Box2D Forums

Hi,

Does the Step function in b2World, take up a lot of memory over time? I'm finding that after playing my game after a few minutes it causes all of the objects to stick to one another rather than bounce. The sticking only lasts parts of seconds but it's noticible enough to cause problems.

Is there something I'm not doing properly?
Any help would be appreciated.
Alex.

Unless there's a bug in Box2D, repeated calls to Step() shouldn't result in steadily increasing memory usage (I wouldn't think).

How do you know that memory usage is increasing? It seems a little odd to associate objects sticking together in Box2D with increased memory usage (unless you're talking about framerate hitching or something like that).

In any case, there are plenty of other ways to leak memory, so if you know that memory usage is increasing over time, it may be due to some other part of your code.

Box2D uses a high water-mark for memory allocation. So if you ever allocate 200 bodies, Box2D will retain space for 200 bodies, even if you reduce the body count to 100.

Besides that, I have not seen any reports of leaks in Box2D. You should try to instrument the allocator to test your theory.

I'm not using that many bodies. Max is 10. I have them floating around in no gravity, with one that I control with my mouse. So when I go hit them around with my mouse controlled body, after a while it starts to lag (just the motion of the bodies) not the actual program. It seems that it's just taking longer to process after a while. Any reason that this may happen? I'm just speeculating that it's memory. Not entirely sure it is.

Thanks again.

Sorry just to follow up. It starts to happen a lot after there are two objects that just brush up against one another. After that happens once, it causes most collisions to lag. The collisions that seem to lab are the ones that are slower speed collisions. The high speed collisions work well.

Thanks

It sounds like an older version of continuous collision. Try turning that off. The most recent code in SVN doesn't stall for continuous collision events.

Hi,

I am using v2.0.1, v2.1 was released after I had a lot of major code written and I tried to implement it and it caused a lot of problems so I had to keep it in v2.0.1

How do I turn off continuous collisions?

Thanks

There should be a function on b2World that allows you to turn off continuous physics.

Hi Erin,

I found where you turn off the CCD but once I do that, the collision detection is much worse. Is there any way to fix my prior problem without switching over to v2.1? Or is that my only option.

Any help would be appreciated.
Alex.

I really have no idea what your actual problem is. Can you show a video or reproduce the problem in the testbed?