[PD] GEM/math: correctly rotating in space

Fri Oct 14 20:26:08 CEST 2005

Hallo,

could someone maybe help me do something against my headache, which
has its reason in the buggy patch attached (open "move-in-space.pd")? 

Problem: I want to move and scale a primitive like [cube] or [sphere]
etc. so that both its ends fall on two given points in the 3D space. I
currently use a combination of stretching with scaleXYZ, translating
and rotating the [cube]. Lok in [solid-link] for details. It's very
likely that I do the rotation stuff wrong, however I can't fidn the
right way. Sometimes it sucks being an audio guy primarily.

In just two dimensions what I want to achieve already works as can be
seen in attached patch - which requires [list] btw. However as soon as
the two points don't fall into the (x,y) plane anymore, that is, one
of them has a differenc Z-coordinate than the other, everything falls
apart. 

I kind of know that the order of rotations probably is wrong, that I
should use some kind of matrix transformation instead, quaterions,
etc. however I'm so confused now: Any help is appreciated! 

Ciao
-- 
 Frank Barknecht                 _ ______footils.org_ __goto10.org__
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