[ODE] Some objects pass through other objects

[Jon Watte (ODE)]

> chain to represent the sling with a pouch in the middle.  However,  I 
> haven't learned how to use trimeshes in ODE yet, so my pouch is  
> actually a few links in the middle of my chain that are wider than  the 

Trimesh-to-trimesh collisions are not very robust; I recommend against 
modeling the chain links as actual links. Instead, I would model it as a 
series of bodies linked with universal joints, and model the chain 
collision as a series of ccylinders. I'd also make the model much 
coarser than the rendered representation -- maybe five links between the 
axle and the pouch.

In general, it's important to not get too tied down in details of how 
you would build your thing in real life, but instead think of the 
simplest, most robust arrangement of primitives that will accomplish the 
simulation goal you're after.

This is somewhat mentioned in the documentation and FAQ, but not at all 
in the amount of detail that someone new to game physics simulation 
would need to be able to absorb it.

Cheers,

			/ h+