Bullet Physics in D

[BLM768]

> I've used Bullet in a professional capacity, and I'd hesitant 
> to force the GC on your users.  I'd port their allocators and 
> supply implementations that map to malloc or the GC and let 
> users that have their own heap implementations map them to 
> those.
>
> There are a couple of reasons for this:
> 1) Most large game engines/simulations probably already have 
> several types of custom allocators that they'd like to map 
> bullet allocations to.
>
> 2) GC is not necessarily the best model for keeping track of 
> physics data.  Usually, physics objects are tied to their game 
> entity counterparts and should be cleaned up as soon as those 
> go away.  This ownership is mostly unambiguous, so its not much 
> of a burden to remember to clean up the physics objects. I used 
> ref counting when I set up my company's implementation but even 
> that is probably not necessary.

I'll probably mainly keep Bullet's system in place, then. I might 
at least replace Bullet's C++ "new" and/or malloc with GC 
allocations, but I'm undecided on that.