moving Image gets stuck off screen

[marshusensei]

Hi guys,

I followed a tutorial to make a 'dodge' style game. I've adapted mine so that when the moving images are bumped by another image, they animate and move in another direction.

My problem is that if I bump the image beyond the boundaries they get get 'stuck' of screen...

Any advice on how I can fix this problem?

Thanks

Matt

Here is the part of my code that 'should' keep the images within the screen... what am i doing wrong?

- (void) onTimer {
    
    q1.center = CGPointMake(q1.center.x+pos4.x, q1.center.y+pos4.y);
    
    if (q1.center.x > 320 || q1.center.x < 0)
        pos4.x = - pos4.x;
    
    if (q1.center.y > 480 || q1.center.x < 0)
        pos4.y = -pos4.y;
    
    q2.center = CGPointMake(q2.center.x+pos5.x, q2.center.y+pos5.y);
    
    if (q2.center.x > 320 || q1.center.x < 0)
        pos5.x = - pos5.x;
    
    if (q2.center.y > 480 || q2.center.x < 0)
        pos5.y = -pos5.y;

My pos4 and pos5 are defined as following in ViewDidLoad:

pos4 = CGPointMake(7.0,6.9);
    
pos5 = CGPointMake(7.0,2.6);

[mashercakes]

I think your lines "pos4.x = - pos4.x" should be:

pos4 = CGPointMake(-pos4.x, pos4.y);

And then obviously the same for all the other ones.

[Mizonnz]

   if (q1.center.y > 480 || q1.center.x < 0)

should be

   if (q1.center.y > 480 || q1.center.y < 0)

Same for q2 further down.

[marshusensei]

Thanks for your help guys, tried those things, but it still gets stuck off screen... Will keep trying things...

[marshusensei]

I think it is my rotating animation command that gets the images stuck off screen (once they've passed the boundaries) the rotate animation seems to override the boundary??? Any advice on this

Here is my animation code:

       //animation - spin the thing if hit
        
        [UIButton beginAnimations:nil context:NULL];
        [UIButton setAnimationDuration:1.5];
        
        q1.transform = CGAffineTransformMakeRotation(3.054326191);
        
        q1.transform = CGAffineTransformIdentity;
        
        [UIButton commitAnimations];
        
        //end animation

[Feldspar]

if something else is updating the .center positions, you could end up getting stuck. for example, if the x position is too far to one side, then reversing direction might not be enough to put it back inside the boundary. in this case, the boundary check would continue to fail every frame, causing it to reverse direction back and forth constantly.

try something like this:

if (q1.center.x > 320) {
     q1.center.x = 320;
     pos4.x = -pos4.x;
}
if (q1.center.x < 0) {
     q1.center.x = 0;
     pos4.x = -pos4.x;
}
// etc for q1.center.y, q2...

[marshusensei]

Hey mate, tried this but had error with

q1.center.x = 0;

expression not assignable,

will keep trying. thanks for your help

[Bobarino]

Originally Posted by marshusensei

Hey mate, tried this but had error with

q1.center.x = 0;

expression not assignable,

will keep trying. thanks for your help

Hello marshusensei,
The links below are for a dodge game tutorial that works, hope this helps:
Part 1

YouTube - iPhone SDK Tutorial: Making An Image Dodging Game (Part 1)

Part 2

YouTube - iPhone SDK Tutorial: Making An Image Dodging Game (Part 2)

Part 3

YouTube - iPhone SDK Tutorial: Making An Image Dodging Game (Part 3)

[mashercakes]

Originally Posted by marshusensei

Hey mate, tried this but had error with

q1.center.x = 0;

expression not assignable,

will keep trying. thanks for your help

It should be:

[q1 setCenter:CGPointMake(0, q1.center.y)];