On Wed, 17 Jan 2001 08:48:48 +1000, "Chris Colefax"
<chr### [at] tagpovrayorg> wrote:

>Where indeed?  I don't specify any bounding boxes internally in the Spline
>Macro File, as these will be overridden by POV-Ray unless the -UR command
>line option is used.  Instead, each torus is clipped using boxes that fit
>the desired segment as closely as possible.  Ideally, POV-Ray would the
>bound each torus by its clipping box.  You may find it's best to perform
>some manual bounding, however (at least for the union that forms the
>weaving, to prevent slow rendering above and below).

The easiest would be to bound each torus segment like this:

bounded_by { clipped_by }

and then use -UR in the command line. POV *might* just be doing
something wrong.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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Peter Popov <pet### [at] vipbg> wrote:
: and then use -UR

  I understand why this feature was firstly added in povray 3.0: Because
most old scenes had manually made bounding objects which weren't necessarily
optimal ones.

  However, this was so long ago that I think a change could be necessary.
  Nowadays it's more a rule than an exception that if people define a
bounding box to an object, it's for a good reason.
  I think that the default should be changed, that is, by default povray
does NOT remove user-defined bounding objects, but you can, if you want,
make it remove them with +UR.

-- 
char*i="b[7FK@`3NB6>B:b3O6>:B:b3O6><`3:;8:6f733:>::b?7B>:>^B>C73;S1";
main(_,c,m){for(m=32;c=*i++-49;c&m?puts(""):m)for(_=(
c/4)&7;putchar(m),_--?m:(_=(1<<(c&3))-1,(m^=3)&3););}    /*- Warp -*/

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Ron Parker <ron### [at] povrayorg> wrote:
> Isn't that what bounded_by{clipped_by} is for?

A quick test shows that POV-Ray's automatic bounding is winning out for the
most part - on a torus spline with 100 segments (201 objects including
joining spheres), using manual bounds removal renders in 32 seconds compared
to 68 when bounded_by {clipped_by} is used with -UR.

The problem John is having might be something to do with the number of
objects he's rendering, or their CSG structure, and possibly highlights a
failing of the automatic bounding system - I'll leave it to John to post the
offending code...

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> The problem John is having might be something to do with the number of
> objects he's rendering, or their CSG structure, and possibly highlights a
> failing of the automatic bounding system - I'll leave it to John to post
the
> offending code...

Here is a complete file.

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