Merge branch 'master' into lilypond/translation

[lilypond.git] / lily / beam-concave.cc

diff --git a/lily/beam-concave.cc b/lily/beam-concave.cc
index 2b88e0807ac55a13af98475e17f29028188560e3..48d45c859945eaa87ded018191bb9ab421b7b640 100644 (file)
--- a/lily/beam-concave.cc
+++ b/lily/beam-concave.cc
@@ -1,5 +1,24 @@
+/* 
+  beam-concave.cc -- implement Concaveness for beams.
+  
+  source file of the GNU LilyPond music typesetter
+  
+  (c) 2004 Han-Wen Nienhuys <hanwen@lilypond.org>
+  
+*/
+
 /*
   Determine whether a beam is concave.
+
+  A beam is concave when the middle notes get closer to the
+  beam than the left and right edge notes.
+
+  This is determined in two ways: by looking at the positions of the
+  middle notes, or by looking at the deviation of the inside notes
+  compared to the line connecting first and last.
+
+  The tricky thing is what to do with beams with chords. There are no
+  real guidelines in this case.
 */
 
 #include "pointer-group-interface.hh"
@@ -23,7 +42,7 @@ is_concave_single_notes (vector<int> const &positions, Direction beam_dir)
   /*
     notes above and below the interval covered by 1st and last note.
   */
-  for (vsize i = 1; i < positions.size () - 1; i++)
+  for (vsize i = 1; i + 1 < positions.size (); i++)
     {
       above = above || (positions[i] > covering[UP]);
       below = below || (positions[i] < covering[DOWN]);
@@ -36,7 +55,7 @@ is_concave_single_notes (vector<int> const &positions, Direction beam_dir)
   */
   int dy = positions.back () - positions[0];
   int closest = max (beam_dir * positions.back (), beam_dir * positions[0]);
-  for (vsize i = 2; !concave && i < positions.size () - 1; i++)
+  for (vsize i = 2; !concave && i + 1 < positions.size (); i++)
     {
       int inner_dy = positions[i] - positions[i - 1];
       if (sign (inner_dy) != sign (dy)
@@ -46,7 +65,7 @@ is_concave_single_notes (vector<int> const &positions, Direction beam_dir)
     }
 
   bool all_closer = true;
-  for (vsize i = 1; all_closer && i < positions.size () - 1; i++)
+  for (vsize i = 1; all_closer && i + 1 < positions.size (); i++)
     {
       all_closer = all_closer
        && (beam_dir * positions[i] > closest);
@@ -62,7 +81,7 @@ calc_positions_concaveness (vector<int> const &positions, Direction beam_dir)
   Real dy = positions.back () - positions[0];
   Real slope = dy / Real (positions.size () - 1);
   Real concaveness = 0.0;
-  for (vsize i = 1; i < positions.size () - 1; i++)
+  for (vsize i = 1; i + 1 < positions.size (); i++)
     {
       Real line_y = slope * i + positions[0];
 
@@ -118,7 +137,6 @@ Beam::calc_concaveness (SCM smob)
        Hmmm.. wait, for the beams in the last measure of morgenlied,
        this doesn't look so good. Let's try the heads farthest from
        the beam.
-
       */
       Interval posns = Stem::head_positions (stems[i]);
 
@@ -128,7 +146,7 @@ Beam::calc_concaveness (SCM smob)
 
   Real concaveness = 0.0;
 
-  if (is_concave_single_notes (far_positions, beam_dir))
+  if (is_concave_single_notes (beam_dir == UP ? close_positions : far_positions, beam_dir))
     {
       concaveness = 10000;
     }