Re: [Pyode-user] Geom's without bodies and collision detection

[Jonathan V T. <to...@ph...>]

Chris,
	I had been having problems with passing None to the j.attach call
in Windows. I am still having these problems, but found that if I test for
None and instead pass ode.environment, the program functions as expected.
	I guess I should submit a bug report, but hopefully if anyone else
is having this problem, they can find this post in the archives.
	-Vincent

On Thu, 3 Mar 2005, Chris Bainbridge wrote:

> On Wed, 2 Mar 2005 23:35:28 -0500 (EST), Jonathan V Toups
> <to...@ph...> wrote:
> >
> >         j.attach(geom1.getBody(),geom2.getBody());
> >
> > Causes a nasty error.  This is because if one of the Geom objects is an
> > immovable object, getBody returns None.  This behaviour is puzzling, since
> > in Linux, I am clearly getting a body, perhaps where I shouldn't be.
>
> Are you sure? The behaviour under linux and windows should be
> identical... it's the same code. getBody should return None.
>
> >         So the question is, how do you handle adding contact joints to
> > objects which do not have bodies?  Or, how do you make an object with a
> > body permanantly fixed in space?  Or, am I doing something totally
> > ridiculous?
>
> You can't add joints to geoms. You can only use joint constraints on
> ODE bodies. You can fix a body in space by creating a fixedjoint with
> the environment (pass 0 as the body arg). However, this is generally
> advised against since it adds unnecessary constraints. The usual way
> to get what your trying to do is to place the geom somewhere, and then
> calculate contact joints. The contact joint should be attached to the
> static environment.  afaik, calling getBody should return None, and
> your contact joint is created with that and a real body, so your code
> should already work!
>