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

[Chris B. <chr...@gm...>]

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!