Sure Houdini's simulation tools are great. But i think there could be other options for simulations - and i think that this could be much faster simulation option than Houdini's own simulation engine.

PhysBam - http://physbam.stanford.edu/ [physbam.stanford.edu]

But it isn't that accurate than Houdini's simulation - so it is important to have this for option (if user needs to create simulation in short time then user should have option to change simulation to this multi-physics library)

-kind regards, Jumaku

Does their opensource version support multithreading yet? At last SIGGRAPH, I talked to some Pixar guys that lamented that their physbam (ie. the opensource version) was much slower than ILM's physbam (their internal version).

the question is, is it really faster in general?
what specific areas are fast? cloth?fluids? etc..

I think Bullet does wonders in Houdini. recently finished a project for a movie, where we had 4 buildings to collapse, with tens of thousands of pieces, windows, bricks, wooden parts, several glue constraints ,with activation, propagation etc etc. A single pc with 2x - Xeon E-5 2620 could deliver each building in few hours.

But there definitely is a space for improvement. For test sake, I did the same setup test on my home machine an i7 at 4.5 ghz, and I outrun the Dual Cpu Xeon machine, which was the result of weak multhithreading in pretty much all solvers except flip and pyro.

RBD solvers and the new SOLID solver does not seem to be able to utilize the Cores when there are a lot of collisions happening.