Re[2]: arrowheads too long in PostScript terminal

[Hans-Bernhard B. <br...@ph...>]

On Fri, 31 Oct 2003, Alan G Isaac wrote:

> I found two widespread conventions:
> i. The arrowhead ink ends right at the point the arrow is
> drawn to.  This is the convention that I have been pushing
> for.
> ii. The arrowhead ink ends right at the edge of a filled
> circle, the center of which is the point that the arrow
> is drawn "to".  I find this odd conceptually, but I confess
> it does produce some nice looking graphics.

These two conventions aren't necessarily all that different as they
appear.  Think of the first as a special case of the second, with the
curve radius of the tip reduced to zero --- or more precisely to some
value too small to be visible as a round tip, so it appears sharp.
Obviously, this also requires to interpret the tip radius as a feature
independent of the arrow linewidth.

Summing it up, the core problem all around is that arrows shouldn't ever
have been drawn using wide lines in the first place.

> However due to case (ii) above---a case that Ethan first
> drew my attention to---it seems it would also be useful to
> introduce a new option for set arrow: "point", which would
> work like similarly to how it does for label.

Or, more generally, consider a global terminal-wide option like the
postscript one for mitered vs. rounded joins of polyline, and work from
there onward.  Note that quite a collection of terminal drivers don't
even offer a choice like that.  IOW: we're looking at a pile of work
here.

> "offset" (interpreted as a shortening of the arrowlength)
> which would be specified in pointsize units.

That offset would be to specific.
>  (I guess one
> might be wanted at each end, in which case there could also
> be an option "points" that accepts two numbers an offset,
> one for each end.)
>
> fwiw,
> Alan
>
>
>
>
>
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-- 
Hans-Bernhard Broeker (br...@ph...)
Even if all the snow were burnt, ashes would remain.