POV-Ray : Newsgroups : povray.newusers : CSG Intersection and Planes Server Time
5 Sep 2024 04:17:26 EDT (-0400)
  CSG Intersection and Planes (Message 1 to 4 of 4)  
From: Dawn McKnight
Subject: CSG Intersection and Planes
Date: 25 Feb 2002 13:13:34
Message: <3C7A7EF1.3020907@mac.com>
I'm hoping someone can clear up some confusion I'm feeling.

In the CSG Intersection documentation for POV 3.1, it says that 
intersection leaves just those portions of the two object which exist 
within both objects.

A plane is an infinately thin object which extends infinatly in two 
directions.

Therefore, it would seem to me that, if you intersected two planes, you 
would get a line; if you intersected three planes... provided they 
intersected at all... you would get a point.

But if I do:


   intersection
      {
      plane { -y, -0.555 }

      plane
         {
         x, 0
         rotate -4.3012223*z
         translate <.59831012, .555, 0>
         }

      plane
         {
         -x, 0
         rotate 4.3012223*z
         translate <-.59831012, .555, 0>
         }
      }

   scale <1, .5, 1>
   }

I get a strange, flat-bottomed V shape.

Why?


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From: Christoph Hormann
Subject: Re: CSG Intersection and Planes
Date: 25 Feb 2002 13:26:56
Message: <3C7A81F0.ED4E4E7B@gmx.de>
Dawn McKnight wrote:
> 
> [...]
> 
> A plane is an infinately thin object which extends infinatly in two
> directions.
> 
> Therefore, it would seem to me that, if you intersected two planes, you
> would get a line; if you intersected three planes... provided they
> intersected at all... you would get a point.

Then maybe read the chapter on the plane object again, esp. the fourth
paragraph.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 21 Feb. 2002 _____./\/^>_*_<^\/\.______


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From: Christopher James Huff
Subject: Re: CSG Intersection and Planes
Date: 25 Feb 2002 13:48:37
Message: <chrishuff-0B2533.13483025022002@netplex.aussie.org>
In article <3C7### [at] maccom>,
 Dawn McKnight <blu### [at] maccom> wrote:

> A plane is an infinately thin object which extends infinatly in two 
> directions.

Planes are infinitely thick. Anything on one side of a plane is "inside".
An intersection of two planes is an infinite "wedge".

-- 
Christopher James Huff <chr### [at] maccom>
POV-Ray TAG e-mail: chr### [at] tagpovrayorg
TAG web site: http://tag.povray.org/


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From: Apache
Subject: Re: CSG Intersection and Planes
Date: 26 Feb 2002 20:42:25
Message: <3c7c3981@news.povray.org>
If planes would be infinitely thin, why using CSG on them in povray then?
Any lines or points would be too thin to be visible in the (rastered)
output.


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