[ODE] Question about Performance using quadspace collision

[Olle Persson]

Hello!

Im new to this mailing list and have a question regarding performance. Tried 
to find the answer in the FAQ and mail archives but was unable to find 
anything.

Background: Im using ODE for collision detection only. I have a large number 
(1000+) of objects that is contained in a quadspace. This space represents 
world geometry (a forest or dungeon walls) I also have another space which 
only contains one sphere representing a player avatar. When I collide these 
spaces using dSpaceCollide2() function I get very good results compared to a 
simpleSpace. The problem is the "precalc" time to setup the quadspace. I 
dont know if there is another way to do it but I initalize the quadspace by 
calling dSpaceCollide2() once in the beginning of my application. This first 
call takes a considerable time but the following calls are all very fast so 
I suspect that the quadspace is actually filled with geoms in the first 
dSpaceCollide2().

Anyway. I run in Release mode on Windows XP 866 MHz PentiumIII and the 
problem is that 5000 objects in quadspace gives a precalc time of 175ms 
(which is OK) but if I have 10000 objects the precalc time is 2925ms	?!! 
This seems a bit out of order. It doesnt matter what depth I use. Have tried 
2, 3, 5, 7 and 10 all gives around 3seconds which is too much for my needs. 
Anyone know whats going on here? Havent found much documentation about the 
QuadSpace algorithm...

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