On Mon, May 10, 2010 at 10:46 PM, Shaun Friedberg (Pyrokinesis) <
[email protected]> wrote:

> Apparently once you get more than 10 or so translations deep, the math gets
> pretty intense.
>

I'm not sure what you mean by that, Shaun. If you're only using Quaternions
for rotation, (which is why it's uesful for in 3D), there are only about 3
ways to do it. The most popular way is the "sandwich".

If Q is a quaternion, and Qc is its conjugate (w, -x, -y, -z), then the
rotation is basically:

Q * vector * Qc.

Where the multiplication is the Quaternion
multiplication<http://gpwiki.org/index.php/OpenGL:Tutorials:Using_Quaternions_to_represent_rotation#Multiplying_quaternions>
.

Then you only really need two other things:
 - How to convert rotation to quaternions
 - How to convert qutations back to xyz coordinates.

That's about it. Most of the translations build up from these principles, so
they shouldn't get "deeper" or "intense". And many websites describe how to
perform these tasks.

(Although, if you're going anywhere deeper than that, then yes, it gets
pretty intense. Starting with 4D spacial
rotation<http://en.wikipedia.org/wiki/SO%284%29#Algebra_of_4D_rotations>,
which I haven't had the time to look into..)

Have fun and good luck!

Cheers,
Xav

-- 
http://groups.google.com/group/python_inside_maya

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