Le 2020-05-07 à 21:45, William F Pokorny a écrit :
> <---------------------- References. Seven previous posts
> 
>
http://news.povray.org/povray.beta-test.binaries/thread/%3C5ea57285%241%40news.povray.org%3E/

> 
> 
> and
> 
>
http://news.povray.org/povray.beta-test.binaries/thread/%3C5ead9027%40news.povray.org%3E/

> 
> 
> Replacing the f_agate simple pattern{} wrap in functions.inc with a new 
> inbuilt f_agate which brings out the x,y,z directions and power exponent 
> as parameters in addition to parameters for the turbulence call's 
> octaves, omega and lambda.
> 
> Parameters: x, y, z
> 7 extra parameter required:
> ---
> 1. 0,1 or 2 for x, y or z agate alignment. Pattern's agate always uses z 
> (2).
> 
> 2. Turbulence multiplier. Called agate_turb in the pattern version. (1.0).
> 
> 3. Power exponent for pow(). Hard coded to 0.77 in the pattern version. 
> (0.77)
> 
> 4. Number of octaves for the turbulence call. Pattern version defaults 
> to (6).
> 
> 5. Omega value for the turbulence call. Pattern version defaults to 0.5.
> 
> 6. Lambda value for the turbulence call. Pattern version defaults to 2.0.
> 
> 7. The noise generator to use. Valid values 1-3. Pattern agate uses 
> pattern or global setting.
> 
> Notes. To match the default pattern agate: 
> f_agate(x,y,z,2,1.0,0.77,6,0.5,2.0,2)  <-- Matches pattern agate when 
> everything defaulted.  With the pattern agate octaves, omega and lambda 
> can be set with those bare keywords immediately after agate changing 
> agate's inbuilt turbulence.
> 
> For the bottom of the attached image creating an isosurface using both 
> the non-preferred directions looks like:
> 
> #declare Iso99 = isosurface {
>      function { y+f_agate(x*2,y*2,z*2,0,0.08,0.20,6,0.5,2.0,2)*0.135
>                  +f_agate(x*2,y*2,z*2,2,0.08,0.20,6,0.5,2.0,2)*0.135
>      }
> ...
> 
> On the top of the image subtracted both f_agate()s at multiplier of 0.035.
> 
> In a surprise, I expected f_agate() to be a little slower than the 
> inbuilt used as a pattern in a pigment, for example. It's running about 
> 16% faster for reasons not currently understood. This the first pattern 
> where - other than f_dents which is cheap - the inbuilt function 
> implementation can match the pattern one exactly. (My f_granite23 
> inbuilt doesn't match granite.) A mystery for another day.
> 
> Bill P.

Those looks like a slightly turbulent quilted pattern. Especially the 
top example.

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