Tracking: Implement tracks average operator

Average selected tracks into the new one. This can be used to improve
stability of tracking on blurry or non-very-sharp feature shapes.

Averaging happens for all position, pattern corners and search area.
Disabled markers do not take effect on averaging. Keyframed flag is
copied from source.

Gaps in the source tracks will be linearly interpolated, to reduce
result track jump. Note that this only applies to gaps "inbetween".
This means that if an input track doesn't have markers in the
beginning/end of it, there is nothing to interpolate with and the
result track will jump.

Available from the Track panel, under the Merge category.

Differential Revision: https://developer.blender.org/D6323

1 files changed, 22 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_tracking.h b/source/blender/blenkernel/BKE_tracking.h
index 5da8d969f1e..c2544c06514 100644
--- a/source/blender/blenkernel/BKE_tracking.h
+++ b/source/blender/blenkernel/BKE_tracking.h
@@ -89,6 +89,23 @@ struct MovieTrackingTrack *BKE_tracking_track_duplicate(struct MovieTrackingTrac
 void BKE_tracking_track_unique_name(struct ListBase *tracksbase, struct MovieTrackingTrack *track);
 void BKE_tracking_track_free(struct MovieTrackingTrack *track);
 
+void BKE_tracking_track_first_last_frame_get(const struct MovieTrackingTrack *track,
+                                             int *r_first_frame,
+                                             int *r_last_frame);
+
+void BKE_tracking_tracks_first_last_frame_minmax(/*const*/ struct MovieTrackingTrack **tracks,
+                                                 const int num_tracks,
+                                                 int *r_first_frame,
+                                                 int *r_last_frame);
+
+int BKE_tracking_count_selected_tracks_in_list(const struct ListBase *tracks_list);
+int BKE_tracking_count_selected_tracks_in_active_object(/*const*/ struct MovieTracking *tracking);
+
+/* Get array of selected tracks from the current active object in the tracking structure.
+ * If nothing is selected then the result is nullptr and `r_num_tracks` is set to 0. */
+struct MovieTrackingTrack **BKE_tracking_selected_tracks_in_active_object(
+    struct MovieTracking *tracking, int *r_num_tracks);
+
 void BKE_tracking_track_flag_set(struct MovieTrackingTrack *track, int area, int flag);
 void BKE_tracking_track_flag_clear(struct MovieTrackingTrack *track, int area, int flag);
 
@@ -96,10 +113,15 @@ bool BKE_tracking_track_has_marker_at_frame(struct MovieTrackingTrack *track, in
 bool BKE_tracking_track_has_enabled_marker_at_frame(struct MovieTrackingTrack *track, int framenr);
 
 void BKE_tracking_track_path_clear(struct MovieTrackingTrack *track, int ref_frame, int action);
+
 void BKE_tracking_tracks_join(struct MovieTracking *tracking,
                               struct MovieTrackingTrack *dst_track,
                               struct MovieTrackingTrack *src_track);
 
+void BKE_tracking_tracks_average(struct MovieTrackingTrack *dst_track,
+                                 /*const*/ struct MovieTrackingTrack **src_tracks,
+                                 const int num_src_tracks);
+
 struct MovieTrackingTrack *BKE_tracking_track_get_named(struct MovieTracking *tracking,
                                                         struct MovieTrackingObject *object,
                                                         const char *name);