[ODE] Playstation 2

[Geoff Carlton]

I've used ODE for a pitch project on the PS2.  Yordon has also used ODE 
for PS2. 

In summary I would say if you can use a commercial physics engine, go 
for it.  If you are stuck with ODE, then it can be done.  Keep an eye 
out for unnecessary doubles around the place, particularly in the dRand 
function.  Here's what Yordon had to say on the subject:

"I used quickstep. In the inner loop of the solver it uses dRandInt to 
reorder randomly the rows of the matrix. I complie "single" as as 
doubles are emulated on PS2. However the dRandInt uses "double" under 
the bonet and basicallly kills performance. By just replacing the 
dRandInt with inline simplistic rand function (something like 
multiply/add/truncate) I got about 200% performance increase. It may 
also be of relevance to other platforms as floats are usually faster 
although I don't imagine as radical as on PS2.

I also tried lifting some of the solver strucutres in the scratchpad 
(that are otherwise allocated on the stack) but that didn't produce any 
gains. In fact the opposite - with scratchpad ussage the thing was few 
percent."

Cheers,
Geoff