X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fsimple-spacer.cc;h=9cdf664797db8c803369129ab7d3530aa75d389e;hb=60d641c51caa5a53b185d40b6f6825417670887e;hp=c8b6490c37bff61117c6fefbc4effa9d2a4aba49;hpb=3a46c0c5944963e1b3e5dc0bc5c5f843e908d884;p=lilypond.git

diff --git a/lily/simple-spacer.cc b/lily/simple-spacer.cc
index c8b6490c37..9cdf664797 100644
--- a/lily/simple-spacer.cc
+++ b/lily/simple-spacer.cc
@@ -1,12 +1,23 @@
 /*
-  simple-spacer.cc -- implement Simple_spacer
+  This file is part of LilyPond, the GNU music typesetter.
 
-  source file of the GNU LilyPond music typesetter
-
-  (c) 1999--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
+  Copyright (C) 1999--2010 Han-Wen Nienhuys <hanwen@xs4all.nl>
 
   TODO:
   - add support for different stretch/shrink constants?
+
+  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.
+
+  LilyPond is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 #include <cstdio>
@@ -81,8 +92,11 @@ Real
 Simple_spacer::rod_force (int l, int r, Real dist)
 {
   Real d = range_ideal_len (l, r);
-  Real c = range_stiffness (l, r, d > dist);
+  Real c = range_stiffness (l, r, dist > d);
   Real block_stretch = dist - d;
+
+  if (isinf (c) && block_stretch == 0) /* take care of the 0*infinity_f case */
+    return 0;
   return c * block_stretch;
 }
 
@@ -102,7 +116,12 @@ Simple_spacer::add_rod (int l, int r, Real dist)
       Real spring_dist = range_ideal_len (l, r);
       if (spring_dist < dist)
 	for (int i = l; i < r; i++)
-	  springs_[i].set_distance (springs_[i].distance () * dist / spring_dist);
+	  {
+	    if (spring_dist)
+	      springs_[i].set_distance (springs_[i].distance () * dist / spring_dist);
+	    else
+	      springs_[i].set_distance (dist / (r - l));
+	  }
 
       return;
     }
@@ -167,6 +186,9 @@ Simple_spacer::expand_line ()
   for (vsize i=0; i < springs_.size (); i++)
     inv_hooke += springs_[i].inverse_stretch_strength ();
 
+  if (inv_hooke == 0.0) /* avoid division by zero. If springs are infinitely stiff */
+    return 0.0;         /* anyway, then it makes no difference what the force is */
+
   assert (cur_len <= line_len_);
   return (line_len_ - cur_len) / inv_hooke + force_;
 }
@@ -200,11 +222,14 @@ Simple_spacer::compress_line ()
 
   vector<Spring> sorted_springs = springs_;
   sort (sorted_springs.begin (), sorted_springs.end (), greater<Spring> ());
+
   for (vsize i = 0; i < sorted_springs.size (); i++)
     {
       Spring sp = sorted_springs[i];
 
-      assert (sp.blocking_force () <= cur_force);
+      if (sp.blocking_force () > cur_force)
+	continue;
+
       if (isinf (sp.blocking_force ()))
 	break;
 
@@ -222,7 +247,7 @@ Simple_spacer::compress_line ()
 	}
       
       cur_len -= block_dist;
-      inv_hooke -= sp.inverse_compress_strength ();
+      inv_hooke -= compressed ? sp.inverse_compress_strength () : sp.inverse_stretch_strength ();
       cur_force = sp.blocking_force ();
     }
 
@@ -259,25 +284,11 @@ Simple_spacer::force_penalty (bool ragged) const
 
   /* Use a convex compression penalty. */
   Real f = force_;
-  return f - (f < 0 ? f*f*f*f*4 : 0);
+  return f - (f < 0 ? f*f*f*f*2 : 0);
 }
 
 /****************************************************************/
 
-/*
-  TODO: should a add penalty for widely varying spring forces (caused
-  by constraints, eg.
-
-
-  .     =====
-  .     |   |
-  .o|o|x ##x
-  .
-
-  The ## forces the notes apart; we shouldn't allow the O's to touch
-  this closely.
-*/
-
 struct Rod_description
 {
   vsize r_;