Re: slurs avoid stafflines: move far enough; issue 3628 (issue 35310043)

[k-ohara5a5a]

Reviewers: janek,


https://codereview.appspot.com/35310043/diff/1/lily/slur-configuration.cc
File lily/slur-configuration.cc (right):

https://codereview.appspot.com/35310043/diff/1/lily/slur-configuration.cc#newcode64
lily/slur-configuration.cc:64: :
state.parameters_.gap_to_staffline_outside_);
On 2013/12/07 17:04:00, janek wrote:
> You forgot about staffline thickness:

I was ignoring line thicknesses.  There is the line-width for the
staff-lines and for the outline of the slur itself. I don't want to look
up grob-properties for every potential slur in the beauty contest, so I
cached the layout line-thickness in slur-scoring. The tapering of the
slur is a bigger effect, so I accounted for that as well.

Description:
slurs avoid stafflines: move far enough; issue 3628

Suggestion from Janek Warchoł to account for the fact that the curve
of a slur moves less than its control points, and to consider flattening
as well as increasing the curve.

Please review this at https://codereview.appspot.com/35310043/

Affected files (+41, -12 lines):
  M lily/include/slur-score-parameters.hh
  M lily/include/slur-scoring.hh
  M lily/slur-configuration.cc
  M lily/slur-score-parameters.cc
  M lily/slur-scoring.cc
  M lily/slur.cc
  M scm/layout-slur.scm


Index: lily/include/slur-score-parameters.hh
diff --git a/lily/include/slur-score-parameters.hh  
b/lily/include/slur-score-parameters.hh
index  
75b1ae8e4623cd75c45917e968a5a24f472cae30..7db1ba417c5c78836a8d0614e9881a010d064ec1  
100644
--- a/lily/include/slur-score-parameters.hh
+++ b/lily/include/slur-score-parameters.hh
@@ -40,6 +40,8 @@ struct Slur_score_parameters
   Real free_head_distance_;
   Real extra_encompass_collision_distance_;
   Real extra_encompass_free_distance_;
+  Real gap_to_staffline_inside_;
+  Real gap_to_staffline_outside_;
   Real absolute_closeness_measure_;
   Real edge_slope_exponent_;
   Real close_to_edge_length_;
Index: lily/include/slur-scoring.hh
diff --git a/lily/include/slur-scoring.hh b/lily/include/slur-scoring.hh
index  
e5ff38d6112c73750aab1d89e0baa8d1cbff4303..2fc069b9023c06d9a6f7c1a3e5214ae0d45d184a  
100644
--- a/lily/include/slur-scoring.hh
+++ b/lily/include/slur-scoring.hh
@@ -100,6 +100,7 @@ struct Slur_score_state
   Drul_array<Offset> base_attachments_;
   vector<Slur_configuration *> configurations_;
   Real staff_space_;
+  Real line_thickness_;
   Real thickness_;

   Slur_score_state ();
Index: lily/slur-configuration.cc
diff --git a/lily/slur-configuration.cc b/lily/slur-configuration.cc
index  
332995ac99ef051d760cf1a786080a16f8bf6314..46e9d917a119de2c03d2c985ddbdae878b3c3431  
100644
--- a/lily/slur-configuration.cc
+++ b/lily/slur-configuration.cc
@@ -43,27 +43,41 @@ avoid_staff_line (Slur_score_state const &state,
       && (state.extremes_[LEFT].staff_ == state.extremes_[RIGHT].staff_)
       && state.extremes_[LEFT].staff_ && state.extremes_[RIGHT].staff_)
     {
-      Real y = bez.curve_point (ts[0])[Y_AXIS];
+      Real t = ts[0]; //the first (usually only) point where slur is  
horizontal
+      Real y = bez.curve_point (t)[Y_AXIS];
+      // A Bezier curve at t moves 3t-3t² as far as the middle control  
points
+      Real factor = 3.0 * t * (1.0 - t);

       Grob *staff = state.extremes_[LEFT].staff_;

       Real p = 2 * (y - staff->relative_coordinate (state.common_[Y_AXIS],  
Y_AXIS))
                / state.staff_space_;

-      Real const round = my_round (p);
-      Real const frac = p - round;
-      if (fabs (frac) < 4 * state.thickness_
-          && Staff_symbol_referencer::on_staff_line (staff, int (round)))
+      int round_p = (int) my_round (p);
+      if (!Staff_symbol_referencer::on_staff_line (staff, round_p))
+        round_p += (p > round_p) ? 1 : -1;
+      if (!Staff_symbol_referencer::on_staff_line (staff, round_p))
+        return bez;
+
+      Real const distance = (p - round_p) * state.staff_space_ / 2.0;
+      // Allow half the thickness of the slur at the point t, plus one  
basic
+      // blot-diameter (half for the slur outline, half for the staff line)
+      Real const min_distance = 0.5 * state.thickness_ * factor
+        + state.line_thickness_
+        + ((state.dir_ * distance > 0.0)
+           ? state.parameters_.gap_to_staffline_inside_
+           : state.parameters_.gap_to_staffline_outside_);
+      if (fabs (distance) < min_distance)
         {
-          Direction resolution_dir = frac ? state.dir_ : CENTER;
+          Direction resolution_dir = (distance > 0.0) ? UP : DOWN;

