Run `make grand-replace'.

[lilypond.git] / lily / spring.cc

diff --git a/lily/spring.cc b/lily/spring.cc
index e63fee0891b0d1fab26bc63031b9015dd89b1721..cd63afa6702bc4b4ba9c59ce6ecca61512a920e8 100644 (file)
--- a/lily/spring.cc
+++ b/lily/spring.cc
@@ -1,56 +1,167 @@
-/*   
-  spring.cc --  implement Spring
-  
+/*
+  spring.cc -- declare Spring
+
   source file of the GNU LilyPond music typesetter
-  
-  (c) 1999--2001 Han-Wen Nienhuys <hanwen@cs.uu.nl>
-  
- */
+
+  (c) 2007--2008 Joe Neeman <joeneeman@gmail.com>
+*/
 
 #include "spring.hh"
-#include "debug.hh"
-#include "item.hh"
-#include "spaceable-grob.hh"
-#include "paper-column.hh"
 
 Spring::Spring ()
 {
-  item_l_drul_[LEFT]  =item_l_drul_[RIGHT] =0;
-  distance_f_ =0.;
-  strength_f_ =1.0;
+  distance_ = 1.0;
+  min_distance_ = 1.0;
+  inverse_stretch_strength_ = 1.0;
+  inverse_compress_strength_ = 1.0;
+
+  update_blocking_force ();
 }
 
-/*
+Spring::Spring (Real dist, Real min_dist)
+{
+  distance_ = 1.0;
+  min_distance_ = 1.0;
 
- ugh : if we go from items to cols, we should adjust distance and strength.
- */
+  set_distance (dist);
+  set_min_distance (min_dist);
+  set_default_strength ();
+  update_blocking_force ();
+}
 
 void
-Spring::add_to_cols ()
+Spring::update_blocking_force ()
 {
-  Spaceable_grob::add_spring (item_l_drul_[LEFT]->column_l (),
-                                item_l_drul_[RIGHT]->column_l (),
-                                distance_f_, strength_f_);
+  if (distance_ == min_distance_)
+    blocking_force_ = 0.0;
+  else
+    blocking_force_ = (min_distance_ - distance_) / inverse_compress_strength_;
 }
 
+/* scale a spring, but in a way that doesn't violate min_distance */
 void
-Spring::set_to_cols( )
+Spring::operator*= (Real r)
+{
+  distance_ = max (min_distance_, distance_ * r);
+  inverse_compress_strength_ = distance_ - min_distance_;
+  inverse_stretch_strength_ *= 0.8;
+}
+
+bool
+Spring::operator> (Spring const &other) const
+{
+  return blocking_force_ > other.blocking_force_;
+}
+
+/* merge springs, basically by averaging them, but leave a little headroom
+   above the largest minimum distance so that things don't get too cramped */
+Spring
+merge_springs (vector<Spring> const &springs)
 {
-  Direction d = LEFT;
-  do
+  Real avg_distance = 0;
+  Real min_distance = 0;
+  Real avg_stretch = 0;
+  Real avg_compress = 0;
+
+  for (vsize i = 0; i < springs.size (); i++)
     {
-      item_l_drul_[d] = item_l_drul_[d]->column_l ();
+      avg_distance += springs[i].distance ();
+      avg_stretch += springs[i].inverse_stretch_strength ();
+      avg_compress += 1 / springs[i].inverse_compress_strength ();
+      min_distance = max (springs[i].min_distance (), min_distance);
     }
-  while (flip (&d) != LEFT);
 
+  avg_stretch /= springs.size ();
+  avg_compress /= springs.size ();
+  avg_distance /= springs.size ();
+  avg_distance = max (min_distance + 0.3, avg_distance);
+
+  Spring ret = Spring (avg_distance, min_distance);
+  ret.set_inverse_stretch_strength (avg_stretch);
+  ret.set_inverse_compress_strength (1 / avg_compress);
+
+  return ret;
 }
 
-Column_spring::Column_spring ()
+void
+Spring::set_distance (Real d)
 {
-  other_l_ = 0;
-  distance_f_ =0;
-  strength_f_ =1.0;
+  if (d < 0 || isinf (d) || isnan (d))
+    programming_error ("insane spring distance requested, ignoring it");
+  else
+    {
+      min_distance_ = min (min_distance_, d);
+      distance_ = d;
+      update_blocking_force ();
+    }
 }
 
+void
+Spring::set_min_distance (Real d)
+{
+  if (d < 0 || isinf (d) || isnan (d))
+    programming_error ("insane spring min_distance requested, ignoring it");
+  else
+    {
+      min_distance_ = d;
+      distance_ = max (distance_, min_distance_);
+      update_blocking_force ();
+    }
+}
 
+void
+Spring::set_inverse_stretch_strength (Real f)
+{
+  if (isinf (f) || isnan (f) || f < 0)
+    programming_error ("insane spring constant");
+  else
+    inverse_stretch_strength_ = f;
+}
+
+void
+Spring::set_inverse_compress_strength (Real f)
+{
+  if (isinf (f) || isnan (f) || f < 0)
+    programming_error ("insane spring constant");
+  else
+    inverse_compress_strength_ = f;
+
+  update_blocking_force ();
+}
+
+void
+Spring::set_blocking_force (Real f)
+{
+  if (isinf (f) || isnan (f))
+    {
+      programming_error ("insane blocking force");
+      return;
+    }
 
+  blocking_force_ = -infinity_f;
+  min_distance_ = length (f);
+  distance_ = max (distance_, min_distance_);
+  update_blocking_force ();
+}
+
+void
+Spring::set_default_strength ()
+{
+  inverse_compress_strength_ = distance_ - min_distance_;
+  inverse_stretch_strength_ = distance_ - min_distance_;
+}
+
+Real
+Spring::length (Real f) const
+{
+  Real force = max (f, blocking_force_);
+  Real inv_k = force < 0.0 ? inverse_compress_strength_ : inverse_stretch_strength_;
+
+  if (isinf (force))
+    {
+      programming_error ("cruelty to springs");
+      force = 0.0;
+    }
+
+  return distance_ + force * inv_k;
+}