RE:Decaying squiggle

[Stephen MacNeil]

Hi Andrew

This is common in guitar. Modern scores. Mark Witmer wrote code for this it's old but I still use it.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

\version "2.16.0"

% vibrato.ly

% Author: Mark Witmer

% 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) (list? number?) #{

\once \override TrillSpanner #'after-line-breaking = $(lambda (grob)

(ly:grob-set-property! grob 'stencil (makevib grob amplitudes wavelength)))

#})

#(define adjustvib #t)

% Creates the postscript for one system of the vibrato marking

#(define (make_ps no-sib? lbound xspan span-so-far amplitude-vector wavelength)

(if (or (= xspan -inf.0) (= xspan +inf.0))

""

(let ((lbound

(cond

((and (> span-so-far 0) adjustvib)

(- lbound 18))

(no-sib? (+ lbound 1))

(else lbound)))

(last

(inexact->exact (floor (/ (+ span-so-far xspan) wavelength)))))

(format

#f "gsave currentpoint translate 0.15 setlinewidth newpath /x ~a\

def\nx 0.0 moveto\n ~a ~a"

lbound

(let make-curve

((current (inexact->exact (floor (/ span-so-far wavelength)))))

(cond

((= current (vector-length amplitude-vector)) "")

((< (vector-ref amplitude-vector current) 0) "")

(else

(let ((current-ps

(format

#f " x ~a add ~a x ~a add ~a x ~a \

add 0.0 curveto\n/x x ~a add def\n"

(exact->inexact (/ wavelength 3))

(vector-ref amplitude-vector current)

(exact->inexact (* 2 (/ wavelength 3)))

(- (vector-ref amplitude-vector current))

wavelength

wavelength)))

(if (= (+ current 1) last)

current-ps

(format #f "~a~a" current-ps

(make-curve (+ 1 current))))))))

"stroke grestore"))))

% Returns the width of a grob

#(define (grob-width grob)

(if (or (= (car (ly:grob-property grob 'X-extent)) -inf.0)

(= (car (ly:grob-property grob 'X-extent)) +inf.0))

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 (floor (/ 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)

(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 3) (- (calcfull siblings 0) 3)))

(lbound (if (or (null? siblings) (eq? (car siblings) grob))

0 (+ 14 (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 (null? siblings) lbound xspan span-so-far

(make-amplitude-vector amplitudes total-span wavelength)

wavelength))

'(0 . 0) '(-0.7 . 0.5))))

vib = #(define-music-function (parser location sizes) (list?) #{ \vibrato $sizes #0.7 #})

sVib = \startTrillSpan

eVib = \stopTrillSpan

% Example:

\relative c' {\time 4/4 \key d \major \vibrato #'(4 0 4) #1.5 c\startTrillSpan d e d c d e d c\stopTrillSpan

\vibrato #'(1 6 2 1 3 7 4) #1 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 #'(4 .2 0) #1.2 c1\startTrillSpan c\stopTrillSpan

}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%

HTH

Stephen