Please help me,

Declared:
        A = Solid  (Cone, box, cylinder)
        B = Polyhedron (Prism or generic surface realized with union of
polygons)


I want to make

difference:
                1)      A - A    (OK)
                2)      A - B   no results
                3)      B - A   no surface of difference
                4)      B - B   no results

                What is the solution for the cases 2,3,4 ?

Excuse my english,

                Thanks

                Tst### [at] capoleucait

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tommaso wrote:
> 
> Please help me,
> 
> Declared:
>         A = Solid  (Cone, box, cylinder)
>         B = Polyhedron (Prism or generic surface realized with union of
> polygons)
> 
> I want to make
> 
> difference:
>                 1)      A - A    (OK)
>                 2)      A - B   no results
>                 3)      B - A   no surface of difference
>                 4)      B - B   no results
> 
>                 What is the solution for the cases 2,3,4 ?
> 
> Excuse my english,
> 
>                 Thanks
> 
>                 Tst### [at] capoleucait

  Polygons, bicubic patches, meshes, triangles and a two other types
of pov objects are considered infinitely thin objects. They have no
well defined inside and outside. Because of this they are not allowed
to be used in a CSG operation except for the union CSG operation.

-- 
Ken Tyler

mailto://tylereng@pacbell.net

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Ken wrote:
> 
> tommaso wrote:
> >
> > Please help me,
> >
> > Declared:
> >         A = Solid  (Cone, box, cylinder)
> >         B = Polyhedron (Prism or generic surface realized with union of
> > polygons)
> >
> > I want to make
> >
> > difference:
> >                 1)      A - A    (OK)
> >                 2)      A - B   no results
> >                 3)      B - A   no surface of difference
> >                 4)      B - B   no results
> >
> >                 What is the solution for the cases 2,3,4 ?
> >
> > Excuse my english,
> >
> >                 Thanks
> >
> >                 Tst### [at] capoleucait
> 
>   Polygons, bicubic patches, meshes, triangles and a two other types
> of pov objects are considered infinitely thin objects. They have no
> well defined inside and outside. Because of this they are not allowed
> to be used in a CSG operation except for the union CSG operation.

All is not lost.  It is possible (though tedious) to construct a
polyhedron as the intersection of planes such that one could perform CSG
operations with it.

-- 
Mark Gordon
mtg### [at] mailbagcom
http://www.mailbag.com/users/mtgordon/index.html

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GCS/S d-- s-: a- C++$ UA+$ UH+$ UO+$ US+$ UL++++ P+++ L++(+++) E W++ N+
o-- 
K++ w---$ O- M$ V--$ PS++ PE- Y+ PGP->+ t+ 5++ X R+ tv-- b++ DI++$ D+ G 
e++>++++ h- r*%-- y-
------END GEEK CODE BLOCK------

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Mark Gordon <mtg### [at] mailbagcom> wrote:
: All is not lost.  It is possible (though tedious) to construct a
: polyhedron as the intersection of planes such that one could perform CSG
: operations with it.

  And if you do this remember to bound the resulting object manually.
Povray will not do this automatically (because planes are infinite shapes).

: -----BEGIN GEEK CODE BLOCK-----
: Version: 3.12
: GCS/S d-- s-: a- C++$ UA+$ UH+$ UO+$ US+$ UL++++ P+++ L++(+++) E W++ N+
: o-- 
: K++ w---$ O- M$ V--$ PS++ PE- Y+ PGP->+ t+ 5++ X R+ tv-- b++ DI++$ D+ G 
: e++>++++ h- r*%-- y-
: ------END GEEK CODE BLOCK------

  I have seen geek code in many signatures, but I have never seen an
explanation or syntax for it. Can you explain it or give some URL?

-- 
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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