2 simple-spacer-scheme.cc -- implement Simple_spacer
4 source file of the GNU LilyPond music typesetter
6 (c) 2005--2007 Han-Wen Nienhuys <hanwen@xs4all.nl>
11 #include "paper-column.hh"
14 #include "simple-spacer.hh"
16 LY_DEFINE (ly_solve_spring_rod_problem, "ly:solve-spring-rod-problem",
17 4, 1, 0, (SCM springs, SCM rods, SCM length, SCM ragged),
18 "Solve a spring and rod problem for @var{count} objects, that "
19 "are connected by @var{count-1} springs, and an arbitrary number of rods "
20 "Springs have the format (ideal, hooke) and rods (idx1, idx2, distance) "
21 "@var{length} is a number, @var{ragged} a boolean "
22 "Return: a list containing the force (positive for stretching, "
23 "negative for compressing and #f for non-satisfied constraints) "
24 "followed by the @var{spring-count}+1 positions of the objects. ")
26 LY_FUNC_NOTE_FIRST_ARG(springs);
28 int len = scm_ilength (springs);
30 return scm_list_2 (scm_from_double (0.0), scm_from_double (0.0));
32 SCM_ASSERT_TYPE (len >= 0, springs, SCM_ARG1, __FUNCTION__, "list of springs");
33 SCM_ASSERT_TYPE (scm_ilength (rods) > 0, rods, SCM_ARG1, __FUNCTION__, "list of rods");
34 LY_ASSERT_TYPE(scm_is_number, 3);
36 bool is_ragged = ragged == SCM_BOOL_T;
38 for (SCM s = springs; scm_is_pair (s); s = scm_cdr (s))
40 Real ideal = scm_to_double (scm_caar (s));
41 Real hooke = scm_to_double (scm_cadar (s));
43 spacer.add_spring (ideal, 1 / hooke);
46 for (SCM s = rods; scm_is_pair (s); s = scm_cdr (s))
48 SCM entry = scm_car (s);
49 int l = scm_to_int (scm_car (entry));
50 int r = scm_to_int (scm_cadr (entry));
51 entry = scm_cddr (entry);
53 Real distance = scm_to_double (scm_car (entry));
54 spacer.add_rod (l, r, distance);
57 spacer.solve (scm_to_double (length), is_ragged);
59 vector<Real> posns = spacer.spring_positions ();
61 SCM force_return = spacer.fits () ? scm_from_double (spacer.force ()) : SCM_BOOL_F;
64 for (vsize i = posns.size (); i--;)
65 retval = scm_cons (scm_from_double (posns[i]), retval);
67 retval = scm_cons (force_return, retval);