Op 28-4-2021 om 00:17 schreef Bald Eagle:
> Here's the half-noise half-cells pattern I worked out.
> 
> Adjusting Start and End to be both 0.5 gives results identical to cells.   Due
> to the smoothstep, you can never get pure gradient noise.
> 
> I thought it was wasted time as it still has some gradient to it, but with
> double-entry color_maps, you get a sharp delineation anyway...
> 
> Please "give it the treatment" and see if this produces something better or
> worse than the turbulated cells.
> 

I do not want to have you wait: This is the first render with StepNoise. 
My judgment is: perfection.

-- 
Thomas

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hi,

Thomas de Groot <tho### [at] degrootorg> wrote:
> ... perfection.

"Flanders (medium) Gray".  :-)


regards, jr.

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Thomas de Groot <tho### [at] degrootorg> wrote:

> I do not want to have you wait: This is the first render with StepNoise.
> My judgment is: perfection.

.... holy crap!  :O

I would have never guessed it would THAT good!  Thanks for not making me wait.
That is indeed MUCH better than the turbulated cells experiment.  I'm glad that
it's panning out and we have something to work with as a good base pattern.

I'd say the next thing to do would be to have that texture be an entry in a
marble pattern texture_map, with a quartz texture as the vein.

After that, you're going to be the geological expert on whatever else might make
worthwhile additions.

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Quick stab at adding the vein.

Didn't like marble or planar, so I coded a Boolean math function for the stripe,
and let it blend on the sides.

Adding a mod to the function will repeat it, but it's too regular.
I tried warp {repeat x*4} but that repeats the whole pattern, and you get hard
lines.

I thought maybe I could layer it, but it's a pattern texture, and POV-Ray says
"No way!"

I also tried to add a specular highlight, and I'm too inept to get that to work
either.

Nor could I get the void created by using a difference to be anything but black.

It's unclear to me at the present time how to have separate turbulence values
for the stripe and the base StepNoise pattern, but I guess we'll figure that out
as we proceed.

Currently using the sum of two turbulated stripe patterns, so maybe the
placement of the stripes will have to be generated by a macro and an array of
plane offsets.

Anyway, this gives the general idea.

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And the code:

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Op 28/04/2021 om 17:47 schreef jr:
> hi,
> 
> Thomas de Groot <tho### [at] degrootorg> wrote:
>> ... perfection.
> 
> "Flanders (medium) Gray".  :-)
> 
> 
> regards, jr.
> 

For the time being, yes ;-)

-- 
Thomas

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Op 28/04/2021 om 19:26 schreef Bald Eagle:
> Thomas de Groot <tho### [at] degrootorg> wrote:
> 
>> I do not want to have you wait: This is the first render with StepNoise.
>> My judgment is: perfection.
> 
> .... holy crap!  :O
> 
Indeed. Was what I thought too.

> I would have never guessed it would THAT good!  Thanks for not making me wait.
> That is indeed MUCH better than the turbulated cells experiment.  I'm glad that
> it's panning out and we have something to work with as a good base pattern.
> 
I still have to test the grain size control and such but we can indeed 
ditch the turbulated cells. I was happy and not happy at the same time 
with those; especially the larger grains were problematic.

> I'd say the next thing to do would be to have that texture be an entry in a
> marble pattern texture_map, with a quartz texture as the vein.
> 
Sure, and don't forget the quartz veins in the granite :-)

> After that, you're going to be the geological expert on whatever else might make
> worthwhile additions.
> 
Good. Work enough on the horizon.

-- 
Thomas

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Op 28/04/2021 om 22:37 schreef Bald Eagle:
> Quick stab at adding the vein.
> 
> Didn't like marble or planar, so I coded a Boolean math function for the stripe,
> and let it blend on the sides.
> 
My latest experiments with veins was by using agate and agate_turb as 
second texture layer. Needed to add a warp{turbulence *z} to hide the 
layering of agate. The results were promising if not perfect. I do not 
have an example render at hand at this moment.

> Adding a mod to the function will repeat it, but it's too regular.
> I tried warp {repeat x*4} but that repeats the whole pattern, and you get hard
> lines.
> 
> I thought maybe I could layer it, but it's a pattern texture, and POV-Ray says
> "No way!"
> 
> I also tried to add a specular highlight, and I'm too inept to get that to work
> either.
> 
> Nor could I get the void created by using a difference to be anything but black.
> 
> It's unclear to me at the present time how to have separate turbulence values
> for the stripe and the base StepNoise pattern, but I guess we'll figure that out
> as we proceed.
> 
It's a first step.

> Currently using the sum of two turbulated stripe patterns, so maybe the
> placement of the stripes will have to be generated by a macro and an array of
> plane offsets.
> 
> Anyway, this gives the general idea.
> 


-- 
Thomas

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Op 29/04/2021 om 03:17 schreef Bald Eagle:
> And the code:
> 

Thanks. Shall play with that too.

-- 
Thomas

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alright. Getting tired after a day of tweaking.

Second, overhauled, StepNoise version. Several things learned:

- to be careful with the /scale/ of the grains. This is as good as I 
dare to go. Larger minerals become increasingly unbelievable, so one 
needs to find the balance (as with the turbulated cells obviously, but 
StepNoise does a much better, although not perfect, job).

- the mask for the pigment_pattern needs a /very/ careful adjustment. 
The present one is good but could probably be improved further. Good 
enough for now.

- white grains are present but hardly visible. In the first version they 
were placed at the wrong place within the colour_map, rendering rings 
instead of mineral grains. Corrected that but need now to be enhanced a bit.

- sslt would probably increase realism, even in the frosted version. I 
am going to look into that.

-- 
Thomas

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