[ODE] box-trimesh collision trouble

[Martin Insulander]

Hi all,

I'm having a bit of trouble using trimeshes for terrain. My problem is that
boxes fall through the terrain (the usual it seems). The odd thing is that
a few of the triangles work pretty much all the time, but most don't. And
spheres work flawlessly. When dropping boxes on some of the triangles they
appear to bounce off in the wrong direction as if the normal was messed up,
but most of the time the boxes just fall right through (no contacts
generated).

I've tried the common gotchas I found from the archives:
* Reducing size of the trimesh (it's 16x16 triangles at the moment, doesn't
  seem to make a difference)
* Getting the winding right. Turned on backface culling while drawing using
  the same vertex and index data. Tried messing with the index order.
* Set MAX_CONTACTS to 128.
* I tried to pass pre-generated normals to dGeomTriMeshDataBuild with no
  apparent effect (btw, are these supposed to be 4 dReals as in *BuildSimple?)

So now I'm out of ideas.. Please help if you feel like it. 

Thanks, 
Martin