2 simple-spacer-scheme.cc -- implement Simple_spacer
4 source file of the GNU LilyPond music typesetter
6 (c) 2005 Han-Wen Nienhuys <hanwen@xs4all.nl>
13 #include "paper-column.hh"
16 #include "simple-spacer.hh"
18 LY_DEFINE (ly_solve_spring_rod_problem, "ly:solve-spring-rod-problem",
19 4, 1, 0, (SCM springs, SCM rods, SCM length, SCM ragged),
20 "Solve a spring and rod problem for @var{count} objects, that "
21 "are connected by @var{count-1} springs, and an arbitrary number of rods "
22 "Springs have the format (ideal, hooke) and rods (idx1, idx2, distance) "
23 "@var{length} is a number, @var{ragged} a boolean "
24 "Return: a list containing the force (positive for stretching, "
25 "negative for compressing and #f for non-satisfied constraints) "
26 "followed by the @var{spring-count}+1 positions of the objects. ")
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_ARG2, __FUNCTION__, "list of rods");
34 SCM_ASSERT_TYPE (scm_is_number (length) || length == SCM_BOOL_F,
35 length, SCM_ARG3, __FUNCTION__, "number or #f");
37 bool is_ragged = ragged == SCM_BOOL_T;
39 for (SCM s = springs; scm_is_pair (s); s = scm_cdr (s))
41 Real ideal = scm_to_double (scm_caar (s));
42 Real hooke = scm_to_double (scm_cadar (s));
44 spacer.add_spring (ideal, 1 / hooke);
47 for (SCM s = rods; scm_is_pair (s); s = scm_cdr (s))
49 SCM entry = scm_car (s);
50 int l = scm_to_int (scm_car (entry));
51 int r = scm_to_int (scm_cadr (entry));
52 entry = scm_cddr (entry);
54 Real distance = scm_to_double (scm_car (entry));
55 spacer.add_rod (l, r, distance);
58 spacer.line_len_ = scm_to_double (length);
61 spacer.my_solve_natural_len ();
63 spacer.my_solve_linelen ();
67 for (int i = 0; i < spacer.springs_.size (); i++)
69 Real l = spacer.springs_[i].length ((is_ragged) ? 0.0 : spacer.force_);
70 posns.push (posns.top () + l);
73 SCM force_return = SCM_BOOL_F;
74 if (!isinf (spacer.force_)
75 && (spacer.is_active () || is_ragged))
76 force_return = scm_from_double (spacer.force_);
79 && posns.top () > spacer.line_len_)
80 force_return = SCM_BOOL_F;
83 for (int i = posns.size (); i--;)
84 retval = scm_cons (scm_from_double (posns[i]), retval);
86 retval = scm_cons (force_return, retval);