glTF exporter: Fix #129548 - Regression - Export ShapeKeys when only Armature modifier

Set a custom property (ignore at export) that can identify and differenciate:
- evaluated mesh
- geometry node with SK

scripts/addons_core/io_scene_gltf2/__init__.py

@@ -5,7 +5,7 @@
 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": (4, 2, 70),
+    "version": (4, 2, 71),
     'blender': (4, 2, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

scripts/addons_core/io_scene_gltf2/blender/com/gltf2_blender_extras.py

@@ -8,7 +8,7 @@ from .gltf2_blender_json import is_json_convertible
 
 
 # Custom properties, which are in most cases present and should not be imported/exported.
-BLACK_LIST = ['cycles', 'cycles_visibility', 'cycles_curves', 'glTF2ExportSettings']
+BLACK_LIST = ['cycles', 'cycles_visibility', 'cycles_curves', 'glTF2ExportSettings', 'gltf2_mesh_applied']
 
 
 def generate_extras(blender_element):

scripts/addons_core/io_scene_gltf2/blender/exp/gltf2_blender_gather_mesh.py

@@ -107,7 +107,7 @@ def __gather_extras(blender_mesh: bpy.types.Mesh,
         extras = generate_extras(blender_mesh) or {}
 
     # Not for GN Instances
-    if export_settings['gltf_morph'] and blender_mesh.shape_keys and blender_mesh.users != 0:
+    if export_settings['gltf_morph'] and blender_mesh.shape_keys and ((blender_mesh.is_evaluated is True and blender_mesh.get('gltf2_mesh_applied') is not None) or blender_mesh.is_evaluated is False):
         morph_max = len(blender_mesh.shape_keys.key_blocks) - 1
         if morph_max > 0:
             extras['targetNames'] = [k.name for k in get_sk_exported(blender_mesh.shape_keys.key_blocks)]
@@ -150,7 +150,7 @@ def __gather_weights(blender_mesh: bpy.types.Mesh,
         return None
 
     # Not for GN Instances
-    if blender_mesh.users == 0:
+    if blender_mesh.is_evaluated is True and blender_mesh.get('gltf2_mesh_applied') is None:
         return None
 
     morph_max = len(blender_mesh.shape_keys.key_blocks) - 1

scripts/addons_core/io_scene_gltf2/blender/exp/gltf2_blender_gather_nodes.py

@@ -307,6 +307,8 @@ def __gather_mesh(vnode, blender_object, export_settings):
                     # But we need to remove some properties that are not needed
                     for prop in [p for p in blender_object.data.keys() if p in BLACK_LIST]:
                         del blender_mesh[prop]
+                # Store that this evaluated mesh has been created by the exporter, and is not a GN instance mesh
+                blender_mesh['gltf2_mesh_applied'] = True
 
                 if export_settings['gltf_skins']:
                     # restore Armature modifiers

scripts/addons_core/io_scene_gltf2/blender/exp/gltf2_blender_gather_primitives_extract.py

@@ -151,8 +151,7 @@ class PrimitiveCreator:
         # We need to check if we are in a GN Instance, because for GN instances, it seems that shape keys are preserved,
         # even if we apply modifiers
         # (For classic objects, shape keys are not preserved if we apply modifiers)
-        # We can check it by checking if the mesh is used by a user
-        if self.blender_mesh.shape_keys and self.export_settings['gltf_morph'] and self.blender_mesh.users != 0:
+        if self.blender_mesh.shape_keys and self.export_settings['gltf_morph'] and ((self.blender_mesh.is_evaluated is True and self.blender_mesh.get('gltf2_mesh_applied') is not None) or self.blender_mesh.is_evaluated is False):
             self.key_blocks = get_sk_exported(self.blender_mesh.shape_keys.key_blocks)
 
         # Fetch vert positions and bone data (joint,weights)