Re: [PlayerStage-Gazebo] How do joints work?

[Nate K. <nat...@gm...>]

Hi Ryan,

Responses are below.

On 11/29/05, Repiphany <rep...@gm...> wrote:
> Hello Nate,

> -What effect does moving the Body have?  I tried changing the position
> of the body in all three axes, but I couldn't tell any difference in
> it's reaction to being dropped from various heights.  The Body holds
> the mass information, but apparently the position of the body is
> different from the Center of Mass?

The position of a Body is it's abosulte location in the world. So if
you move a body to (1,2,3),   it will be positioned at x=3D1, y=3D2, z=3D3.
The center of mass of a body is relative to the body. Take a look at
Body::UpdateCoM in Body.cc

> -When using setRelativePos() during geometry setup, what determines
> the point that this vector is relative to?  Is this determined from
> whether or not the geom is attached to a canonical body?  It seems
> that when I change the values for the geom attached to the first body,
> it's absolute(relative to the origin), because if I change the values
> of the body position, the block doesn't appear to move, is this right?

SetRelativePos moves the Geom relative to the body it is attached to.
Try creating and moving the body, then attach a geom to it and set its
relative position.

> P.S. - Yesterday I registered an IRC channel called #gazebo on the
> FreeNode server.  I think this will be a beneficial forum for gazebo
> users/developers to discuss things a bit more...interactively.  I'm
> always signed in, so feel free to stop by.  Is there some place we can
> publicize this?

You can send a message out the gazebo mailing list informing people of
the IRC channel.

-nate