/*
This file is part of LilyPond, the GNU music typesetter.
- Copyright (C) 2006--2012 Joe Neeman <joeneeman@gmail.com>
+ Copyright (C) 2006--2015 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
#include <deque>
#include <cstdio>
-#include "ly-smobs.icc"
-
/* A skyline is a sequence of non-overlapping buildings: something like
this:
_______
This means that the merging routine doesn't need to be aware of direction,
but the distance routine does.
- Be careful about numerical accuracy. When dealing with extremely small values,
- computation errors may arise due to the use of floating point arithmetic.
- For example, if left and right have equal values to start with, in C++
- they may not receive the same value after
-
- left = left*factor + offset;
- right = right*factor + offset;
-
- Which is very unfortunate. Maybe using GCC compiler options to disallow
- extended precision for intermediate results and/or the choice to store
- intermediates with less than full precision would retain some kind of
- deterministic behavior that way.
-
- Anyway, it seems that accepting extremely narrow building in skylines
- doesn't cause accuracy problems to us, so we allow arbitrarily small buildings.
- However, as Keith pointed out, problems may appear if more than one operation
- is done before storing the result, and/or there are different code paths
- for doing the operations to the different ends of an interval.
+ From 2007 through 2012, buildings of width less than EPS were discarded,
+ citing numerical accuracy concerns. We remember that floating point
+ comparisons of nearly-equal values can be affected by rounding error.
+ Also, some target machines use the x87 floating point unit, which provides
+ extended precision for intermediate results held in registers. On this type
+ of hardware comparisons such as
+ double c = 1.0/3.0; boolean compare = (c == 1.0/3.0)
+ could go either way because the 1.0/3.0 is allowed to be kept
+ higher precision than the variable 'c'.
+ Alert to these considerations, we now accept buildings of zero-width.
*/
static void
assert (start_height == end_height);
y_intercept_ = start_height;
}
+ else if (fabs (slope_) > 1e6)
+ // too steep to be stored in slope-intercept form, given round-off error
+ {
+ slope_ = 0.0;
+ y_intercept_ = max (start_height, end_height);
+ }
else
y_intercept_ = start_height - slope_ * start;
}
return isnan (ret) ? -infinity_f : ret;
}
-void
-Building::leading_part (Real chop)
-{
- assert (chop <= end_);
- end_ = chop;
-}
-
// Returns a shift s such that (x + s, y) intersects the roof of
// this building. If no such shift exists, returns infinity_f.
Real
return infinity_f;
}
-static Real
-first_intersection (Building const &b, list<Building> *const s, Real start_x)
-{
- while (!s->empty () && start_x < b.end_)
- {
- Building c = s->front ();
-
- // conceals and intersection_x involve multiplication and
- // division. Avoid that, if we can.
- if (c.y_intercept_ == -infinity_f)
- {
- if (c.end_ > b.end_)
- return b.end_;
- start_x = c.end_;
- s->pop_front ();
- continue;
- }
-
- if (c.conceals (b, start_x))
- return start_x;
-
- Real i = b.intersection_x (c);
- if (i > start_x && i <= b.end_ && i <= c.end_)
- return i;
-
- start_x = c.end_;
- if (b.end_ > c.end_)
- s->pop_front ();
- }
- return b.end_;
-}
-
bool
-Building::conceals (Building const &other, Real x) const
+Building::above (Building const &other, Real x) const
{
- if (slope_ == other.slope_)
- return y_intercept_ > other.y_intercept_;
-
- /* their slopes were not equal, so there is an intersection point */
- Real i = intersection_x (other);
- return (i <= x && slope_ > other.slope_)
- || (i > x && slope_ < other.slope_);
+ return (isinf (y_intercept_) || isinf (other.y_intercept_) || isinf (x))
+ ? y_intercept_ > other.y_intercept_
+ : (slope_ - other.slope_) * x + y_intercept_ > other.y_intercept_;
}
// Remove redundant empty buildings from the skyline.
}
void
-Skyline::deholify ()
-{
- // Since a skyline should always be normalized, we can
- // assume that there are never two adjacent empty buildings.
- // That is, if center is empty then left and right are not.
