POV-Ray : Newsgroups : povray.binaries.images : A special texture with circle : Re: A special texture with circle Server Time30 Sep 2023 09:12:05 EDT (-0400)
 Re: A special texture with circle
 From: And Date: 16 May 2022 03:40:00 Message:
```
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"headline": "Re: A special texture with circle",
"dateCreated": "2022-05-16T07:40:00+00:00",
"datePublished": "2022-05-16T07:40:00+00:00",
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"Bald Eagle" <cre### [at] netscapenet> wrote:
> "And" <49341109@ntnu.edu.tw> wrote:
> > When I tried to combine function to form a wood bumps pattern, I create a
> > interesting picture. With concentric circles.
>
> This would probably look _really_ cool as a height field!

Why? I don't imagine it so clear.

This pattern here: --------------------------

// basic functions -----

#declare f_theta =
function(x, y) {
select(y, 2*pi - acos(x/sqrt(x*x + y*y)) , acos(x/sqrt(x*x + y*y)))
}

#declare f_r =
function(x, y) {
sqrt(x*x + y*y)
}

#declare f_noise3d = function { internal(76) }

// theme -----

#declare f_rising_noise =
function (x, y) {
f_r(x, y) * f_noise3d(x*5, y*5, 0)

}

#declare f_bumps =
function {f_noise3d(x, y, z)}

#declare radial_growth_speed = 0.1; // m/year

#declare f_time_mockup =
function(x, y, z) {
}

#declare feather_extent = 2.3;

#declare f_t_noise_apply =
function(var_t, change_value) {
f_noise3d(var_t*feather_extent, change_value*50, 200)
}

#declare f_result =
function (x,y) {
f_t_noise_apply(
f_time_mockup(x, y, 0),
f_bumps(f_rising_noise(x, y)*2, 0, 0) // change value
)
}

// ---------------------------------------

Then it can show on a x - y plane. range -5 < x < 5,    -5 < y < 5
```