POV-Ray : Newsgroups : povray.general : <no subject> : Re: <no subject> Server Time
3 Mar 2024 17:20:23 EST (-0500)
  Re: <no subject>  
From: Bald Eagle
Date: 1 Feb 2024 07:05:00
Message: <web.65bb887c6f92e8561f9dae3025979125@news.povray.org>
"Thomas Fester" <tfe### [at] scivitde> wrote:

> Hi Bill,

> Referring to basic chemistry, I am a bit unsure to which extent people are
> really interested in this.

It's just like anything else - people may not be interested .... until they are.
And they may be interested for different reasons.  So include some variety.

> Admittedly my script is quite lengthy and I could have shortened by using loops
> and arrays. I already introduced loops and arrays in other scripts and I will
> use them later at other opportunities, but I thought for people unexperienced in
> Pov-Ray this lengthy form might be easier to understand.

Of course - and like I said, it was a great overview of how to go about making
such a thing from the dihedral angle values.  Not a trivial task.
Of course, now you have an example of the long way to do it, and can compare and
contrast hand-coding every primitive with using loops, arrays, and equations to
take advantage of _patterns_ and symmetry and repetition.  I think that if you
chose your next large structure carefully, you would have a topic that a lot of
people would be very interested in.

> I had a look at the wiki file for truncated isoahedrons and, o.k., this is also
> possible. Even superior, when it is about elegance/shortness of code. The
> advantage of my code is a) that I completely understand the approach (...) and
> b) that after this lengthy definition of points I can now address each point
> separately, knowing which point is where. So I could take this structure as a
> basis for something else. (O.k., currently I have no idea what I actually could
> do, in particular since fullerenes are not very reactive I guess...)

Yes, having designed many spreadsheets and databases, there is much to be said
for keeping everything separate.  Of course, you can again show how you can
generate the same data programmatically, and store that data in arrays with
labels, etc.
And if you wanted to try using the #read function (and #write), you could try an
approach that folks here have used with complicated scenes: The first thing your
povray script does is check for the existence of the data file.  If it's NOT
there, it generates on with algorithms and #write.  Then when the scene is run a
second time, the data file exists, and it skips the algorithm part, and either
uses #read, or #include to import the data into the scene. (You could also just
set a flag to turn on/off the calculations in case you wanted to overwrite

> I have to admit that I can't really follow the technical discussion about blobs.
> It only came to my mind that blobs are somewhat similar to electron orbitals.
> Orbitals as far as I understand are clouds of probability to encounter an
> electron with, if I remember correctly, increasing probability towards the
> center of the cloud. This is actually quite similar to metaballs. I'm not
> claiming, of course that the blobs I have been using are somehow resembling the
> actual fullerene orbitals.

Metaballs are essentially just the sum of the distances from the centers, but
there are other functions that provide a smoother, crease-free surface, which
gives a much better result when used with shiny surfaces due to the
discontinuous nature of the tangent / curvature at the overlap points.
Also, orbitals have the greatest density at the center of the _cloud_, not the
nucleus.  And so I hunted down a few threads that might interest you.
Also, I thought that somewhre POV-Ray had an internal function that approximated
the orbitals...  I looked in functions.inc, but didn't see anything.






> As a teaser for these larger molecules, here comes a detail from the active
> center of an endoglucanase with its substrate.

Excellent!  That's a beauty.  Youm ight also just try image searching the web
for journal covers made using povray - it might give you some ideas.

> Btw, I apologize for posting so rarely and that it will also take some more time
> until my next video...

No worries - it takes a lot of time to focus, write code, and organize
everything to make a video.

- Bill

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