If I am making a CSG object by using intersections of a bunch of planes
through say a box, my final CSG object will be hollow.  Is there an easy way
to make my CSG object solid using this method, or an easier method perhaps
than cutting with boxes using a difference?



Mike Metheny
lon### [at] vtedu
http://loneshepherd.ml.org/

"When one's words are no better than silence, one should keep silent."

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On Thu, 14 Jan 1999 09:56:00 -0500, Mike Metheny <lon### [at] vtedu> wrote:
>If I am making a CSG object by using intersections of a bunch of planes
>through say a box, my final CSG object will be hollow.  Is there an easy way
>to make my CSG object solid using this method, or an easier method perhaps
>than cutting with boxes using a difference?

First, what do you mean by hollow?  

If you mean "you'll be able to see the inside from the outside", then this 
is not true if you intersect or difference with a plane, only if you clip 
with a plane.  You might get this if you have "coincident surfaces", which
have been known to mess up the logic used by intersection.  If this is the
case, move the planes a miniscule amount in either direction and the 
problem will go away.

If you mean "You can't use it in CSG", as with a mesh, that's not true
either.  Planes are solid objects, with the inside defined as "everything
on the side of the plane opposite the direction of the normal vector"

If you mean "You can use media in it", the statement isn't true unless
you explicitly say "hollow".  So you probably didn't mean that.

If you mean "When I put my camera in it, I see the inside walls", that's
true of every object in POV.

If you explain what you're seeing, with perhaps a short snippet of sample 
code, maybe we can more effectively help you solve your problem.

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There's no difference between a regular box and one made by intersecting
six planes.
  Except that the latter will render a lot slower.

-- 
main(i){char*_="BdsyFBThhHFBThhHFRz]NFTITQF|DJIFHQhhF";while(i=
*_++)for(;i>1;printf("%s",i-70?i&1?"[]":" ":(i=0,"\n")),i/=2);} /*- Warp. -*/

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Hm, I might be adding a bit here...
I made a #macro for this some time ago...
get it at http://www.bahnhof.se/~spider/
at least, if yoyu have a javascript capable browser...
Sorry, I'm doing a rewrite on the site to get rid of the JS and add some more
frameset's... (Lot o' files)

//Spider

Mike Metheny wrote:
> 
> If I am making a CSG object by using intersections of a bunch of planes
> through say a box, my final CSG object will be hollow.  Is there an easy way
> to make my CSG object solid using this method, or an easier method perhaps
> than cutting with boxes using a difference?
> 
> Mike Metheny
> lon### [at] vtedu
> http://loneshepherd.ml.org/
> 
> "When one's words are no better than silence, one should keep silent."

Post a reply to this message