\version "2.18.0"

#(define-markup-command (arrow-at-angle layout props angle-deg length fill)
  (number? number? boolean?)
  (let* (
      (PI-OVER-180 (/ (atan 1 1) 34))
      (degrees->radians (lambda (degrees) (* degrees PI-OVER-180)))
      (angle-rad (degrees->radians angle-deg))
      (target-x (* length (cos angle-rad)))
      (target-y (* length (sin angle-rad))))
    (interpret-markup layout props
      (markup
      #:translate (cons (/ target-x 2) (/ target-y 2))
      #:rotate angle-deg
      #:translate (cons (/ length -2) 0)
      #:concat (#:draw-line (cons length 0)
      #:arrow-head X RIGHT fill)))))

splitStaffBarLine = {
  \once \override Staff.BarLine.stencil =
  #(lambda (grob)
    (ly:stencil-combine-at-edge
    (ly:bar-line::print grob)
    X RIGHT
    (grob-interpret-markup grob #{
      \markup\with-dimensions #'(0 . 0) #'(0 . 0) {
        %%%%% ATTENTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        %%%%% translations à régler en fonction de l'armure
        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
        \translate #'(7.1 . .35)\arrow-at-angle #60 #(sqrt 8) ##t
        \translate #'(6.4 . .05)\arrow-at-angle #20 #(sqrt 8) ##t
        \translate #'(5.7 . -.05)\arrow-at-angle #-20 #(sqrt 8) ##t
        \translate #'(5.3 . -.35)\arrow-at-angle #-60 #(sqrt 8) ##t }#})
    0))
  \break
}

convDownStaffBarLine = {
  \once \override Staff.BarLine.stencil =
  #(lambda (grob)
    (ly:stencil-combine-at-edge
    (ly:bar-line::print grob)
    X RIGHT
    (grob-interpret-markup grob #{
        \markup\with-dimensions #'(0 . 0) #'(0 . 0) {
          %%%%% ATTENTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
          %%%%% translations à régler en fonction de l'armure
          %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
          \translate #'(5.4 . -.1)\arrow-at-angle #-45 #(sqrt 8) ##t }#})
      0))
  \break
}

convUpStaffBarLine = {
  \once \override Staff.BarLine.stencil =
  #(lambda (grob)
    (ly:stencil-combine-at-edge
    (ly:bar-line::print grob)
    X RIGHT
    (grob-interpret-markup grob #{
        \markup\with-dimensions #'(0 . 0) #'(0 . 0) {
          %%%%% ATTENTION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
          %%%%% translations à régler en fonction de l'armure
          %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
          \translate #'(5.4 . .1)\arrow-at-angle #45 #(sqrt 8) ##t }#})
      0))
  \break
}


\paper {
  ragged-right = ##f
  short-indent = 5\mm
  left-margin = 15\mm
  right-margin = 15\mm
}

\score {
  <<
    \new ChoirStaff <<
      \new Staff 
      \with { 
        instrumentName = \markup\column { "HI + HII +" "HIII + HIV" }
      } {
        \key f\minor
        <<
          \repeat unfold 4 f''1
          \\
          \repeat unfold 4 des''1
        >>
        \key f\major
        \splitStaffBarLine
      }
      \new Staff \with { instrumentName = #"Low" } {
        \key f\minor
        <<
          \repeat unfold 4 bes'1
          \\
          \repeat unfold 4 g'1
        >>
        \key f\major
      }

      \new Staff \with { shortInstrumentName = #"I" } {
        \key f \major
        R1*4
        \repeat unfold 2 { r4 f''2 r4 } \repeat unfold 2 e''1
        \key f\minor
        \convDownStaffBarLine
      }
      \new Staff \with { shortInstrumentName = #"II" } {
        \key f \major
        R1*4
        \repeat unfold 4 bes'2 \repeat unfold 2 c''1
        \key f\minor
        \convDownStaffBarLine
      }
      \new Staff \with { shortInstrumentName = #"III" } {
        \key f \major
        R1*4
        \repeat unfold 4 bes'2 \repeat unfold 2 c''1
        \key f\minor
        \convUpStaffBarLine
      }
      \new Staff \with { shortInstrumentName = #"IV" } {
        \key f \major
        R1*4
        \repeat unfold 4 bes'2 \repeat unfold 2 c''1
        \key f\minor
        \convUpStaffBarLine
      }
      \new Staff \with { shortInstrumentName = #"L" } {
        \key f\major
        R1*4
        <<
          \repeat unfold 4 g'1
          \\
          \repeat unfold 4 c'1
        >>
        \key f\minor
      }
      
      \new Staff 
      \with { 
        shortInstrumentName =\markup\column { "I+II+" "III+IV" }
      } {
        \key f\minor
        R1*8
        <<
          \repeat unfold 4 f''1
          \\
          \repeat unfold 4 des''1
        >>
      }
      \new Staff \with { shortInstrumentName = #"L" } {
        \key f\minor
        R1*8
        <<
          \repeat unfold 4 bes'1
          \\
          \repeat unfold 4 g'1
        >>
      }
    >>
  >>
  \layout {
    \context {
      \Staff \RemoveEmptyStaves
      \override VerticalAxisGroup #'remove-first = ##t
    }
  }
}