Fair enough. Well, the grops code worked for me too <https://github.com/Alhadis/language-roff/commit/ec8e287cb35f7a91924e02e09af68202d8cddade>, actually.
Thanks to everybody again for their help. =) On 9 May 2017 at 21:23, Deri James <d...@chuzzlewit.myzen.co.uk> wrote: > On Tue 09 May 2017 13:55:38 John Gardner wrote: > > Looks like there's a mistake in groff_out(5). It describes its > arc-drawing > > command as: > > > > *Draw arc from current position to (h1, v1)+(h2, v2) with center at (h1, > > > > > v1);* > > > > However, gropdf.pl tells a different story. To quote line #2791: > > <http://git.savannah.gnu.org/cgit/groff.git/tree/src/ > devices/gropdf/gropdf.p > > l?id=453a8aa7c8f8dd0c78160466301f81be8c40df2e#n2791> > > > > *Documentation is wrong. Groff does not use Dh1,Dv1 as centre of the > > circle!* > > > > I noticed something odd when drawing an arc which wasn't an evenly-sized > > quarter-circle. For instance, the following Pic code: > > > > .PS > > > > > move down > > > A: box > > > arc at A.n > > > line right > > > .PE > > > > ... generates the following output: > > > … > > > > V84000 > > > > H99000 > > > > > Da 0 -36000 18000 54000 > > > > Which looks like this in gropdf and my own canvas code, respectively: > > > > In gropdf I adjust the circle centre using code I found in the geometry.cpp > library used by the grops driver, so that I could duplicate the output > produced by grops. > >