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  3d math question (Message 1 to 5 of 5)  
From: James Taylor
Subject: 3d math question
Date: 20 Sep 2002 17:48:43
Message: <3d8b97bb@news.povray.org>
Hi all,

If I have a set of 3d points which lay on a plane and a defined direction
vector, what's the simplest way of rotating the points such that the normal
of the plane points the same of the direction vector. I have a feeling this
will be soooo simple but as always with this sort of thing, need a nudge in
the right direction...

thanks
jim


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From: ABX
Subject: Re: 3d math question
Date: 20 Sep 2002 17:56:41
Message: <ev5nou0gse9a1dbjmiggri6mll1tkfjnqq@4ax.com>
On Fri, 20 Sep 2002 22:46:44 +0100, "James Taylor"
<jim### [at] blueyondercouk> wrote:
> Hi all,
>
> If I have a set of 3d points which lay on a plane and a defined direction
> vector, what's the simplest way of rotating the points such that the normal
> of the plane points the same of the direction vector. I have a feeling this
> will be soooo simple but as always with this sort of thing, need a nudge in
> the right direction...

1. Get normal of plane as cross product of vectors on plane.
2. Use Reorient_Trans macro from "transforms.inc".

Is this sufficient ?

ABX


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From: James Taylor
Subject: Re: 3d math question
Date: 20 Sep 2002 18:05:14
Message: <3d8b9b9a@news.povray.org>
"ABX" <abx### [at] abxartpl> wrote in message
news:ev5nou0gse9a1dbjmiggri6mll1tkfjnqq@4ax.com...
> On Fri, 20 Sep 2002 22:46:44 +0100, "James Taylor"
> <jim### [at] blueyondercouk> wrote:
> > Hi all,
> >
> > If I have a set of 3d points which lay on a plane and a defined
direction
> > vector, what's the simplest way of rotating the points such that the
normal
> > of the plane points the same of the direction vector. I have a feeling
this
> > will be soooo simple but as always with this sort of thing, need a nudge
in
> > the right direction...
>
> 1. Get normal of plane as cross product of vectors on plane.
> 2. Use Reorient_Trans macro from "transforms.inc".
>
> Is this sufficient ?


unfortunately not, maybe I've got the wrong end of the stick, but I need to
know the new positions of the set of 3d points which lay on the plane.

jim


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From: ABX
Subject: Re: 3d math question
Date: 20 Sep 2002 18:13:21
Message: <s67nouk35h6aafdt0u62if664l9uhvebbt@4ax.com>
On Fri, 20 Sep 2002 23:03:06 +0100, "James Taylor"
<jim### [at] blueyondercouk> wrote:
> unfortunately not, maybe I've got the wrong end of the stick, but I need to
> know the new positions of the set of 3d points which lay on the plane.

Result of Reorient_Trans is a transformation. Use it in loop over set vertices
with vtransform. Of course I'm talking about 3.5.

ABX


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From: James Taylor
Subject: Re: 3d math question
Date: 20 Sep 2002 19:37:24
Message: <3d8bb134@news.povray.org>
"ABX" <abx### [at] abxartpl> wrote in message
news:s67nouk35h6aafdt0u62if664l9uhvebbt@4ax.com...
> On Fri, 20 Sep 2002 23:03:06 +0100, "James Taylor"
> <jim### [at] blueyondercouk> wrote:
> > unfortunately not, maybe I've got the wrong end of the stick, but I need
to
> > know the new positions of the set of 3d points which lay on the plane.
>
> Result of Reorient_Trans is a transformation. Use it in loop over set
vertices
> with vtransform. Of course I'm talking about 3.5.
>
> ABX

thanks, that's got it sorted - although I now have a fully unfunctioning
sphere_sweep mesh macro :(

jim


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