X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fsimple-spacer.cc;h=47eff23a031ed7d91a4b6f29b2ae0387e3285687;hb=998986bbd15afaafb24904a777e8be9ba1233799;hp=3616155b02534700bc4142eb5c1e1193b79d2adb;hpb=6e5d53a85f4ab98c5ebf94474338619f30ff4e96;p=lilypond.git

diff --git a/lily/simple-spacer.cc b/lily/simple-spacer.cc
index 3616155b02..47eff23a03 100644
--- a/lily/simple-spacer.cc
+++ b/lily/simple-spacer.cc
@@ -1,10 +1,258 @@
 /*   
-  simple-spacer.cc --  implement Simple_spacer
+  simple-spacer.cc -- implement Simple_spacer
   
   source file of the GNU LilyPond music typesetter
   
   (c) 1999 Han-Wen Nienhuys <hanwen@cs.uu.nl>
+
+  TODO:
+  - add support for different stretch/shrink constants?
+  - Use force as a minimizing function, and use it to discourage mixes of
+  wide and tight lines.
   
- */
+*/
+
+
+#include "simple-spacer.hh"
+#include "paper-column.hh"
+#include "spring.hh"
+#include "rod.hh"
+#include "warn.hh"
+#include "column-x-positions.hh"
+
+Simple_spacer::Simple_spacer ()
+{
+  force_f_ = 0.;
+}
+
+void
+Simple_spacer::add_rod (int l, int r, Real dist)
+{
+  Real c = range_stiffness (l,r);
+  Real d = range_ideal_len (l,r);
+  Real block_stretch = dist - d;
+  
+  Real block_force = c * block_stretch;
+  force_f_ = force_f_ >? block_force;
+  
+  for (int i=l; i < r; i++)
+    springs_[i].block_force_f_ = block_force >?
+      springs_[i].block_force_f_ ;
+}
+
+Real
+Simple_spacer::range_ideal_len (int l, int r)   const
+{
+  Real d =0.;
+  for (int i=l; i < r; i++)
+    d += springs_[i].ideal_f_;
+  return d;
+}
+
+Real
+Simple_spacer::range_stiffness (int l, int r) const
+{
+  Real den =0.0;
+  for (int i=l; i < r; i++)
+    den += 1 / springs_[i].hooke_f_;
+
+  return 1 / den;
+}
+
+Real
+Simple_spacer::active_blocking_force () const
+{
+  Real bf = - infinity_f; 
+  for (int i=0; i < springs_.size (); i++)
+    if (springs_[i].active_b_)
+      {
+	bf = bf >? springs_[i].block_force_f_;
+      }
+  return bf;
+}
+
+Real
+Simple_spacer::active_springs_stiffness () const
+{
+  Real den = 0.0;
+  for (int i=0; i < springs_.size (); i++)
+    if (springs_[i].active_b_)
+      {
+	den += 1 / springs_[i].hooke_f_;
+      }
+  return 1/den;
+}
+
+void
+Simple_spacer::set_active_states ()
+{
+  // safe, since
+  // force is only copied.
+  for (int i=0 ; i <springs_.size (); i++)
+    if (springs_[i].block_force_f_ >= force_f_) 
+      springs_[i].active_b_ = false;
+}   
+
+Real
+Simple_spacer::configuration_length () const
+{
+  Real l =0.;
+  for (int i=0; i < springs_.size (); i++)
+    l += springs_[i].length (force_f_);
+
+  return l;
+}
+
+Real
+Spring_description::length (Real f) const
+{
+  if (!active_b_)
+    f = block_force_f_;
+  return ideal_f_ + f / hooke_f_ ;
+}
+
+bool
+Simple_spacer::active_b () const
+{
+   for (int i=0; i < springs_.size (); i++)
+    if (springs_[i].active_b_)
+      return true;
+   return false;
+}
+
+void
+Simple_spacer::my_solve_linelen ()
+{
+  while (active_b ())
+    {
+      force_f_ = active_blocking_force ();
+      Real conf = configuration_length ();
+
+      if (conf < line_len_f_)
+	{
+	  force_f_ +=  (line_len_f_  - conf) * active_springs_stiffness ();
+	  break;
+	}
+      else
+	set_active_states ();
+    }
+}
+
+
+void
+Simple_spacer::my_solve_natural_len ()
+{
+  while (active_b ())
+    {
+      force_f_ = active_blocking_force () >? 0.0;
+
+      if (force_f_ < 1e-8) // ugh.,
+	break;
+      
+      set_active_states ();
+    }
+}
+
+void
+Simple_spacer::add_columns (Link_array<Paper_column> cols)
+{
+  for (int i=0; i < cols.size () - 1; i++)
+    {
+      Paper_column * c = cols [i];
+      Column_spring *to_next = 0;
+      for (int j =0; !to_next && j < c->spring_arr_drul_[RIGHT].size( ); j++)
+	{
+	  Column_spring &sp = c->spring_arr_drul_[RIGHT] [j];
+	  if (sp.other_l_ != cols[i+1])
+	    continue;
+
+	  to_next = &sp;
+	}
+
+      Spring_description desc;
+      if (to_next)
+	{
+	  desc.hooke_f_ = to_next->strength_f_;
+	  desc.ideal_f_ = to_next->distance_f_;
+	}
+      else
+	{
+	  desc.hooke_f_ = 1.0;
+	  desc.ideal_f_ = default_space_f_;
+	}
+      desc.block_force_f_ = - desc.hooke_f_ * desc.ideal_f_; // block at distance 0
+      springs_.push  (desc);
+    }
+  
+  for (int i=0; i < cols.size () - 1; i++)
+    {
+      Array<Column_rod> * rods = &cols [i]->minimal_dists_arr_drul_[RIGHT];
+      for (int j =0; j < rods->size( ); j++)
+	{
+	  int oi = cols.find_i (rods->elem (j).other_l_ );
+	  if (oi >= 0)
+	    {
+	      add_rod (i, oi, rods->elem (j).distance_f_);
+	    }
+	}
+    }
+
+  if (line_len_f_ < 0)
+    my_solve_natural_len ();
+  else
+    my_solve_linelen ();
+}
+
+void
+Simple_spacer::solve (Column_x_positions *positions) const
+{
+  positions->energy_f_  = energy_f ();  // abs (force_f_);
+  positions->config_.push (indent_f_);
+  for (int i=0; i <springs_.size (); i++)
+    {
+      positions->config_.push (positions->config_.top () + springs_[i].length (force_f_));
+    }
+
+  positions->satisfies_constraints_b_ = active_b ();
+}
+
+void
+Simple_spacer::lower_bound_solution (Column_x_positions * posns) const
+{
+  solve (posns);
+}
+
+
+Spring_description::Spring_description( )
+{
+  ideal_f_ =0.0;
+  hooke_f_ =0.0;
+  active_b_ = true;
+  block_force_f_ = 0.0;
+}
+
+Real
+Spring_description::energy_f (Real force) const
+{
+  Real stretch = (force >? block_force_f_) / hooke_f_;
+  Real e = 0.5 * stretch * stretch * hooke_f_;
+
+  /*
+    be harder to compress.
+   */
+  if (stretch < 0)
+    e *= 4;
+
+  return e;
+}
 
+Real
+Simple_spacer::energy_f () const
+{
+  Real e =0.;
 
+  for (int i=0; i <springs_.size (); i++)
+    e += springs_[i].energy_f (force_f_);
+      
+  return e;
+}