scottishrob41 <sco### [at] gmailcom> wrote:
> Howdy Pov-Rayers. I was curious about something I discovered while trying to
> create a difference with a cylinder and a hollow box. When I try to use the
> cylinder to open a hole in one side of the box, I notice the cylinder is still
> visible as if I had just merged them together. I figured out playing around
> with it, that the only way to get the cylinder to dissappear and leave the
> difference hole in the box is to assign a 'Clear' pigment to the cylinder. Has
> anyone else noticed this?

  No, nobody has ever noticed this before. Thanks for the report.

  Sarcasm aside, you have to think about primitives as if they were solid
objects. That's what "constructive solid geometry" means: Surfaces are treated
as if they enclosed solid objects.
  The 'difference' between a box and a cylinder means that you are removing
the cylinder from the box: This leaves a hole with the shape of the cylinder
in the box, of course. It's like you were carving the box with the cylinder.

  The keyword 'hollow' has absolutely nothing to do with this.

  And the proper way to *cut* a hole on the surface of the box with the
cylinder is to use 'clipped_by'.

-- 
                                                          - Warp

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