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3 Jul 2024 00:56:54 EDT (-0400)
  TekWallPuzzle (Message 1 to 10 of 10)  
From: William F Pokorny
Subject: TekWallPuzzle
Date: 8 Oct 2014 20:51:32
Message: <5435dc14@news.povray.org>
In another thread Norbert Kern mentioned working through older 
contributions of textures for his 300+ materials study and finding 
mysterious techniques. I'm with him on being amazed at what others have 
worked out over time. His comment reminded me of a particular trick Tek 
found 10 years or more back to create lace like patterns from rotations 
and warp repeat statements with flipping across axes. I tried again over 
the past couple days to make sense of why the trick works at all. Many 
experiments and variations and no luck. It is still a mystery to me.

I decided to turn one - not very lace like - result of Tek's trick into 
a more complete image before moving on to other things.

Bill P.


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From: Bald Eagle
Subject: Re: TekWallPuzzle
Date: 8 Oct 2014 22:55:01
Message: <web.5435f8f8376dde075e7df57c0@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:
.... a particular trick Tek
> found 10 years or more back to create lace like patterns from rotations
> and warp repeat statements with flipping across axes.

That's some crazy stuff right there!
http://news.povray.org/povray.binaries.images/thread/%3C3ff78b57%241%40news.povray.org%3E/

I was unaware of "flip"

I wonder if it's possible to discretize the warp and vary the color so that
maybe you can see what's going on better.  Maybe create an animation that lays
down each "step".

I've also noticed in my dabbling that POV-Ray is now so huge and packed with
tools and features that it's sometimes confusing to even know which variation of
a feature to use.  Surely there is much to be discovered in all the combinations
of things one has the option to use.

....and of course you couldn't figure it out --- that's the EVIL part of his
super brain!  ;)


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From: Bald Eagle
Subject: Re: TekWallPuzzle
Date: 9 Oct 2014 01:05:01
Message: <web.54361694376dde075e7df57c0@news.povray.org>
See animation in p.b.a.


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From: Norbert Kern
Subject: Re: TekWallPuzzle
Date: 9 Oct 2014 16:35:01
Message: <web.5436f13b376dde071a48b46c0@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:

> ....and of course you couldn't figure it out --- that's the EVIL part of his
> super brain!  ;)

lace patterns were a nice (simple?) code masterpiece. Variating patterns shows
influence of code vs. patterns. Below is shown - with the same setup and
colormap - quilted, wrinkles and granite.


Norbert


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From: Norbert Kern
Subject: Re: TekWallPuzzle
Date: 9 Oct 2014 16:40:01
Message: <web.5436f25c376dde071a48b46c0@news.povray.org>
"Bald Eagle" <cre### [at] netscapenet> wrote:

> ....and of course you couldn't figure it out --- that's the EVIL part of his
> super brain!  ;)

by the way - lace patterns code reminds to a similar masterpiece (imho) -
Kingdom from Samuel T. Benge (
http://news.povray.org/povray.binaries.scene-files/thread/%3C486725ee%40news.povray.org%3E/?ttop=328092&toff=50
).

Shown below are wrinkles, crackle metric 700 and ripples...


Norbert


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From: William F Pokorny
Subject: Re: TekWallPuzzle
Date: 10 Oct 2014 05:51:10
Message: <5437ac0e$1@news.povray.org>
On 10/09/2014 04:34 PM, Norbert Kern wrote:
>
> lace patterns were a nice (simple?) code masterpiece. Variating patterns shows
> influence of code vs. patterns. Below is shown - with the same setup and
> colormap - quilted, wrinkles and granite.
>
> Norbert
>
Neat & thanks for the pointer to Sam's similar invention.

Code vs patterns. Yes, a good way to think of it. Though, thus far I am 
unable to understand the whole of what is happening on the path from 
code & pattern to result.
Bill P.


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From: Norbert Kern
Subject: Re: TekWallPuzzle
Date: 10 Oct 2014 17:45:00
Message: <web.54385260376dde07d1571c050@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:

> unable to understand the whole of what is happening on the path from
> code & pattern to result.
> Bill P.


