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From: Lark
Subject: hollow intersections and differences! AARGH!
Date: 29 Jan 1999 20:59:54
Message: <36b2679a.0@news.povray.org>
I'm trying to make a semicircular lense with a CSG made out of a cylinder
and a cube.  The cube kind of cuts half of the cylinder off.  Anyway, when I
do this, the half-cylinder that remains is hollow, like a wierd taco shell!
I've checked, and nothing is hollow(I'm using moray 3.01).  A lense doesn't
work too well with no insides.  Can anyone help?  Thanks!


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From: Bob Hughes
Subject: Re: hollow intersections and differences! AARGH!
Date: 30 Jan 1999 07:51:12
Message: <36B30034.4E422C42@aol.com>
You must be clipping it instead of differencing. I don't use Moray but
obviously this is waht happened. 'hollow' doesn't matter in CSG, it's
for fog, media, atmosphere, halo to see or not.
Posting at news.povray.org/moray.win might be better for answers.

Lark wrote:
> 
> I'm trying to make a semicircular lense with a CSG made out of a cylinder
> and a cube.  The cube kind of cuts half of the cylinder off.  Anyway, when I
> do this, the half-cylinder that remains is hollow, like a wierd taco shell!
> I've checked, and nothing is hollow(I'm using moray 3.01).  A lense doesn't
> work too well with no insides.  Can anyone help?  Thanks!

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/POVring.htm
=Bob


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From: Ken
Subject: Re: hollow intersections and differences! AARGH!
Date: 30 Jan 1999 08:15:42
Message: <36B305DF.AE9EA63B@pacbell.net>
Lark wrote:
> 
> I'm trying to make a semicircular lense with a CSG made out of a cylinder
> and a cube.  The cube kind of cuts half of the cylinder off.  Anyway, when I
> do this, the half-cylinder that remains is hollow, like a wierd taco shell!
> I've checked, and nothing is hollow(I'm using moray 3.01).  A lense doesn't
> work too well with no insides.  Can anyone help?  Thanks!

A quick introduction to working CSG operations. Render this
example code. It demonstrates lens properties, material
properties, and just a few of the possible methods of using
CSG operations to create lens shaped objects.

If you need further assistance feel free to ask.

// Using an intersection with a plane to slice off half the cylinder

  #declare Lens1 =
  intersection{
   cylinder{x*-3,x*3,1
    pigment{rgbf<1,.7,.7,1>}
     interior{ior 1.95}
  }

  plane{-z,-0
   pigment{rgbf<1,.7,.7,1>}
    interior{ior 1.95}
  }
 }

 // Using a difference to create a concave cylindrical lense

  #declare Lens2 =
  difference{
   cylinder{x*-3,x*3,1
    pigment{rgbf<.7,.7,1,1>}
   interior{ior 1.95}
  }

  cylinder{x*-3.1,x*3.1,1
   translate<0,0,-.25>
    pigment{rgbf<.7,.7,1,1>}
   interior{ior 1.95}
  }
 }


  // Using an intersection to create a convex lense from 2 spheres

  #declare Lens3 =
   intersection{
    sphere{<0,0, .75>,1.5
     pigment{rgbf 1}
      interior{ior 1.95}
    }

    sphere{<0,0,-.75>,1.5
     pigment{rgbf 1}
      interior{ior 1.95}
    }
   }
 
  object{Lens1 rotate 90*-y translate< 2, 2,0>}
  object{Lens2 rotate 90*y  translate<-2, 2,0>}
  object{Lens3 rotate 90*y  translate< 2,-4,0>}
  object{Lens1 translate< 3,-1,0>}
  object{Lens2 translate<-3,-1,0>}
  object{Lens3 translate<-2,-4,0>}

  plane{-z,-15 pigment{checker color rgb 1 color rgb 0 scale 5}}

  light_source{<0,190,-300>rgb 1}
  light_source{<0, 15,-575>rgb 1}

  camera{location<0,0,-12>look_at  0}

-- 
Ken Tyler

tyl### [at] pacbellnet


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