> The trick here is to not start out with a standard orientation, but
> instead start out with the orientation of the previous circle and rotate
> that one so that it is aligned with the normal.
>
> In order for this to make sense you need of course to keep completely
> track of the orientation of the circles, not just their normals. For
> example, if the normal of each circle is "forward" then you additionally
> need to have an "up" direction for each circle, which could be the place
> where the first node is build. The point now is that for each circle you
> take the forward and up vectors from the previous circle and rotate them
> both by the same amount around the same axis in such a way that the new
> forward vector is aligned with the spline.
>
> This method is rather simple, since instead of correcting the twisting,
> you prevent the twisting from happening in the first place. Let me know
> if you need more details.

I think I've understood your idea and know how to solve it, now that you've
given some basic instructions. My problem is that though I do understand
matrix-transformation and different vector-arithmetics like vdot and such to
get angles, I tend to think more in direct steps. With the technique you
mentioned, and have to do some inbetween calculations to get the desired
angles, like projecting the forward vector onto a plane with the sky-vector,
thus getting vectors with which I can calculate the "internal" spin to get
the up-vectors lined up...

It's my perspective on things that stands in my way of finding efficient
solutions for problems like these. Don't play around with vectors,
matrix-transformations and angles enough, I guess...

Well, thanks for the help!

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>
Email: tim.nikias (@) nolights.de

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