[ODE] Terrain LOD and trimesh collision detection

[Jean-Sebastien Guay]

Hello again,

Since I'm looking into using terrain with collision detection, I have another
question. I was looking into implementing quadtree LOD into my terrain, to be
able to send a much lower amount of polygons to the video card [1].

I was wondering what to do with collision detection in that case. Should I just
make a trimesh with the highest resolution terrain and let the collision
detection always use that, or should I update the trimesh with the results of
LOD every frame / time step?

Since the only object interacting directly with the terrain in my case is the
player's submarine, which is really close to the point of view (where the LOD
gives the finest level of detail anyways), I guess I could do the latter, but
I'm having a hard time figuring out if updating the trimesh often will take
more time that just using the full resolution terrain in the first place.

Another solution might be to just evaluate the heightmap's height at the
player's current position and not allow the player to go below that height,
while not making a terrain trimesh at all. Would that be better / faster /
easier? I can't approximate the terrain with a plane since it's very irregular
(and that's the fun part of the game) but that might be the next best thing?

Any hints from people who have done something similar would be appreciated.

J-S

P.S. I saw some mails on the list about adding heightmap support to ODE, is that
available and usable now or is it just planned?

[1] http://www.gamasutra.com/features/20000228/ulrich_01.htm
--
______________________________________________________
Jean-Sebastien Guay     jean-sebastien.guay at polymtl.ca
                         http://whitestar02.webhop.org