Re: programming error for thickness/control-points of Slur

[Thomas Morley]

Am Fr., 27. Mai 2022 um 11:58 Uhr schrieb Thomas Morley
<thomasmorley65@gmail.com>:
>
> Am Fr., 27. Mai 2022 um 11:22 Uhr schrieb Thomas Morley
> <thomasmorley65@gmail.com>:
> >
> > Hi,
> >
> > lsr-snippet "Variable bow thickness depending on length"
> > https://lsr.di.unimi.it/LSR/Item?u=1&id=1028 looks at 'control-points
> > to calculate a modified thickness.
> >
> > For recent lily-versions this throws
> > programming error: cyclic dependency: calculation-in-progress
> > encountered for Slur.thickness
> > as soon as 'control-points are called in a thickness-override.
> >
> > Stripped down example:
> >
> > \version "2.23.9"
> >
> > {
> >   \override Slur.thickness =
> >   #(lambda (grob)
> >     ;; all of below trigger the programming error
> >     (ly:slur::calc-control-points grob)
> >     ;(ly:grob-property grob 'control-points)
> >     ;((assoc-get 'control-points (ly:grob-basic-properties grob)) grob)
> >     2)
> >
> >   b1( b')
> > }
> >
> > I think I can make it work with an override for 'after-line-breaking
> > (calling 'control-points, set 'thickness to the result of calculations
> > based on the 'control-points and finally redo setting
> > 'control-points).
> >
> > Is there a better way?
> >
> > Thanks,
> >   Harm
>
> Btw, the snippet-description says " bow length is estimated by
> calculating the linear distance between its endpoints".
> Is it worth the effort to calculate the real bow-length?
>
> Thanks,
>   Harm

I decided to go for a better approximation of the bow-length, but
dropped some comments what to do, if execution time gets worse.
https://lsr.di.unimi.it/LSR/Item?u=1&id=1028

Cheers,
  Harm