Re: adjusting double glissandi

[Aaron Hill]

On 2022-01-25 11:46 am, Rachel Green wrote:
> Hi,
> I’m trying to adjust the glissandi in this excerpt so that the lines
> are parallel and not too close to each other. I found some settings
> for adjusting a single glissando, but not for a double glissando. Any
> ideas?

There is prior work on this subject.  Harm has provided some code [1] 
before.

[1]: 
https://lists.gnu.org/archive/html/lilypond-user/2013-08/msg00547.html

Here is an adaptation of that logic:

%%%%
glissandoTweak =
#(define-music-function
  (after? tweaks) ((boolean? #t) list?)
  (define (proc grob)
   (if after? (ly:spanner::kill-zero-spanned-time grob))
   (for-each
    (lambda (x)
     (let ((prop (car x)) (value (cdr x)))
      (if (key-list? prop)
       (ly:grob-set-nested-property! grob prop value)
       (ly:grob-set-property! grob prop value))))
    (ly:assoc-get
     (ly:grob-property grob 'glissando-index) tweaks '())))
  (if after?
   #{ \once \override Glissando.after-line-breaking = #proc #}
   #{ \once \override Glissando.before-line-breaking = #proc #}))

{
 \glissandoTweak
 #`((0 . ((color . ,red)
          (Y-offset . -0.5)))
    (1 . ((color . ,blue)
          ((bound-details right arrow) . #t))))
 <c' e'>2\glissando <g'' b''>
}
%%%%


-- Aaron Hill