Re: [Groff] Arrow between ellipses - How to chop (remove overlap) ?

[Frank G. Hahn]

----- Original Message -----
From: "Ralph Corderoy" <address@hidden>
To: "Frank G. Hahn" <address@hidden>
Cc: <address@hidden>
Sent: Sunday, October 01, 2000 11:12 PM
Subject: Re: [Groff] Arrow between ellipses - How to chop (remove overlap) ?


>
> Hi,
>
> > > Try
> > >
> > >     arrow from E1 to E2 chop 0.3
> >
> > This would have been nice .. but I need something more generic than
> > that.  I got a program reading a hugin (Bayesian Network) file and
> > generating the output in PIC-format.  Which results in "many"
> > ellipses scattered about on a page. Some of these are connected
> > (using arrows).  How do I get pic to chop the arrow correctly in BOTH
> > ends.
> >
> > I can't chop them using a constant, because I don't really know how
> > the ellipses will be placed relative to one another.
>
> If you're leaving the placement of the nodes up to pic then pic knows.
>
> > > and see also the definition of chop around page 10 of Kernighan's
> > > _PIC -- A Graphics Language for Typesetting_ mentioned at the end
> > > of groff's pic man page.
> > > <URL:http://cm.bell-labs.com/cm/cs/cstr/116.ps.gz>
>
> Did you read this fine document?  It explains that pic's trig functions
> should be used.  Will that work in your case?
>

I'm not sure. Currently I'm reading up on Ellipse-Line-intersection.

I got:
Ellipse 1:  center(x0, y0), size(width, height)
Ellipse 2:  center(x1, y1), size(width, height);
Line: (x0, y0) through (x1, y1).

If I can decide/calculate the closest intersection-points I can use
arrow from (ix0, iy0) to (ix1, iy1)

but this does not seem to be quite as easy to find the correct formula for
as I thought..

Thanks for the doc-link.

/Frank


> Ralph.