Re: [Groff] Rules drawn with \D are rounded

[Werner LEMBERG]

> Equally, unfilled polygons drawn with
>
>     \D'p <co-ordinates>
>
> all have rounded corners, whereas filled polygons drawn with
>
>     \D'P <co-ordinates>'
>
> produces the expected "sharp" corners.
>
> Typographically speaking, this is not an expected, or--in my
> experience--justifiable default behaviour for rules and polygons.

Well, it is justifiable, but it isn't documented correctly.

> 1.  What is the rational behind groff's drawing rounded caps on
>     rules, and rounded corners on unfilled polygons?

An unfilled polygon uses strokes to connect the points; those strokes
obey the settings of PS functions `setlinecap' and `setlinejoin',
which are both activated.  On the other hand, a filled polygon simply
fills the area defined by straight lines which connect its corner
coordinates.  Since no lines are explicitly drawn, the setlinecap and
setlinejoin parameters aren't taken into account.

The right solution to get filled polygons with rounded corners is to
draw both a filled and an unfilled polygon.

> 2.  Can this behaviour be changed in user space?

What exactly do you want to change?  By default, the corners are
always rounded -- since this is a detail on the PS level I think it is
just fair to use PS stuff to change that (with \X or with .device).

> 3.  Could this behaviour be changed in the applicable groff binaries
>     themselves?

It is possible to replace the default PS prologue of grops with a
different one, but I think this is not worth the trouble.  Instead I
suggest to add some PS code to the initialization routines of mom.


    Werner