[metapost] reverse clip operation

Andreas Matthias andreas.matthias at tuwien.ac.at
Tue Sep 19 12:37:48 CEST 2006

lfinsto1 at gwdg.de wrote:

>> Is it possible to reverse the clip operation? I.e. clip
>> everything that's /inside/ a clipping path and leave
>> the outside as is.
> Unless I'm misunderstanding you, it seems to me that unfilling the path
> would do the trick.

Yes, that's possible. But then everything within the clipping
path gets deleted (or actually filled with the background color),
which I would like to avoid.

I have several small pictures which I would like to connect with
lines (actually thick lines, which need to be clipped correctly).
While drawing these pictures I calculated special point, which
will be the start and end points of the connection lines. Therefor
the connection lines must be drawn /after/ the small pictures.
But if I do the clipping of the connection lines with unfill
I have to redraw the small pictures later.

Redrawing everything looks a bit clumsy but might be acceptable
if you are the only one using these macros. But it might by
incomprehensible for other users using your macros.

I would prefer a reverse clipping operation. Would it be possible
to write a macro, which does a reverse clipping?


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