2 files changed, 19 insertions, 10 deletions
diff --git a/source/blender/windowmanager/WM_types.h b/source/blender/windowmanager/WM_types.h
index 26c394a2ad3..7476410ec19 100644
--- a/source/blender/windowmanager/WM_types.h
+++ b/source/blender/windowmanager/WM_types.h
@@ -377,17 +377,24 @@ typedef struct wmTabletData {
 	float Ytilt;		/* as above */
 } wmTabletData;
 
-typedef struct {
+typedef enum { // motion progress, for modal handlers
+	P_NOT_STARTED,
+	P_STARTING,    // <--
+	P_IN_PROGRESS, // <-- only these are sent for NDOF motion
+	P_FINISHING,   // <--
+	P_FINISHED
+	} wmProgress;
+
+typedef struct wmNDOFMotionData {
 	/* awfully similar to GHOST_TEventNDOFMotionData... */
-
-   /* Each component normally ranges from -1 to +1, but can exceed that. */
-
-   float tx, ty, tz; /* translation: -x left, +y forward, -z up */
-   float rx, ry, rz; /* rotation:
-   	axis = (rx,ry,rz).normalized
-   	amount = (rx,ry,rz).magnitude [in revolutions, 1.0 = 360 deg] */
-   
-   float dt; // time since previous NDOF Motion event (or zero if this is the first)
+	// Each component normally ranges from -1 to +1, but can exceed that.
+	// These use blender standard view coordinates, with positive rotations being CCW about the axis.
+	float tx, ty, tz; // translation
+	float rx, ry, rz; // rotation:
+		// axis = (rx,ry,rz).normalized
+		// amount = (rx,ry,rz).magnitude [in revolutions, 1.0 = 360 deg]
+	float dt; // time since previous NDOF Motion event
+	wmProgress progress; // is this the first event, the last, or one of many in between?
 } wmNDOFMotionData;
 
 typedef struct wmTimer {
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index b41eebc5298..c2df53c9e91 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -2324,6 +2324,8 @@ static void attach_ndof_data(wmEvent* event, const GHOST_TEventNDOFMotionData* g
 
 	data->dt = ghost->dt;
 
+	data->progress = (wmProgress) ghost->progress;
+
 	event->custom = EVT_DATA_NDOF_MOTION;
 	event->customdata = data;
 	event->customdatafree = 1;