3 files changed, 48 insertions, 1 deletions

diff --git a/source/blender/blenkernel/BKE_action.h b/source/blender/blenkernel/BKE_action.h
index fdfea95937b..60d988ab21e 100644
--- a/source/blender/blenkernel/BKE_action.h
+++ b/source/blender/blenkernel/BKE_action.h
@@ -122,6 +122,9 @@ void action_groups_add_channel(struct bAction *act,
 /* Remove the given channel from all groups */
 void action_groups_remove_channel(struct bAction *act, struct FCurve *fcu);
 
+/* Reconstruct group channel pointers. */
+void BKE_action_groups_reconstruct(struct bAction *act);
+
 /* Find a group with the given name */
 struct bActionGroup *BKE_action_group_find_name(struct bAction *act, const char name[]);
 
diff --git a/source/blender/blenkernel/intern/action.c b/source/blender/blenkernel/intern/action.c
index ad6c696b655..b474e3f5ec5 100644
--- a/source/blender/blenkernel/intern/action.c
+++ b/source/blender/blenkernel/intern/action.c
@@ -343,6 +343,43 @@ void action_groups_add_channel(bAction *act, bActionGroup *agrp, FCurve *fcurve)
   fcurve->grp = agrp;
 }
 
+/* Reconstruct group channel pointers.
+ * Assumes that the channels are still in the proper order, i.e. that channels of the same group
+ * are adjacent in the act->channels list. It also assumes that the groups
+ * referred to by the FCurves are already in act->groups.
+ */
+void BKE_action_groups_reconstruct(bAction *act)
+{
+  /* Sanity check. */
+  if (ELEM(NULL, act, act->groups.first)) {
+    return;
+  }
+
+  /* Clear out all group channels. Channels that are actually in use are
+   * reconstructed below; this step is necessary to clear out unused groups. */
+  LISTBASE_FOREACH (bActionGroup *, group, &act->groups) {
+    BLI_listbase_clear(&group->channels);
+  }
+
+  bActionGroup *grp;
+  bActionGroup *last_grp = NULL;
+  LISTBASE_FOREACH (FCurve *, fcurve, &act->curves) {
+    if (fcurve->grp == NULL) {
+      continue;
+    }
+
+    grp = fcurve->grp;
+    if (last_grp != grp) {
+      /* If this is the first time we see this group, this must be the first channel. */
+      grp->channels.first = fcurve;
+    }
+
+    /* This is the last channel, until it's overwritten by a later iteration. */
+    grp->channels.last = fcurve;
+    last_grp = grp;
+  }
+}
+
 /* Remove the given channel from all groups */
 void action_groups_remove_channel(bAction *act, FCurve *fcu)
 {
diff --git a/source/blender/editors/curve/editcurve.c b/source/blender/editors/curve/editcurve.c
index f18b6e91d0f..e7803fdaafb 100644
--- a/source/blender/editors/curve/editcurve.c
+++ b/source/blender/editors/curve/editcurve.c
@@ -922,11 +922,15 @@ static void fcurve_path_rename(AnimData *adt,
       nfcu = copy_fcurve(fcu);
       spath = nfcu->rna_path;
       nfcu->rna_path = BLI_sprintfN("%s%s", rna_path, suffix);
+
+      /* copy_fcurve() sets nfcu->grp to NULL. To maintain the groups, we need to keep the pointer.
+       * As a result, the group's 'channels' pointers will be wrong, which is fixed by calling
+       * `action_groups_reconstruct(action)` later, after all fcurves have been renamed. */
+      nfcu->grp = fcu->grp;
       BLI_addtail(curves, nfcu);
 
       if (fcu->grp) {
         action_groups_remove_channel(adt->action, fcu);
-        action_groups_add_channel(adt->action, fcu->grp, nfcu);
       }
       else if ((adt->action) && (&adt->action->curves == orig_curves)) {
         BLI_remlink(&adt->action->curves, fcu);
@@ -1077,6 +1081,9 @@ static void curve_rename_fcurves(Curve *cu, ListBase *orig_curves)
   }
 
   *orig_curves = curves;
+  if (adt != NULL) {
+    BKE_action_groups_reconstruct(adt->action);
+  }
 }
 
 /* return 0 if animation data wasn't changed, 1 otherwise */