[ODE] Up direction

[Aras Pranckevicius]

> I've tried several physics engines, and have used Y for up in all of
> them. In ODE it seems that Z is the default, and I'm not sure if it can
> even be replaced (for example, will the quadtree space work on XZ?). Am
> I stuck with Z for up?

In the solver itself, there's no "up" concept at all as far as I know.

In some collision stuff, yes, it assumes "something" (most notably
quadtree space and dTerrain contribution). For the quadtree case, you
can set the "side" and "up" axes in the sourcecode
(collision_quadtreespace.cpp) - while this isn't very friendly, it
does work. In the dTerrain case, the contribution explicitly provides
dTerrainY and dTerrainZ classes.

-- 
Aras 'NeARAZ' Pranckevicius
http://nesnausk.org/nearaz | http://nearaz.blogspot.com