Alain <aze### [at] qwertyorg> wrote:

> > Hi
> > Can anybody tell me why I get a bright rim when I clip this CSG difference ?
> > Thanks for your help !
> >
> > object { difference { sphere { 0, 15.01  }
> >                        sphere { 0, 15.0 }
> >                      }
> >           clipped_by { cone { 0, 0.0,<0,50,0>, 50*tand(45) } }
> >           pigment { rgbt 1 }
> >           hollow
> >           interior { media { emission 0.3*White } }
> >        }
> >
> >
>
> This object is used as a container for your media.
> This object is NOT fully closed: clipped leaves the clipped part open.
> You hit the first surface, you are now considered inside the object. The
> next surface encountered is the iner surface of the oposite side. The
> third surface is the outer surface. There is NO fourth surface, leading
> to an "infinite" path through your media.
>
> Solution: DO NOT use clipped_by.
>
> Change your object as follow:
> object { difference { sphere { 0, 15.01  }
>                        sphere { 0, 15.0 }// Makes your shell
>                     // }
>           //clipped_by { cone { 0, 0.0, <0,50,0>, 50*tand(45) } }
>           cone { 0, 0.0, <0,50,0>, 50*tand(45) inverse}
> // removes the part outside the cone and properly close the edge of the
> shell.
>           }
>           pigment { rgbt 1 }
>           hollow
>           interior { media { emission 0.3*White } }
>        }
>
>
>
> Alain

Sorry for asking such a stupid question ! Your reply is perfect,
and the explanation on the virtual infinite path perfectly clear.

And, as usual : "you never read deeply enough the manual" !
Thanks a lot !

And, by the way : is there some reason for the clipped objects beeing left open
by default in PovRay ?

Gilles

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