[ODE] Joints and bodies

[gl]

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> > I'm trying to figure out how the joints connect the bodies... you can
set
> > the anchor for the joints, but I can't figure out how it determines the
end
> > points where the joint is connected to the bodies, unless it just uses
the
> > centers of mass for this. The pretty pictures in the ODE docs show the
joint
> > being connected to one side of the boxes, but what about spheres,
capsules
> > and arbitrary geometry?

I was wondering the same thing, but I haven't gotten around to joints yet.

> Imagine joining two real-world blocks of wood with a real-world hinge,
> like a door hinge... For any location of the hinge, there are an infinite
> number of places you could ALSO put the hinge, which would create exactly
> the same effect.  All that's necessary is that all of the hinge axes lie
> along a common line in space.

I can't quite see that.  On those real blocks, the side the hinge is
connected to very much affects where they end up in space (see attached
picture).  Sure, the rotation is the same, but the resulting position isn't.
So presumably the joints _are_ assumed to go through the body 'position',
ie. currently the center of mass.  Or am I missing something?
--
gl

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