logreg at free.fr
Sat Mar 17 07:41:56 MST 2007
When it does not work, the mass is a spere mass or a computed mass (but i don't
think it's really the problem, i certainly miss something ...).
you can see video at
http://files.marilou-roboticsstudio.com/ode/notorqueonsphere.avi (xvid, 3,2 mo):
you can see a ray witch apply force on contact point using dBodyAddForceAtPos:
Situation 1] Body with Sphere offsets = 0, joint hinge :
nothing appends when applying absolute force
Situation 2] Body with Box offsets = 0, joint hinge :
body turns around the joint axis (OK !!)
Situation 3] : Box and Sphere in a body, mass computed from sphere and box:
When ray is in contact whith sphere : nothing appends
When ray is in contact with box : the entire body rotates (OK !!)
Situation 4] : A body with sphere, mass= sphere:
Force is applyed to the sphere
The problem is the situation 1 : why does the sphere do not rotates ????? doeas
i have to add torque myself ?
Thank you for your help
Selon "Jon Watte (ODE)" <hplus-ode at mindcontrol.org>:
> There is no difference between a box body and a sphere body except for
> the mass distribution.
> What is the mass (or, rather, inertia tensor) of the sphere when "it
> doesn't work" ?
> Also, adding a force that points straight towards/away from the center
> of gravity will add no torque.
> / h+
> LR wrote:
> > Hi,
> > I've a question about dBodyAddForceAtPos:
> > using dBodyAddForceAtPos on a box (box is centered to its body, body is
> > on its joint axis), makes the box rotates around its joint axis. It seems
> > absolute force is decomposed to produce force AND torque ... (OK)
> > Doing the same thing on a sphere does not produce any torque ...
> > Is it notmal or i'm missing something ?
> > Thank you for your help.
> > LR
> > (if my explains are not enaught, i can produce video )
> > --
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