Re: Sponsored feature request--cross-staff chords, ties

[Han-Wen Nienhuys]

Trevor Bača wrote:
> On 8/22/06, Han-Wen Nienhuys <address@hidden> wrote:
> > Hello,
> >
> > I once made an estimate for doing x-staff chords, for 400 EUR.  I think
> > that would be the most difficult task. If the stems + noteheads work
> > correctly, adding arpeggios and ties should be relatively easy.
> >
> > For reference, I insert what I wrote to Hans Forbrich:

> Well I had always wondered why the pricing on cross-staff stuff was so
> high. I thought it might be because it breaks the Voice model, but I
> wasn't sure ...

no, there are 2 issues: how to deal with the Staff/Voice model, and how 
to keep the typesetting engine free of cyclic-dependencies. The latter 
problem needs to be solved first, then we can invent ways for the 
Staff/Voice model to control the typesetting engine.

> Well, if Steve or Vivian or Hans or somebody is willing to help out,
> then I'm willing to pitch in on the sponsoring too.
>
> I'm about to have cross-staff stuff all over some piano music and also
> between different *string* staves as well. So a question.
>
> QUESTION: will the proposed cross-staff implementation path enable
> cross-staff stemming and beaming between *nonadjacent* staves (eg, 1st
> violins and basses, passing over the 2nd violins, violas and cellos)?

This is fraught with cyclic dependencies. It might be possible, but you 
have to have some restrictions, eg.

 * the distances between these staves have been fixed in advance.

or

 * all x-staff beams are horizontal


or

 * stem directions have no influence over spacing.


In general:

  * spacing depends on stem directions,
  * line breaks depend on spacing
  * y-distance between staves depends on line breaks
  * beam configurations depend on y-distances
  * stem directions depend on beam configurations

hence, if we want x-staff stems, we must have restrictions: currently, 
the y-distance between staves is fixed, and this works pretty well for 
x-staff beams.  There might be other ways to break this cycle, but there 
might be other cycles as well.

--

Han-Wen Nienhuys - address@hidden - http://www.xs4all.nl/~hanwen

LilyPond Software Design
 -- Code for Music Notation
http://www.lilypond-design.com