[ODE] Making Bodies Immobile

[Olivier Parisy]

Olivier Parisy wrote:
> Jon Watte wrote:
> 
>  >>If possible, how can I keep the body from moving without adding any
>  >>fixed joints, or hacking it with infinite mass etc?
>  >
>  > Don't create a body for the fixed item; just create a Geom for the 
> item and attach the next hinge to the fixed world (body 0).
> 
> I just tried this and got this error message:
> ODE INTERNAL ERROR 2: joint can not be attached to just one body in 
> dJointAttach()
> 
> My setting : a ball&socket joint linked at one side to the world,
> and at the other side to a sphere.

My mistake! The error happened when I tried to connect an AMotor
to my sphere and the world. So, AMotors can't be connected to the
world, which mean the movements of an object connected to a
"fixed" object (actually, the ground) with a ball and socket
can't be controlled.

I modified my setting by adding a real "base" object, and by
gluing it to the ground using a fixed joint. But it doesn't
seem like the best way to do this...

Best regards,
Olivier.