Re: [Pyode-user] force,mass and geomtransform problem

[Ethan Glasser-C. <gl...@cs...>]

Sorry to Ting Li for the duplicate messages -- I do this all the time,
I'm really sorry.

Ting Li wrote:
> I expect the sphere1 should move in an arc. But I cannot see the change=

> in y-axis.
> what's wrong here? BTW, can anyone give an example of a dumbbell I
> described above
> using geomtransform?  Thanks in advance!

Hi,

I just started looking at your program and haven't found anything yet,
but one suggestion I would make: when troubleshooting, take out as
much code as you can, and see if you still have the error. In ODE, the
dynamics is done separately from the collision detection. You could
take out the collision detection, the contactGroup, the GeomSpheres,
and see if you still have the same problem.

Basically, I think the behavior you are seeing is "correct", but not
what you want. The center of mass of a body is always at that object's
center, as far as I know, even when you use mass.translate(). I think
mass.translate() is only useful for combining masses and finding out
where their combined center of mass will be.

You might want to try joining the two bodies together using a joint,
or using GeomTransform. I don't have an example handy right now, sorry.

Ethan