I have been using a bit of code written by Mark Witmer to achieve wavy
lines above a series of notes. It co-opts the trill spanner mechanism
for this.
I just found a bug in that code. When there is a line break the
calculation of
(ly:grob-property grob 'X-extent)
- with the grob being a #<Grob TrillSpanner > -
then the value (+inf.0 -inf.0) is returned and in consequence an error
is thrown later when the value is used.
Unfortunately, I don't know what the status of the original file is or
where it came from, but attached is a version which prevents the error
being thrown by returning 0 instead. This results in the wavy line
running off the right margin but the typesetting at least succeeds.
I'm sending this in case anyone else has this problem or needs to
typeset vibrato marks, and - just in case - someone can suggest a
correct way to handle line breaks with these vibrato markings.
Richard Shann
%\version "2.18.2"
% vibrato.ly
% Author: Mark Witmer
% Modified for thickness by Richard Shann
% Sets the next trill spanner to draw a waveform with the provided wevelength
% and amplitudes. The waveform will go from one amplitude to the next in a
% linear fashion.
vibrato = #(define-music-function (parser location amplitudes wavelength thickness) (list? number? number?) #{
\once \override TrillSpanner.after-line-breaking = #(lambda (grob)
(ly:grob-set-property! grob 'stencil (makevib grob amplitudes wavelength thickness)))
#})
% Creates the postscript for one system of the vibrato marking
#(define (make_ps lbound xspan span-so-far amplitude-vector wavelength thickness)
(letrec (
(frontmatter
(string-append "gsave currentpoint translate "
(number->string thickness) " setlinewidth newpath\n "))
(backmatter "stroke grestore")
(make-curve (lambda (current last)
(if (= current (vector-length amplitude-vector)) ""
(if (< (vector-ref amplitude-vector current) 0) ""
(let (
(current-ps (string-append " x " (number->string (exact->inexact (/ wavelength 3))) " add " (number->string (vector-ref amplitude-vector current))
" x " (number->string (exact->inexact (* 2 (/ wavelength 3)))) " add " (number->string (- (vector-ref amplitude-vector current)))
" x " (number->string wavelength) " add 0.0 curveto
/x x " (number->string wavelength) " add def\n")))
(if (= current last) current-ps (string-append current-ps (make-curve (+ 1 current) last)))))))))
(if (or (= xspan -inf.0) (= xspan +inf.0))
(string-append frontmatter backmatter)
(string-append frontmatter " /x " (number->string lbound) " def
x 0.0 moveto\n"
(make-curve (inexact->exact (ceiling span-so-far)) (+ (inexact->exact (ceiling span-so-far)) (inexact->exact (floor xspan))))
backmatter))))
% Returns the width of a grob
#(define (grob-width grob)
(if (inf? (cdr (ly:grob-property grob 'X-extent)))
0
(- (cdr (ly:grob-property grob 'X-extent)) (car (ly:grob-property grob 'X-extent)))))
% Returns the number of ems already traversed by the grob's siblings in previous systems
#(define (width-up-to grob siblings count)
(if (eq? (car siblings) grob) count (+ (+ count (width-up-to grob (cdr siblings) count)) (grob-width (car siblings)))))
% Returns the total width of the individual grobs for each system that make up the original grob
#(define (calcfull siblings count)
(if (eqv? (length siblings) 0)
count
(calcfull (cdr siblings) (+ count (grob-width (car siblings))))))
% Fills a vector of length len with linear interpolations between the values found in amplitudes
#(define (fill-amplitude-vector! amplitude-vector len current-index amplitudes)
(if (> (length amplitudes) 1)
(let ((start-amplitude (car amplitudes))
(end-amplitude (cadr amplitudes))
(start-index current-index)
(end-index (+ current-index (inexact->exact (floor (/ (vector-length amplitude-vector) (- len 1)))))))
(do ((n current-index (+ 1 n))) ((or (> n (+ start-index end-index)) (>= n (vector-length amplitude-vector))))
(vector-set! amplitude-vector n (exact->inexact (+ start-amplitude (* (/ (- n start-index) (- end-index start-index)) (- end-amplitude start-amplitude))))))
(fill-amplitude-vector! amplitude-vector len end-index (cdr amplitudes)))))
% Makes the vector of amplitudes for the vibrato marking
#(define (make-amplitude-vector amplitudes total-span wavelength)
(let* (
(current-start 0)
(len (inexact->exact (ceiling (/ total-span wavelength))))
(amplitude-vector (make-vector len)))
(if (> (length amplitudes) 1)
(fill-amplitude-vector! amplitude-vector (length amplitudes) 0 amplitudes)
(vector-fill! amplitude-vector (car amplitudes)))
amplitude-vector))
% Creates a stencil that draws a sine wave for vibrato based on the provided amplitudes and wavelength
#(define (makevib grob amplitudes wavelength thickness)
(let* ((orig (ly:grob-original grob))
(siblings (if (ly:grob? orig) (ly:spanner-broken-into orig) '()))
(span (ly:grob-property grob 'X-extent))
(xbeg (car span))
(xend (cdr span))
(xspan (- xend xbeg))
(total-span (if (eqv? (length siblings) 0) xspan (calcfull siblings 0)))
(lbound (if (or (null? siblings) (eq? (car siblings) grob)) 0 (cdr (assq 'X (ly:grob-property grob 'left-bound-info)))))
(span-so-far (if (null? siblings) 0 (width-up-to grob siblings 0))))
(ly:make-stencil (list 'embedded-ps (make_ps lbound xspan span-so-far (make-amplitude-vector amplitudes total-span wavelength) wavelength thickness)) (cons 0 0) (cons -1 1))))
%{
% Example:
\relative c' {\time 4/4 \key d \major \vibrato #'(4 0 4) #1.5 #0.15 c\startTrillSpan d e d c d e d c\stopTrillSpan
\vibrato #'(1 6 2 1 3 7 4) #1 #0.05 c\startTrillSpan d e d c d e d c d e d c d e d c d e d c d e d c d e d c d e d
c d e d c d e d c d e d c d e d c d e d c d e d c d e d c d e\stopTrillSpan}
%%%%%%%%%%%
\paper {
ragged-right = ##f
}
\relative c' {
\vibrato #'(0.62 0.42) #1.2 #0.25 c1\startTrillSpan c\stopTrillSpan
}
%}
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