Thanks again for your help.

The trig solution should have been obvious but for some reason didn't occur
to me in this context.

Vector math is something we did not study 45years ago when I was at school
and I have had little time to try and understand it since. I have learnt
allot from this discussion about vrotate and have solved my original problem
now, using both vrotate and trig.

One last point. Many of us do not work in environments full of high powered
mathematical brains and computer gurus - we rely on this news groups to help
us understand. I for one thank you for all your patience.

Mick
--
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       http://www.minda.swinternet.co.uk/index.htm

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"Chris Huff" <chr### [at] yahoocom> wrote in message
news:chrishuff_99-A18175.07020309032000@news.povray.org...
> In article <38C78FBC.E0929D84@nanterre.marelli.fr>, Bouf
> <Chr### [at] nanterremarellifr> wrote:
>
> > Chris Huff wrote:
> > >
> > > Note that your solution should be <sin(degrees(bla)), 0,
> > > cos(degrees(bla))>, unless you specify your angles in radians. But
> >
> > It should be <sin(radians(bla), 0, cos(radians(bla)))>, isn't it ?
> > Assuming bla is in degrees...
>
> Er, yes. My explanation? I was only on my second cup of coffee this
> morning. :-)
>
> Oh, another way to do it(assuming you are using MegaPOV) would be
> vtransform(<1,0,0>, rotate bla*y). Not necessarily the best way in this
> case, but if you are using several transformations in a row, you can
> #declare them as a transform and use that to modify both the object and
> the vector. Like this:
>
> #declare Vect = < 1, 0, 0>;
> #declare Trans =
> transform {
>     rotate, scale, translate...
> }
>
> object {MyObj
>     transform {Trans}
> }
> #declare startVect = vtransform(Vect, Trans);
>
> --
> Chris Huff
> e-mail: chr### [at] yahoocom
> Web page: http://chrishuff.dhs.org/

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