[ODE] "relative velocity" joint type

Patrick Enoch Hendrix_ at gmx.net
Fri May 25 01:40:18 MST 2007

Hi Remi,

I was thinking of something like a relative 3d lin velocity and  
angvel, but I guess I find the secret in the "motor" sources then.

Is there a how-to for motors? I found the one for joints by Russel  
Smith "How to make new joints in ODE" which I found very useful.


On 25. May 2007, at 2:28 Uhr, Remi Ricard wrote:

> Hi Patrick,
>> Hello all,
>> has anyone implemented a joint that makes two objects have some  
>> fixed  relative lin/ang velocity?
> If you create a joint between two bodies and set the speed of the  
> joint
> then the velocity is the relative velocity of the 2 bodies.
>> Alternatively, anyone has a hint what I have to do for that?
> In C++ you can do
> dJoint *j = new dSliderJoint(worldID, 0;  (or maybe dJointSlider)
> j->attach(bodyID1, bodyID2);
> j->setParam(dParamFMax, some_force_value);
> j->setParam(dParamVel, 10);
> In C it is something similar to
> dJointID j = dJointCreateSlider(worldID, 0);
> dJointAttach(j, bodyID0, boduID2);
> dJointSetSliderParam(dParamFMax, some_force_value);
> dJointSetSliderParam(j, dParamVel, 10);
> With this you will have a the two bodies trying to reach the  
> relative velocity of 10 units with a force not exceeding  
> some_force_value. The some_force_value should be large enough to  
> counteract any force that try to stop the bodies from moving.
> Remi

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