Ball floats off of screen (Tutorial)

[Sbasham]

I finally got the ball to move and the paddle to move when i click the screen but now when i make it so the ball collides with the paddle. there is no screen border. so i will just float off of the screen and never come back.

Following: Beginning iPhone Games Development.


I have narrowed it down to these lines of code:

BOOL paddleCollision = ball.center.y >= paddle.center.y - 16 &&
	ball.center.y <= paddle.center.y + 16 &&
	ball.center.x > paddle.center.x - 32 &&
	ball.center.x < paddle.center.x + 32;
	
	if(paddleCollision) {
		ballMovement.y = -ballMovement.y;
		
		if (ball.center.y >= paddle.center.y - 16 && ballMovement.y < 0) {
			ball.center = CGPointMake(ball.center.x, paddle.center.y - 16);
		} else if (ball.center.y <= paddle.center.y + 16 && ballMovement.y > 0) {
			ball.center = CGPointMake(ball.center.x, paddle.center.y + 16); 
		} else if (ball.center.x >= paddle.center.x - 32 && ballMovement.x < 0) {
			ball.center = CGPointMake(ball.center.x - 32, ball.center.y);
		} else if (ball.center.x <= paddle.center.x + 32 && ballMovement.x > 0) {
			ball.center = CGPointMake(paddle.center.x + 32, ball.center.y);
		}

[Sbasham]

[Win]

This looks like the example from the aPress bbok: introduction to iPhone gaming.

Basically, you need to calculate the position of the ball and if it's x value is less than say 5 and greater than 300 (just example #'s) reverse it's x direction. Same thing for the Y value. It's very similiar to making the ball "bounce" off the paddle.


This code goes inside the gameLogic or animateBall method called by the timer.

if (ball.center.x > 310 || ball.center.x < 16)
		ballMovement.x = -ballMovement.x;
	if (ball.center.y < 32)
		ballMovement.y = -ballMovement.y;

	if (ball.center.y > 444) {

		[self pauseGame];
		isPlaying = NO;
		lives--;
		livesLabel.text = [NSString stringWithFormat:@"%d", lives];

		if (!lives) {
			[self saveGameState];
			messageLabel.text = @"Game Over";
		} else {
			messageLabel.text = @"Ball Out of Bounds";
		}
		messageLabel.hidden = NO;
	}

The source code is available for free @ APRESS.COM: Beginning iPhone Games Development

[Sbasham]

So i just coded the boundaries in the wrong part of the code?

I downloaded the source code but i cant run it. says SDK is missing.

I used that code in place of what i had. and it still travels out of bounds.