POV-Ray : Newsgroups : povray.binaries.images : B-DNA : Re: B-DNA Server Time
3 Mar 2024 16:51:34 EST (-0500)
  Re: B-DNA  
From: Thomas de Groot
Date: 7 Feb 2024 02:11:35
Message: <65c32d27@news.povray.org>
Op 07/02/2024 om 01:32 schreef Bald Eagle:
> Thomas de Groot <tho### [at] degrootorg> wrote:
> 
>> Impressive. I have started to play, first with a complex mesh2 object,
>> and it works like a charm. I still need to dig deeper obviously, but I
>> love it.
> 
> Thanks Thomas,
> 
> I'm glad it's working well for you.
> Please try to apply a null/identity transform where the starting points are the
> same as the destination points.
> 
> I rendered a loop of triangles and they all wound up exactly where they were
> supposed to, so I'm hopeful that this is all it will take.
> 
OK. I shall do that today. There are a couple of questions I am hoarding 
at the moment, but that can wait until I have a more complete picture of 
the thing.

> I believe this is what is referred to as a "rigid body transform", as opposed to
> an affine transform, which may apply things like scaling or shear.
> So I think I just need the ordered triple, which gives us a triangle with a face
> normal, and that's all that's necessary and sufficient to completely describe
> the orientation.
> 
It is smart indeed.

I dimly remembered an old post about Euler matrix rotations:

https://news.povray.org/povray.general/thread/%3Cweb.44d8fc1ca05d1ece40d56c170%40news.povray.org%3E/?ttop=438426&toff=2650

which I almost lost but was hiding in an obscure nook. At the end of the 
thread there is a bit of interesting/useful code which seems related to 
what you have so smartly cooked up here.

> I'm sure TOK probably coded something like 15 years ago ;)
> 
Oh! I am sure he did!

-- 
Thomas


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