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From: William F Pokorny
Subject: Nov 29 2020 povr doodle
Date: 29 Nov 2020 12:51:54
Message: <5fc3996a@news.povray.org>
A doodle using povr tweaks on top of v3.8.

Bill P.


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From: Thomas de Groot
Subject: Re: Nov 29 2020 povr doodle
Date: 30 Nov 2020 07:28:32
Message: <5fc49f20$1@news.povray.org>
Op 29/11/2020 om 13:51 schreef William F Pokorny:
> A doodle using povr tweaks on top of v3.8.
> 
> Bill P.

Intriguing... Basically, a sphere_sweep?

-- 
Thomas


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From: William F Pokorny
Subject: Re: Nov 29 2020 povr doodle
Date: 30 Nov 2020 10:28:44
Message: <5fc4c95c$1@news.povray.org>
On 11/30/20 2:28 AM, Thomas de Groot wrote:
> Op 29/11/2020 om 13:51 schreef William F Pokorny:
>> A doodle using povr tweaks on top of v3.8.
>>
>> Bill P.
> 
> Intriguing... Basically, a sphere_sweep?
> 
One could get the same (or better) "loose ball of wires" with a 
spheresweep, but here it's an isosurface.

//--- code below written for povr branch of POV-Ray.
#declare Fn00 = function (x,y,z,xn,zn) {
    f_planar(
        f_sphere(x+f_noise3d(xn+pi,y-pi,zn,2)*0.3,
                 y,
                 z+f_noise3d(xn,y+pi,zn-pi,2)*0.3,0.7),
        0.002,1
    )
}
#declare Fn01 = function { f_planar(f_ph(x,abs(y),z)/pi-0.2,0.002,1) }
#declare Fn02 = function { f_planar(f_ph(x,abs(y),z)/pi-0.4,0.002,1) }
#declare Fn03 = function { min(Fn01(x,y,z),Fn02(x,y,z)) }
#declare Fn04 = function { min(Fn03(x,y,z),Fn03(y,x,z),Fn03(x,z,y)) }
#declare Fn98 = function { max(Fn04(x,y,z),Fn00(x,y,z,x*4,z*4)) }

#declare Iso99 = isosurface {
     function { Fn98(x,y,z) }
...
     jitter on
...
}

---
Let's see. In povr:

f_planar is an inbuilt function with an "f_shell" functionality. If the 
value argument is x,y,z or any f_gradient() instead of f_sphere(), or 
whatever, it's very similar to the planar pattern in result excepting 
for not being clamped to a 0-1 value range - so I kept the naming.

f_noise3d has an extra parameter for the noise generator as do all 
in-built functions using noise generators directly. In POV-Ray you 
always get generator 2 excepting for one special noise function allowing 
the selection (I cannot recall the name - it's unnecessary and gone in 
povr).

In the isosurface itself, I used povr's "jitter on."

In this case, used mode 2 AA with "bigger (+j7)" truly random jitter and 
the +a0.0 internal optimizations avoiding the internal AA gamma 
calculations and color channel difference calculations. The truly random 
jitter is better at picking up the small wires (with the shadow of the 
wires more of a resolution problem). In the end, I increased the wire 
size to something less a hint of something - which was my original aim. 
The povr AA changes probably not strictly needed for the image as posted.

Bill P.


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From: Paolo Gibellini
Subject: Re: Nov 29 2020 povr doodle
Date: 30 Nov 2020 13:48:07
Message: <5fc4f817@news.povray.org>
William F Pokorny wrote on 29/11/2020 13:51:
> A doodle using povr tweaks on top of v3.8.
> 
> Bill P.

Very interesting!
Paolo


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From: Mr
Subject: Re: Nov 29 2020 povr doodle
Date: 30 Nov 2020 15:45:01
Message: <web.5fc512f082247dc26adeaecb0@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:
> A doodle using povr tweaks on top of v3.8.
>
> Bill P.

WOW an Isosurface can do that?! It's definitely one of the most powerful and
versatile POV feature... is it not?


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From: Cousin Ricky
Subject: Re: Nov 29 2020 povr doodle
Date: 30 Nov 2020 23:12:12
Message: <5fc57c4c$1@news.povray.org>
On 2020-11-30 11:42 AM (-4), Mr wrote:
> William F Pokorny <ano### [at] anonymousorg> wrote:
>> A doodle using povr tweaks on top of v3.8.
>>
>> Bill P.
> 
> WOW an Isosurface can do that?! It's definitely one of the most powerful and
> versatile POV feature... is it not?

If it exists or can be conceived by the human imagination, Bill can make 
an isosurface of it.


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From: Ash Holsenback
Subject: Re: Nov 29 2020 povr doodle
Date: 1 Dec 2020 01:09:17
Message: <5fc597bd$1@news.povray.org>
On 11/30/20 6:12 PM, Cousin Ricky wrote:
> On 2020-11-30 11:42 AM (-4), Mr wrote:
>> William F Pokorny <ano### [at] anonymousorg> wrote:
>>> A doodle using povr tweaks on top of v3.8.
>>>
>>> Bill P.
>>
>> WOW an Isosurface can do that?! It's definitely one of the most 
>> powerful and
>> versatile POV feature... is it not?
> 
> If it exists or can be conceived by the human imagination, Bill can make 
> an isosurface of it.

indeed... respect


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From: Thomas de Groot
Subject: Re: Nov 29 2020 povr doodle
Date: 1 Dec 2020 07:28:25
Message: <5fc5f099$1@news.povray.org>
Op 30/11/2020 om 11:28 schreef William F Pokorny:
> On 11/30/20 2:28 AM, Thomas de Groot wrote:
>> Op 29/11/2020 om 13:51 schreef William F Pokorny:
>>> A doodle using povr tweaks on top of v3.8.
>>>
>>> Bill P.
>>
>> Intriguing... Basically, a sphere_sweep?
>>
> One could get the same (or better) "loose ball of wires" with a 
> spheresweep, but here it's an isosurface.
> 

"petje af", which translates from Dutch as something like "I drop my cap 
to you". I am impressed indeed.

-- 
Thomas


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From: William F Pokorny
Subject: Re: Nov 29 2020 povr doodle
Date: 1 Dec 2020 13:17:42
Message: <5fc64276$1@news.povray.org>
On 11/30/20 10:42 AM, Mr wrote:
> William F Pokorny <ano### [at] anonymousorg> wrote:
...
> 
> ... It's definitely one of the most powerful and
> versatile POV feature... is it not?
> 
Yes, I'd put it near the top of the list in terms of shape/surface 
formation. It's ability to represent very complex shapes in great detail 
- very concisely - is, I believe, unmatched.

However, it's not the easiest to use and it's difficult to diversely 
texture. There is no easy way to "paint" what surface materials you want 
in a uv map sort of way(1).

The more complex a shape gets in terms of major forms; the slower it is 
to render and the harder it is to assemble the functions. Meaning, there 
are practical specification and compute limits on what it can do in theory.

(1) - I'm playing with functionality in the povr branch which helps.

Bill P.


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From: William F Pokorny
Subject: Re: Nov 29 2020 povr doodle
Date: 1 Dec 2020 13:20:59
Message: <5fc6433b$1@news.povray.org>
On 11/30/20 6:12 PM, Cousin Ricky wrote:
> On 2020-11-30 11:42 AM (-4), Mr wrote:
...
> 
> If it exists or can be conceived by the human imagination, Bill can make 
> an isosurface of it.

:-) Your elliptical torus has me stumped!


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