Hi,
how can I calculate ROTATE so that point <0,1,0> after rotation by 
vrotate(<0,1,0> , ROTATE) will be equal to some given <XX,YY,ZZ> ?

Post a reply to this message

If you take a look at my Download-Section, you'll find "look_at.inc", which
rotate <0,0,-1> to look at a given point. But I think there is also some
macro supplied with POV-Ray, though I don't have a clue how it's named or
where to find it. I'm just the "Do-It-Yourself"-Guy, hence the Include-File.

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

Post a reply to this message

Wasn't it Raf256 who wrote:
>Hi,
>how can I calculate ROTATE so that point <0,1,0> after rotation by 
>vrotate(<0,1,0> , ROTATE) will be equal to some given <XX,YY,ZZ> ?

In general it can't be done. When you rotate the point with vrotate, the
distance from the origin will always be 1. If <XX,YY,ZZ> is at a
different distance from the origin then you can't get there with just a
vrotate().

The Point_At_Trans() macro in transforms.inc will rotate <0,1,0> into
vnormalize(XX,YY,ZZ). If you must have a vrotate(), then you might be
able to reverse engineer that macro to convert it from a matrix
transform to a rotation.

-- 
Mike Williams
Gentleman of Leisure

Post a reply to this message