How to write a slur to nothing in LilyPond?

Question

Just like this:

This is a Piano Staff, the example was created on MuseScore.

The \laissezVibrer slur only creates a small slur. I don't mind whether the slur crosses the measure or not, I just don't want it to be that short.

This is LilyPond's Engraving:

Also, as they're two voices, in LilyPond the last two rests appear above the default position in both staves. But they're written on a single line as << { } \\ { } >> and I don't know how to make the second voice disappear after that bar so the rest goes back to the default position.

Answer 1

The easiest way to achieve this is to insert empty chords with <> that catch the open slur or tie. The following code ...

<<
\new Staff {
    << { f'1( <>) } \\ { \voiceThree e'4_( dis'8 cis') dis'2_( <>) } >> R1 R1
}

\new Staff {
    << { g'8 d'' g''2.( <>) } \\ { g'1( <>) } >> R1 R1
}
>>

results in the following output:

The nice thing here is that, like in the original score, all the open slurs end at about the same position. Moreover, you can put the rests outside the double-voice part so that they will be typeset at their regular vertical position.

Empty chords have no rhythmic length and can be used to catch spanners such as crescendi etc. With \voiceThree, you tell LilyPond that the notes should be shifted a bit to the right in case where note heads overlap with other voices, but the stems should be upwards. You then need to explicitly set the direction of the slurs and ties with _(.

Answer 2

A simple way to achieve this is to write a normal note that looks as if it's a rest, like this:

b8 fis' b2.~ | b1\rest |

(It's also possible to tweak almost every individual property of every object using \override, but I have to look those up again every time I need them.)