"Thomas Fester" <tfe### [at] scivitde> wrote:
> Hello everybody,
>
> recently I posted a video about snail shells, where I talk about producing
> images like the one attached. I thought about including my code in the youtube
> comments section, but there are technical problems. So I am including this code
> right here. Please tell me, in case there are better forms of distributing such
> scripts. Also suggestions for improving the readability of my code are
> welcome...

You _might_ consider posting on github, as this is apparently what many people
do with their code repositories.

Also, it would be better to post the .pov file as an attachment.
If you use the web reader, then it's only 1 attachment per post, and you'll have
to post 2 messages - 1 for the .pov file, and 1 for the rendered image.  If you
use a news reader like Thunderbird, then you can attach multiple files to a
single message.

I like your coding style.  Very close to my own, with spacing, etc.

I reformatted your file to use tabbed indentations (Hi, jr!) and added a few
comments.

Since your purpose will be to write these scenes for educational purposes, let
me suggest a few things to consider:

1.  References.
I almost went off on a huge shell tangent myself, so I know that there are
several excellent websites and textbooks which cover this topic.  It might be
good for to include a few references to acknowledge prior work, as well as give
them some resources to investigate and inspire.

2. Magic numbers.
Your spiral parameters are just hard coded numbers, but if they are derived from
anything, or have some relationship between one another, then it's usually good
coding practice to try to explain why the values are what they are, or express
values that are based on prior values as functions of the base value.

3. Code hierarchy
Since you're probably coding for people new to either coding or SDL in
particular, it's always a good idea to keep the instantiation of primitives and
code-control directives clear and easy to follow.  Everything in SDL terminates
either with an } or and #end - so there's no way to know what you're ending
without scrolling back up through the scene - which if the indentation isn't
clearly demarcated, can be hell to follow (and debug).

4. Colors
It looks like your color values are derived from an external color picker, so
you're dividing by 255.  First, you may want to use the srgb keyword, and
second, there's a lot more to this simple color conversion than there might
appear at first glance.  I'll let you search the forums for the fun
conversations we've had about colors and gamma correction, and srgb.

5. union {}
Your shell and your stripes are 2 different objects, which means they will not
be transformed together.   Just put them in a union.

6. Versatility
For many of the morphologies that you're modeling, there are parameters than be
altered to produce different results.
You might consider making a macro so that the parameters can be changed easily.
Then you might make your renders with a variety of parameters to show how easily
one can produce a wide variety of results with essentially the same code.

7. Diagrams
For things like the shells, you might consider adding a small diagram showing
angles and translations-per-turn, etc.
The more you add visual pieces that can be used as instructional tools, the more
your work might be consulted and referenced in other work ---- which gets people
to consult your work even further.
The blobs are _excellent_.  What you're doing with blobs/metaballs is really
great, and more than what I'm usually capable of pulling off.
That said, you might show where that approach can go wrong - or at least be
picky in terms of distance and field strength.
You might also consider using spheres or a mesh or a wireframe to show the basic
structure - and then show how the blobs melt everything together.

8. A "Final" render, or a growing add-on scene.
You have all of these various plants and creatures, but how about placing them
into a nice scene to show them in context?
It would be easy enough to make a simple beach scene and start adding modeled
creature after modeled creature.  So every video gets an addition to a base
scene.  Model 1 shell, then scatter 500 into the sand.  Model 1 beach grass
plant, then plant a few hundred on a dune.  Add some radiosity and an HDR light
probe, and the results can be dramatic.
Sometime people will put a line of commented code at the top of their scene, to
provide recommended command-line options for getting the best results for
certain scenes.

Gotta have some clever and entertaining ways to slip in those "like" and
"subscribe" requests.  Written in the sand.  The pattern of shells on the beach.
 An aerial banner or skywriting over the ocean.  A message in a bottle.   Go
nuts.  ;)

And as always, you can always solicit advice, code, textures, or scene files to
use in your work.  Maybe throw some POV-Ray logos in there as well to show off
your favorite script-driven raytracer.

- Bill

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Download 'snailshells.pov.txt' (4 KB)