POV-Ray : Newsgroups : povray.binaries.images : Crackle : Re: Crackle Server Time
26 Nov 2022 03:58:00 EST (-0500)
  Re: Crackle  
From: Chris R
Date: 14 Nov 2022 11:00:00
Message: <web.637265f9302862a47aaec48e5cc1b6e@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:
> "Chris R" <car### [at] comcastnet> wrote:
>
> > What controls the pigment value selected for the cell?  Is it just a random
> > number, or do proximate cells select from the same value range.  I'm finding the
> > more variation with smaller ranges in my pigment_map, the less "clumpy" the
> > cells become, but does it follow the normal ramp_wave or is it just a linear
> > random number?
>
>
> From source/core/material/pattern.cpp
>
> There's a few extra pre-main-pattern sections, and I've always wanted to
> translate the source code algorithm into SDL so that people could vary the field
> of random points, or otherwise modify the pattern to suit their needs.
>
> The following may also interest you:
>
>
http://news.povray.org/povray.binaries.images/thread/%3C5acf08bc%241%40news.povray.org%3E/
>
> ...

Thanks, that's very helpful.  I should probably spend some time looking over the
source code more often.  My C++ is a little rusty from disuse, though.

So, the _map entry based on the node point of the cell, and uses the noise
generator chosen in your global options for the scene.  It doesn't appear there
is a way to separately scale the node points for the call to the noise
generator, so creating more randomness across neighboring cells is a matter of
having fine-grained _maps to choose from.

-- Chris R.


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