\version "2.18.2"

% maybe for string portamento 
% 'jib' as on a tower crane
              
 % draw a single sloping straight line pointing through ensuing notehead 
 % SLOPE is degrees above/below horizontal; +/- = rising/sinking
 % the line lies between FAR and NEAR, distances from the notehead centre
 % distance units are half staff-spaces
 #(define ((jibSt slope far near) grob)
  (ly:stencil-add
    (ly:note-head::print grob)
    (grob-interpret-markup grob
      (markup #:translate (cons (- 0.5  0)  0)  ; approx notehead centre 
              #:rotate (- slope 180) 
              #:with-dimensions '(0 . 0) '(0 . 0)
              #:translate (cons (/ near 2)  0)
              #:draw-line (cons (/ (- far near) 2) 0) 
              ))))

jib = 
#(define-music-function (parser location slope far near mus) 
   (number? (number? 7) (number? 2) ly:music?)
  #{
    \tweak #'stencil #(jibSt slope far near) $mus
  #}
  ) % usage: \jib 30  or  \jib 30 5  or  \jib 60 5 1.5



{ c'4 \jib 40 5 g'4 c'4 \jib 50 c''4 c'4  \jib 65 10 4 g''4  \jib -60 10 c'4 }