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From: Jan Walzer
Subject: SimpleFunction ...
Date: 16 Apr 2002 10:41:37
Message: <3cbc3821@news.povray.org>
OK ... after ca. 3,5 weeks the image is done
I don't think it was worth the time as it was only an testrender

its a (quite simple) isosurface (with a std texture, nothing fancy)
and a scattering media container and some lights inside the media ...
Only I had to set maxgradient to 120, so it was quite slow...

so tell me now, why I left it render so long ...

I think I won't test any longer on this source, as I planned to add
some (variable) reflection to the iso and modify the function in a
way, that the "hardcuts" go away ...

Also you will notice, that the image has no AA ...
I can't believe that the img would have taken even longer with AA on ..

now, here it is ...

Post your comments, but don't count that I'll do modifications to it
...


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From:
Subject: Re: SimpleFunction ...
Date: 16 Apr 2002 10:47:39
Message: <j7eobu8bo5dfe0cbgojrb5ema2ppe57560@4ax.com>
On Tue, 16 Apr 2002 16:41:04 +0200, "Jan Walzer" <jan### [at] lzernet> wrote:
> OK ... after ca. 3,5 weeks the image is done

Perhaps something could be optimized in function ?
How simple it is ? It's secret ? Nice.

ABX


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From: Shay
Subject: Re: SimpleFunction ...
Date: 16 Apr 2002 11:14:43
Message: <3cbc3fe3@news.povray.org>
Will you share your function? The surface is beautiful, but looks like it
could be easily approximated with a mesh.

 -Shay

Jan Walzer <jan### [at] lzernet> wrote in message
news:3cbc3821@news.povray.org...


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From: Jan Walzer
Subject: Re: SimpleFunction ...
Date: 16 Apr 2002 11:40:14
Message: <3cbc45de$1@news.povray.org>
now the idea of the function is, to take a suitable pattern (I took the bozo),
stretch it along the X-axis and then apply some noise in the Y+Z direction ...

this is quite simple done, but for easy tweaking I encapsulated it into
several functions, so the code is a mess and there are probably some
operations I could have spared ...

But if you really want to see the code, here it is:

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

#declare F=function(x,y,z) {
    P_func(
            x/20,
            y*3-f_noise3d(x+y*0.2,0,0)*5,
            z*3-f_noise3d(x+z*0.2,0,0)*5
          )
    }

#declare IsoMin=-x-2;
#declare IsoMax=x+2;

#declare MyIso=isosurface {
    function{F(x/0.4,y*4,z*4)}
    max_gradient 45.0
    threshold 0.2
    contained_by {
        box { IsoMin IsoMax}
        }
    }


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From: Jan Walzer
Subject: Re: SimpleFunction ...
Date: 16 Apr 2002 11:43:12
Message: <3cbc4690$1@news.povray.org>
"Shay" <sah### [at] simcopartscom> wrote:
> Will you share your function?
look into my answer to ABX
> The surface is beautiful, but looks like it
> could be easily approximated with a mesh.

if you leave the "easily" out, I'd go with this,
but I don't believe it will give good results ...


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From: TinCanMan
Subject: Re: SimpleFunction ...
Date: 16 Apr 2002 11:47:24
Message: <3cbc478c@news.povray.org>
"Jan Walzer" <jan### [at] lzernet> wrote in message
news:3cbc3821@news.povray.org...
> OK ... after ca. 3,5 weeks the image is done
> I don't think it was worth the time as it was only an testrender

Nice function but man, I get impatient if my render takes longer then 5
minutes.  My longest render to date was ~30h  2048x1536 AA0.0, no media, no
photons, no radiosity.  Longest wait of my life...so far.

-tgq


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From: Jan Walzer
Subject: Re: SimpleFunction ...
Date: 16 Apr 2002 11:50:22
Message: <3cbc483e@news.povray.org>
"TinCanMan" <Tin### [at] hotmailcom> wrote:
> > OK ... after ca. 3,5 weeks the image is done
> > I don't think it was worth the time as it was only an testrender
>
> Nice function but man, I get impatient if my render takes longer then 5
> minutes.  My longest render to date was ~30h  2048x1536 AA0.0, no media, no
> photons, no radiosity.  Longest wait of my life...so far.

Seems I got used to it... after some time ...

at least it stopped me from playing with other POV-images while I should be
learning for some exams ...

As a sidenote: This image was rendered with 3 different POV-versions, as I had
to restart my machine sometimes in between (nothing POV-related) ...


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From:
Subject: Re: SimpleFunction ...
Date: 17 Apr 2002 03:06:27
Message: <ik6qbu8h0s4b4pedqf9upp69r30e04kcma@4ax.com>
On Tue, 16 Apr 2002 17:40:12 +0200, "Jan Walzer" <jan### [at] lzernet> wrote:
> #declare P_func = function(x,y,z) { f_bozo(x,y,z) }
> #declare F = function(x,y,z) {
>    P_func(
>            x/20,
>            y*3-f_noise3d(x+y*0.2,0,0)*5,
>            z*3-f_noise3d(x+z*0.2,0,0)*5
>          )
>    }
> #declare MyIso=isosurface { function{F(x/0.4,y*4,z*4)} ...

1. No need to encapsulate f_bozo as additional token P_func. Some day I asked
in p.a-u if it is just assigned or makes another level of reference. There was
no answer..

2. I think that calling f_noise twice with the same parameters is slower than
calculating it ones and pass as fourth parameter to the function.

3. No need for double scaling of parameters. You can even avoid scaling of
parameters if you properly scale whole isosurface.

My proposition is:

#declare F = function(x,y,z,N) { f_bozo( x, y-N, z-N ) }

#declare MyIso=isosurface {
  function{ F(x/8,y*12,z*12,f_noise3d(x/0.4+y*0.8,0,0)*5) } ...

or with scaling

#declare F = function(x,y,z,N) { f_bozo( x, y-N, z-N ) }

#local Scale=<8,1/12,1/12>;
#declare IsoMin=(-x-2)/Scale;
#declare IsoMax=(x+2)/Scale;

#declare MyIso=isosurface {
    function{ F(x,y,z,f_noise3d(20*x+y/15,0,0)*5) } ...
    contained_by {box { IsoMin IsoMax}}}
    scale Scale

ABX


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From: Jan Walzer
Subject: Re: SimpleFunction ...
Date: 17 Apr 2002 04:22:20
Message: <3cbd30bc@news.povray.org>
... as I said... I did this for
easy tweaking of the parameters

If I have some time or a second
computer, I'll give these hints
a try... Thanks anyway for care


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From:
Subject: Re: SimpleFunction ...
Date: 17 Apr 2002 04:36:40
Message: <cscqbuc2fthoub4jh7qdbib4q2rmpp5s8d@4ax.com>
On Wed, 17 Apr 2002 10:22:20 +0200, "Jan Walzer" <jan### [at] lzernet> wrote:
> If I have some time or a second
> computer, I'll give these hints
> a try... Thanks anyway for care

Post whole sorce to me (or upload it somewhere) and I can start it on one of
machines near me.

ABX


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