[ODE] Should trimeshes react to physics?

[Keith Wiley]

I'm trying to understand trimesh roles in ODE.  I realize that,  
according to the docs, they are new and not fully developed.  I am  
using one massive trimesh for a nonoverlapping extruded terrain right  
now.  One thing I have noticed is that the trimesh is unaffect by  
gravity.  If I create the entire terrain at some height up in the  
air, it doesn't fall down, it just floats permanently in space, even  
though other objects are rolling and crashing around on the top  
surface of the terrain, so it must clearly be enabled due to all the  
collisions it is experiencing.

Likewise, since a trimesh is infinitely thin, I'm curious how mass  
works with respect to trimeshes.

There is an option to precalculate the face normals for a trimesh and  
give them to the trimesh building routine.  When should this be used  
and when shouldn't it be used?

And lastly, there is a brief mention of temporal coherence, which as  
I understand it, reduces overall collision checks by assuming that  
objects don't move very far between adjacent timesteps.  So, it  
sounds like a good idea.  When would it *not* be a good idea to use?

Thanks.

________________________________________________________________________
Keith Wiley         kwiley at cs.unm.edu         http://www.unm.edu/~keithw

"Luminous beings are we, not this crude matter."
                                            --  Yoda
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