source file of the GNU LilyPond music typesetter
- (c) 1999--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
+ (c) 1999--2009 Han-Wen Nienhuys <hanwen@xs4all.nl>
TODO:
- add support for different stretch/shrink constants?
Real
Simple_spacer::rod_force (int l, int r, Real dist)
{
- Real c = range_stiffness (l, r);
Real d = range_ideal_len (l, r);
+ 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;
}
Real spring_dist = range_ideal_len (l, r);
if (spring_dist < dist)
for (int i = l; i < r; i++)
- springs_[i].ideal_ *= 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;
}
force_ = max (force_, block_force);
for (int i = l; i < r; i++)
- springs_[i].block_force_ = max (block_force, springs_[i].block_force_);
+ springs_[i].set_blocking_force (max (block_force, springs_[i].blocking_force ()));
}
Real
{
Real d = 0.;
for (int i = l; i < r; i++)
- d += springs_[i].ideal_;
+ d += springs_[i].distance ();
return d;
}
Real
-Simple_spacer::range_stiffness (int l, int r) const
+Simple_spacer::range_stiffness (int l, int r, bool stretch) const
{
Real den = 0.0;
for (int i = l; i < r; i++)
- den += springs_[i].inverse_hooke_;
+ den += stretch ? springs_[i].inverse_stretch_strength ()
+ : springs_[i].inverse_compress_strength ();
return 1 / den;
}
Simple_spacer::solve (Real line_len, bool ragged)
{
Real conf = configuration_length (force_);
- double inv_hooke = 0;
- for (vsize i=0; i < springs_.size (); i++)
- inv_hooke += springs_[i].inverse_hooke_;
ragged_ = ragged;
line_len_ = line_len;
- if ((inv_hooke > 0) && (conf < line_len_))
+ if (conf < line_len_)
force_ = expand_line ();
else if (conf > line_len_)
force_ = compress_line ();
fits_ = true;
for (vsize i=0; i < springs_.size (); i++)
- inv_hooke += springs_[i].inverse_hooke_;
+ 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_;
double inv_hooke = 0;
double cur_len = configuration_length (force_);
double cur_force = force_;
+ bool compressed = false;
+
+ /* just because we are in compress_line () doesn't mean that the line
+ will actually be compressed (as in, a negative force) because
+ we start out with a stretched line. Here, we check whether we
+ will be compressed or stretched (so we know which spring constant to use) */
+ if (configuration_length (0.0) > line_len_)
+ {
+ cur_force = 0.0;
+ cur_len = configuration_length (0.0);
+ compressed = true;
+ }
fits_ = true;
for (vsize i=0; i < springs_.size (); i++)
- inv_hooke += springs_[i].inverse_hooke_;
+ inv_hooke += compressed
+ ? springs_[i].inverse_compress_strength ()
+ : springs_[i].inverse_stretch_strength ();
assert (line_len_ <= cur_len);
- vector<Spring_description> sorted_springs = springs_;
- sort (sorted_springs.begin (), sorted_springs.end (), greater<Spring_description> ());
+ vector<Spring> sorted_springs = springs_;
+ sort (sorted_springs.begin (), sorted_springs.end (), greater<Spring> ());
+
for (vsize i = 0; i < sorted_springs.size (); i++)
{
- Spring_description sp = sorted_springs[i];
+ Spring sp = sorted_springs[i];
- assert (sp.block_force_ <= cur_force);
- if (isinf (sp.block_force_))
+ assert (sp.blocking_force () <= cur_force);
+ if (isinf (sp.blocking_force ()))
break;
- double block_dist = (cur_force - sp.block_force_) * inv_hooke;
+ double block_dist = (cur_force - sp.blocking_force ()) * inv_hooke;
if (cur_len - block_dist < line_len_)
{
- cur_force += (line_len_ - cur_len) / inv_hooke;
- cur_len = line_len_;
+ cur_force += (line_len_ - cur_len) / inv_hooke;
+ cur_len = line_len_;
- /*
- Paranoia check.
+ /*
+ Paranoia check.
