glTF exporter: Do not export special attributes, used internally by Blender

io_scene_gltf2/__init__.py

@@ -4,7 +4,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Scurest, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (3, 4, 43),
+    "version": (3, 4, 44),
     'blender': (3, 3, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/com/gltf2_blender_default.py

@@ -3,4 +3,12 @@
 
 BLENDER_IOR = 1.45
 BLENDER_SPECULAR = 0.5
-BLENDER_SPECULAR_TINT = 0.0
+BLENDER_SPECULAR_TINT = 0.0
+
+
+SPECIAL_ATTRIBUTES = {
+    ".select_vert",
+    ".select_edge",
+    ".select_poly",
+    "material_index"
+    }

io_scene_gltf2/blender/exp/gltf2_blender_gather_primitives_extract.py

@@ -9,6 +9,7 @@ from ...io.com.gltf2_io_debug import print_console
 from io_scene_gltf2.blender.exp import gltf2_blender_gather_skins
 from io_scene_gltf2.io.com import gltf2_io_constants
 from io_scene_gltf2.blender.com import gltf2_blender_conversion
+from io_scene_gltf2.blender.com import gltf2_blender_default
 
 
 def extract_primitives(blender_mesh, uuid_for_skined_data, blender_vertex_groups, modifiers, export_settings):
@@ -137,6 +138,11 @@ class PrimitiveCreator:
     def define_attributes(self):
         # Manage attributes + COLOR_0
         for blender_attribute_index, blender_attribute in enumerate(self.blender_mesh.attributes):
+
+            # Excluse special attributes (used internally by Blender)
+            if blender_attribute.name in gltf2_blender_default.SPECIAL_ATTRIBUTES:
+                continue
+
             attr = {}
             attr['blender_attribute_index'] = blender_attribute_index
             attr['blender_name'] = blender_attribute.name