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.
--
Mike Williams
Gentleman of Leisure
