[ODE] Joints where only 1 body is affected

ChrisC zppz at yahoo.com
Wed Dec 13 01:18:19 MST 2006

This sounds similar to a post I made recently.
I've since figured that it doesn't really make sense
for a joint to only affect one of its attached bodies,
if you are trying to make a realistic simulation.
In the real world, you cant attach a rope to something
and have the rope not affecting what it is attached
to. If you tie a rope to an ocean liner and pull, some
force will be exerted on it. Whether it moves or not
is a factor of the ratio of its mass and the force you
apply to it. To get the situation you describe,
the body the rope is attached to is extremely heavy
there is some kind of force holding the body in
Both of these should be simulatable in ODE.

Alternatively, you could always attached the rope to
the static environment and make it look like it's
attached to the body. When the body moves, reattach
the rope to the static environment in the new
position. ;)

--- Wesley Smith <wesley.hoke at gmail.com> wrote:

> I'm trying to figure out how to attach a joint
> betwen 2 objects and
> only have it act on one of them.  Both objects can
> move in the
> environment, so setting the body to 0 for one of th
> ebodies in
> dJointAttach is not an option.  Is there a flag
> somewhere that says
> only affect body 2?  I'm trying to simulate an
> object moving with a
> rope attached to it where the rope is anchored to
> the moving body.
> For this I need to attach a ball joint between the
> body and the first
> link of the rope, but this causes the body to move
> as well.  Any
> ideas?
> thanks,
> wes
> _______________________________________________
> ODE mailing list
> ODE at q12.org
> http://q12.org/mailman/listinfo/ode

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