[ODE] trimesh - trimesh collision contact points

[Tang, Dacheng]

Thanks for help with my last question.

The problem this time is that the contacts returned by trimesh - trimesh
collisions are not always on the actual contact.

So far I have meshes built and rendering with drawstuff.  I've borrowed
from test_moving_trimesh.cpp and am drawing the contact points as little
red boxes.  There is no physics, just collision detection.

Some of the contact points are out a little by themselves only on one
surface and not inside the penetrating volume.  I've tried triangles of
varying side lengths from >0.01 to 1.  It is most noticeable when the
triangles are forming a flat surface (ground) but happens in all cases.
Smaller triangles produce smaller errors.

Has anyone else seen this before?

Thanks,

Dacheng