Re: pov-ray: Interesect finite object with half space

In article <m6RycQHzxYcIFwdA@[EMAIL PROTECTED]
>,
 Mike Williams <nospam@[EMAIL PROTECTED]
> wrote:

> Wasn't it S M Ryan who wrote:
> >I want to intersect a finite object with the half space above or below 
> >a plane.
> >The only thing I can think of is a box that big enough so that only one
side
> >(representing the plane) intersect the object the the other faces are
outside
> >the object; but that requires figuring out a just large enough box. Are
there
> >simpler ways to do this?
> 
> Intersect it with the plane. One side of a plane is the "inside" and the

> other is the "outside" for the purpose of CSG.
> 
> Which side of the plane is the "inside" isn't intuitively obvious, and 
> whenever I try to work it out I always end up getting it wrong. However,

> since there are only two sides to choose from, you can try one and when 
> it turns out to be the wrong one you can inverse it.

Thanks. A quick check shows the direction the normal vector points to is
the 
outside half space.