dick balaska <dic### [at] buckosoftcom> wrote:
> On 10/03/2018 06:48 AM, Bald Eagle wrote:
>
> >
> > The distinction between 2 and 3-axis is artificial.
>
> For this application, I disagree.  For a static image, yes, there is no
> difference. But for an animation, hmm...
> You can choose any one final vector using 2 axii, but to animate the
> three rotations simultaneously requires all 3.

Yet the visual result of using all three definitely looks...odd.

Going back to first principles: An object starts out as being static (that is,
no ROTATIONS at all.) Then a force has to impinge on it to start it rotating-- a
'point' force for simplicity's sake. That force has a direction vector, and acts
on the object in 3 (de-composed) vector directions, toward the center of mass.
The magnitudes of those three vectors depend on where the force was applied on
the surface (relative to the object's center of mass) and the angle of contact
with the surface. If I understand the concept of 'Euler angles' correctly, those
three force vectors can be 'simplified/combined' into just two resulting
rotations.

That's about the limit of my understanding so far ;-)

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