Re: Setting up classical guitar fingerings

[Luca Fascione]

Hi Valentin, thank you this is super interesting. There's a lot of information in there I want to read more carefully,

but for the moment I have one question: when is after-line-breaking invoke? 

Or actually, better question: where do I go to discover when (and I guess by what) after-line-breaking is invoked?

Another thing at the moment I don't follow is the 'engraver' variable in the scheme engraver you wrote:

where does that come from? (I suspect it's some kind of name available where the engraver is invoked, but again: how would I go at discovering this?)

Many thanks, this is very helpful

Luca

On Sun, Feb 20, 2022 at 11:07 PM Valentin Petzel <valentin@petzel.at> wrote:

Hello,

our problem here is that such things like the positioning of beams are not
known for quite some time. But we could use something like after-line-breaking
to adjust the results. Somewhat like here.

Valentin

Am Sonntag, 20. Februar 2022, 21:17:31 CET schrieb Luca Fascione:
> So... would anybody be able to lend a hand here please?
>
> Many thanks
> Luca
>
> On Sat, Feb 12, 2022 at 7:49 PM Luca Fascione <l.fascione@gmail.com> wrote:
> > Hello,
> > sorry for the double-post, I'm unsure whether this should go to -user or
> > -devel.
> >
> > I'm looking for some guidance to set up fingering on classical guitar
> > sheets.
> >
> > I am attaching a simple piece of music, with two engraving sets (measures
> > 1-5 and 6-10), one "as-is" from lilypond, the other using some trickery
> > involving one-note chords, purely to show a sample of what the result I'm
> > after (and it's an approximation), vs what I get at the moment.
> >
> > Measures 1-5 in the source look like what I am intending to type, but it
> > has a number of engraving defects I don't understand (you can see the
> > beams
> > don't  avoid the fingerings, nor they are located correctly wrt the
> > accidentals, the second beat of measure 5 illustrates this well. I'm not
> > super in love with measure 10 either, but if I understand the docs
> > correctly, the issue there is that the 'offset' correction is applied
> > post-layout, and so naturally it won't back-affect the placement of the
> > beams.
> >
> > I have made several other experiments, I'm just not wanting to waste
> > people's time. But setting Fingering.side-axis = #X seems somewhat
> > promising, but it seems unable to find any usable Y data about the
> > parents,
> > and smashes all numbers on the B line, as well as not dealing with
> > accidentals.
> >
> > I have an engraving project in front of me, for which I'm more than happy
> > to put in the time to contribute the code to a proper solution myself, and
> > I really don't want to make poor use of time from folks busy with other
> > work, but I feel I'll need some level of guidance as to what to do. For
> > context I can do C++ and I can manage guile ok (I'm a software engineer
> > for
> > work, I'm mostly working in the field of computer graphics).
> >
> > I was looking into this problem several years ago also, and Han-Wen
> > Nienhuys at the time suggested I should use a positioning callback
> > attached
> > to the Fingering grobs, but I couldn't find a way to do such a thing (in
> > particular I can't find what property to use for this). So far I've traced
> > the Fingering system to be an instance of the Articulations/Scripts
> > system,
> > but that's as far as I got.
> >
> > It seems to me what's needed would be to decide where the heads go, then
> > the accidentals, at this stage deal with the fingering and only then there
> > would be enough bboxes to reason about the beaming (this is the skyline
> > concept I think). In reasoning about how Articulations are engraved, it's
> > possible the order of events for fingering would be different from the
> > order of events in other articulations (which I think are laid out after
> > beams are in place, if I am not mistaken), warranting a bigger change, but
> > I have no idea where that is located/managed.
> >
> > Many thanks for your time,
> > Luca