CODEWITHSUNDEEP
iphoneioscocos2d-iphonegame-engine
mm24
mm24

Reputation: 9596

Cocos2d doubts on CCDirector pause method

I have seen several posts (E.g. this one) on this but I still don't get it.

If I call the CCDirector pause method it sets the animation interval to 1/4 and the value isPaused_ to YES (see code below). In the CCDirector.m class the isPaused_ variable doesn't seem to be used much apart of in the pause and resume methods.

I thus decided to call also the stopAnimation method but in some posts this is not mentioned:

   [[CCDirector sharedDirector] stopAnimation]

It doesn't apparently stop accelerometer data and input data to be sent to the main scene. It kind of does make sense to me because the developer of the Game might want to allow the user to resume by shaking the iPhone or tapping a resume button. Is this the reason behind this choice?

Also, why is the animation interval set to 1/4 and why things even with this value don't move (apart of my player entity that moves using accelerometer input)?

Thanks a lot!

-(void) pause
{
    if( isPaused_ )
        return;

    oldAnimationInterval_ = animationInterval_;

    // when paused, don't consume CPU
    [self setAnimationInterval:1/4.0];

    [self willChangeValueForKey:@"isPaused"];
    isPaused_ = YES;
    [self didChangeValueForKey:@"isPaused"];
}

Upvotes: 1

Views: 752

Answers (1)

CodeSmile
CodeSmile

Reputation: 64477

Pausing CCDirector reduces framerate to 4 fps in order to conserve both battery and CPU cycles. The latter is necessary if you use UIKit views, in some cases it is necessary to pause the director in order for UIKit animations to animate smoothly.

What pausing the director also does is that it stops updating all nodes. Specifically the CCScheduler doesn't fire any scheduled selectors or update methods. It also prevents touches from being passed on to nodes, because they are relayed through the CCTouchDispatcher which is also paused when the director is paused.

But as you noticed, the accelerometer isn't paused. That's because cocos2d doesn't provide a wrapper for UIAccelerometer and therefore you get these notifications directly from iOS, ignoring the pause status of the director. If you then change the position of nodes inside the didAccelerate method or another method called directly from it, that node will change its position despite director being paused.

This is but one reason why director's pause isn't really suitable for a "pause game" feature. Another issue is that pausing simply would prevent any pause menu built with cocos2d features would also be paused, which kind of defies the purpose.

Then startAnimation and stopAnimation are simply extreme measures that prevent cocos2d from updating the screen altogether. This is normally only used in situations where either the cocos2d view is removed temporarily from the view hierarchy, or hidden, or some UIKit view is going fullscreen. In that sense stopAnimation is like a suspend feature.

Upvotes: 2

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