Fix T69822: Switching sculpt objects breaks undo

This introduces object mode tagging for data which hasn't yet been
written back to the ID data.

Now when selecting other sculpt objects, the original objects data is
flushed back to the ID before writing a memfile undo step.

1 files changed, 13 insertions, 14 deletions

diff --git a/source/blender/editors/sculpt_paint/sculpt_undo.c b/source/blender/editors/sculpt_paint/sculpt_undo.c
index fc990c01bfb..052f2bd03a4 100644
--- a/source/blender/editors/sculpt_paint/sculpt_undo.c
+++ b/source/blender/editors/sculpt_paint/sculpt_undo.c
@@ -1027,6 +1027,8 @@ SculptUndoNode *sculpt_undo_push_node(Object *ob, PBVHNode *node, SculptUndoType
   /* list is manipulated by multiple threads, so we lock */
   BLI_thread_lock(LOCK_CUSTOM1);
 
+  ss->needs_flush_to_id = 1;
+
   if (ss->bm || ELEM(type, SCULPT_UNDO_DYNTOPO_BEGIN, SCULPT_UNDO_DYNTOPO_END)) {
     /* Dynamic topology stores only one undo node per stroke,
      * regardless of the number of PBVH nodes modified */
@@ -1142,17 +1144,6 @@ typedef struct SculptUndoStep {
   UndoSculpt data;
 } SculptUndoStep;
 
-static bool sculpt_undosys_poll(bContext *C)
-{
-  Object *obact = CTX_data_active_object(C);
-  if (obact && obact->type == OB_MESH) {
-    if (obact && (obact->mode & OB_MODE_SCULPT)) {
-      return true;
-    }
-  }
-  return false;
-}
-
 static void sculpt_undosys_step_encode_init(struct bContext *UNUSED(C), UndoStep *us_p)
 {
   SculptUndoStep *us = (SculptUndoStep *)us_p;
@@ -1161,7 +1152,7 @@ static void sculpt_undosys_step_encode_init(struct bContext *UNUSED(C), UndoStep
 }
 
 static bool sculpt_undosys_step_encode(struct bContext *UNUSED(C),
-                                       struct Main *UNUSED(bmain),
+                                       struct Main *bmain,
                                        UndoStep *us_p)
 {
   /* dummy, encoding is done along the way by adding tiles
@@ -1174,6 +1165,11 @@ static bool sculpt_undosys_step_encode(struct bContext *UNUSED(C),
     us->step.use_memfile_step = true;
   }
   us->step.is_applied = true;
+
+  if (!BLI_listbase_is_empty(&us->data.nodes)) {
+    bmain->is_memfile_undo_flush_needed = true;
+  }
+
   return true;
 }
 
@@ -1256,7 +1252,11 @@ static void sculpt_undosys_step_decode(
         me->flag &= ~ME_SCULPT_DYNAMIC_TOPOLOGY;
         ED_object_sculptmode_enter_ex(bmain, depsgraph, scene, ob, true, NULL);
       }
-      BLI_assert(sculpt_undosys_poll(C));
+
+      if (ob->sculpt) {
+        ob->sculpt->needs_flush_to_id = 1;
+      }
+      bmain->is_memfile_undo_flush_needed = true;
     }
     else {
       BLI_assert(0);
@@ -1295,7 +1295,6 @@ void ED_sculpt_undo_geometry_end(struct Object *ob)
 void ED_sculpt_undosys_type(UndoType *ut)
 {
   ut->name = "Sculpt";
-  ut->poll = sculpt_undosys_poll;
   ut->step_encode_init = sculpt_undosys_step_encode_init;
   ut->step_encode = sculpt_undosys_step_encode;
   ut->step_decode = sculpt_undosys_step_decode;