- list<Building>::iterator left = buildings_.begin ();
- list<Building>::iterator center = buildings_.begin ();
- list<Building>::iterator right;
-
- for (right = buildings_.begin (); right != buildings_.end (); right++)
- {
- if (center != buildings_.begin () && center->y_intercept_ == -infinity_f)
- {
- Real p1 = left->height (left->end_);
- Real p2 = right->height (right->start_);
- *center = Building (center->start_, p1, p2, center->end_);
-
- left = center;
- center = right;
- }
- }
-}
-
-void
-Skyline::internal_merge_skyline (list<Building> *s1, list<Building> *s2,
+Skyline::internal_merge_skyline (list<Building> *sb, list<Building> *sc,
list<Building> *const result) const
{
- if (s1->empty () || s2->empty ())
+ if (sb->empty () || sc->empty ())
{
programming_error ("tried to merge an empty skyline");
return;
}
- Real x = -infinity_f;
- Real last_end = -infinity_f;
- while (!s1->empty ())
+ Building b = sb->front ();
+ for (; !sc->empty (); sc->pop_front ())
{
- if (s2->front ().conceals (s1->front (), x))
- swap (s1, s2);
-
- Building b = s1->front ();
- Building c = s2->front ();
-
- // Optimization: if the other skyline is empty at this point,
- // we can avoid testing some intersections. Just grab as many
- // buildings from s1 as we can, and shove them onto the output.
- if (c.y_intercept_ == -infinity_f
- && c.end_ >= b.end_)
+ /* Building b is continuing from the previous pass through the loop.
+ Building c is newly-considered, and starts no earlier than b started.
+ The comments draw b as if its roof had zero slope ----.
+ with dashes where b lies above c.
+ The roof of c could rise / or fall \ through the roof of b,
+ or the vertical sides | of c could intersect the roof of b. */
+ Building c = sc->front ();
+ if (b.end_ < c.end_) /* finish with b */
{
- list<Building>::iterator i = s1->begin ();
- i++;
- while (i != s1->end () && i->end_ <= c.end_)
- i++;
-
- s1->front ().start_ = x;
- result->splice (result->end (), *s1, s1->begin (), i);
- x = result->back ().end_;
- last_end = x;
- continue;
- }
-
- Real end = first_intersection (b, s2, x);
- if (s2->empty ())
- {
- b.start_ = last_end;
- result->push_back (b);
- break;
+ if (b.end_ <= b.start_) /* we are already finished with b */
+ ;
+ else if (c.above (b, c.start_)) /* -| . | */
+ {
+ Building m (b);
+ m.end_ = c.start_;
+ if (m.end_ > m.start_)
+ result->push_back (m);
+ if (b.above (c, b.end_)) /* -|\--. */
+ {
+ Building n (c);
+ n.end_ = b.start_ = b.intersection_x (c);
+ result->push_back (n);
+ result->push_back (b);
+ }
+ }
+ else
+ {
+ if (c.above (b, b.end_)) /* ---/ . | */
+ b.end_ = b.intersection_x (c);
+ else /* -----. */
+ c.start_ = b.end_;
+ result->push_back (b);
+ }
+ /* 'c' continues further, so move it into 'b' for the next pass. */
+ b = c;
+ swap (sb, sc);
}
-
- if (end >= x)
+ else /* b.end_ > c.end_ so finish with c */
{
- b.leading_part (end);
- b.start_ = last_end;
- last_end = b.end_;
- result->push_back (b);
+ if (c.above (b, c.start_)) /* -| |---. */
+ {
+ Building m (b);
+ m.end_ = c.start_;
+ if (m.end_ > m.start_)
+ result->push_back (m);
+ if (b.above (c, c.end_)) /* -| \---. */
+ c.end_ = b.intersection_x (c);
+ }
+ else if (c.above (b, c.end_)) /* ---/|--. */
+ {
+ Building m (b);
+ c.start_ = m.end_ = b.intersection_x (c);
+ result->push_back (m);
+ }
+ else /* c is completely hidden by b */
+ continue;
+ result->push_back (c);
+ b.start_ = c.end_;
}
-
- if (end >= s1->front ().end_)
- s1->pop_front ();
-
- x = end;
}
+ if (b.end_ > b.start_)
+ result->push_back (b);
}
static void
continue;
}
- if (x1 >= last_end)
+ // Insert empty Buildings into any gaps. (TODO: is this needed? -KOH)
+ if (x1 > last_end)
result.push_back (Building (last_end, -infinity_f, -infinity_f, x1));
result.push_back (*i);
empty_skyline (&buildings_);
}
-Skyline::Skyline (Skyline const &src)
-{
- sky_ = src.sky_;
-
