Wasn't it Andrew Coppin who wrote:
>OK, so maybe I'm dumb, but I think the docs for POV-Ray's bounding are a
>little vague. (Actually I think the same thing about media, photons,
>radiosity, etc - but let's not get ahead of ourselves here ;-)
>
>Let me put a specific question. If I create a shape that is the CSG
>intersection of several planes, do I need to bound it automatically, or can
>POV-Ray figure out its extent? (Assuming it's finite.) In other words, if I
>do something like
>
>intersection
>{
>  plane {...}
>  plane {...}
>  plane {...}
>  ...
>}
>
>will POV-Ray make an automatic bounding box? Or should I add one manually to
>speed things up? Also, if I do add one, do I need to turn off manual bounds
>removal (-UR)?

A quick experiment shows that the Tetrahedron from "shapes2.inc" takes
about twice as long to render if you remove the manual bounding sphere.

It is not affected by -UR. 

It's not much affected by -MB either. With +MB1 POV draws an automatic
bounding box around the manual bounding sphere, and only tests the
manual bounding sphere when the box test succeeds, with -MB it still
tests the manual bounding sphere.

-- 
Mike Williams
Gentleman of Leisure

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