move a little in the appropriate direction ball.move(xSpeed, ySpeed); pause(DELAY_TIME); } ball.removeFromCanvas(); } }