Permits all positive and zero-length buildings in skylines (issue 3161)

[lilypond.git] / lily / skyline.cc

diff --git a/lily/skyline.cc b/lily/skyline.cc
index 1d6e4d5e78e81c2efb24b88a54ddae297035e4fa..9908c611d59efaea501e94e30c414a7c23ebc705 100644 (file)
--- a/lily/skyline.cc
+++ b/lily/skyline.cc
@@ -56,10 +56,6 @@
    but the distance routine does.
 */
 
-/* If we start including very thin buildings, numerical accuracy errors can
-   arise. Therefore, we ignore all buildings that are less than epsilon wide. */
-#define EPS 1e-5
-
 static void
 print_buildings (list<Building> const &b)
 {
@@ -213,6 +209,7 @@ Skyline::normalize ()
 {
   bool last_empty = false;
   list<Building>::iterator i;
+
   for (i = buildings_.begin (); i != buildings_.end (); i++)
     {
       if (last_empty && i->y_intercept_ == -infinity_f)
@@ -300,8 +297,7 @@ Skyline::internal_merge_skyline (list<Building> *s1, list<Building> *s2,
           break;
         }
 
-      /* only include buildings wider than epsilon */
-      if (end > x + EPS)
+      if (end >= x)
         {
           b.leading_part (end);
           b.start_ = last_end;
@@ -328,18 +324,15 @@ empty_skyline (list<Building> *const ret)
 static void
 single_skyline (Building b, list<Building> *const ret)
 {
-  if (b.end_ > b.start_ + EPS)
-    {
-      ret->push_back (Building (-infinity_f, -infinity_f,
-                                -infinity_f, b.start_));
-      ret->push_back (b);
-      ret->push_back (Building (b.end_, -infinity_f,
-                                -infinity_f, infinity_f));
-    }
-  else
-    {
-      empty_skyline (ret);
-    }
+  assert (b.end_ >= b.start_);
+
+  if (b.start_ != -infinity_f)
+    ret->push_back (Building (-infinity_f, -infinity_f,
+                              -infinity_f, b.start_));
+  ret->push_back (b);
+  if (b.end_ != infinity_f)
+    ret->push_back (Building (b.end_, -infinity_f,
+                              -infinity_f, infinity_f));
 }
 
 /* remove a non-overlapping set of boxes from BOXES and build a skyline
@@ -374,7 +367,7 @@ non_overlapping_skyline (list<Building> *const buildings)
           continue;
         }
 
-      if (x1 > last_end + EPS)
+      if (x1 >= last_end)
         result.push_back (Building (last_end, -infinity_f, -infinity_f, x1));
 
       result.push_back (*i);
@@ -473,20 +466,16 @@ Skyline::Skyline (Direction sky)
 /*
   Build skyline from a set of boxes.
 
-  Boxes should have fatness in the horizon_axis, otherwise they are ignored.
+  Boxes should be non-empty on both axes.  Otherwise, they will be ignored
  */
 Skyline::Skyline (vector<Box> const &boxes, Axis horizon_axis, Direction sky)
 {
   list<Building> buildings;
   sky_ = sky;
 
-  Axis vert_axis = other_axis (horizon_axis);
   for (vsize i = 0; i < boxes.size (); i++)
-    {
-      Interval iv = boxes[i][horizon_axis];
-      if (iv.length () > EPS && !boxes[i][vert_axis].is_empty ())
-        buildings.push_front (Building (boxes[i], horizon_axis, sky));
-    }
+    if (!boxes[i].is_empty ())
+      buildings.push_front (Building (boxes[i], horizon_axis, sky));
 
   buildings_ = internal_build_skyline (&buildings);
   normalize ();
@@ -495,7 +484,8 @@ Skyline::Skyline (vector<Box> const &boxes, Axis horizon_axis, Direction sky)
 /*
   build skyline from a set of line segments.
 
-  Buildings should have fatness in the horizon_axis, otherwise they are ignored.
+  Segments can be articulated from left to right or right to left.
+  In the case of the latter, they will be stored internally as left to right.
  */
 Skyline::Skyline (vector<Drul_array<Offset> > const &segments, Axis horizon_axis, Direction sky)
 {
@@ -515,7 +505,7 @@ Skyline::Skyline (vector<Drul_array<Offset> > const &segments, Axis horizon_axis
       Real y1 = left[other_axis (horizon_axis)] * sky;
       Real y2 = right[other_axis (horizon_axis)] * sky;
 
-      if (x1 + EPS < x2)
+      if (x1 <= x2)
         buildings.push_back (Building (x1, y1, y2, x2));
     }
 
@@ -553,6 +543,7 @@ Skyline::Skyline (Box const &b, Axis horizon_axis, Direction sky)
   sky_ = sky;
   Building front (b, horizon_axis, sky);
   single_skyline (front, &buildings_);
+  normalize ();
 }
 
 void
@@ -590,8 +581,7 @@ Skyline::insert (Box const &b, Axis a)
     }
 
   /* do the same filtering as in Skyline (vector<Box> const&, etc.) */
-  Interval iv = b[a];
-  if (iv.length () <= EPS || b[other_axis (a)].is_empty ())
+  if (b.is_empty ())
     return;
 
   my_bld.splice (my_bld.begin (), buildings_);
@@ -650,6 +640,12 @@ Skyline::internal_distance (Skyline const &other, Real horizon_padding, Real *to
 Skyline
 Skyline::padded (Real horizon_padding) const
 {
+  if (horizon_padding < 0.0)
+    warning ("Cannot have negative horizon padding.  Junking.");
+
+  if (horizon_padding <= 0.0)
+    return *this;
+
   list<Building> pad_buildings;
   for (list<Building>::const_iterator i = buildings_.begin (); i != buildings_.end (); ++i)
     {
@@ -766,6 +762,12 @@ Skyline::max_height () const
   return sky_ * ret;
 }
 
+Direction
+Skyline::direction () const
+{
+  return sky_;
+}
+
 Real
 Skyline::left () const
 {
@@ -922,3 +924,12 @@ 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));
 }
+
+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);
+  LY_ASSERT_SMOB (Skyline, sky, 1);
+  return scm_from_bool (s->is_empty ());
+}