POV-Ray : Newsgroups : povray.unofficial.patches : Possible Error in the Superpatch Server Time
3 Sep 2024 00:17:49 EDT (-0400)
  Possible Error in the Superpatch (Message 1 to 9 of 9)  
From: Mark Wagner
Subject: Possible Error in the Superpatch
Date: 22 Jun 1999 00:38:09
Message: <376f1331@news.povray.org>
I was rendering a scene using the SuperPatch, and when I looked at the
rendering statistics, they indicated that there was a CSG Merge in the
scene, when I know that I didn't put one in.  Is this really an error, or is
it just the way POV does things?  Here is the simplest code I could create
that has this possible error:

#include "colors.inc"

#declare MainObject =
difference{
 union{
  box{ <1699,360,800>,<1001,375,900> pigment{ Green } }
 }
 //Note: This intersection appears to be the merge.
 intersection{
  box{ <1700,366,848.5>,<1000,369,851.5> }
  cylinder{ <1701,363,850>,<1000,363,850>,5.5 }
  pigment{Red}
 }
}

#declare camera1 = camera{
 location <2100,380,690>
 look_at <1900,370,770>
 angle 20
}

light_source{ y*10000000 White*1.8 }
light_source{ <1150,367,850> White }//Tunnel light
light_source{ <1600,367,850> White }//Tunnel light

camera{ camera1 }

object{ MainObject }


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From: Ron Parker
Subject: Re: Possible Error in the Superpatch
Date: 22 Jun 1999 09:14:04
Message: <376f8c1c@news.povray.org>
On Tue, 22 Jun 1999 00:37:05 -0400, Mark Wagner wrote:
>I was rendering a scene using the SuperPatch, and when I looked at the
>rendering statistics, they indicated that there was a CSG Merge in the
>scene, when I know that I didn't put one in.  Is this really an error, or is
>it just the way POV does things?  Here is the simplest code I could create
>that has this possible error:

It's just the way POV does things.  Here's why:

difference {
  object {A}
  intersection {
    object {B}
    object {C}
  }
}

is represented internally as

intersection {
  object {A}
  intersection {
    object {B}
    object {C}
    inverse
  }
}

which POV distills to

intersection {
  object {A}
  merge {
    object {B inverse}
    object {C inverse}
  }
}

Earlier versions of POV would have used union instead of
merge, but that can lead to weird artifacts if you're 
dealing with transparent surfaces.


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From: TonyB
Subject: Re: Possible Error in the Superpatch
Date: 22 Jun 1999 17:27:12
Message: <376FF16C.AD31F081@panama.phoenix.net>
That sure is odd.

I wish there was a way to make POV count a union of objects as one object,
instead of counting as if they were separate. The only way I see to eliminate
this is to merge, but that just slows things down. It's just a thing I would
like, I don't think it serves any useful purpose.

--
Anthony L. Bennett
http://welcome.to/TonyB

Graphics rendered
by the Dreamachine.


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From: Nathan Kopp
Subject: Re: Possible Error in the Superpatch
Date: 23 Jun 1999 00:05:43
Message: <37705C3E.E61CE12B@Kopp.com>
UVPov has the keyword experimental keyword 'split_union' to turn union
splitting on & off on a per-object basis ('split_union on' or
'split_union off').  The official version allows this as an INI or
command line option.  From the docs in the section "Removing User Bounding":

Split_Unions=bool	Turn split bounded unions on/off
+SU	Turn split bounded unions on
-SU	Turn split bounded unions off

-Nathan

TonyB wrote:
> 
> That sure is odd.
> 
> I wish there was a way to make POV count a union of objects as one object,
> instead of counting as if they were separate. The only way I see to eliminate
> this is to merge, but that just slows things down. It's just a thing I would
> like, I don't think it serves any useful purpose.
> 
> --
> Anthony L. Bennett
> http://welcome.to/TonyB
> 
> Graphics rendered
> by the Dreamachine.


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From: Nieminen Mika
Subject: Re: Possible Error in the Superpatch
Date: 23 Jun 1999 09:48:44
Message: <3770e5bc@news.povray.org>
TonyB <ben### [at] panamaphoenixnet> wrote:
: The only way I see to eliminate this is to merge, but that just slows
: things down.

  Are you sure?
  See http://iki.fi/warp/povVFAQ.html#csgspeed

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/


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From: TonyB
Subject: Re: Possible Error in the Superpatch
Date: 23 Jun 1999 16:11:52
Message: <377131B4.FC44B77E@panama.phoenix.net>
>   Are you sure?
>   See http://iki.fi/warp/povVFAQ.html#csgspeed

Yes, sir. I am absolutely sure that every time -I- use merge, it just slows
things down. The only moment I have seen it as useful is with transparent
objects, or in the hollow interior of merged objects. BTW, thank you for your
wonderful FAQ, game (I can't seem to pass the 2JOES level), and utilities
(esp. the frame averager, which I use very often).

--
Anthony L. Bennett
http://welcome.to/TonyB

Graphics rendered
by the Dreamachine.


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From: Nieminen Mika
Subject: Re: Possible Error in the Superpatch
Date: 24 Jun 1999 10:06:25
Message: <37723b61@news.povray.org>
TonyB <ben### [at] panamaphoenixnet> wrote:
: Yes, sir. I am absolutely sure that every time -I- use merge, it just slows
: things down. The only moment I have seen it as useful is with transparent
: objects, or in the hollow interior of merged objects.

  It makes no sense to use merge in non-transparent objects anyways...

: BTW, thank you for your
: wonderful FAQ, game (I can't seem to pass the 2JOES level), and utilities
: (esp. the frame averager, which I use very often).

  You're welcome.

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/


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From: TonyB
Subject: Re: Possible Error in the Superpatch
Date: 24 Jun 1999 17:51:34
Message: <377299BF.6A3B18EB@panama.phoenix.net>
Umm. You seem to have missed my little hint there. How do I pass the 2JOES level?
I've invited friends over to try to solve that thing and there is always a
problem... please explain. You can e-mail me at ben### [at] panamaphoenixnet.
Thanks.

--
Anthony L. Bennett
http://welcome.to/TonyB

Graphics rendered
by the Dreamachine.


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From: Juha Leppälä
Subject: Re: Possible Error in the Superpatch
Date: 2 Jul 1999 11:10:14
Message: <377CD6AA.4D4B9FC@kolumbus.fi>
TonyB wrote:
> 
> Umm. You seem to have missed my little hint there. How do I pass the 2JOES level?
> I've invited friends over to try to solve that thing and there is always a
> problem... please explain. You can e-mail me at ben### [at] panamaphoenixnet.
> Thanks.

Ha Ha, I've solved it all by myself. I'm just going to laugh at you...
Hehe, had to do it :)
 
*--------------------------------------------------

| juh### [at] kolumbusfi
| http://www.kolumbus.fi/juha-matti.leppala/
*--------------------------------------------------


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