io_scene_fbx/export_fbx_bin.py

@@ -77,7 +77,7 @@ from .fbx_utils import (
     # Animation.
     AnimationCurveNodeWrapper,
     # Objects.
-    ObjectWrapper, fbx_name_class,
+    ObjectWrapper, fbx_name_class, ensure_object_not_in_edit_mode,
     # Top level.
     FBXExportSettingsMedia, FBXExportSettings, FBXExportData,
 )
@@ -3497,6 +3497,14 @@ def save(operator, context,
                 ctx_objects = context.view_layer.objects
         if use_visible:
             ctx_objects = tuple(obj for obj in ctx_objects if obj.visible_get())
+
+        # Ensure no Objects are in Edit mode.
+        # Copy to a tuple for safety, to avoid the risk of modifying ctx_objects while iterating.
+        for obj in tuple(ctx_objects):
+            if not ensure_object_not_in_edit_mode(context, obj):
+                operator.report({'ERROR'}, "%s could not be set out of Edit Mode, so cannot be exported" % obj.name)
+                return {'CANCELLED'}
+
         kwargs_mod["context_objects"] = ctx_objects
 
         depsgraph = context.evaluated_depsgraph_get()
@@ -3528,6 +3536,16 @@ def save(operator, context,
         else:
             data_seq = tuple((scene, scene.name, 'objects') for scene in bpy.data.scenes if scene.objects)
 
+        # Ensure no Objects are in Edit mode.
+        for data, data_name, data_obj_propname in data_seq:
+            # Copy to a tuple for safety, to avoid the risk of modifying the data prop while iterating it.
+            for obj in tuple(getattr(data, data_obj_propname)):
+                if not ensure_object_not_in_edit_mode(context, obj):
+                    operator.report({'ERROR'},
+                                    "%s in %s could not be set out of Edit Mode, so cannot be exported"
+                                    % (obj.name, data_name))
+                    return {'CANCELLED'}
+
         # call this function within a loop with BATCH_ENABLE == False
 
         new_fbxpath = fbxpath  # own dir option modifies, we need to keep an original

io_scene_fbx/fbx_utils.py

@@ -540,6 +540,58 @@ def fast_first_axis_unique(ar, return_unique=True, return_index=False, return_in
             return result
 
 
+def ensure_object_not_in_edit_mode(context, obj):
+    """Objects in Edit mode usually cannot be exported because much of the API used when exporting is not available for
+    Objects in Edit mode.
+
+    Exiting the currently active Object (and any other Objects opened in multi-editing) from Edit mode is simple and
+    should be done with `bpy.ops.mesh.mode_set(mode='OBJECT')` instead of using this function.
+
+    This function is for the rare case where an Object is in Edit mode, but the current context mode is not Edit mode.
+    This can occur from a state where the current context mode is Edit mode, but then the active Object of the current
+    View Layer is changed to a different Object that is not in Edit mode. This changes the current context mode, but
+    leaves the other Object(s) in Edit mode.
+    """
+    if obj.mode != 'EDIT':
+        return True
+
+    # Get the active View Layer.
+    view_layer = context.view_layer
+
+    # A View Layer belongs to a scene.
+    scene = view_layer.id_data
+
+    # Get the current active Object of this View Layer, so we can restore it once done.
+    orig_active = view_layer.objects.active
+
+    # Check if obj is in the View Layer. If obj is not in the View Layer, it cannot be set as the active Object.
+    # We don't use `obj.name in view_layer.objects` because an Object from a Library could have the same name.
+    is_in_view_layer = any(o == obj for o in view_layer.objects)
+
+    do_unlink_from_scene_collection = False
+    try:
+        if not is_in_view_layer:
+            # There might not be any enabled collections in the View Layer, so link obj into the Scene Collection
+            # instead, which is always available to all View Layers of that Scene.
+            scene.collection.objects.link(obj)
+            do_unlink_from_scene_collection = True
+        view_layer.objects.active = obj
+
+        # Now we're finally ready to attempt to change obj's mode.
+        if bpy.ops.object.mode_set.poll():
+            bpy.ops.object.mode_set(mode='OBJECT')
+        if obj.mode == 'EDIT':
+            # The Object could not be set out of EDIT mode and therefore cannot be exported.
+            return False
+    finally:
+        # Always restore the original active Object and unlink obj from the Scene Collection if it had to be linked.
+        view_layer.objects.active = orig_active
+        if do_unlink_from_scene_collection:
+            scene.collection.objects.unlink(obj)
+
+    return True
+
+
 # ##### UIDs code. #####
 
 # ID class (mere int).