- /* doesn't a list's copy constructor do this? -- jneem */
- for (list<Building>::const_iterator i = src.buildings_.begin ();
- i != src.buildings_.end (); i++)
- {
- buildings_.push_back (Building ((*i)));
- }
-}
-
Skyline::Skyline (Direction sky)
{
sky_ = sky;
sky_ = sky;
for (vsize i = 0; i < boxes.size (); i++)
- if (!boxes[i].is_empty ())
+ if (!boxes[i].is_empty (X_AXIS)
+ && !boxes[i].is_empty (Y_AXIS))
buildings.push_front (Building (boxes[i], horizon_axis, sky));
buildings_ = internal_build_skyline (&buildings);
Skyline::Skyline (Box const &b, Axis horizon_axis, Direction sky)
{
sky_ = sky;
- Building front (b, horizon_axis, sky);
- single_skyline (front, &buildings_);
- normalize ();
+ if (!b.is_empty (X_AXIS) && !b.is_empty (Y_AXIS))
+ {
+ Building front (b, horizon_axis, sky);
+ single_skyline (front, &buildings_);
+ normalize ();
+ }
}
void
}
/* do the same filtering as in Skyline (vector<Box> const&, etc.) */
- if (b.is_empty ())
+ if (b.is_empty (X_AXIS) || b.is_empty (Y_AXIS))
return;
my_bld.splice (my_bld.begin (), buildings_);
/****************************************************************/
-IMPLEMENT_SIMPLE_SMOBS (Skyline);
-IMPLEMENT_TYPE_P (Skyline, "ly:skyline?");
-IMPLEMENT_DEFAULT_EQUAL_P (Skyline);
-
-SCM
-Skyline::mark_smob (SCM s)
-{
- ASSERT_LIVE_IS_ALLOWED (s);
- return SCM_EOL;
-}
-
-int
-Skyline::print_smob (SCM s, SCM port, scm_print_state *)
-{
- Skyline *r = (Skyline *) SCM_CELL_WORD_1 (s);
- (void) r;
-
- scm_puts ("#<Skyline>", port);
-
- return 1;
-}
+const char * const Skyline::type_p_name_ = "ly:skyline?";
MAKE_SCHEME_CALLBACK_WITH_OPTARGS (Skyline, get_touching_point, 3, 1, "")
SCM
LY_ASSERT_SMOB (Skyline, other_skyline_scm, 1);
Real horizon_padding = 0;
- if (horizon_padding_scm != SCM_UNDEFINED)
+ if (!SCM_UNBNDP (horizon_padding_scm))
{
LY_ASSERT_TYPE (scm_is_number, horizon_padding_scm, 3);
horizon_padding = scm_to_double (horizon_padding_scm);
}
- Skyline *skyline = Skyline::unsmob (skyline_scm);
- Skyline *other_skyline = Skyline::unsmob (other_skyline_scm);
+ Skyline *skyline = unsmob<Skyline> (skyline_scm);
+ Skyline *other_skyline = unsmob<Skyline> (other_skyline_scm);
return scm_from_double (skyline->touching_point (*other_skyline, horizon_padding));
}
LY_ASSERT_SMOB (Skyline, other_skyline_scm, 1);
Real horizon_padding = 0;
- if (horizon_padding_scm != SCM_UNDEFINED)
+ if (!SCM_UNBNDP (horizon_padding_scm))
{
LY_ASSERT_TYPE (scm_is_number, horizon_padding_scm, 3);
horizon_padding = scm_to_double (horizon_padding_scm);
}
- Skyline *skyline = Skyline::unsmob (skyline_scm);
- Skyline *other_skyline = Skyline::unsmob (other_skyline_scm);
+ Skyline *skyline = unsmob<Skyline> (skyline_scm);
+ Skyline *other_skyline = unsmob<Skyline> (other_skyline_scm);
return scm_from_double (skyline->distance (*other_skyline, horizon_padding));
}
SCM
Skyline::get_max_height (SCM skyline_scm)
{
- return scm_from_double (Skyline::unsmob (skyline_scm)->max_height ());
+ return scm_from_double (unsmob<Skyline> (skyline_scm)->max_height ());
}
MAKE_SCHEME_CALLBACK (Skyline, get_max_height_position, 1)
SCM
Skyline::get_max_height_position (SCM skyline_scm)
{
- return scm_from_double (Skyline::unsmob (skyline_scm)->max_height_position ());
+ return scm_from_double (unsmob<Skyline> (skyline_scm)->max_height_position ());
}
MAKE_SCHEME_CALLBACK (Skyline, get_height, 2)
Skyline::get_height (SCM skyline_scm, SCM x_scm)
{
Real x = robust_scm2double (x_scm, 0.0);
- return scm_from_double (Skyline::unsmob (skyline_scm)->height (x));
+ return scm_from_double (unsmob<Skyline> (skyline_scm)->height (x));
}
LY_DEFINE (ly_skyline_empty_p, "ly:skyline-empty?",
1, 0, 0, (SCM sky),
"Return whether @var{sky} is empty.")
{
- Skyline *s = Skyline::unsmob (sky);
+ Skyline *s = unsmob<Skyline> (sky);
LY_ASSERT_SMOB (Skyline, sky, 1);
return scm_from_bool (s->is_empty ());
}
projects / lilypond.git / blobdiff