\version "2.23.9"

#(use-modules (ice-9 match)
   (srfi srfi-71))

#(define (cluster::dashed-fill grob)
   (let* ((columns (ly:grob-object grob 'columns))
          (column-list (ly:grob-array->list columns)))
     (if (not (pair? column-list)) ;; see issue #3654
         #f
         (let* ((x-refp (ly:grob-common-refpoint-of-array grob columns X))
                (y-refp (ly:grob-common-refpoint-of-array grob columns Y))
                (my-exts (map (lambda (c)
                                (ly:grob-extent c y-refp Y))
                           column-list))
                (my-coords (map (lambda (c)
                                  (ly:grob-relative-coordinate c x-refp X))
                             column-list))
                (after-me (find-tail (lambda (s)
                                       (eq? s grob))
                            (ly:spanner-broken-into
                             (ly:grob-original grob))))
                (neighbor (and after-me
                               (pair? (cdr after-me))
                               (cadr after-me)))
                (exts coords (if neighbor
                                 (let* ((neighbor-cols (ly:grob-object
                                                        neighbor 'columns))
                                        (neighbor-col-list
                                         (ly:grob-array->list neighbor-cols)))
                                   (if (not (null? neighbor-col-list))
                                       ;; issue #3654 as well
                                       (let* ((first-neighbor-col (car
                                                                   neighbor-col-list))
                                              (neighbor-refp
                                               (ly:grob-common-refpoint-of-array
                                                neighbor
                                                neighbor-cols
                                                Y))
                                              (bound (ly:spanner-bound
                                                      grob RIGHT)))
                                         (values
                                          (append my-exts
                                            (list (ly:grob-extent
                                                   first-neighbor-col neighbor-refp Y)))
                                          (append my-coords
                                            (list
                                             (ly:grob-relative-coordinate bound x-refp X)))))
                                       (values my-exts my-coords)))
                                 (values my-exts my-coords)))

                (details (ly:grob-property grob 'details))
                (increment (assq-ref details 'increment))
                (contour-thickness (assq-ref details 'contour-thickness))
                (polygon-points-1 (map cons coords (map car exts)))
                (polygon-points-2 (map cons coords (map cdr exts)))
                (polygon-stencil
                 (ly:round-polygon (append-reverse polygon-points-1
                                     polygon-points-2)
                   contour-thickness
                   1
                   #f)))
           (let loop ((exts exts)
                      (coords coords)
                      (current (car coords))
                      (stil empty-stencil))
             (if (null? (cdr coords))
                 (ly:stencil-translate
                  (ly:stencil-add stil polygon-stencil)
                  (cons (- (ly:grob-relative-coordinate grob x-refp X))
                    (- (ly:grob-relative-coordinate grob y-refp Y))))
                 (let* ((t (/ (- current (car coords))
                             (- (cadr coords)
                               (car coords))))
                        (1-t (- 1 t))
                        (ext1 (car exts))
                        (ext2 (cadr exts))
                        (lo (+ (* 1-t (car ext1))
                              (* t (car ext2))))
                        (hi (+ (* 1-t (cdr ext1))
                              (* t (cdr ext2))))
                        (part (ly:line-interface::line grob current lo
                                current hi))
                        (new-stil (ly:stencil-add stil part))
                        (next (+ current increment))
                        (stay (<= next (cadr coords))))
                   (loop (if stay exts (cdr exts))
                     (if stay coords (cdr coords))
                     next
                     new-stil))))))))

\layout {
  \context {
    \Voice
    %\override ClusterSpanner.stencil = #cluster::dashed-fill
    %\override ClusterSpanner.style = #'dashed-line
    \override ClusterSpanner.thickness = 1.5
    \override ClusterSpanner.dash-period = 0.8
    \override ClusterSpanner.details.increment = 0.5
    \override ClusterSpanner.details.contour-thickness = 0.2
  }
}

%%%

\paper {
  ragged-right = ##t
}
kbdRHMI = \relative c' {
  \new Voice \with {
    \override ClusterSpanner.stencil = #cluster::dashed-fill
    \override ClusterSpanner.style = #'dashed-line
  } {
    R1*3 | r2 r4.
    \makeClusters { <d f>8 | q1 | q8 <d d'> <d' f>2. | q1 | q1 | q2 }
    r2
    \barNumberCheck #10
    \makeClusters {
      <d, f>1 | q4. <d d'>8 <d' f>2 | q1 | q2 <d, f>2 |
      % \barNumberCheck #14 %1
      q2 <d d'>2 | q2 <d a'> | <d a' d>2 q8. <f d'>8. <d d'>8 | q1 | q1 | q2. <d f>4 |
    }
    %\barNumberCheck #20
    r1
    R1*46
    %\barNumberCheck #67 %5
    \makeClusters {
      <d g>1 | q1 | <d f>1 | <d d'>1 | <d' f>1 | q1 | q1 | q1 |
    }
    \barNumberCheck #75
    r1
    R1*10
    \barNumberCheck #86
  }
}

kbdLHMI = \relative c {
  \clef bass
  \new Voice \with {
    \override ClusterSpanner.stencil = #cluster::dashed-fill
    \override ClusterSpanner.style = #'dashed-line
  } {
    R1*13
    R1*14
    \makeClusters { <g b>1 q1 |q1 | <g g'>1 | q1 | q1 | <e' g>1 | q1 | q1 | q1 | }
    r1
    R1*7
    R1*16
    R1*5
    \makeClusters { <f g>1 | q1 | q1 | q1 | }
    r2 r4
    \makeClusters { <d,f> | q1 | q1 | q2. }
    r8
    \makeClusters { q8 | q8 <d a'>8 <d a' d>2. | q1 | <d a'>1 <d a' d>1 | q8 <d a'>2.. | q4 <d a' d>2. | q1 | q1 | <d f>4 }
    r r2 |
  }
  R1*2
  \barNumberCheck #86
}

\score {
  <<
    \new PianoStaff \with {
      \consists #Span_stem_engraver
      instrumentName = "Keyboard"
      shortInstrumentName = "Kbd"
    } <<
      \new Staff = "kbdrh" \kbdRHMI
      \new Staff = "kbdlh" \kbdLHMI
    >>
    %%% COMMENT ME OR THE OTHER ME TO MAKE THIS FILE COMPILE
    \new Staff = "voice" \relative c' { c4 d e f g a b c ~ | c1 }
  >>
  \layout {
    %%% COMMENT ME OR THE OTHER ME TO MAKE THIS FILE COMPILE
    #(layout-set-staff-size 16)
  }
}