Op 4-6-2021 om 12:20 schreef Bald Eagle:
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> ...but seriously, I would be interested to know how to use voronoi
>> diagrams for this particular project, apart from the crackles pattern.
>> Something where the individual cells (and distribution of them) would be
>> more "controlled" by the user. Beyond the "using voronoi without knowing
>> it", that would completely change the whole granite setup I think.
> Correct, and there has been some interest in exactly that for quite some time.
> I have 2 or 3 implementations of Voronoi algorithms coded in GLSL/Shadertoy that
> I've been meaning to start converting to SDL, in the hopes that I could get
> something reasonably functional.
I did a bit of browsing about voronoi diagrams, in particular MathWorks,
and it occurred to me (just thinking aloud here) that if we could
generate a 3d voronoi volume based on a random set of points in an
array, that volume - intersected by the object we want to texture with
granite - would give a 2d voronoi granite pattern. At least, that was
how I interpreted the info given in MathWorks, which somehow seemed to
click right away with those papers you directed me to.
Perhaps, we do not even need a 3d volume at all, but it seems to me that
it would be a better, or more "natural", approach to the problem.
> I didn't get to spend ANY POV-time yesterday, but I was thinking about exactly
> what you're talking about, and it occurred to me that one thing we could
> probably do is plug crackle into a function and then operate on the function
> coordinates - like I did with the vortex. That would give spatial control.
> Then the whole bricks pattern trick would give further control over the
That is an interesting idea... we should certainly follow up that line
to see where it would get us.
> And, of course Jerome Grimbert has already addressed this in hgpovray38
Ok. I need to look at that.
> I mean, even for now, we could probably just add some gentle black hole warps or
> other warps to the basic granite pattern and introduce a little bit of
> variation. I'm bad at implementing warps, but maybe the quartz veins could
> benefit from some clever application of them.
Maybe. I am not sure what the black hole warp would really add to the
turbulence warp already in place. Granites are not very turbulent by
themselves and rather monotonous in fact.
>> this moment, beyond the beta and beyond the final version.
> Yes, just looking at the POV-Ray source code for the crackle and other
> voronoi-based pattern shows it to be a little complex, and IIRC, the problem was
> really that it's one of those things that you can do fairly straightforwardly
> with an algorithm when directly shading pixels, but would be difficult or
> impossible to do with straight SDL functions.
Well, it appears we shall not have time to get bored or idle. ;-)
In the meantime, I have started to write that piece of documentation you
asked about. Steadily growing.
Post a reply to this message