/*
- spring.cc -- declare Spring
+ This file is part of LilyPond, the GNU music typesetter.
- source file of the GNU LilyPond music typesetter
+ Copyright (C) 2007--2012 Joe Neeman <joeneeman@gmail.com>
- (c) 2007--2009 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.
+
+ 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 "spring.hh"
{
distance_ = 1.0;
min_distance_ = 1.0;
+ inverse_stretch_strength_ = 1.0;
+ inverse_compress_strength_ = 1.0;
set_distance (dist);
set_min_distance (min_dist);
void
Spring::update_blocking_force ()
{
+ // blocking_force_ is the value of force
+ // below which length(force) is constant, and
+ // above which length(force) varies according to inverse_*_strength.
+ // Simple_spacer::compress_line() depends on the condition above.
+ // We assume inverse_*_strength are non-negative.
if (min_distance_ > distance_)
- blocking_force_ = (min_distance_ - distance_) / inverse_stretch_strength_;
- else
+ if (inverse_stretch_strength_ > 0.0)
+ blocking_force_ = (min_distance_ - distance_) / inverse_stretch_strength_;
+ else
+ // Conceptually, this should be +inf, but 0.0 meets the requirements
+ // of Simple_spacer and creates fewer cases of 0.0*inf to handle.
+ blocking_force_ = 0.0;
+ else if (inverse_compress_strength_ > 0.0)
blocking_force_ = (min_distance_ - distance_) / inverse_compress_strength_;
-
- // If the spring is fixed, it's not clear what the natural value
- // of blocking_force_ would be. -infinity_f works fine for now.
- if (isnan (blocking_force_) || blocking_force_ == infinity_f)
- blocking_force_ = -infinity_f;
-
- if (blocking_force_ >= 0)
- inverse_compress_strength_ = 0;
+ else
+ blocking_force_ = 0.0;
}
/* scale a spring, but in a way that doesn't violate min_distance */
void
-Spring::operator*= (Real r)
+Spring::operator *= (Real r)
{
distance_ = max (min_distance_, distance_ * r);
inverse_compress_strength_ = max (0.0, distance_ - min_distance_);
}
bool
-Spring::operator> (Spring const &other) const
+Spring::operator > (Spring const &other) const
{
return blocking_force_ > other.blocking_force_;
}
min_distance = max (springs[i].min_distance (), min_distance);
}
- avg_stretch /= springs.size ();
- avg_compress /= springs.size ();
- avg_distance /= springs.size ();
+ avg_stretch /= Real (springs.size ());
+ avg_compress /= Real (springs.size ());
+ avg_distance /= Real (springs.size ());
avg_distance = max (min_distance + 0.3, avg_distance);
Spring ret = Spring (avg_distance, min_distance);
void
Spring::set_default_strength ()
+{
+ set_default_stretch_strength ();
+ set_default_compress_strength ();
+}
+
+void
+Spring::set_default_compress_strength ()
{
inverse_compress_strength_ = (distance_ >= min_distance_) ? distance_ - min_distance_ : 0;
- inverse_stretch_strength_ = distance_;
update_blocking_force ();
}
+void
+Spring::set_default_stretch_strength ()
+{
+ inverse_stretch_strength_ = 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 (force == infinity_f)
+ if (isinf (force))
{
programming_error ("cruelty to springs");
force = 0.0;