Box2D Forums

on my desktop machine (q6600 - Ubuntu 64bit ) the following code works fine


however on my eeePc (intel celeron M) it causes the following error



In both cases I'm using the float variant of the library
(I've noticed some errors with the fixed version using the testbed on my desktop)

I'm using SVN revision 166

btw nice library, I like the idea of prototype (def) objects to save dozens of parameters in a single call, its nice and fast, and seems straight forward. Thanks!

I've run into similar issues even on the same processor - with B2_TOI_JOINTS enabled (which at the moment they are not, since the implementation is not finished), it turned out that even in the unfinished state, the examples all ran stably on OS X, but some of them blew up in Windows. I gave up on tracking the difference down completely, since the blowups were actually to be expected given that the joints were not meant to be used with TOI, but from what I could tell, the fundamental issue was the difference between the default internal precision that OS X uses (80 bit) as opposed to Windows (53 bit, or somewhere around there).

I don't know the details of the eeePC, but there might be something similar going on.

That said, from what I remember, having run into that assert several times myself recently, I've almost always been able to trace the cause to a NaN popping up somewhere, usually due to an accidental divide by zero in my own code (which, again, could be coming up sporadically because to different internal precision/compiler optimization settings). What is that shape colliding with?

I rather think its a symptom of another problem as its started happening on my desktop machine.
(the eeePc is running Debian btw but it *is* a 32bit machine - so was maybe giving early warning)

The problem will sometimes change depending on what shapes I initially add

I think its some kind of memory corruption problem, but for the life of me I can't see it
(the test bed is working fine in float mode so I know this is all down to me - alas!!)

I altered my "entity" class to have a separate shape and body "define" object as the way I was sharing them seemed to be causing problems??