Making slurs with complex dash structure

Slurs can be made with complex dash patterns by defining the dash-definition property. dash-definition is a list of dash-elements. A dash-element is a list of parameters defining the dash behavior for a segment of the slur.

The slur is defined in terms of the bezier parameter t which ranges from 0 at the left end of the slur to 1 at the right end of the slur. dash-element is a list (start-t stop-t dash-fraction dash-period). The region of the slur from start-t to stop-t will have a fraction dash-fraction of each dash-period black. dash-period is defined in terms of staff spaces. dash-fraction is set to 1 for a solid slur.

\version "2.24"

\relative c' {
  \once \override
    Slur.dash-definition = #'((0 0.3 0.1 0.75)
                                (0.3 0.6 1 1)
                                (0.65 1.0 0.4 0.75))
  c4( d e f)
  \once \override
    Slur.dash-definition = #'((0 0.25 1 1)
                                (0.3 0.7 0.4 0.75)
                                (0.75 1.0 1 1))
  c4( d e f)
}