POV-Ray : Newsgroups : povray.programming : CSG Bounding box algorithm : Re: CSG Bounding box algorithm Server Time
5 Dec 2021 14:43:03 EST (-0500)
  Re: CSG Bounding box algorithm  
From: omniverse
Date: 24 Aug 2017 05:50:01
Message: <web.599ea041818ca7929c5d6c810@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 24.08.2017 um 03:04 schrieb omniverse:
> > I was wondering about this after coming across something about the automatic
> > bounding from the version 3.5 sample scene chess2.pov while rendering some of
> > those old files.
> ...
> > According to what is said here, I suppose that particular CSG object must be a
> > problem due to the intersecting planes and quartics (infinite shapes).
> Looks like the b'box computation for quadrics (sorry, not quartics; got
> that wrong in the previous post) fails to respect the `inverse` keyword
> for /some/ reason.

Oops, yep, quadric is what I meant too. Checked with versions 3.6.2, 3.7.0 and
that same Rook example I posted here is okay. It's 3.7.1-rc1 causing the missing
parts. Likewise same for beta 9.

> > curiously, for me anyhow, is that the deformation changes depending on
> > orientation or camera view.
> Bounding boxes have that effect. Essentially your shape gets clipped in
> "image space" by the outline of the b'box, which changes shape as the
> b'box is viewed from different angles: Head-on it's a rectangle, while
> at other angles it changes into an irregular hexagon.

Makes sense now that you said it, and "bounding slabs" per the docs, I should
have obviously read that first. I get to thinking there might be fancy things
going on like sphere shapes for bounding being used automatically as well.

And I forget about the ability to show those bounding boxes too. Or so I
thought... hmmmm... doesn't Vista_Buffer=on or +UV do that?
Tried just now in v3.6.2, v3.7.0, v3.7.1-beta9 and v3.7.1-rc1, nothing seen of
bounding boxes in render window.

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