Fix T76078: GPencil: frames interpolation erase strokes

In some situations the stroke could be tagged and this tag was used to delete the interpolated strokes.

Now, the frames used as interpolated range are untagged before creating the interpolated strokes.

1 files changed, 17 insertions, 0 deletions

diff --git a/source/blender/editors/gpencil/gpencil_interpolate.c b/source/blender/editors/gpencil/gpencil_interpolate.c
index e6661e886b1..b6e84205815 100644
--- a/source/blender/editors/gpencil/gpencil_interpolate.c
+++ b/source/blender/editors/gpencil/gpencil_interpolate.c
@@ -134,6 +134,19 @@ static void gp_interpolate_free_temp_strokes(bGPDframe *gpf)
     }
   }
 }
+
+/* Helper: Untag all strokes. */
+static void gp_interpolate_untag_strokes(bGPDframe *gpf)
+{
+  BLI_assert(gpf != NULL);
+
+  LISTBASE_FOREACH (bGPDstroke *, gps, &gpf->strokes) {
+    if (gps->flag & GP_STROKE_TAG) {
+      gps->flag &= ~GP_STROKE_TAG;
+    }
+  }
+}
+
 /* Helper: Update all strokes interpolated */
 static void gp_interpolate_update_strokes(bContext *C, tGPDinterpolate *tgpi)
 {
@@ -265,6 +278,10 @@ static void gp_interpolate_set_points(bContext *C, tGPDinterpolate *tgpi)
     tgpil->prevFrame = gpl->actframe;
     tgpil->nextFrame = gpl->actframe->next;
 
+    /* Untag interpolated strokes to be sure nothing is pending. */
+    gp_interpolate_untag_strokes(tgpil->prevFrame);
+    gp_interpolate_untag_strokes(tgpil->nextFrame);
+
     BLI_addtail(&tgpi->ilayers, tgpil);
 
     /* create a new temporary frame */