clipka <ano### [at] anonymousorg> wrote:

>
> I still haven't understood all the details yet, but I can already tell
> that you've exposed a bug there.
>
>
> Obviously the only reason this leads to artifacts in this case is due to
> the - well-known - issue of sphere_sweep automatic bounding being
> unreliable. However, there may also be cases where the unintended
> overriding of custom bounding boxes will impact render performance.

Do you think the basic problem is the nature of the cubic spline math *itself*?
Or is it the overall interactions with the sphere_sweep code (and camera and
auto-bounding and...etc.)?  My own (layman's) opinion--from purely visual
results--is that the cubic_spline is producing *infinities* in places. At least,
that's what the 'discontinuities' in the sphere_sweep used to look like, in 3.61
and currently in 3.62. (Don't know about this new bounding-box issue, though.)

I've been playing around with a test set-up again (in 3.62) and managed to
arrange things to get a very clear and close-up view of the discontinuities; I
made an animation of this and will post it. Maybe it will prove helpful.

This cubic spine business has been causing problems with the sphere sweep for
years (and apparently continues to do so.) At this point, I would venture an
opinion: get rid of that spline. *If* there is a suitable replacement. (I'm no
mathematician, so I don't know such things--not sure I even want to know! So
this opinion might be a very naive one.)

It's unfortunate that, of the three spline types that can be used in a sweep,
the cubic spline is the only one that is both 'curvy' AND actually goes through
all the points...which makes it more 'understandable' (controllable?) than a
b_spline. Not the same 'curvy' results, of course.

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