io_scene_fbx/export_fbx_bin.py

@@ -2594,12 +2594,30 @@ def fbx_data_from_scene(scene, depsgraph, settings):
                 # If modifiers has been altered need to update dependency graph.
                 if backup_pose_positions or tmp_mods:
                     depsgraph.update()
-                ob_to_convert = ob.evaluated_get(depsgraph) if settings.use_mesh_modifiers else ob
+                if settings.use_mesh_modifiers:
+                    ob_to_convert = ob.evaluated_get(depsgraph)
                     # NOTE: The dependency graph might be re-evaluating multiple times, which could
                     # potentially free the mesh created early on. So we put those meshes to bmain and
                     # free them afterwards. Not ideal but ensures correct ownerwhip.
                     tmp_me = bpy.data.meshes.new_from_object(
                         ob_to_convert, preserve_all_data_layers=True, depsgraph=depsgraph)
+                    free = True
+
+                    # Usually the materials of the evaluated object will be the same, but modifiers, such as Geometry
+                    # Nodes, can change the materials.
+                    orig_mats = tuple(slot.material for slot in ob.material_slots)
+                    eval_mats = tuple(slot.material.original if slot.material else None
+                                      for slot in ob_to_convert.material_slots)
+                    if orig_mats != eval_mats:
+                        # Override the default behaviour of getting materials from ob_obj.bdata.material_slots.
+                        ob_obj.override_materials = eval_mats
+                else:
+                    # Creates a temporary mesh owned by the Object without adding it to bpy.data.meshes. Most
+                    # importantly, compared to bpy.data.meshes.new_from_object, it does not remove shape keys from the
+                    # new mesh. We'll forcefully free these temporary meshes at the end of the export.
+                    tmp_me = ob.to_mesh(preserve_all_data_layers=True, depsgraph=depsgraph)
+                    free = False
+
                 # Triangulate the mesh if requested
                 if settings.use_triangles:
                     import bmesh
@@ -2608,15 +2626,8 @@ def fbx_data_from_scene(scene, depsgraph, settings):
                     bmesh.ops.triangulate(bm, faces=bm.faces)
                     bm.to_mesh(tmp_me)
                     bm.free()
-                # Usually the materials of the evaluated object will be the same, but modifiers, such as Geometry Nodes,
+
-                # can change the materials.
+                data_meshes[ob_obj] = (get_blenderID_key(tmp_me), tmp_me, free)
-                orig_mats = tuple(slot.material for slot in ob.material_slots)
-                eval_mats = tuple(slot.material.original if slot.material else None
-                                  for slot in ob_to_convert.material_slots)
-                if orig_mats != eval_mats:
-                    # Override the default behaviour of getting materials from ob_obj.bdata.material_slots.
-                    ob_obj.override_materials = eval_mats
-                data_meshes[ob_obj] = (get_blenderID_key(tmp_me), tmp_me, True)
             # Change armatures back.
             for armature, pose_position in backup_pose_positions:
                 print((armature, pose_position))
@@ -3007,7 +3018,10 @@ def fbx_scene_data_cleanup(scene_data):
     """
     # Delete temp meshes.
     done_meshes = set()
-    for me_key, me, free in scene_data.data_meshes.values():
+    for ob_obj, (me_key, me, free) in scene_data.data_meshes.items():
+        # Clear temporary meshes created by Object.to_mesh().
+        ob_obj.bdata.to_mesh_clear()
+        # Clear temporary meshes created when applying modifiers.
         if free and me_key not in done_meshes:
             bpy.data.meshes.remove(me)
             done_meshes.add(me_key)