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

[Han-Wen Nienhuys]

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:

**
Hello Hans,

I've had another look at X-staff chords. I've put the price at 400 euro. 
 It might be on the pricey side, but the stem is pretty central to the 
layout engine, and I expect that drastic changes will touch a lot of 
code, which would require a lot debugging and tweaking. It's also the 
reason why I don't want to do it for the 2.8 release.

FYI, the todo list is below:

CONCEPT

  - a Voice still is in a single Staff context

  - isolated noteheads may be tagged to be on another staff

  - in this case, stem directions are determined by the staff
  configuration: if voice is in bottom staff,  extra note heads in
  the top staff always make the stem direction go up.

  - Caveat: this doesn't handle the case where the beam is vertically
  centered between note heads in both staves.

  - Caveat: Since the x-staff note heads are not broadcast in a Voice
  context, they are not caught by Voice context engravers.  They won't
  participate in arpeggios, or have private fingering/articulation
  symbols.



IMPLEMENTATION


Create

  Stem::staff_head_positions - positions of heads in the stem's staff.

  Stem::all_head_positions - positions of all heads relative to stem's
  staff.

Revise all use of Stem::head_positions().

- stem.cc: direction calculations use staff_head_positions,
- stem.cc: length calculations use all_head_positions
- note-collision use staff_head_positions
- spacing uses staff_head_positions
- tie uses all_head_positions
- tuplet-bracket uses staff_head_positions

Revise the stem direction code to handle the x-staff case
especially.

Make Note_heads_engraver broadcast x-staff note heads in the right
Staff context. This puts the note heads in the right staff.

Add a music function to tag chord notes appropriately.
**

Steve D wrote:
> I know that cross-staff beaming has been mentioned periodically on the
> LilyPond lists.
>
> It would be great, for the sake of piano and other polyphonic instrument
> scores, for there to exist in LilyPond some mechanism that would allow
> for chords to change staff, perhaps like single-note melodies already
> can do (with \change Staff = staff-name), and which includes all of the
> tie functionality.
>
> For an example in piano music-- an arpeggiated chord played with both
> hands across both staves, tied to a following chord that crosses the
> staves. I recently wrote a piece in which there is a grace-note
> descending arpeggio played with both hands (sequentially, first the
> right then the left), that crosses from the treble to the bass staff,
> and is tied to every note but the lowest note of the following chord
> (see attached GIF graphic).
>
> To do so required some "inventive" LilyPond code, hidden notes, etc.,
> and in this case, the chord following the cross-staff grace-note
> arpeggio was not itself a cross-staff chord. However, it would be great,
> if it can be implemented, for the following to exist in LilyPond:
>
> * chords that cross staves (perhaps like <f c \change Staff = bass g d>)
>
> * cross-staff chords that can be tied to cross-staff chords (using
>    automatic and manual tie formatting)
>
> * cross-staff arpeggios that can be tied to cross-staff chords
>    (with auto and manual tie formatting)
>
> * grace-note arpeggios that can be tied to cross-staff chords
>    (with auto and manual tie formatting)
>
> I would be happy to sponsor such functionality.
>
> Best wishes,
>
> Steve
>
> Stephen Doonan
> Portales, New Mexico US
> http://www.xscd.com/pub/
>
>
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--

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

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