On 03/10/2018 13:13, Kenneth wrote:
> 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 ;-)
> 
> 
> 
> 
Well here is my tuppence worth.
I think that it is the ratio of the rotations that makes 3 axes look 
odd. in this animation the X axis rotates 3 times for one rotation of 
the Z axis and the Y axis rotates twice.
(I am wedded to cyclic animations)


-- 

Regards
     Stephen

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