[ODE] degrees of freedom in a slider

[Remi Ricard]

Hi Bram,

> ODE's slider has one degree of freedom.
> So when considering this image:
> http://stolk.org/tmp/sliders.jpeg
>
> ODE would be the one on the left.
>   

You are right I was also confused by this a couple of month ago.

Can you create something similar to the figure on the left and something 
that look like
the joints figure in the wiki so we can display the right one.

> Is there a way to get an additional degree of freedom, as
> for the slider on the right?
>   
You can add an hinge or a ball between the block and the cylinder but 
you will need an extra body.

Block body -> Hinge Joint -> Extra Body -> Slider Joint -> Block body


I created a new joint which I call "Rotoide prismatic"  but the rotation 
axis is perpendical to the axis of the  slider.

I should be able to create a patch to submit in the next following days.

Remi