FBX IO: Update for new meshes being smooth by default

Blender 3.6 changed newly created meshes to be smooth by default,
therefore, it is no longer necessary to remove the "sharp_face"
attribute if face smoothing was not set when importing a mesh.

The only time when "sharp_face" needs to be removed is if we create the
attribute when attempting to set face smoothing, but setting face
smoothing fails.

No changes to the import of .fbx files are expected with this patch.

Pull Request: https://projects.blender.org/blender/blender-addons/pulls/105039

io_scene_fbx/__init__.py

@@ -5,7 +5,7 @@
 bl_info = {
     "name": "FBX format",
     "author": "Campbell Barton, Bastien Montagne, Jens Restemeier, @Mysteryem",
-    "version": (5, 11, 0),
+    "version": (5, 11, 1),
     "blender": (4, 1, 0),
     "location": "File > Import-Export",
     "description": "FBX IO meshes, UVs, vertex colors, materials, textures, cameras, lamps and actions",

io_scene_fbx/import_fbx.py

@@ -1638,7 +1638,7 @@ def blen_read_geom_layer_smooth(fbx_obj, mesh):
     fbx_layer = elem_find_first(fbx_obj, b'LayerElementSmoothing')
 
     if fbx_layer is None:
-        return False
+        return
 
     # all should be valid
     (fbx_layer_name,
@@ -1651,13 +1651,13 @@ def blen_read_geom_layer_smooth(fbx_obj, mesh):
 
     # udk has 'Direct' mapped, with no Smoothing, not sure why, but ignore these
     if fbx_layer_data is None:
-        return False
+        return
 
     if fbx_layer_mapping == b'ByEdge':
         # some models have bad edge data, we can't use this info...
         if not mesh.edges:
             print("warning skipping sharp edges data, no valid edges...")
-            return False
+            return
 
         blen_data = MESH_ATTRIBUTE_SHARP_EDGE.ensure(mesh.attributes).data
         fbx_item_size = 1
@@ -1669,21 +1669,23 @@ def blen_read_geom_layer_smooth(fbx_obj, mesh):
             1, fbx_item_size, layer_id,
             xform=np.logical_not,  # in FBX, 0 (False) is sharp, but in Blender True is sharp.
             )
-        return False
     elif fbx_layer_mapping == b'ByPolygon':
-        blen_data = MESH_ATTRIBUTE_SHARP_FACE.ensure(mesh.attributes).data
+        sharp_face = MESH_ATTRIBUTE_SHARP_FACE.ensure(mesh.attributes)
+        blen_data = sharp_face.data
         fbx_item_size = 1
         assert(fbx_item_size == MESH_ATTRIBUTE_SHARP_FACE.item_size)
-        return blen_read_geom_array_mapped_polygon(
+        sharp_face_set_successfully = blen_read_geom_array_mapped_polygon(
             mesh, blen_data, MESH_ATTRIBUTE_SHARP_FACE.foreach_attribute, MESH_ATTRIBUTE_SHARP_FACE.dtype,
             fbx_layer_data, None,
             fbx_layer_mapping, fbx_layer_ref,
             1, fbx_item_size, layer_id,
             xform=lambda s: (s == 0),  # smoothgroup bitflags, treat as booleans for now
             )
+        if not sharp_face_set_successfully:
+            mesh.attributes.remove(sharp_face)
     else:
         print("warning layer %r mapping type unsupported: %r" % (fbx_layer.id, fbx_layer_mapping))
-        return False
+
 
 def blen_read_geom_layer_edge_crease(fbx_obj, mesh):
     fbx_layer = elem_find_first(fbx_obj, b'LayerElementEdgeCrease')
@@ -1883,7 +1885,7 @@ def blen_read_geom(fbx_tmpl, fbx_obj, settings):
         print("ERROR: No polygons, but edges exist. Ignoring the edges!")
 
     # must be after edge, face loading.
-    ok_smooth = blen_read_geom_layer_smooth(fbx_obj, mesh)
+    blen_read_geom_layer_smooth(fbx_obj, mesh)
 
     blen_read_geom_layer_edge_crease(fbx_obj, mesh)
 
@@ -1905,23 +1907,12 @@ def blen_read_geom(fbx_tmpl, fbx_obj, settings):
         clnors = np.empty(len(mesh.loops) * 3, dtype=bl_nors_dtype)
         mesh.attributes["temp_custom_normals"].data.foreach_get("vector", clnors)
 
-        if not ok_smooth:
-            sharp_face = MESH_ATTRIBUTE_SHARP_FACE.get(attributes)
-            if sharp_face:
-                attributes.remove(sharp_face)
-            ok_smooth = True
-
         # Iterating clnors into a nested tuple first is faster than passing clnors.reshape(-1, 3) directly into
         # normals_split_custom_set. We use clnors.data since it is a memoryview, which is faster to iterate than clnors.
         mesh.normals_split_custom_set(tuple(zip(*(iter(clnors.data),) * 3)))
     if settings.use_custom_normals:
         mesh.attributes.remove(mesh.attributes["temp_custom_normals"])
 
-    if not ok_smooth:
-        sharp_face = MESH_ATTRIBUTE_SHARP_FACE.get(attributes)
-        if sharp_face:
-            attributes.remove(sharp_face)
-
     if settings.use_custom_props:
         blen_read_custom_properties(fbx_obj, mesh, settings)