POV-Ray : Newsgroups : povray.beta-test : wrong sphere-sweep bounding example Server Time
1 Nov 2024 15:28:05 EDT (-0400)
  wrong sphere-sweep bounding example (Message 1 to 4 of 4)  
From:
Subject: wrong sphere-sweep bounding example
Date: 24 Apr 2002 06:09:04
Message: <2g0dcu8kasg84pqde8hdq9d60nkoa1cvka@4ax.com>
POV 3.5 RC2 icl on WinNT Sp 6 PII 233 with 128 MB

I have made concrete example of my suspicions. Thorsten, now you can turn out
any part for testing. Artifacts are probably becouse of epsilon problem but
disappearing regular part can't be artifacts.

#macro Make(R,T)
  sphere_sweep{
    cubic_spline 4
    <.000,.375,1.275>+T R
    <.355,.280,1.275>+T R
    <.200,.190,1.275>+T R
    <.045,.100,1.275>+T R
  }
  sphere_sweep{
    cubic_spline 4
    <.129544, 0.062436,1.382759>+T R
    <.389922,-0.189898,1.442598>+T R
    <.226876,-0.191609,1.368181>+T R
    <.063829,-0.193320,1.293764>+T R
  }
  sphere_sweep{
    cubic_spline 4
    <.500,.375,1.275>+T R
    <.145,.280,1.275>+T R
    <.300,.190,1.275>+T R
    <.455,.100,1.275>+T R
  }
  sphere_sweep{
    cubic_spline 4
    <.546506,-0.179102,1.516184>+T R
    <.214798,-0.088453,1.386560>+T R
    <.310268,-0.239917,1.394866>+T R
    <.405738,-0.391381,1.403172>+T R
  }
#end

background{1}
camera{orthographic}
Make(.02,x/6)
Make(.009,-x/4)
Make(.002,-2*x/3)

ABX


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From: ABX
Subject: Re: wrong sphere-sweep bounding example
Date: 27 Feb 2004 11:16:29
Message: <i9ru30dt2jssegeldmnogac4lh5msq2bpa@4ax.com>
Below is still valid for 3.6 beta

On Wed, 24 Apr 2002 12:08:22 +0200, Włodzimierz ABX Skiba <abx### [at] babilonorg>
wrote:
>POV 3.5 RC2 icl on WinNT Sp 6 PII 233 with 128 MB
>
>I have made concrete example of my suspicions. Thorsten, now you can turn out
>any part for testing. Artifacts are probably becouse of epsilon problem but
>disappearing regular part can't be artifacts.
>
>#macro Make(R,T)
>  sphere_sweep{
>    cubic_spline 4
>    <.000,.375,1.275>+T R
>    <.355,.280,1.275>+T R
>    <.200,.190,1.275>+T R
>    <.045,.100,1.275>+T R
>  }
>  sphere_sweep{
>    cubic_spline 4
>    <.129544, 0.062436,1.382759>+T R
>    <.389922,-0.189898,1.442598>+T R
>    <.226876,-0.191609,1.368181>+T R
>    <.063829,-0.193320,1.293764>+T R
>  }
>  sphere_sweep{
>    cubic_spline 4
>    <.500,.375,1.275>+T R
>    <.145,.280,1.275>+T R
>    <.300,.190,1.275>+T R
>    <.455,.100,1.275>+T R
>  }
>  sphere_sweep{
>    cubic_spline 4
>    <.546506,-0.179102,1.516184>+T R
>    <.214798,-0.088453,1.386560>+T R
>    <.310268,-0.239917,1.394866>+T R
>    <.405738,-0.391381,1.403172>+T R
>  }
>#end
>
>background{1}
>camera{orthographic}
>Make(.02,x/6)
>Make(.009,-x/4)
>Make(.002,-2*x/3)
>
>ABX


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From: Thorsten Froehlich
Subject: Re: wrong sphere-sweep bounding example
Date: 27 Feb 2004 12:58:28
Message: <403f8544$1@news.povray.org>
In article <i9ru30dt2jssegeldmnogac4lh5msq2bpa@4ax.com> , ABX 
<abx### [at] abxartpl>  wrote:

> Below is still valid for 3.6 beta

We all know!  Nobody ever wanted to fix it also I asked multiple times if
anybody would be willing to do so in public; and I even explained what is
wrong (in short: the bounds-finding is nonsensical).  Obviously there isn't
enough interest for it getting fixed by anybody who is able (or has enough
time, it is some heavy math one has to get right before implementing the
correct bounds-finding) to fix it :-(

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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From: ABX
Subject: Re: wrong sphere-sweep bounding example
Date: 27 Feb 2004 13:06:21
Message: <8m1v30dhhk8j5eaj0l5r62a4jms5imrstb@4ax.com>
On Fri, 27 Feb 2004 18:58:27 +0100, "Thorsten Froehlich" <tho### [at] trfde>
wrote:
> > Below is still valid for 3.6 beta
>
> We all know!

I remembered a few patches to sphere sweeps were applied so I tried if there
could be some side effect since I couldn't do anything more currently :-(

ABX


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