David Buck <dav### [at] simberoncom> wrote:

> I wrote out the general equation of a quadric
> surface that was rotated, scaled and translated.  I calculated the
> intersection of a ray with the generic quadric surface.  I then needed
> partial derivatives to calculate the surface normal at that point.

This sounds . . . familiar.
https://news.povray.org/povray.advanced-users/thread/%3Cweb.635dc3c46f7bb9f1f9dae3025979125%40news.povray.org%3E/

> One thing I really enjoyed was writing the procedural texture code.  I
> took a lot of inspiration from a technical article called "An image
> synthesizer" by Ken Perlin (Computer Graphics 19, 3 1985).  It really
> made the textures look amazing.

I caught the procedural patterns bug a while back.
It's amazing what you can do with a few lines of code.
It's also amazing how a lot of lines of code look like nothing but crap - until
you add that one last line that makes it all come together the way it sould.

https://news.povray.org/povray.advanced-users/thread/%3Cweb.659879b9cca34dee1f9dae3025979125%40news.povray.org%3E/

> CSG made it possible to do modeling
> and procedural textures made them look good.

I started down the CSG path, but really need to learn a lot more about how all
of the nested operations work.  There was a lot more that you can do with the
simplest CSG than I was aware.

https://news.povray.org/povray.documentation.inbuilt/thread/%3Cweb.68573b7934ec28cb1f9dae3025979125%40news.povray.org%3
E/

And yes, textures on geometry can make all the difference in the world!
Also lighting.  That can be a whole other quantum leap forward.



> I thought it would be interesting to add octree subdivision to the
> raytracer.

I do believe that we have Binary Space Partitioning (BSP) for most things.
https://www.povray.org/documentation/3.7.0/r3_2.html
3.2.8.6 BSP Bounding

> I always thought that it would dramatically speed up the rendering by
> eliminating the vast majority of the ray/object intersection calculations.

I have experimented with Quadtree, jr wrote a custom Nonatree to do a 3x3
variant of that, and I know some people have done the Octree partitioning.

And you are right - it would dramatically speed up a lot of things - especially
the parametric () object.

> Somehow, I've always liked creating scenes by text.  I know graphical
> interfaces make it easy, but I can always be more precise with text.

Yes.  For diagramming and drawing in 2D, jr will tell you how much I like VISIO.
 You can you use the GUI to drag and drop shapes, and rubber-band them all over
the screen, but you can also select shapes or control points and manually enter
coordinates or dimensions.  It also has "Smart Sheets" which are like embedded
spreadsheets to control what a shape does.  Also, CNC uses G-code, and most
CAD/CAM software of course allows you to snap to grids or dimension lines as
well as manually enter exact dimensions.

https://news.povray.org/moray.win/message/%3Cweb.637f784db7839011f9dae3025979125%40news.povray.org%3E

> I would like to see the POV-Ray rendering code extracted as a shared
> library with an API interface.  That way, I can write other software to
> do any modeling I want without having to output a scene file and run the
> renderer separately.  I think that would open the door to a lot of new
> innovation.

It would, and Chris Cason has discussed going in this direction as well.
We need developers.

> I often run across images and suspect they're done with POV-Ray.
> Sometimes I can prove that I'm right and other times I can just never be
> sure.  I like when the artists explicitly mention the tool they used.

I've helped with some people writing articles or theses, and it was strongly
suggested that they put POV-Ray in the footnotes/bibliography.  When looking for
new ideas, I often do searches for "POV-Ray" in math and science papers to see
who's doing what.  There are also some great people in academia like Paul Bourke
and Oliver Knill who obviously do a lot of amazing stuff with POV-Ray.

> Thanks, those were fun questions.
> David

Thanks for the answers - they were great to read!  :)
POV-Ray makes exploring ideas with visual feedback easy and fun.  All the
different primitives, mathematical surfaces, equations, colors, textures,
optical phenomena - it opens up so many possibilities to explore ideas and see
the implementation of something that might otherwise take fantastic amounts of
time, skill, and money to create in the real world.

- BE

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