doubleSlurs-alike workaround

[Antanas Budriūnas]

Hello,

there is a tiny fragment from a polyphonic choir piece. By idea I need
\set doubleSlurs = ##t but seems it didn't allow slur placement
control.
So following documentation I wrote this way:

\new Staff = sa <<
  \new Voice = soprano \relative c'' { \voiceOne
    << { \once \override Slur
        #'control-points = #'((1.6 . 2.2) (2.5 . 2.7) (5.5 . 2.5) (6.3 . 1.5))
          <c e>4( <b d>8) } \\
        { \hideNotes \stemUp \slurUp \once \override Slur
        #'control-points = #'((1.6 . 1.2) (2.5 . 1.7) (5.5 . 1.5) (6.3 . 0.5))
        c4( b8) } >> \unHideNotes
        }
  \new Voice = alto \relative c'' { \voiceTwo
     a4. }
>>

Badly slur control points are set relative to starting note and
therefore lilypond-book output is unpredictable.

Desired output attached.

Suggestions, comments are highly appreciated.


Antanas

quasi-doubleslurs.png
Description: PNG image