4.4 Polyphony

The easiest way to enter fragments with more than one voice on a staff is to split chords using the separator \\. You can use it for small, short-lived voices or for single chords:

     \context Staff \relative c'' {
       c4 << { f d e  } \\ { b c2 } >>
       c4 << g' \\ b, \\  f' \\ d >>
     }

The separator causes Voice (lilypond-internals) contexts¹ to be instantiated. They bear the names "1", "2", etc. In each of these contexts, vertical direction of slurs, stems, etc. is set appropriately.

This can also be done by instantiating Voice (lilypond-internals) contexts by hand, and using \voiceOne, up to \voiceFour to assign a stem directions and horizontal shift for each part:

     \relative c''
     \context Staff << \new Voice { \voiceOne cis2 b  }
       \new Voice { \voiceThree b4 ais ~ ais4 gis4 }
       \new Voice { \voiceTwo fis4~  fis4 f ~ f  } >>

Normally, note heads with a different number of dots are not merged, but when the object property merge-differently-dotted is set in the NoteCollision (lilypond-internals) object, they are merged:

     \relative c'' \context Voice << {
          g8 g8
          \property Staff.NoteCollision \override
             #'merge-differently-dotted = ##t
          g8 g8
       } \\ { g8.[ f16] g8.[ f16] }
       >>

Similarly, you can merge half note heads with eighth notes, by setting merge-differently-headed:

     \context Voice << {
         c8 c4.
         \property Staff.NoteCollision
           \override #'merge-differently-headed = ##t
         c8 c4. } \\ { c2 c2 } >>

LilyPond also vertically shifts rests that are opposite of a stem:

     \context Voice << c''4 \\  r4 >>

Predefined commands

\oneVoice, \voiceOne, \voiceTwo, \voiceThree, \voiceFour.

The following commands specify in what chords of the current voice should be shifted: the outer voice has \shiftOff, and the inner voices have \shiftOn, \shiftOnn, etc.

\shiftOn, \shiftOnn, \shiftOnnn, \shiftOff.

See also

The objects responsible for resolving collisions are NoteCollision (lilypond-internals) and RestCollision (lilypond-internals). See also example files input/regression/collision-dots.ly, input/regression/collision-head-chords.ly, input/regression/collision-heads.ly, input/regression/collision-mesh.ly, and input/regression/collisions.ly.

Bugs

Resolving collisions is a intricate subject, and only a few situations are handled. When LilyPond cannot cope, the force-hshift property of the NoteColumn (lilypond-internals) object and pitched rests can be used to override typesetting decisions.

When using merge-differently-headed with an upstem 8th or a shorter note, and a downstem half note, the 8th note gets the wrong offset.

This page is for LilyPond-2.0.3 (stable-branch). Report errors to <bug-lilypond@gnu.org>.