Double LineJoint

[R Doi]

I feel pretty stupid, but I admit I am completely newbie in physics mathematics, so I need help to get a kind of "double" LineJoint constraint (AS3).

So what I basically need is a constraint that keep two parallel bodys sliding in each other, something like a ice cube over a table. 

I think I can implement this using a pair of LineJoints and update each fixed anchor each step, but I believe it is better by properly extend the UserConstraint class, right?

So could anyone around that have experience working with constraints in Nape help me with this?

Any help appreciated.

[T1m_]

How about to disallow rotation for one of body (or for both) ?

body1.allowRotation = false;