Jim's question in povray.advanced-users about usage of the Shear_Trans macro
made me play around with shearing of different shapes.

This image shows some supertorus isosurfaces sheared in different directions.

-- 
Tor Olav
http://subcube.com

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Download 'sheared_supertori.jpg' (275 KB)

Preview of image 'sheared_supertori.jpg'

"Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote in message 
news:4b5a4460@news.povray.org...
>
> Jim's question in povray.advanced-users about usage of the Shear_Trans 
> macro
> made me play around with shearing of different shapes.
>
> This image shows some supertorus isosurfaces sheared in different 
> directions.

WOW .... care to post the code? I've been looking for something to twiddle 
with between between projects.

Jim

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Tor Olav Kristensen wrote:
> 
> Jim's question in povray.advanced-users about usage of the Shear_Trans 
> macro
> made me play around with shearing of different shapes.
> 
> This image shows some supertorus isosurfaces sheared in different 
> directions.
> 
> 
> ------------------------------------------------------------------------
> 
Beautiful effect, makes me think, a little, of soapstone carving.  The 
method gives an interesting insight also. Applying the shearing macro to 
an iso-surface is something I would not have expected.  Being a mere 
mortal with maths, I would have guessed, rather, that you'd done the 
shearing with the iso-surface function somehow.

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"Jim Charter" <jrc### [at] msncom> schreef in bericht 
news:4b5b0875$1@news.povray.org...
>>
> Beautiful effect, makes me think, a little, of soapstone carving.  The 
> method gives an interesting insight also. Applying the shearing macro to 
> an iso-surface is something I would not have expected.  Being a mere 
> mortal with maths, I would have guessed, rather, that you'd done the 
> shearing with the iso-surface function somehow.

Yes indeed, and within the isosurface function, there is a shear code that 
can be used, I remember from my *ancient* geomorph macro. It is explained in 
the isosurface part of the docs iirc   :)

Thomas

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> "Jim Charter"<jrc### [at] msncom>  schreef in bericht
> news:4b5b0875$1@news.povray.org...
>>>
>> Beautiful effect, makes me think, a little, of soapstone carving.  The
>> method gives an interesting insight also. Applying the shearing macro to
>> an iso-surface is something I would not have expected.  Being a mere
>> mortal with maths, I would have guessed, rather, that you'd done the
>> shearing with the iso-surface function somehow.
>
> Yes indeed, and within the isosurface function, there is a shear code that
> can be used, I remember from my *ancient* geomorph macro. It is explained in
> the isosurface part of the docs iirc   :)
>
> Thomas
>
>

Prety simple:

you just call the function like this:

My_function( x+y/2, y, z)

This will shear toward -x as y get larger.

You can do something like this:

My_function( x+(cos(y*3)+sin(z*2))*2, y, z-sin(y*3) )

and have your shape twists around.


Alain

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Jim Holsenback wrote:
> "Tor Olav Kristensen" <tor### [at] TOBEREMOVEDgmailcom> wrote in message 
> news:4b5a4460@news.povray.org...
>> Jim's question in povray.advanced-users about usage of the Shear_Trans 
>> macro
>> made me play around with shearing of different shapes.
>>
>> This image shows some supertorus isosurfaces sheared in different 
>> directions.
> 
> WOW .... care to post the code? I've been looking for something to twiddle 
> with between between projects.

I've just posted two versions of the source code in this thread:
http://news.povray.org/povray.text.scene-files/thread/%3C4b5bd4d4%40news.povray.org%3E/

Newsgroup: povray.text.scene-files	
Date: 24 Jan 2010 04:54:58
Subject: Source code for "Sheared supertori" image

-- 
Tor Olav
http://subcube.com

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Jim Charter wrote:
> Tor Olav Kristensen wrote:
>>
>> Jim's question in povray.advanced-users about usage of the Shear_Trans 
>> macro
>> made me play around with shearing of different shapes.
>>
>> This image shows some supertorus isosurfaces sheared in different 
>> directions.
>>
>>
>> ------------------------------------------------------------------------
>>
> Beautiful effect, makes me think, a little, of soapstone carving.  The 

Yes, that effect is from some textures and light settings that Gilles Tran
once made. I like to play around with it.

http://news.povray.org/povray.binaries.images/thread/%3C398DAC6E.810C4E7%40inapg.inra.fr%3E/
Newsgroup: povray.binaries.images
Date: 6th August 2000
Subject: Radiosity test (60kbu)

http://news.povray.org/povray.binaries.images/thread/%3C398EE60E.DCFE0C7E%40inapg.inra.fr%3E/
Newsgroup: povray.binaries.images
Date: 7th August 2000
Subject: Radiosity test #2 70 kbu


> The 
> method gives an interesting insight also. Applying the shearing macro to 
> an iso-surface is something I would not have expected.  Being a mere 
> mortal with maths, I would have guessed, rather, that you'd done the 
> shearing with the iso-surface function somehow.

I've made some code for doing the shearing of these shapes within the
functions for the isosurfaces, but it's a lot more work. If I finish it,
then I'll post that code too.

-- 
Tor Olav
http://subcube.com

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