Re: My own Figured Bass number set, where do I start?

[Nils]

On Mon, 20 Feb 2012 20:26:36 +0100
Reinhold Kainhofer <address@hidden> wrote:

> On 20/02/2012 14:44, Reinhold Kainhofer wrote:
> > On 20/02/2012 14:18, Nils wrote:
> >> my pusblisher wants baroque figured bass gylphs. They have the strokes in 
> >> different places than the Lilypond versions.
> >> I guess nobobdy did this so far, so I have to do it myself. 
> > Yes, we have a feature request
> > (http://code.google.com/p/lilypond/issues/detail?id=2042 ), but no one
> > has done any work on it.
> >
> >> Where is the point in the code where I have to start? I want to do it 
> >> right and use the same lilypond syntax like 4\+ or 6\\.
> > I suppose that the proper way would be to create new glyphs in our fonts
> > (using metafont, source file mf/feta-numbers.mf) and then adjust the
> > format-bass-figure function (in scm/translation-functions.scm) to use
> > those glyphs for the slashed figures.
> 
> Despite my lack of metafont knowledge, I have started tweaking some of
> the glyphs:
> http://codereview.appspot.com/5683051
> 
> That patch simply takes the digits 2, 4 and 5 of the feta font,
> stretches the one line that will be slashed, and adds a vertical box as
> a slash through it. These glyphs are not yet used by the figured bass
> formatting functions, but you can already use them via the musicglyph
> markup function. Attached is a simple test file showing the glyphs.
> 
> 
> Some issues:
> -) I have no idea how to properly implement the 6+ (the upper arc should
> have much less curvature and the slash is drawn through it. I would like
> the flare to have less turning angle, but with beta != +-90 it is no
> circle any more).
> -) Currently I place the slashes at more or less hardcoded positions and
> they are straight vertical. In particular for the 2 it might make sense
> to calculate the real intersection of the slash with the lower wavy
> line, so the slash is vertically centered. It might also be slanted to
> be perpendicular to the line it slashes through. Similarly, I'm not sure
> if the 5 should get a slightly slanted slash...
> -) I have no idea whether I should adjust the height of the boxes to
> include the slash.
> -) etc.
> 
> It would be great if someone with more metafont knowledge could improve
> those issues.
> 
> Cheers,
> Reinhold


Very good! For me the next step would to get these automatically for lilypond 
syntax 2\+  and after that worry about the 6, 7 and 9. Detailed tweaks like 
microplacement and shape of the slashes are in the end the most important for 
the viewer, though. I agree on that.
Maybe one of the readers who are better lilypond-educated than me could answer 
this?

Nils