Force top-system-spacing to be absolute

[Urs Liska]

Hi,

I nearly went nuts trying to figure out what I did wrong with converting 
staffsize to staffspace to mm to points to bigpoints and not getting 
anywhere with my score.

I want to have a score start with a defined position of the first staff 
symbol to match the type area of a surrounding text document. For this I 
thought to set the margin to zero and calculate the value for the actual 
margin in points. Then I'd set top-system-spacing to that value (plus 2 
to shift from the middle to the top staffline).


%%%
\version "2.19"
\header {
  copyright = ""
  tagline = ##f
}

\paper{
  indent = 0
  print-page-number = ##f
  top-margin = 0\pt
  top-system-spacing =
  #'((basic-distance . 16)
     (minimum-distance . 0)
     (padding . 0)
     (stretchability . 0))
  annotate-spacing = ##t
}

{
  \repeat unfold 50 { c' d' e' d' }
}
%%%

Now I've finally found out my calculations are actually correct, as can 
be seen from the annotated output in top-margin.png.

However, when I change the repeat to 150 LilyPond compresses the output 
pretty much, which is still nice as an engraving but also moves the 
first system up (see top-margin-compressed.png). You can see that the 
distance of "16" is still in place, but it doesn't point to the middle 
staffline anymore.

I assume that it's not the reference point that has changed but the 
system has been offset vertically from that reference point.

What is the correct way to force the first system to be at an absolute 
position on the staff, i.e. in the example the center line exactly 16 
staff spaces below the page border?

Thanks
Urs

top-margin.png
Description: PNG image