IMHO, it's understandable seeing at the center.
In short, rotation + warp repeat y flip y acts as a kaleidoscope, as long as you
rotate 180 degrees (ncount_max * fA) or a multiple of it.

To show, what I mean, I add an image with code spippets included.
Distance from origin is needed to get rid of the kaleidoscope effect...

Norbert


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From: William F Pokorny
Subject: Re: TekWallPuzzle
Date: 11 Oct 2014 03:29:32
Message: <5438dc5c@news.povray.org>
On 10/10/2014 05:40 PM, Norbert Kern wrote:
>
> IMHO, it's understandable seeing at the center.
> In short, rotation + warp repeat y flip y acts as a kaleidoscope, as long as you
> rotate 180 degrees (ncount_max * fA) or a multiple of it.
>
> To show, what I mean, I add an image with code spippets included.
> Distance from origin is needed to get rid of the kaleidoscope effect...
>
> Norbert
>
Hi Norbert,
I agree with your outline for how the method works. However, at a 
fundamental level this trick still confuses me. Attached is a series of 
4 renders of a unit square centered at the origin. On the left is just 



All good thus far in that it makes sense to me. The introduction of the 
warp in the third introduces no change as I'd expect given the repeat 
should not happen until +- 1.0 in Y. Now for the final image on the 

nothing more than what I would see from the two rotations of the 
original pattern.

Instead, there is a discontinuity in the pattern in the upper left and 
lower right quadrants. I believe this a necessary component of the 
method, but I do not really understand what happened to pull the repeat 

quadrants of the square +-0.5 in x&y. In other words I expect the second 

than the original rotated -36*z pattern into the first warp.


and this continues in the full method as we layer the repeats. Is the 
trailing repeat partly folding or collapsing the spatial coordinates of 
the one before it?

We get very cool results I suppose no matter whether I can understand 
things...




and I thought - more interesting result.

Bill P.


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From: Norbert Kern
Subject: Re: TekWallPuzzle
Date: 11 Oct 2014 05:10:01
Message: <web.5438f233376dde07efed510f0@news.povray.org>
William F Pokorny <ano### [at] anonymousorg> wrote:


> and this continues in the full method as we layer the repeats. Is the
> trailing repeat partly folding or collapsing the spatial coordinates of
> the one before it?
>
> Bill P.

This is right, if I watch at the results.
Repeating your renders I got left the expected (only rotation), but after a
single rotation and warp there is the discontinuity. Adding another rotation and
warp (third from left) and with fA = 10 the result is strange.

Obviously the warp displaces the rotated pattern one unit in y axis. Since
scaling doesn't match the pattern, you see one discontinuity. After a second
rotation and warp you see two lines of discontinuity (enlarging would clarify it
more). Every rotation + warp adds another discontinuity...


Norbert


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From: FractRacer
Subject: Re: TekWallPuzzle
Date: 11 Oct 2014 13:19:46
Message: <543966b2@news.povray.org>

> William F Pokorny <ano### [at] anonymousorg> wrote:
> .... a particular trick Tek
>> found 10 years or more back to create lace like patterns from rotations
>> and warp repeat statements with flipping across axes.
>
> That's some crazy stuff right there!
>
http://news.povray.org/povray.binaries.images/thread/%3C3ff78b57%241%40news.povray.org%3E/
>
> I was unaware of "flip"
>
> I wonder if it's possible to discretize the warp and vary the color so that
> maybe you can see what's going on better.  Maybe create an animation that lays
> down each "step".
>
> I've also noticed in my dabbling that POV-Ray is now so huge and packed with
> tools and features that it's sometimes confusing to even know which variation of
> a feature to use.  Surely there is much to be discovered in all the combinations
> of things one has the option to use.
>
> ....and of course you couldn't figure it out --- that's the EVIL part of his
> super brain!  ;)
>

If you add warp { repeat x flip x } the pattern fill the plane.

-- 
Lionel
<b>Do not judge my words, judge my actions.</b>

---

http://www.avast.com


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