Re: note-spacing: stretch somewhat uniformly; issue 3304 (issue 36830045)

[k-ohara5a5a]

Reviewers: MikeSol,

Message:
On 2013/12/16 07:42:52, MikeSol wrote:

> If you understand this stuff, could you put a comment in
lily/include/spring.hh
> as to what inverse_compress_strength and inverse_stretch_strength are?

They are the stretchability and compressibility of the space.
Next time I have linux up I'll put a comment, or just change the names.

You should try the patch on your music.  You probably have a lot of
staggered timing in the style of 3-against-2 hemiola, which should be
aligned more evenly with the patch.

The greater compressibility between note-columns makes it easier for me
to make readable piano music with fewer page-turns, so I like it.
Before the patch, there is extra stiffness between a note-column and a
following column with accidentals or other protrusions, and I wonder if
this stiffness is needed for readability.

Description:
note-spacing: stretch somewhat uniformly; issue 3304

From the ideal note-spacing, including optical corrections and the
tweaked allowances for flags and accidentals, we can set spring
stiffness so that the music stretches/compresses uniformly, until
objects come within padding of each other.  This lets lines compress
somewhat more easily.

Please review this at https://codereview.appspot.com/36830045/

Affected files (+11, -17 lines):
  M input/regression/glissando.ly
  M input/regression/spacing-multi-tuplet.ly
  M input/regression/spanner-alignment.ly
  M lily/note-spacing.cc


Index: input/regression/glissando.ly
diff --git a/input/regression/glissando.ly b/input/regression/glissando.ly
index  
bdb5124483b4100baafbde788795ec5b1498c139..04a9a8677ab64090c95bebb1c93147668d976ee2  
100644
--- a/input/regression/glissando.ly
+++ b/input/regression/glissando.ly
@@ -25,7 +25,7 @@ The engraver does no time-keeping, so it involves some  
trickery to get
   %% consecutive
   c \glissando d, \glissando e'
   << { e8 \glissando g8 } \\
-     { \repeat unfold 4 d16 } >>
+     { \repeat unfold 4 d16 } >> \break
   \override Glissando.style = #'zigzag
   c4 \glissando c,, \glissando c' \glissando d
 }
Index: input/regression/spacing-multi-tuplet.ly
diff --git a/input/regression/spacing-multi-tuplet.ly  
b/input/regression/spacing-multi-tuplet.ly
index  
bab9232a8d1b7113ec43676e601aaa1352c96622..4c84dad0d8b90947c91f6e1cc73b03704c73d545  
100644
--- a/input/regression/spacing-multi-tuplet.ly
+++ b/input/regression/spacing-multi-tuplet.ly
@@ -2,28 +2,18 @@

  \header{

-  texidoc = "Concurrent tuplets should be equidistant on all staves.
-Such equidistant spacing is at odds with elegant engraver spacing;
-hence it must be switched on explicitly with the
address@hidden property of @code{SpacingSpanner}."
+  texidoc = "Concurrent tuplets should be equidistant on all staves."
 }

-\layout{
-  \context{
-    \Score
-    \override SpacingSpanner.uniform-stretching = ##t
-  }
-}
+\paper {ragged-right = ##f }

 \relative c' {
   \context StaffGroup <<
     \new Staff  \context Voice {
-      \tuplet 10/2 {  c8[ c c c c c c c c c] }
-      \tuplet 10/2 {  c[  c c c c c c c c c] }
+      \tuplet 10/8 {  c8[ c c c c c c c c c] }
     }
     \new Staff  \context Voice {
-      \tuplet 11/2 {  c8[ c c c c c c c c c c] }
-      \tuplet 11/2 {  c[  c c c c c c c c c c] }
+      \tuplet 8/8 {  c8[ c c c c c c c] }
     }
   >>
 }
Index: input/regression/spanner-alignment.ly
diff --git a/input/regression/spanner-alignment.ly  
b/input/regression/spanner-alignment.ly
index  
02e04ece7dddd98bf094e30c71f5efa10dc79e31..af5523fa3594470f648b8e6b0e22672f92a07bad  
100644
--- a/input/regression/spanner-alignment.ly
+++ b/input/regression/spanner-alignment.ly
@@ -17,6 +17,7 @@ ignoring things like pedal marks.
       \new Dynamics = "dynamics" {
         \repeat unfold 2 {
           s1\cresc s1\f s1\dim s1\p
+          \break
         }
       }
       \new Staff = "down" {
Index: lily/note-spacing.cc
diff --git a/lily/note-spacing.cc b/lily/note-spacing.cc
index  
1d0d21fbbb502e5ae977c0e90781cfe63233aca2..597c719c30879ed0ea3bbd334d5d0ea7b3a93f1d  
100644
--- a/lily/note-spacing.cc
+++ b/lily/note-spacing.cc
@@ -110,8 +110,11 @@ Note_spacing::get_spacing (Grob *me, Item *right_col,
   /* TODO: grace notes look bad when things are stretched. Should we  
increase
      their stretch strength? */
   Spring ret (max (0.0, ideal), min_dist);
-  ret.set_inverse_compress_strength (max (0.0, ideal - min_desired_space));
-  ret.set_inverse_stretch_strength (max (0.1, base_space - increment));
+  /* Strech and compress simlarly to the default springs
+     added by Spacing_Spanner::musical_column_spacing()
+     so that polyphonic music compresses/stretches uniformly. */
+  ret.set_inverse_compress_strength (base_space);
+  ret.set_inverse_stretch_strength (base_space);
   return ret;
 }