-          // TODO: parameter
-          Real newp = round + resolution_dir * 5 * state.thickness_;
-
-          Real dy = (newp - p) * state.staff_space_ / 2.0;
+          Real dy = resolution_dir * (min_distance - fabs (distance));

+          // Shape the curve, moving the horizontal point by factor * dy
           bez.control_[1][Y_AXIS] += dy;
           bez.control_[2][Y_AXIS] += dy;
+          // Move the entire curve by the remaining amount
+          bez.translate (Offset (0.0, dy - factor * dy));
         }
     }
   return bez;
Index: lily/slur-score-parameters.cc
diff --git a/lily/slur-score-parameters.cc b/lily/slur-score-parameters.cc
index  
a8cbe4b7f90b7d610ad240633f6153de0e0cdc95..789e31ea4b4fbafaf1cecf576365f2bfd7b94ecd  
100644
--- a/lily/slur-score-parameters.cc
+++ b/lily/slur-score-parameters.cc
@@ -56,6 +56,10 @@ Slur_score_parameters::fill (Grob *me)
     = get_detail (details, ly_symbol2scm ("max-slope-factor"));
   free_head_distance_
     = get_detail (details, ly_symbol2scm ("free-head-distance"));
+  gap_to_staffline_inside_
+    = get_detail (details, ly_symbol2scm ("gap-to-staffline-inside"));
+  gap_to_staffline_outside_
+    = get_detail (details, ly_symbol2scm ("gap-to-staffline-outside"));
   absolute_closeness_measure_
     = get_detail (details, ly_symbol2scm ("absolute-closeness-measure"));
   extra_object_collision_penalty_
Index: lily/slur-scoring.cc
diff --git a/lily/slur-scoring.cc b/lily/slur-scoring.cc
index  
47bb40611c483018713bae43ec380b3ed1cd9461..98e3f2a45d0766b878343b0e6782906715d2bae9  
100644
--- a/lily/slur-scoring.cc
+++ b/lily/slur-scoring.cc
@@ -226,8 +226,8 @@ Slur_score_state::fill (Grob *me)

   Slur::replace_breakable_encompass_objects (me);
   staff_space_ = Staff_symbol_referencer::staff_space (me);
-  Real lt = me->layout ()->get_dimension (ly_symbol2scm  
("line-thickness"));
-  thickness_ = robust_scm2double (me->get_property ("thickness"), 1.0) *  
lt;
+  line_thickness_ = me->layout ()->get_dimension (ly_symbol2scm  
("line-thickness"));
+  thickness_ = robust_scm2double (me->get_property ("thickness"), 1.0) *  
line_thickness_;

   dir_ = slur_direction ();
   parameters_.fill (me);
Index: lily/slur.cc
diff --git a/lily/slur.cc b/lily/slur.cc
index  
0aa96c787d1d7ba482ed0170e3990ee703258236..10069aacd4323505577d4dea430569f545a56393  
100644
--- a/lily/slur.cc
+++ b/lily/slur.cc
@@ -542,6 +542,12 @@ ADD_INTERFACE (Slur,
                "@item head-slur-distance-max-ratio\n"
                "The maximum value for the ratio of distance between a"
                " note head and slur.\n"
+               "@item gap-to-staffline-inside\n"
+               "Minimum gap inside the curve of the slur"
+               " where the slur is parallel to a staffline.\n"
+               "@item gap-to-staffline-outside\n"
+               "Minimum gap outside the curve of the slur"
+               " where the slur is parallel to a staffline.\n"
                "@item free-slur-distance\n"
                "The amount of vertical free space that must exist"
                " between adjacent slurs.  This subproperty only works"
Index: scm/layout-slur.scm
diff --git a/scm/layout-slur.scm b/scm/layout-slur.scm
index  
7e5ab5858cb4750fba15b5f22d8b092c678fe810..7ad02ec09e3c921b4108ddb014757eb5017823dd  
100644
--- a/scm/layout-slur.scm
+++ b/scm/layout-slur.scm
@@ -28,6 +28,8 @@
     (max-slope-factor . 10)
     (free-head-distance . 0.3)
     (free-slur-distance . 0.8)
+    (gap-to-staffline-inside . 0.2)
+    (gap-to-staffline-outside . 0.1)
     (extra-object-collision-penalty . 50)
     (accidental-collision . 3)
     (extra-encompass-free-distance . 0.3)