Thomas de Groot <tho### [at] degrootorg> wrote:

>
> Visually indeed, the 2-axis rotation looks more "natural" than the
> 3-axis rotation. However, I wonder if it is correct and my hunch would
> be that in RL rotation would imply 3-axis rotation nonetheless. This
> /must/ have been investigated somewhere, mustn't it?
>

It *would* seem that every CGI company on the planet must have thought this out
in detail long ago (as to which scheme is actually correct), as it's a rather
FUNDAMENTAL idea relating to falling or exploding objects. I likewise wonder if
there is an original technical paper somewhere that deals with it-- rather than
each CGI techie just using math/physics principles on his or her own to come up
with the proper scheme when it's necessary (and without taking the time to write
up a paper.) Strangely, I've never done a search for such a technical article;
I've been using the 'two-axis' scheme for a long time, just because it *looks*
more natural. SIGGRAPH *must* have something about it, I'm guessing; but I'm not
sure what to search for.

The interesting thing about two-axis rotation is that the object *eventually*
assumes every possible orientation, at least according to the many visual tests
I've done (or else I'm much mistaken!)

I haven't really tested 3-axis rotation as much I'd like; I'm still wondering if
the *order* of POV-ray rotations matters in that case. (It does NOT seem to
matter for the two-axis scheme, or even which axes are used-- although I haven't
*thoroughly* tested that either.) I have a hunch that for 3-axes, the y-rotation
should come first. I can't even verbalize why-- but I'd like to see if that
could eliminate the crazy behavior. Nothing but a hunch!

There's also the matter of 'real world' physics vs. computer simulations of
them. A real object doesn't have 'artificial' <x,y,z>-ordered movements--
everything happens simultaneously instead!

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