Tempo ramps - improve constraint mod + bbt dragging begavior.

1 files changed, 32 insertions, 34 deletions

diff --git a/libs/ardour/tempo.cc b/libs/ardour/tempo.cc
index 7fd41b12c1..30b4935c3d 100644
--- a/libs/ardour/tempo.cc
+++ b/libs/ardour/tempo.cc
@@ -2798,7 +2798,6 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
 		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;
-		double new_bpm = 0.0;
 
 		if (prev_t && prev_t->pulse() > 0.0) {
 			prev_to_prev_t = const_cast<TempoSection*>(&tempo_section_at_locked (future_map, prev_t->frame() - 1));
@@ -2808,30 +2807,34 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
 		   constant to constant is straightforward, as the tempo prev to prev_t has constant slope.
 		*/
 		double contribution = 0.0;
-		frameoffset_t frame_contribution = 0;
-		frameoffset_t prev_t_frame_contribution = fr_off;
 
 		if (prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
 			/* prev to prev_t's position will remain constant in terms of frame and pulse. lets use frames. */
-			contribution = (prev_t->frame() - prev_to_prev_t->frame()) / (double) (frame - prev_to_prev_t->frame());
-			frame_contribution = contribution * (double) fr_off;
-			prev_t_frame_contribution -= frame_contribution;
+			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;
+
+		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();
+
 		if (prev_t->type() == TempoSection::Constant || prev_t->c_func() == 0.0) {
 
 			if (prev_t->position_lock_style() == MusicTime) {
 				if (prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
 					new_bpm = prev_t->beats_per_minute() * ((frame - prev_t->frame())
-										/ (double) (frame + prev_t_frame_contribution - prev_t->frame()));
+										/ (double) ((frame + prev_t_frame_contribution) - prev_t->frame()));
 
 				} else {
 					/* prev to prev is irrelevant */
-					const double meter_pulse = prev_t->pulse_at_frame (frame, _frame_rate);
-					const double frame_pulse = prev_t->pulse_at_frame (end_frame, _frame_rate);
 
-					if (frame_pulse != prev_t->pulse()) {
-						new_bpm = prev_t->beats_per_minute() * ((meter_pulse - prev_t->pulse()) / (frame_pulse - prev_t->pulse()));
+					if (start_pulse != prev_t->pulse()) {
+						new_bpm = prev_t->beats_per_minute() * ((start_pulse - prev_t->pulse()) / (end_pulse - prev_t->pulse()));
 					} else {
 						new_bpm = prev_t->beats_per_minute();
 					}
@@ -2840,7 +2843,7 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
 				/* AudioTime */
 				if (prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
 					new_bpm = prev_t->beats_per_minute() * ((frame - prev_t->frame())
-										/ (double) (frame + prev_t_frame_contribution - prev_t->frame()));
+										/ (double) ((frame + prev_t_frame_contribution) - prev_t->frame()));
 				} else {
 					/* prev_to_prev_t is irrelevant */
 
@@ -2852,38 +2855,33 @@ TempoMap::gui_dilate_tempo (const framepos_t& frame, const framepos_t& end_frame
 				}
 			}
 		} else if (prev_t->c_func() < 0.0) {
-			if (prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
-				new_bpm = prev_t->tempo_at_frame (prev_t->frame() + frame_contribution, _frame_rate) * (double) prev_t->note_type();
-			} else {
-				/* prev_to_prev_t is irrelevant */
-				new_bpm = prev_t->tempo_at_frame (prev_t->frame() + fr_off, _frame_rate) * (double) prev_t->note_type();
 
-			}
-			const double end_minute = ((end_frame - prev_t->frame()) / (double) _frame_rate) / 60.0;
-			const double end_tempo = prev_t->tempo_at_frame (end_frame, _frame_rate);
+			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 > -20.1 && future_c  < 20.1) {
-				new_bpm = prev_t->beats_per_minute() * ((frame - prev_t->frame())
-									/ (double) ((frame + prev_t_frame_contribution) - prev_t->frame()));
+			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) {
-			if (prev_to_prev_t && prev_to_prev_t->type() == TempoSection::Ramp) {
-				new_bpm = prev_t->tempo_at_frame (prev_t->frame() - frame_contribution, _frame_rate) * (double) prev_t->note_type();
-			} else {
-				/* prev_to_prev_t is irrelevant */
-				new_bpm = prev_t->tempo_at_frame (prev_t->frame() - fr_off, _frame_rate) * (double) prev_t->note_type();
-			}
-			const double end_minute = ((end_frame - prev_t->frame()) / (double) _frame_rate) / 60.0;
-			const double end_tempo = prev_t->tempo_at_frame (end_frame, _frame_rate);
+
+			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));
+
 			/* limits - a bit clunky, but meh */
-			if (future_c > -20.1 && future_c  < 20.1) {
-				new_bpm = prev_t->beats_per_minute() * ((frame - prev_t->frame())
-									/ (double) ((frame + prev_t_frame_contribution) - prev_t->frame()));
+			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);
 			}
 		}