Re: missing glissando features (bugs?)

[Marc Hohl]

Neil Puttock schrieb:
> 2009/5/2 Marc Hohl <address@hidden>:
>   
> > I have made some observations concerning \glissando:
> >
> > 1) accidentals are not recognised properly; I know this is in the bug list
> > and there are workarounds,
> >  see http://lists.gnu.org/archive/html/bug-lilypond/2005-08/msg00235.html
> >     
>
> This isn't at all straightforward to fix (I had a stab at it a while
> ago, and it's tricky to get the positioning correct on the right hand
> side because the accidental changes the anchor point for the end of
> the glissando.)
>
>   
> > 2) the glissando line between half steps should indicate the direction;
> >  e.g. a glissando line between c and c# should raise a bit and not be
> > parallel to the staff lines;
> >
> > 3) in tablature, the glissando is always indicated upwards, but it should be
> > drawn in respect to the fret number;
> >  e.g. 3/5\3, not 3/5/3;
> >
> > Should (2) and (3) be considered as bugs? I have found a request from
> > 9/2005:
> >     
>
> Probably.
>
> It should be quite easy to fix both problems with a callback for
> 'extra-dy (see below)
>   
I tried this manually, and it works just fine, see attached file.
>   
> > http://lists.gnu.org/archive/html/bug-lilypond/2005-09/msg00112.html
> >
> > and it seems to me that this has been partly implemented
> > (the lines betweeen fret numbers are now sloped, so there _has_ been some
> > progress).
> >
> > Are there any hints/workarounds to solve this problem?
> >     
>
> >From the glissando you can get the left and right noteheads using
> ly:spanner-bound, from which it's possible to retrieve the pitches. A
> simple comparision of pitches should allow you to set the correct
> return value for 'extra-dy.
>   

I tried to receive the informations needed by overriding the Glissando 
#'stencil with
a function which simply displays the values obtained by the 
ly:spanner-bound call
before calling ly:line-spanner::print, but I get only  #<Grob NoteHead > 
on the terminal.

What am I doing wrong here?

Thanks in advance.

Marc

> For TabVoice.Glissando, you can get the staff-positions for the
> bounding notes, so it's possible to apply extra-dy only for glissandos
> between tab notes on the same line.
>
> Regards,
> Neil
>
>   

\version "2.12.2"

\paper {
   ragged-right = ##f
}

#(define (glissando::test grob)
    (let* ((left-bound (ly:spanner-bound grob LEFT))
           (right-bound (ly:spanner-bound grob RIGHT)))
           (display "left-bound: ")(display left-bound)(newline)
           (display "right-bound: ")(display right-bound)(newline)
           ;; for now, we simply use the default printing routine
           (ly:line-spanner::print grob)))

noten = \relative c {
   \override Glissando #'stencil = #glissando::test
   c4 \glissando cis
   \once \override Glissando #'extra-dy = #0.5
   c4 \glissando cis
   c4 \glissando ces
   \once \override Glissando #'extra-dy = #-0.5
   c4 \glissando ces
}

tabs = \relative c {
   \set TabStaff.minimumFret = #2
   c4 \glissando 
   \once \override Glissando #'extra-dy = #-1.0
   d \glissando c2
   c4 \glissando d \glissando c2
   \bar "|."
}



\score {
   <<
      \new Staff { \clef "G_8" \noten }
   >>
}
\score {
   <<
      \new TabStaff { \clef "tab" \tabs }
   >>
}