source file of the GNU LilyPond music typesetter
- (c) 2005 Han-Wen Nienhuys <hanwen@xs4all.nl>
+ (c) 2005--2009 Han-Wen Nienhuys <hanwen@xs4all.nl>
*/
#include <cstdio>
LY_DEFINE (ly_solve_spring_rod_problem, "ly:solve-spring-rod-problem",
4, 1, 0, (SCM springs, SCM rods, SCM length, SCM ragged),
- "Solve a spring and rod problem for @var{count} objects, that "
- "are connected by @var{count-1} springs, and an arbitrary number of rods "
- "Springs have the format (ideal, hooke) and rods (idx1, idx2, distance) "
- "@var{length} is a number, @var{ragged} a boolean "
- "Return: a list containing the force (positive for stretching, "
- "negative for compressing and #f for non-satisfied constraints) "
- "followed by the @var{spring-count}+1 positions of the objects. ")
+ "Solve a spring and rod problem for @var{count} objects, that"
+ " are connected by @var{count}-1 @var{springs}, and an arbitrary"
+ " number of @var{rods}. @var{count} is implicitly given by"
+ " @var{springs} and @var{rods}. The @var{springs} argument has"
+ " the format @code{(ideal, inverse_hook)} and @var{rods} is of"
+ " the form @code{(idx1, idx2, distance)}.\n"
+ "\n"
+ "@var{length} is a number, @var{ragged} a boolean.\n"
+ "\n"
+ "The function returns a list containing the force (positive for"
+ " stretching, negative for compressing and @code{#f} for"
+ " non-satisfied constraints) followed by @var{spring-count}+1"
+ " positions of the objects.")
{
int len = scm_ilength (springs);
if (len == 0)
return scm_list_2 (scm_from_double (0.0), scm_from_double (0.0));
SCM_ASSERT_TYPE (len >= 0, springs, SCM_ARG1, __FUNCTION__, "list of springs");
- SCM_ASSERT_TYPE (scm_ilength (rods) >= 0, rods, SCM_ARG2, __FUNCTION__, "list of rods");
- SCM_ASSERT_TYPE (scm_is_number (length) || length == SCM_BOOL_F,
- length, SCM_ARG3, __FUNCTION__, "number or #f");
+ SCM_ASSERT_TYPE (scm_ilength (rods) > 0, rods, SCM_ARG1, __FUNCTION__, "list of rods");
+ LY_ASSERT_TYPE (scm_is_number, length, 3);
bool is_ragged = ragged == SCM_BOOL_T;
Simple_spacer spacer;
for (SCM s = springs; scm_is_pair (s); s = scm_cdr (s))
{
Real ideal = scm_to_double (scm_caar (s));
- Real hooke = scm_to_double (scm_cadar (s));
+ Real inv_hooke = scm_to_double (scm_cadar (s));
- spacer.add_spring (ideal, 1 / hooke);
+ Spring sp (ideal, 0.0);
+ sp.set_inverse_compress_strength (inv_hooke);
+ sp.set_inverse_stretch_strength (inv_hooke);
+
+ spacer.add_spring (sp);
}
for (SCM s = rods; scm_is_pair (s); s = scm_cdr (s))
spacer.add_rod (l, r, distance);
}
- spacer.line_len_ = scm_to_double (length);
-
- if (is_ragged)
- spacer.my_solve_natural_len ();
- else
- spacer.my_solve_linelen ();
-
- Array<Real> posns;
- posns.push (0.0);
- for (int i = 0; i < spacer.springs_.size (); i++)
- {
- Real l = spacer.springs_[i].length ((is_ragged) ? 0.0 : spacer.force_);
- posns.push (posns.top () + l);
- }
+ spacer.solve (scm_to_double (length), is_ragged);
- SCM force_return = SCM_BOOL_F;
- if (!isinf (spacer.force_)
- && (spacer.is_active () || is_ragged))
- force_return = scm_from_double (spacer.force_);
+ vector<Real> posns = spacer.spring_positions ();
- if (is_ragged
- && posns.top () > spacer.line_len_)
- force_return = SCM_BOOL_F;
+ SCM force_return = spacer.fits () ? scm_from_double (spacer.force ()) : SCM_BOOL_F;
SCM retval = SCM_EOL;
- for (int i = posns.size (); i--;)
+ for (vsize i = posns.size (); i--;)
retval = scm_cons (scm_from_double (posns[i]), retval);
retval = scm_cons (force_return, retval);