Tempo ramps - more bbt ruler drag work.

diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index 30b4935c3de1557c2ed4e16d4dbe1cb1e14ee107..07fa80d52cf69f2cc05137b694478d00b08f2ef1 100644 (file)
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -2788,13 +2788,15 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
        Metrics future_map;
        TempoSection* ts = 0;
 
-
        {
                Glib::Threads::RWLock::WriterLock lm (lock);
+
                ts = const_cast<TempoSection*>(&tempo_section_at_locked (_metrics, frame - 1));
+
                if (!ts) {
                        return;
                }
+
                TempoSection* prev_t = copy_metrics_and_point (_metrics, future_map, ts);
                TempoSection* prev_to_prev_t = 0;
                const frameoffset_t fr_off = end_frame - frame;
@@ -2803,6 +2805,7 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
                        prev_to_prev_t = const_cast<TempoSection*>(&tempo_section_at_locked (future_map, prev_t->frame() - 1));
                }
 
+
                /* the change in frames is the result of changing the slope of at most 2 previous tempo sections.
                   constant to constant is straightforward, as the tempo prev to prev_t has constant slope.
                */
@@ -2813,15 +2816,13 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
                        contribution = prev_to_prev_t->beats_per_minute() / (prev_to_prev_t->beats_per_minute() + prev_t->beats_per_minute());
                }
 
-               frameoffset_t frame_contribution = contribution * (double) fr_off;
-               frameoffset_t prev_t_frame_contribution = fr_off - frame_contribution;
+               frameoffset_t prev_t_frame_contribution = fr_off - (contribution * (double) fr_off);
 
                const double start_tempo = prev_t->tempo_at_frame (frame, _frame_rate);
                const double end_tempo = prev_t->tempo_at_frame (frame + prev_t_frame_contribution, _frame_rate);
                const double start_pulse = prev_t->pulse_at_frame (frame, _frame_rate);
                const double end_pulse = prev_t->pulse_at_frame (end_frame, _frame_rate);
-               const double dpulse = (start_pulse) / (end_pulse);
-               double new_bpm = prev_t->tempo_at_frame (prev_t->frame() - prev_t_frame_contribution, _frame_rate) * (double) prev_t->note_type();
+               double new_bpm;
 
                if (prev_t->type() == TempoSection::Constant || prev_t->c_func() == 0.0) {
 
@@ -2854,35 +2855,12 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
                                        }
                                }
                        }
-               } else if (prev_t->c_func() < 0.0) {
-
-                       const double end_minute = (((frame + prev_t_frame_contribution) - prev_t->frame()) / (double) _frame_rate) / 60.0;
-                       const double future_c = log (end_tempo / (new_bpm / (double) prev_t->note_type())) / end_minute;
-
-                       const double dtempo = (start_tempo) / (end_tempo);
-                       const double dframe = (frame) / (double) ((frame + prev_t_frame_contribution));
-
-                       /* limits - a bit clunky, but meh */
-                       if (future_c > -10.1 && future_c  < 10.1) {
-                               new_bpm = prev_t->beats_per_minute() * (dpulse / dtempo);
-                       } else {
-                               new_bpm = prev_t->beats_per_minute() * (dframe / dtempo);
-                       }
-
-               } else if (prev_t->c_func() > 0.0) {
-
+               } else {
                        const double end_minute = (((frame + prev_t_frame_contribution) - prev_t->frame()) / (double) _frame_rate) / 60.0;
-                       const double future_c = log (end_tempo / (new_bpm / (double) prev_t->note_type())) / end_minute;
 
-                       const double dtempo = (end_tempo) / (start_tempo);
-                       const double dframe = (frame) / (double) ((frame + prev_t_frame_contribution));
+                       new_bpm = (((start_pulse  - prev_t->pulse()) * prev_t->c_func())
+                                  / (exp (end_minute * prev_t->c_func()) - 1)) * (double) prev_t->note_type();
 
-                       /* limits - a bit clunky, but meh */
-                       if (future_c > -10.1 && future_c  < 10.1) {
-                               new_bpm = prev_t->beats_per_minute() * (dpulse / dtempo);
-                       } else {
-                               new_bpm = prev_t->beats_per_minute() * (dframe / dtempo);
-                       }
                }
 
                prev_t->set_beats_per_minute (new_bpm);