Re: glissando lines and accidentals

[Aaron Hill]

On 2020-08-11 3:43 am, Werner LEMBERG wrote:
> > >   { <e' c''>2\glissando <d' bes'> }
> > >
> > > Due to the flat, the lower glissando line is far too short.
> > >
> > > beyond my capabilities right now.  Is there a solution to
> > > circumvent this temporarily?
> >
> > %%%%
> > \version "2.20.0"
> >
> > {
> >   \override Glissando.before-line-breaking =
> >   #(lambda (grob)
> >     (let* ((nh (ly:spanner-bound grob RIGHT))
> >            (acc (ly:grob-object nh 'accidental-grob)))
> >       (ly:grob-set-nested-property!
> >         grob
> >         '(bound-details right end-on-accidental)
> >         (ly:grob? acc))))
> >
> >   <e' c''>2\glissando <d' bes'>
> > }
> > %%%%
>
> Very nice, thanks!  The only thing now is to get the two lines
> parallel, which looks like a lot of additional work...

Oof... I am almost certainly overlooking something easier, but this 
appears to work:

%%%%
\version "2.20.0"

{
  \override Glissando.after-line-breaking =
  #(lambda (grob)
    (let* ((nh (ly:spanner-bound grob RIGHT))
           (acc (ly:grob-object nh 'accidental-grob))
           (acc? (ly:grob? acc)))
      (if acc?
        (let* ((refp (ly:grob-common-refpoint nh acc X))
               (nh-xex (ly:grob-robust-relative-extent nh refp X))
               (acc-xex (ly:grob-robust-relative-extent acc refp X))
               (dx (- (interval-index acc-xex LEFT)
                      (interval-index nh-xex LEFT)))
               (lbi (ly:grob-property grob 'left-bound-info))
               (rbi (ly:grob-property grob 'right-bound-info))
               (left-x (ly:assoc-get 'X lbi))
               (left-y (ly:assoc-get 'Y lbi))
               (right-x (ly:assoc-get 'X rbi))
               (right-y (ly:assoc-get 'Y rbi))
               (max-x (- right-x dx)))
          (ly:grob-set-nested-property!
            grob
            '(right-bound-info Y)
            (+ left-y
               (* (- right-y left-y)
                  (/ (- right-x left-x)
                     (- max-x left-x)))))))
      (ly:grob-set-nested-property!
        grob
        '(bound-details right end-on-accidental)
        acc?)))

  \time 6/2
  <e' c''>2\glissando <d' bes'>
  <e' c''>2\glissando <d' b'>
  <e' c''>2\glissando <d' bis'>
}
%%%%


-- Aaron Hill

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