[ODE] Heightfield Origin Change

[David Walters]

> I was under the impression that I could adjust the size of the
> bounding box; outside of that collisions would not occur. Dave, is
> that correct?

Yeah, that's right - in collision.h I've documented the creation
functions as best I can. The description for the 'thickness' parameter
in the data create functions is what you're looking for - basically
the heightfield extends a solid rectangular region below the lowest
height value for a given number of units. This gives it better
collision response when a fast moving object slams into a relatively
flat terrian (this problem was highlighted by Geoff Carlton).

Regards,
Dave.