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From: Sven Geier
Subject: Beta29 isosurface badly broken
Date: 13 Nov 2008 17:25:01
Message: <web.491ca8f6551ce61b5b4449250@news.povray.org>
As a bit of a followup on the f_crackle posts from earlier, a bunch of tinkering
finds that much of 'isosurface' appears pretty broken in 3.7b29.

To me at least.

To the point where I'm wondering whether it's just me (the "surely someone else
would have noticed that" effect)

Could someone confirm or deny that the following produces something rather
different from what one might assume simply by looking at the code.

Thanks.

// ---------------
camera {
  location <.1,2,-2>
  look_at   <0, -.4, 0> }
sky_sphere{pigment{color rgb <.2,.4,.6>}}
cone {
  1*y,  0.0, 0*y, .3
   pigment {color rgb 10}
}
isosurface { function { 2*sqrt(x*x+z*z)+y-1  }
   pigment { hexagon scale .1  }
}
//--------

(For reference: I would expect a bright cone completely enclosed/obscured by a
larger hexagon-colored cone).


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From: Warp
Subject: Re: Beta29 isosurface badly broken
Date: 13 Nov 2008 17:38:36
Message: <491cac6c@news.povray.org>
Sven Geier <.sven.at.sgeier.dot.net.nospamplease> wrote:
> As a bit of a followup on the f_crackle posts from earlier, a bunch of tinkering
> finds that much of 'isosurface' appears pretty broken in 3.7b29.

  A very relevant info would be if this also happens with previous betas
and/or POV-Ray 3.6, or whether those render it as you expect.

-- 
                                                          - Warp


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From: Darren New
Subject: Re: Beta29 isosurface badly broken
Date: 13 Nov 2008 19:13:07
Message: <491cc293$1@news.povray.org>
Sven Geier wrote:
> As a bit of a followup on the f_crackle posts from earlier, a bunch of tinkering
> finds that much of 'isosurface' appears pretty broken in 3.7b29.

Didn't this expire already? I was all psyched to have my x64 quad-core 
computer set up enough to try this out, but the download page said it 
expired almost 2 weeks ago. Am I missing something obvious (other than 
frobbing your clock to fool the software)?

-- 
Darren New / San Diego, CA, USA (PST)


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From: Warp
Subject: Re: Beta29 isosurface badly broken
Date: 13 Nov 2008 19:20:45
Message: <491cc45c@news.povray.org>
Darren New <dne### [at] sanrrcom> wrote:
> Didn't this expire already? I was all psyched to have my x64 quad-core 
> computer set up enough to try this out, but the download page said it 
> expired almost 2 weeks ago. Am I missing something obvious (other than 
> frobbing your clock to fool the software)?

  There is an official way of extending the expiration date of a beta.
I lost the link to the instructions, though. IIRC it's a post in this
group by Chris Cason.

-- 
                                                          - Warp


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From: Nicolas Alvarez
Subject: Re: Beta29 isosurface badly broken
Date: 13 Nov 2008 20:55:25
Message: <491cda8c@news.povray.org>
Warp wrote:
>   There is an official way of extending the expiration date of a beta.
> I lost the link to the instructions, though. IIRC it's a post in this
> group by Chris Cason.

http://news.povray.org/476af506$1@news.povray.org


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From: Darren New
Subject: Re: Beta29 isosurface badly broken
Date: 13 Nov 2008 23:26:15
Message: <491cfde7$1@news.povray.org>
Nicolas Alvarez wrote:
> http://news.povray.org/476af506$1@news.povray.org

Awesome, both of you. Thank you!

