In article <3cda78bf$1@news.povray.org> , "Gleb" <gk1### [at] sotonacuk> wrote:

> If there is already code for the bounding box of a Bezier spline segment,

In case you did not notice, we are talking about too tight bounding here.  So
this is not the question.  All sphere_sweeps are bounded for speed reasons -
and you don't want to render any sphere_sweep without bounding!

> is it difficult to internally convert Catmull-Rom spline segment into Bezier
> one (to find the two additional control points) and to use it?

A Catmull-Rom spline can extend "beyond" its control points.  It is not a
matter of converting to some other spline type.  The problem is to determine
the bounds of a Catmull-Rom spline segment by just looking at the control
points, which is simply not possible due to the nature of this spline type.

To clarify my original point:

This is not going to be fixed because nobody in the team has the time to look
into this mess.  Making wild suggestions won't help ;-)

Only plain and simple source code, based on the available sphere_sweep code
that can be found in MegaPOV, if contributed by someone _soon_, will fix the
problem in the initial 3.5 release.  The code was already been broken in the
original patch :-(  Its author apparently did not know a good way how to fix
it either, so don't expect magic from us!

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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