[ODE] auto-disable implemented (again)

[Aras Pranckevicius]

> > * When a body has remained a disable-candidate for certain number of
> > successive steps, it gets disabled.
> 
> >From experience, you may want to make this 'elapsed sim time' instead of
> number of steps. Otherwise you can get quite different behaviour 
> when the timestep is different - for example things will turn off 
> more readily if you have a high frame rate or are running in slow-mo.

That's probably a better solution...

However, it does require tracking of "current" time somehow (eg. in the 
World). My impression is that ODE doesn't do any time tracking - it just 
steps by a given time interval, and that's all.

Of course, adding some "dReal time" to World and updating it in step/stepfast 
isn't a big issue (but it could be an issue if single precision is used - 
floats lose accuracy fairly fast). In our work projects, we use 64 bit 
integers for times (provides some 290 thousant years at microsecond 
precision).

Of course, this all isn't necessary if your physics is running at a constant 
rate. I'm games, and my situation having fixed dt is better :)


Aras Pranckevicius aka NeARAZ
http://www.gim.ktu.lt/nesnausk/nearaz/