[PD] Free rotation in GEM

Mathieu Bouchard matju at artengine.ca
Wed Jul 16 06:02:59 CEST 2008

On Wed, 16 Jul 2008, PSPunch wrote:

> I have not looked into GridFlow much, but I had the impression that its 
> main concept was to add matrix manipulation features to Pd, all of its 
> visual capabilities being just one of the many results of data you can 
> manipulate with matrix.

Well, that's sort of it, if you use the name 'matrix' as taken from 
Jitter, or as taken from a plain linear algebra system that has been 
expanded to higher-order structures. I mean that in math, 'matrix' is 
limited to mean a grid of weights that make inputs correspond to outputs. 
the indices of that grid are 2-dimensional, with the rows representing 
inputs and the columns representing outputs or the other way around 
depending on which way you prefer it (or which way your software prefers 
it). The concept of 'matrix' as you would find in Jitter is something more 
generic, meaning that it's more about just storage than any particular 
operators... math is much more operator-oriented: matrices are matrices 
because of how you add and multiply them.

> Anyway, understanding its marvelous potentials, I have lately been stuck
> with Windows platforms. At least I got your point that utilizing
> GridFlow only for crunching numbers may work but not so efficient.

No, you didn't get my point. I was talking about quaternions in 
particular, and not even in comparison to how else you could possibly do 
any quaternions in Pd.

Well, GridFlow is fine for number crunching, but it depends what. I don't 
recall anything in Pd that directly supports quaternions. Depending on 
what plugins you can use, you may or may not have a way to cook your own 
quaternions. I suspect that it's doable in GridFlow and less doable with 
other plugins, as it is usually the case, but I don't know.

> This also calls for a method of summing the rotations when applying 
> multiple times (and my current understanding is that this can only be 
> done by multiplying the quaternion on each rotation)


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| Mathieu Bouchard - tél:+1.514.383.3801, Montréal, Québec

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