POV-Ray : Newsgroups : povray.bugreports : Is sphere_sweep known to be troublesome? : Re: Is sphere_sweep known to be troublesome? Server Time
7 Jun 2023 21:34:36 EDT (-0400)
  Re: Is sphere_sweep known to be troublesome?  
From: Kenneth
Date: 24 Mar 2010 07:30:01
Message: <web.4ba9f7112e5cb7c265f302820@news.povray.org>
> Christian wrote:
> As far as I understand it, the point of removing manual bounding
> is to speed up the rendering of scenes designed before POV-Ray 3.0.
> In all later scenes manual bounding was added with the intent of
> overriding the automatic bounding anyway. So maybe 3.7 might be
> a good time to change the default for Remove_Bound to "off"?

> Warp wrote:
> Nowadays nobody adds bounding shapes to objects (this was only the case
> with POV-Ray 2.x and earlier, where automatic bounding was poor or even
> inexistent), so it would be better to *not* remove bounding boxes by default,
> and have the automatic removal as an option to be specified in the ini file.

and (taken out of context)
> Because default behavior should be that of the least surprise.

I agree. It seems to me that this would eliminate (from the user's standpoint)
any question about which situations are *special cases* and which are not. (A
CSG merge vs. a sphere_sweep, for example.) And would likewise require less
thinking when constructing a scene. E.g., "I've added a bounded_by shape, so now
I need to change Remove_Bounds to OFF--I think."

BTW, experimenting (in v3.6.1) with the OP's scene, going through all the
permutations of
1) adding/not adding a bounded_by shape
2) Remove_Bounds on/off
3) Bounding threshold at default vs. 0 or 1
produces some non-intuitive results for certain cases.

Here's one:
bounded_by object added
Bounding_Threshold=0 or 1
Remove_Bounds=on (default)

Surprisingly, this sucessfully uses the bounded_by object (possibly replacing
the sphere_sweep's own 'automatic' bounding shape)--yet Remove_Bounds is ON, and
POV issues the "bounding object removed" warning anyway.  Perhaps this is some
*special case* concerning just the sphere_sweep, I don't know.  But all in all,
knowing 'what to do when' with any particular object is rather confusing, as is
the error message.


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