POV-Ray : Newsgroups : povray.beta-test : VPerp_To_Vector() macro bug, also Axial_Scale_Trans() : Re: VPerp_To_Vector() macro bug, also Axial_Scale_Trans() Server Time
29 Jul 2024 12:26:52 EDT (-0400)
  Re: VPerp_To_Vector() macro bug, also Axial_Scale_Trans()  
From: Rune
Date: 6 May 2002 16:36:01
Message: <3cd6e931@news.povray.org>
Gelu Stoicescu wrote:
> However, when V has values such as <1, 1, -1> (and
> all proportional vectors such as <2, 2, -2>, <-1, -1, 1>
> etc - what matters is the direction) the two rotations
> performed by vrotate() bring the vector in a round trip
> right where it started

Yes, this has been noticed and the new version will use a different
approach which should work for all input vectors with no exceptions
(well, except <0,0,0>).

> I'm no Einstein, but vectors perpendicular to a given
> vector are more than one (actually a whole plane of them),
> and this function only picks one by its own acquired taste.

That is correct.

> Such a "pick a card" tweak may find its use

( I didn't originally come up with the concept of the macro, I just
rewrote it (with the error that was later spotted, oops...). I
personally prefer the VPerp_Adjust macro, which doesn't leave things to
chance. )

> All above is a beginner's opinion, no IRTC entry yet,
> please no flames (at need I can plead non native
> English speaker). If it's known issue, yesterday news
> etc., merely ignore.

Even though the bug happened to have already been fixed when you
reported it, your bug report was correct and precise, so if you find
other bugs in the future, don't hestitate to report those too. :)

Rune
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