clipka <ano### [at] anonymousorg> wrote:
> Am 16.07.2016 um 15:28 schrieb Dave Blandston:
>
> > So if you can fix POV-Ray's min_extent () and max_extent () functions to work
> > with CSG intersections or think of a work-around, here's a macro to compute
> > kerning values. Good luck!
>
> Talking of "fixing" the functions is a bit off the mark: They're not
> broken; they're specified to give you the coordinates of the bounding
> box, and that's exactly what they do. The auto-computed bounding boxes,
> in turn, do not have to be perfect -- and for fundamental reasons cannot
> be. All that's necessary for bounding boxes is that they are guaranteed
> to include the entire object, while still being reasonably small.
>
> Given the vast palette of geometric primitives supported by POV-Ray,
> computing the exact extensions of an arbitrary CSG intersection or
> difference is in fact a "hard problem" -- in the technical sense as used
> in informatics. Meaning "practically impossible".
>
> Algorithms to compute approximations are feasible, but come with the
> risk of giving erroneous results, computing dimensions that fail to
> include the entire object, which is a no-go for bounding boxes.

Please forgive my poor word choice. That kind of programming is way beyond my
meager capabilities. Thanks for explaining it though.

Regards,
Dave Blandston

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