[ODE] friction anisotropy?

[Gary R. Van Sickle]

> Hey all.  It seems to me that the way ODE handles friction 
> necessarily causes an anisotropic friction with respect to 
> the direction of sliding on the surface.  What I mean is, if 
> I take a simple block and slide it along a ground plane, the 
> friction in a diagonal sliding direction will be greater than 
> the friction in an orthogonal direction, because ODE's 
> friction is a pyramid instead of a cone.  Is my take on this 
> right?  Or am I on acid?
> 

My understanding is that you are not on acid.  But my understanding is
broader than it is deep, so I could be completely wrong.

> The other point I want to ask about with ODE and friction is 
> this:  I slide my block and also have it spinning, like if 
> you were to slide a book across the floor and give it a 
> little spin when you release it. 
> In real life, the book will stop sliding and stop spinning at 
> exactly the same time as it comes to rest.

Is that actually true?  Say you really wound the sucker up rotationally, but
gave it just a small rectilinear push.  Wouldn't it stop sliding but still
keep spinning for a while?  Have you tried with various rotational
rate/slide velocity combos?

-- 
Gary R. Van Sickle