Re: Newbie Joint question

>On Nov 17, 2004, at 5:15 AM, Jon Kleiser wrote:
>
>>Hello,
>>
>>I'v just put together my first breve simulation: A MultiBody 
>>consisting of two pyramides hinged together by a RevoluteJoint. The 
>>two pyramides are instances of the same CustomShape. If I don't 
>>connect the pyramides, I can rotate them independantly, but the 
>>moment I apply the joint this rotation seems to be forgotten, and 
>>they melt together into one pyramide, until the velocity of the 
>>joint moves them apart. How can I hinge together two bodies (of the 
>>same shape) without disturbing their orientation? Is it possible to 
>>have a RevoluteJoint that is totally passive (initially)?
>
>The relative positions and rotations of objects in the world do not 
>get used when the objects are linked.  Instead, this information is 
>handled by the joint.  So instead of setting their rotation in the 
>real world and then linking them, you need to tell the Joint itself 
>what kind of rotation you'd like.
>
>Have a look at the Joint methods set-relative-rotation and 
>set-relative-rotation-matrix.
>
>- jon klein

Thanks. I've got the "set-relative-rotation" method working, but it 
may be somewhat limited as to what it can do with the orientation of 
the connected parts. I suspect that "set-relative-rotation-matrix" 
could be a more powerful solution, but I can't find much info on how 
to figure out the suitable values to use in such a matrix. I've made 
a web page that describes what I try to do, including a snapshot, if 
you care to take a look:

    <http://folk.uio.no/jkleiser/breve/pyramids.html>

I must say that breve is a wonderful tool. Thanks a lot!

Sincerely,

Jon Kleiser
-- 

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