Re: skylines and custom-code

[Thomas Morley]

Am Fr., 30. Apr. 2021 um 09:59 Uhr schrieb Jean Abou Samra <jean@abou-samra.fr>:
>
> Le 05/04/2021 à 12:00, Thomas Morley a écrit :
>
> > Hi Jean,
> >
> > thanks for your reply, though the situation is more complex than the
> > initial minimal. Consider the following:
> >
> > { b'4\glissando 4 4 4 2 b'' }
> >
> > The plan is to print a glissando from b' to b'' and at intermediate
> > NoteColumns print a Stem starting at the glissando line, i.e. the
> > result will be a stemmed Glissando.
> > (1) Obviously I need the intersection points of the y-axis of the
> > Stems and the Glissando.
> > I've coded an engraver to set the relevant pointers (from Stem to
> > Glissando) and use some calculations to get them. This work is done.
> > (2) Then I intend to move all NoteHeads of intermediate NoteColumns to
> > sit on the glissando line, making them transparent (or point-stencil
> > or omit the stencil)
> > This would have the advantage that LilyPond could do the rest, i.e.
> > print Stem, Beam, Script etc accordingly.
> >
> > Obviously the calculation of the intersection points needs to be done
> > after the Glissando is printed, thus a simple override for
> > NoteHead.Y-offset will not work, afaict.
> >  From description in the docs about unpure-pure-containers, this is a
> > similar situation as for Beams and needed Stem lengths.
> >
> > Alas, I never came to grips with unpure-pure-containers. Granted, the
> > explanations/descriptions in the docs improved over the years.
> > Though, we don't have working coding-examples in the docs, "working"
> > in the sense of "let me play with the code, testing what happens if I
> > do this and that":
> > The example in NR 5.5.6 works with and without unpure-pure-containers.
> > The example (sort of) in CG 10.13.3 makes no sense to me, at least I
> > found no situation where "bar" is called at all.
> > The regtest unpure-pure-container.ly is probably ok as a regtest, it
> > shows something is done, but why should a user do that at all. As a
> > user I'd say, don't move the flag if you don't want a moved flag...
> >
> > That's it for the docs or did I overlook something?
> >
> > Unpure-pure-containers in LSR: zero
> >
> > Valentin's example works without unpure-pure-container as well.
> >
> > Thus, I'm at a loss, close to abandoning the work.
> >
> > Nevertheless, many thanks,
> >    Harm
> >
> > P.S. attached an image what works so far (but don't enable skylines)
>
> One month later ...
>
> While researching mailing list archives for unrelated purposes, I
> stumbled upon this:
>
> https://lists.gnu.org/archive/html/lilypond-devel/2011-07/msg00001.html
>
> Cheers,
> Jean
>
>
Hi Jean,

I was aware of Mike's earlier attempt.
Trying to access the problem with scheme-only seemed to circumvent
some of Han-Wen's concerns.
Alas, it looks like we were facing the same problems...

Thanks,
  Harm