POV-Ray : Newsgroups : povray.general : Smooth level for smooth_triangle. : Re: Smooth level for smooth_triangle. Server Time
3 Mar 2024 06:56:33 EST (-0500)
  Re: Smooth level for smooth_triangle.  
From: Tor Olav Kristensen
Date: 22 Nov 2023 15:35:00
Message: <web.655e650584c692a3f473065789db30a9@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote:
>
> > Hi Bill
> >
> > Here's two relevant articles:
>
> Hi Tor,
>
> Thank you as always for sharing some of (what I'm sure is a very extensive)
> reference library.

Yes, I have saved a lot of articles related to computer graphics (and
mathematics, photography, electronics and much more) on a lot of hard
drives during the years, but unfortunately I'm not able to keep track
of them.

So this time I googled a bit and then posted the ones that looked most
relevant and informative. (But I did remember that I had read somewhere
that there are more than one way of weighting the normal vectors of
triangles surrounding a vertex in a mesh, before summing them. And that
there's no single way to choose those weights so that one gets good
results in all cases.)


> Luckily, I had written a fully chamfered box macro not too long ago, so I could
> just piggyback off of that and get right to trying to calculate the normals and
> replicate the work in that first paper.
>
> I normalize all of my cross-product vectors before summing to get the "wrong
> way" and then just use the direct cross-product result to try to get the
> right/improved way - but it still doesn't look very smooth.  So I must have some
> aspect of this that I didn't code right in that second macro.
> (and even seeing the flaws is very lighting and camera angle dependent...)
>
> However, aside from that, what I did find disturbing is that I have an
> interior_texture defined for my smooth_triangles, and that's showing up, even
> though my normals are facing the proper way.
>
> So it seems like we're back to having some triangle mesh rendering errors in the
> source, even after clipka hunted down and fixed the faux-mesh union-of-triangles
> problem that I uncovered when making subdivided spheres.
>
> See attached.
>
> Maybe someone else can confirm.

As you know:
It will be easier for us look at your problems if you show your code.

    ;-)

--
Tor Olav
http://subcube.com
https://github.com/t-o-k


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