POV-Ray : Newsgroups : povray.unofficial.patches : Isosurface is bigger in MegaPov than in v3.5? Server Time
1 Nov 2024 01:23:04 EDT (-0400)
  Isosurface is bigger in MegaPov than in v3.5? (Message 1 to 3 of 3)  
From: Marc-Hendrik Bremer
Subject: Isosurface is bigger in MegaPov than in v3.5?
Date: 9 Oct 2001 11:47:06
Message: <3bc31bfa@news.povray.org>
Hi!

I think, I'm missing something, so can someone explain, why this function

isosurface

       function { (

                           (abs(x)-0.047&abs(z)-0.05)
                          |(x*x+(z+0.05)*(z+0.05)-0.047*0.047)

                        )&abs(y)-0.01
                   }
              //method 2
              //eval
              max_gradient 4
              accuracy 0.01
              contained_by{box {<-0.1,-0.2,-0.2>,<0.1,0.2,0.20>}}
              texture{pigment{rgb 0.1}}
         }

results in Pov v3.5 beta-5 in a shape that is about half as big as if the
same iso is rendered in MegaPov? I'm just not able to find a difference,
that would explain this behaviour. Anyone?

Marc-Hendrik


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From: Christoph Hormann
Subject: Re: Isosurface is bigger in MegaPov than in v3.5?
Date: 9 Oct 2001 12:52:59
Message: <3BC32B6B.85D9BAB3@gmx.de>
Marc-Hendrik Bremer wrote:
> 
> Hi!
> 
> I think, I'm missing something, so can someone explain, why this function
> 
> [...]
> 
> results in Pov v3.5 beta-5 in a shape that is about half as big as if the
> same iso is rendered in MegaPov? I'm just not able to find a difference,
> that would explain this behaviour. Anyone?
> 

Could be a operator precedence problem, try putting in additional
parentheses to clearify the meaning.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/


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From: Marc-Hendrik Bremer
Subject: Re: Isosurface is bigger in MegaPov than in v3.5?
Date: 9 Oct 2001 14:04:38
Message: <3bc33c36@news.povray.org>
Christoph Hormann schrieb in Nachricht <3BC32B6B.85D9BAB3@gmx.de>...
>Could be a operator precedence problem, try putting in additional
>parentheses to clearify the meaning.


Oh, now I see! The precedence of "AND" and "OR" has changed, has it? Megapov
read the function quite different from how it was meant by me. v3.5 did it
the right way (if there is something like the right way in precedence of
logical operators), but unfortunately my scaling was now only correct for
the bigger versions. I'll have to change my function.

Thanks for the help!

Marc-Hendrik


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