Eitan Tal wrote:
> 
> [some code]
> >
> > If you skip the difference (marked in blue) by /* and */ and remove
> > the // of the line above,
> > you get different results: the difference ignores the cutting of the
> > big cylinder. (marked in red above)
> > why? and how do I get over this problem?
> >
> >   Thanks in advance
> >   -Eitan Tal
> > Icq: 1515298
> 
> And if you change the bounded_by into clipped_by, the difference will
> not work at all -- it will make
> the object dissapear. that makes sense because clipped_by makes the
> object to be unreal, I mean
> if you try to fill it, it will take infinite screen. that might be a
> reason.

You seem to assume clipped_by{} and bounded_by{} do the same as CSG
intersection.  But they don't.  

bounded_by{} is for manual bounding and usually does not need to be used
at all.  

clipped_by{} is similar to intersection but it leaves the object open at
the cut areas.  After that the object maybe does no more work correctly in
CSG operations.

All this is explained in detail in the documentation IIRC.

> 
> Question 2: what's the difference between union {} and merge {} ?

union just puts together objects in a logical construct, merge merges the
objects and therefore removes inner surfaces.  

Also this is explained more detailed in the documentation.

BTW your code had errors, needed some modifications to run.

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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