*/
- assert (fabs (configuration_length (cur_force) - cur_len) < 1e-6);
- return cur_force;
+ assert (fabs (configuration_length (cur_force) - cur_len) < 1e-6);
+ return cur_force;
}
cur_len -= block_dist;
- inv_hooke -= sp.inverse_hooke_;
- cur_force = sp.block_force_;
+ inv_hooke -= sp.inverse_compress_strength ();
+ cur_force = sp.blocking_force ();
}
fits_ = false;
}
void
-Simple_spacer::add_spring (Real ideal, Real inverse_hooke)
+Simple_spacer::add_spring (Spring const &sp)
{
- Spring_description description;
-
- description.ideal_ = ideal;
- description.inverse_hooke_ = inverse_hooke;
- if (!description.is_sane ())
- {
- programming_error ("insane spring found, setting to unit");
-
- description.inverse_hooke_ = 1.0;
- description.ideal_ = 1.0;
- }
-
- description.block_force_ = -description.ideal_ / description.inverse_hooke_;
- // block at distance 0
-
- springs_.push_back (description);
+ force_ = max (force_, sp.blocking_force ());
+ springs_.push_back (sp);
}
vector<Real>
/* 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);
}
/****************************************************************/
-Spring_description::Spring_description ()
-{
- ideal_ = 0.0;
- inverse_hooke_ = 0.0;
- block_force_ = 0.0;
-}
-
-bool
-Spring_description::is_sane () const
-{
- return (inverse_hooke_ >= 0)
- && ideal_ >= 0
- && !isinf (ideal_) && !isnan (ideal_)
- && (inverse_hooke_ == 0.0 || fabs (inverse_hooke_) > 1e-8)
- ;
-}
-
-Real
-Spring_description::length (Real f) const
-{
- return ideal_ + max (f, block_force_) * inverse_hooke_;
-}
-
-/****************************************************************/
-
-/*
- 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_;
{
vector<Rod_description> rods_;
vector<Rod_description> end_rods_; /* use these if they end at the last column of the line */
- Real ideal_;
- Real inverse_hooke_;
- Real end_ideal_;
- Real end_inverse_hooke_;
+ Spring spring_;
+ Spring end_spring_;
+
SCM break_permission_;
Interval keep_inside_line_;
Column_description ()
{
- ideal_ = 0;
- inverse_hooke_ = 0;
- end_ideal_ = 0;
- end_inverse_hooke_ = 0;
break_permission_ = SCM_EOL;
}
};
Column_description description;
Grob *next_col = next_spaceable_column (cols, col_index);
if (next_col)
- Spaceable_grob::get_spring (col, next_col, &description.ideal_, &description.inverse_hooke_);
+ description.spring_ = Spaceable_grob::get_spring (col, next_col);
+
Grob *end_col = dynamic_cast<Item*> (cols[col_index+1])->find_prebroken_piece (LEFT);
if (end_col)
- Spaceable_grob::get_spring (col, end_col, &description.end_ideal_, &description.end_inverse_hooke_);
+ description.end_spring_ = Spaceable_grob::get_spring (col, end_col);
for (SCM s = Spaceable_grob::get_minimum_distances (col);
scm_is_pair (s); s = scm_cdr (s))
Simple_spacer spacer;
for (vsize i = breaks[b]; i < end - 1; i++)
- spacer.add_spring (cols[i].ideal_, cols[i].inverse_hooke_);
- spacer.add_spring (cols[end-1].end_ideal_, cols[end-1].end_inverse_hooke_);
+ spacer.add_spring (cols[i].spring_);
+ spacer.add_spring (cols[end-1].end_spring_);
for (vsize i = breaks[b]; i < end; i++)
for (vsize i = 0; i + 1 < ret.cols_.size (); i++)
{
cols.push_back (get_column_description (ret.cols_, i, i == 0));
- spacer.add_spring (cols[i].ideal_, cols[i].inverse_hooke_);
+ spacer.add_spring (cols[i].spring_);
}
for (vsize i = 0; i < cols.size (); i++)
{