[ODE] controling joint forces

Jaroslav Sinecky jsinecky at tiscali.cz
Tue Sep 13 17:32:51 MST 2005

I'm not exactly the ODE experienced one, but as no other replays, I tell you
my opinion based on part of ODE code I have seen.

I think it's not easy to implement what you want (by the way what for do you
need to add joint forces only above certain value?). Joints actually don't
simply add forces to bodies, joint forces in every island of bodies are
interdependent, when one joint applies more force, some other joint may
apply less force, so that joint constraints are maintained. That's what the
LCP solver does.
Maybe some similar trick as for friction limit contact could be used, but I
don't know how this is done.


> -----Original Message-----
> From: ode-bounces at q12.org [mailto:ode-bounces at q12.org]On Behalf
> Of Piotr Obrzut
> Sent: Monday, September 12, 2005 2:24 PM
> To: ode at q12.org
> Subject: [ODE] controling joint forces
> Hi,
>    I'm back to my ODE project again and I started to have more complex
>    needs:
>    I want to control all data about forces that ode aplies to bodies
>    (the most interesting are joint forces). Normaly I use "joint
>    feedback" info (btw. I still must test the patch by Jaroslav
>    Sinecky) and it served me well. Now I want to controll added
>    forces: I want let joint to add its forces only when the force will
>    be greater than certain value. The most convenient way will be to
>    have special *callback* that will be called each time joint will want
>    to add forces to body.
>    I didn't have to look under ODE's interfaces before, so I wanted to
>    ask first more experianced users if this could be done that way and
>    if later this small change could be added to ODE's cvs. I don't
>    want to make my own joints  and have my own version of ODE
>    (I use it through Crystal Space interface that is prepared to work
>    with official ODE's cvs version).
>    So ODE devs: could this change be added to cvs?
>    all ODE experienced: could I do this that way?
> --
> Greetings,
> Piotr Obrzut
> mailto:piotr_obrzut at o2.pl
> _______________________________________________
> ODE mailing list
> ODE at q12.org
> http://q12.org/mailman/listinfo/ode

More information about the ODE mailing list