Approximates cross-staff slurs in VerticalAxisGroup vertical-skylines.

lily/skyline.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 2006--2012 Joe Neeman <joeneeman@gmail.com>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
@@ skipping 190 matching lines @@
 
   /* their slopes were not equal, so there is an intersection point */
   Real i = intersection_x (other);
   return (i <= x && slope_ > other.slope_)
          || (i > x && slope_ < other.slope_);
 }
 
 // Remove redundant empty buildings from the skyline.
 // If there are two adjacent empty buildings, they can be
 // turned into one.
+// Also remove buildings with no width
 void
 Skyline::normalize ()
 {
   bool last_empty = false;
   list<Building>::iterator i;
   for (i = buildings_.begin (); i != buildings_.end (); i++)
     {
-      if (last_empty && i->y_intercept_ == -infinity_f)
+      if (last_empty
+          && (i->y_intercept_ == -infinity_f
+              || i->start_ == i->end_))
         {
           list<Building>::iterator last = i;
           last--;
           last->end_ = i->end_;
           buildings_.erase (i);
           i = last;
         }
       last_empty = (i->y_intercept_ == -infinity_f);
     }
 
@@ skipping 686 matching lines @@
   return scm_from_double (Skyline::unsmob (skyline_scm)->max_height_position ());
 }
 
 MAKE_SCHEME_CALLBACK (Skyline, get_height, 2)
 SCM
 Skyline::get_height (SCM skyline_scm, SCM x_scm)
 {
   Real x = robust_scm2double (x_scm, 0.0);
   return scm_from_double (Skyline::unsmob (skyline_scm)->height (x));
 }