Far as I've known 'clipped_by' behaves similarly to a cut command in an
image processing program, ie. extracts the selected region, discarding
it. I too have thought it opposite the usual way you would want to use
it, but this seems correct if thought of right. Clipping snips off from
the clipped object, unless the surface of the clipping object is
inversed thus making for a collecting instead. Basically it's a
'difference' and 'merge' together sort of thing in my view. By the way I
think 'bounded_by' is intended to be the inversed clipped_by isn't it?


Ron Parker wrote:
> 
> On 27 Apr 1999 13:00:06 -0500, Nieminen Mika <war### [at] cctutfi> wrote:
> >Ron Parker <par### [at] my-dejanewscom> wrote:
> >: This looks like a bug.
> >
> >  It may look like a bug, but certainly this is exactly how it works. It
> >may be an unwanted behaviour, but it's not a bug (ie. a programming mistake).
> 
> Bugs aren't just programming mistakes.  Sometimes they're design mistakes.
> This looks like one of those times.  After all, it is reasonable to do
> what I did, expecting the results I expected.  The results I got are neither
> what I expected (the red box) nor what I perhaps would have expected upon
> further contemplation (the blue box).
> 
> >  Perhaps povray should use a union-like clipped_by when it automatically
> >inverses a clipped object (and of course it should inverse the clipping
> >object too). But is this the wanted behaviour?
> 
> This is exactly what would happen if Inside_Object returned the inverse
> flag for the parent instead of FALSE.  It seems like it wouldn't always
> be the desired behavior, but I'm hard-pressed to find an example of when
> the current behavior would ever be the desired behavior.

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