How do I write hairpins and dynamics between staves in LilyPond?

Question

Here's a minimal example of the sort of result I want to produce in LilyPond. (This was produced in Finale.)

Notice that the crescendo-stop, f, and decrescendo-start align with a note in the bottom staff only and the decrescendo-stop and last p align with a note in the top staff only.

Here's the best approximation I can write in LilyPond with its output.

\version "2.20.0"
\language "english"

\new PianoStaff <<
    \new Staff {
        \clef "treble"
        \time 3/4
        \relative c'' {c4 \p \< c2 | c4 c2 \p}
    }
    \new Staff {
        \clef "bass"
        \relative c' {r4 r4 c4~ \f \> | c2 r4 \!}
    }
>>

Notice that each hairpin doesn't terminate at the dynamic marking in the other staff. I'm not surprised by that output, I just don't know how to get the output I want.

The example I'm giving here is just a toy to illustrate the type of problem I'm facing in many much more complex passages.

Is there a standard solution for connecting dynamics between staves in LilyPond?

Answer 1

I typically solve this problem by using a separate \new Dynamics entry. I find that this a) helps align the dynamics more easily with staff objects, and b) aligns the dynamics vertically as opposed to having them be various distances from the staff.

\version "2.20.0"
\language "english"

\new PianoStaff <<
    \new Staff {
        \clef "treble"
        \time 3/4
        \relative c'' {c4 c2 | c4 c2 }
    }
    \new Dynamics {
      s4\p s\< s\!\f\> |
      s s\p
    }
    \new Staff {
        \clef "bass"
        \relative c' {r4 r4 c4~ | c2 r4 }
    }
>>

This produces:

Obviously you can tweak horizontal spacing to lengthen some of these hairpins, etc.