[PD] Free rotation in GEM

cyrille henry cyrille.henry at la-kitchen.fr
Wed Jul 16 10:24:36 CEST 2008


sorry if i misunderstand.
rotateXYZ will rotate in X direction, then in Y, finally in Z.
if you wish to rotate in Z, then in X, you just need 2 rotate objects:
the 1st for the rotation in Z, then an other for the rotation in X.

anyway, there is no matrix manipulation that i was not able to do with rotate/rotateXYZ/translateXYZ/scaleXYZ/shearXY..
so i'm quite sure you don't need anything else than this standard objects for simple matrix rotation.

so i think you need 1 [rotate] to rotate the vector axis of the object, then a accumrotate.
if i misunderstood, could you please describe your problem better.

I think you can also use GEMgl objects to multiply the matrix with a custom one, but it's to much complex for what you need.


PSPunch a écrit :
> Hi Mathieu,
> 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. (or is the egg first?)
> 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.
> What I am trying to do is rotate the vector axis of the object before 
> applying [rotation]. 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)
> If there is no solution at the moment, perhaps Gem could use a few extra 
> objects to ease advanced rotations?
> I feel like I am complaining about lack of features without pointing out 
> what exactly is missing, when I should be blaming my lack of math skills.
> hmmm..
> --
> David Shimamoto
>> On Wed, 16 Jul 2008, PSPunch wrote:
>>> Trying to achieve free rotation *without* using [accumrotate], I have
>>> come across concepts such as multiplying matrixs and converting a matrix
>>> to "quarternion"
>>> How do you implement precise control of rotation matrixs?
>>> Is this exactly what people use GridFlow for?
>> If you tried GridFlow's bundled examples you'd see what I use GridFlow 
>> for. I suppose that I could add some other people's examples in the 
>> package, if they sent it to me for that purpose. There is already one 
>> patch by Roman Häfeli in GridFlow's examples though.
>> GridFlow does not support quaternions. I bet it's possible to add 
>> support for it using abstractions, but it wouldn't be fast. But I'm 
>> willing to add it to the core... there's already a complex-number 
>> section in number.c, why not quaternion product? It would be called [# 
>> H.*] where H stands for Hamilton (in math the letter Q is already 
>> reserved for rationals, so I'd use H even though the concept of rational 
>> reasonably couldn't appear in that particular place).
>>  _ _ __ ___ _____ ________ _____________ _____________________ ...
>> | Mathieu Bouchard - tél:+1.514.383.3801, Montréal, Québec
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