Marc Schimmler wrote:

> The virtues of a noble POVer ... I wonder if you have sworn an oath for
> it.

Well I do swear from time to time...

> Thank you Ken!  I really mean it.

  Well thank you for thanking me. Looking back to all of the questions
I have answered and all of the people I have helped I am satisfied with
the contributions I have made to the POV-Ray community. At other times
I wonder if I have done enough. Was my help needed ? Were my answers
good enough ? Should I have tired harder, written more, and explained
better ? All I can really do is contribute what I can and hope that
others share what they know when they too have the opportunity to.


-- 
Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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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...

Bouf.

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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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On Thu, 09 Mar 2000 00:30:18 -0800, Ken wrote:
>Patients is a virtue.

Especially if you happen to be a doctor or a dentist.

-- 
These are my opinions.  I do NOT speak for the POV-Team.
The superpatch: http://www2.fwi.com/~parkerr/superpatch/
My other stuff: http://www2.fwi.com/~parkerr/traces.html

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Ken <tyl### [at] pacbellnet> wrote:
: We are here to help not criticize.

  I apologize.
  It's just that sometimes the RTFM-mentality hits me when something looks
so simple (to me) in the manual.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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

*************************************************************
"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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There is a brief visual explanation here:
http://www.spiritone.com/~english/cyclopedia/vrotate.html

hopefully this helps. If not, please send me osme feedback so I can make
this more useful for people

Josh
Mick Hazelgrove wrote:

> >   Or more easier with vrotate().
>
> Please explain, for me and for other maths disadvantaged pov users!
>
> --
> *************************************************************
>        http://www.minda.swinternet.co.uk/index.htm
>
> *************************************************************

--
Josh English
eng### [at] spiritonecom
"May your hopes, dreams, and plans not be destroyed by a few zeros."

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Ken wrote:
> 
> I have but without the proper educational background there are times it
> makes absolutely no sense what so ever. An example is sometimes worth
> 1000 documented words.

There are some vector math examples (in the animations section, I believe). I
really recommend anybody who has trouble understanding the maths render those
examples since, as you say, they are worth a 1000 words.
Heck, they even helped me understand what vdot does. No verbal explanation had
managed to do that.
Perhaps similar examples should be added to encompass more functions. The one
Mick mentioned seems a common requirement.

Margus

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Chris Huff wrote:

> Note that your solution should be <sin(degrees(bla)), 0,
> cos(degrees(bla))>, unless you specify your angles in radians.

Oh yeah, forgot. That's such a pain in the arse.
What's so great about radians anyway? That the arc length of one radian is
the radius? Some magical property of pi? Why do mathematicians always seem
to prefer radians to degrees?

--
___     _______________________________________________
 | \     |_          <dav### [at] faricynet> <ICQ 55354965>
 |_/avid |ontaine        http://www.faricy.net/~davidf/

"The only difference between me and a madman is that I'm not mad." -Dali

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David Fontaine wrote in message <38C833B5.111745F5@faricy.net>...
>What's so great about radians anyway? That the arc length of one radian is
>the radius? Some magical property of pi? Why do mathematicians always seem
>to prefer radians to degrees?


Because calculus works out much better if you use radians.

Mark

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