private GObject checkCorner(double x, double y) {
GObject obj = getElementAt(x, y); // check the corner for GObject
if (obj == paddle) {
vy = -Math.abs(vy);
PrecisionPaddle();
} else if (obj != null && obj != lifeCount) { // check if the ball hits a brick
remove(obj);
vy = -1.05 * vy;
vx = 1.05 * vx;
brickCount--;
AudioClip bounceClip = MediaTools.loadAudioClip("bounce.au");
bounceClip.play();
}
return obj;
}
public class BouncingBall extends GraphicsProgram {
/** Size (diameter) of the ball */
private static final int DIAM_BALL = 30;
/** Amount Y velocity is increased each cycle as a result of gravity */
private static final double GRAVITY = 3;
/** Animation delay or pause time between ball moves */
private static final int DELAY = 50;
/** Initial X and Y location of ball */
private static double X_START = DIAM_BALL / 2;
private static final double Y_START = 100;
/** X Velocity */
private static final double X_VEL = 5;
/** Amount Y Velocity is reduced when it bounces */
private static final double BOUNCE_REDUCE = 0.9;
/** Starting X and Y Velocties */
private double xVel = X_VEL;
private double yVel = 0.0;
/* private instance variable */
private GOval ball;
private AudioClip bounceClip = MediaTools.loadAudioClip("Basketball.wav");
public void run() {
while (true) {
// move ball to right
// end when ball moves off right side of screen
setup();
while (ball.getX() < getWidth()) {
moveBall();
checkForCollision();
pause(DELAY);
}
// move ball to left
xVel = -X_VEL;
X_START = getWidth() - DIAM_BALL;
setup();
while (ball.getX() > -DIAM_BALL - 5) {
moveBall();
checkForCollision();
pause(DELAY);
}
X_START = DIAM_BALL / 2;
xVel = X_VEL;
yVel = 0.0;
}
}
// Create and place ball
private void setup() {
ball = new GOval(X_START, Y_START, DIAM_BALL, DIAM_BALL);
ball.setFilled(true);
add(ball);
}
// Update/move ball down and sideways. yVel increases each cycle, due to gravity.
private void moveBall() {
yVel += GRAVITY;
ball.move(xVel, yVel);
}
private void checkForCollision() {
// check if ball has hit floor. If so, bounce it upwards.
if (ball.getY() > getHeight() - DIAM_BALL) {
bounceClip.play();
yVel = -yVel * BOUNCE_REDUCE; // bounces back almost to BOUNCE_REDUCE * starting height
// moves ball back above the floor the same distance it would have dropped below the floor in
// same time
double diff = ball.getY() - (getHeight() - DIAM_BALL);
ball.move(0, -2 * diff);
}
}
}