Ian Burgmyer wrote:
> 
> What's the difference between merge and union?  I noticed that one (I think
> it was merge) took quite a bit longer then the other.
> 
> Thanks!
> -Ian

  There is a major difference between the two. The union is really not
a true CSG operation and could be more accurately described as a group
container. This makes it possible to combine several elements into one
item that can then be translated, rotated, and scaled as if they were
just on object.

  A merge operation on the otherhand is a true CSG operation and has
specific uses. The main feature of a merge operation is that it will
remove the interior surfaces of over lapping objects. This is useful
it you don't want a "cell" effect when over lapping several objects
since the merge operation removes all internal faces. You will in most
cases use this operation only when using clear objects but the are some
special cases where you can use it with solid colored objects as well.
I would have to dig deep to give you an example of the last but would
gladly do so if you are interested.

-- 
Ken Tyler

See my 1000+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html

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