io_scene_fbx/export_fbx_bin.py

@@ -1431,7 +1431,7 @@ def fbx_data_mesh_elements(root, me_obj, scene_data, done_meshes):
     me_fbxmaterials_idx = scene_data.mesh_material_indices.get(me)
     if me_fbxmaterials_idx is not None:
         # We cannot use me.materials here, as this array is filled with None in case materials are linked to object...
-        me_blmaterials = [mat_slot.material for mat_slot in me_obj.material_slots]
+        me_blmaterials = me_obj.materials
         if me_fbxmaterials_idx and me_blmaterials:
             lay_ma = elem_data_single_int32(geom, b"LayerElementMaterial", 0)
             elem_data_single_int32(lay_ma, b"Version", FBX_GEOMETRY_MATERIAL_VERSION)
@@ -2598,6 +2598,14 @@ 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.
+                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:
@@ -2713,8 +2721,7 @@ def fbx_data_from_scene(scene, depsgraph, settings):
     data_materials = {}
     for ob_obj in objects:
         # If obj is not a valid object for materials, wrapper will just return an empty tuple...
-        for ma_s in ob_obj.material_slots:
-            ma = ma_s.material
+        for ma in ob_obj.materials:
             if ma is None:
                 continue  # Empty slots!
             # Note theoretically, FBX supports any kind of materials, even GLSL shaders etc.

io_scene_fbx/fbx_utils.py

@@ -1174,7 +1174,7 @@ class ObjectWrapper(metaclass=MetaObjectWrapper):
     we need to use a key to identify each.
     """
     __slots__ = (
-        'name', 'key', 'bdata', 'parented_to_armature',
+        'name', 'key', 'bdata', 'parented_to_armature', 'override_materials',
         '_tag', '_ref', '_dupli_matrix'
     )
 
@@ -1229,6 +1229,7 @@ class ObjectWrapper(metaclass=MetaObjectWrapper):
             self.bdata = bdata
             self._ref = armature
         self.parented_to_armature = False
+        self.override_materials = None
 
     def __eq__(self, other):
         return isinstance(other, self.__class__) and self.key == other.key
@@ -1443,11 +1444,14 @@ class ObjectWrapper(metaclass=MetaObjectWrapper):
         return ()
     bones = property(get_bones)
 
-    def get_material_slots(self):
+    def get_materials(self):
+        override_materials = self.override_materials
+        if override_materials is not None:
+            return override_materials
         if self._tag in {'OB', 'DP'}:
-            return self.bdata.material_slots
+            return tuple(slot.material for slot in self.bdata.material_slots)
         return ()
-    material_slots = property(get_material_slots)
+    materials = property(get_materials)
 
     def is_deformed_by_armature(self, arm_obj):
         if not (self.is_object and self.type == 'MESH'):