-- 
Darren New / San Diego, CA, USA (PST)


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From: Bob Hughes
Subject: Re: Beta29 isosurface badly broken
Date: 14 Nov 2008 00:51:56
Message: <491d11fc$1@news.povray.org>
I suspected letting it be defaults might be the problem so I gave this a try
and 3.7 beta doesn't show a message about isosurface 'max_gradient' but when
I checked using 3.6 I found it wanted the number to be 2.217 instead of a
default of 1.1 and putting that larger number in fixed the isosurface cone
for me.
I haven't followed what is supposed to happen about this particular warning
message. Yet to be added, or is missing by mistake (am doubting that).
Got to be careful that tested SDL is adequately correct, comparative with
earlier or non-beta POV as Warp said. It's easy to put something through
these betas and "expect" something without it really being okay in the first
place.  ;^)

----- Original Message ----- 
From: "Sven Geier" <.sven.at.sgeier.dot.net.nospamplease>
Newsgroups: povray.beta-test
Sent: Thursday, November 13, 2008 4:23 PM
Subject: Beta29 isosurface badly broken


> As a bit of a followup on the f_crackle posts from earlier, a bunch of
> tinkering
> finds that much of 'isosurface' appears pretty broken in 3.7b29.
>
> Could someone confirm or deny that the following produces something rather
> different from what one might assume simply by looking at the code.

// ---------------
camera {
 location <.1,2,-2>
 look_at   <0, -.4, 0> }
sky_sphere{pigment{color rgb <.2,.4,.6>}}
cone {
 1*y,  0.0, 0*y, .3
  pigment {color rgb 10}
}
isosurface { function { 2*sqrt(x*x+z*z)+y-1  }
 max_gradient 2.22 /* the fix? */
  pigment { hexagon scale .1  }
}
//--------

> (For reference: I would expect a bright cone completely enclosed/obscured
> by a
> larger hexagon-colored cone).



-- 
/*bob hughes*/


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From: Dan Connelly
Subject: Re: Beta29 isosurface badly broken
Date: 14 Nov 2008 18:10:44
Message: <491e0574@news.povray.org>
Bob Hughes wrote:

> I checked using 3.6 I found it wanted the number to be 2.217 instead of a
> default of 1.1 and putting that larger number in fixed the isosurface cone
> for me.

> isosurface { function { 2*sqrt(x*x+z*z)+y-1  }

Mathematically the max gradient is 2.  I ran beta 29 with max_gradient 2.001 and it
seemed to work,

Dan


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From: Alain
Subject: Re: Beta29 isosurface badly broken
Date: 14 Nov 2008 22:06:42
Message: <491e3cc2$1@news.povray.org>
Sven Geier nous illumina en ce 2008-11-13 17:23 -->
> As a bit of a followup on the f_crackle posts from earlier, a bunch of tinkering
> finds that much of 'isosurface' appears pretty broken in 3.7b29.
> 
> To me at least.
> 
> To the point where I'm wondering whether it's just me (the "surely someone else
> would have noticed that" effect)
> 
> Could someone confirm or deny that the following produces something rather
> different from what one might assume simply by looking at the code.
> 
> Thanks.
> 
> // ---------------
> camera {
>   location <.1,2,-2>
>   look_at   <0, -.4, 0> }
> sky_sphere{pigment{color rgb <.2,.4,.6>}}
> cone {
>   1*y,  0.0, 0*y, .3
>    pigment {color rgb 10}
> }
> isosurface { function { 2*sqrt(x*x+z*z)+y-1  }
>    pigment { hexagon scale .1  }
> }
> //--------
> 
> (For reference: I would expect a bright cone completely enclosed/obscured by a
> larger hexagon-colored cone).
> 
> 
Renders about the same in 3.6 and 3.7. As other have said, max_gradient should 
be 2.1 (2.01 still give some artefacts) and 3.6 need 2.2.

-- 
Alain
-------------------------------------------------
They that can give up essential liberty to obtain a little temporary safety 
deserve neither liberty nor safety.
Benjamin Franklin


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From: Slime
Subject: Re: Beta29 isosurface badly broken
Date: 15 Nov 2008 02:10:56
Message: <491e7600$1@news.povray.org>
>> isosurface { function { 2*sqrt(x*x+z*z)+y-1  }
>
> Mathematically the max gradient is 2.

At (1,0,0), the gradient is (2,1,0) with a magnitude of sqrt(5) or about 
2.236.

 - Slime
 [ http://www.slimeland.com/ ]


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