refactor(tools/gltf_auto_export): complete restructuring of the tool (#67)

* split up code in logical modules instead of one giant file
 * added module structure, imports etc
 * updated README
 * add storing & reloading of lists of scenes
 * minor cleanups & tweaks
 * closes #64 
 * moved gltf_auto_export specific docs/images inside the addon's folder
 * updated main title image

.gitignore

@@ -1,2 +1,3 @@
 *.blend1
 target/
+__pycache__/

README.md

@@ -4,7 +4,7 @@
 
 # Blender_bevy_components_workflow
 
-![demo](./docs/blender_gltf_components.png)
+![demo](./docs/blender_bevy.png)
 
 Crates & tools for adding components from gltf files in the [Bevy](https://bevyengine.org/) game engine.
 

tools/gltf_auto_export/README.md

@@ -1,6 +1,6 @@
 # gltf_auto_export
 
-This [Blender addon](./gltf_auto_export.py)  
+This [Blender addon](./)  
 - automatically exports your level/world from Blender to gltf whenever you save your Blend file.
 - in Blueprints mode (highly recommended !) : 
     - supports automatic exports of used collections as [Gltf blueprints](../../crates/bevy_gltf_blueprints/README.md)
@@ -16,11 +16,11 @@ This [Blender addon](./gltf_auto_export.py)
 
 * in Blender go to edit =>  preferences => install
 
-![blender addon install](../../docs/blender_addon_install.png)
+![blender addon install](./docs/blender_addon_install.png)
 
-* choose the path where ```gltf_auto_export/gltf_auto_export.py``` is stored
+* choose the path where ```gltf_auto_export.zip``` is stored
 
-![blender addon install](../../docs/blender_addon_install2.png)
+![blender addon install](./docs/blender_addon_install2.png)
 
 ## Usage: 
 
@@ -30,32 +30,32 @@ This [Blender addon](./gltf_auto_export.py)
 * before it can automatically save to gltf, you need to configure it
 * go to file => export => gltf auto export
 
-![blender addon use](../../docs/blender_addon_use.png)
+![blender addon use](./docs/blender_addon_use.png)
 
 * set the autoexport parameters  in the **auto export** panel: 
 
-    ![blender addon use3](../../docs/blender_addon_use3.png)
+    ![blender addon use3](./docs/blender_addon_use3.png)
 
 
     - export folder
     - pick your main (level) scenes and library scenes (see the chapter about Blueprints below)   
         - click in the scene picker & select your scene
 
-        ![select scene](../../docs/blender_addon_add_scene.png)
+        ![select scene](./docs/blender_addon_add_scene.png)
 
         - click on the "+" icon
 
-        ![select scene2](../../docs/blender_addon_add_scene2.png)
+        ![select scene2](./docs/blender_addon_add_scene2.png)
 
         - your scene is added to the list
         
-        ![select scene3](../../docs/blender_addon_add_scene3.png) 
+        ![select scene3](./docs/blender_addon_add_scene3.png) 
 
 
 
 * and your standard gltf export parameters in the **gltf** panel
 
-![blender addon use2](../../docs/blender_addon_use2.png)
+![blender addon use2](./docs/blender_addon_use2.png)
 
 
 * click on "apply settings"
@@ -73,41 +73,50 @@ You can enable this option to automatically replace all the **collection instanc
 - this means you will have 
     * one small main gltf file (your level/world)
     * as many gltf files as you have used collections in the main scene , in the library path you specified :
-    for the included [advanced](../../examples/advanced/) example's [assets](../../assets/advanced/models/), it looks something like this: 
+    for the included [basic](../../examples/bevy_gltf_blueprints/basic/) example's [assets](../../examples/bevy_gltf_blueprints/basic/assets/), it looks something like this: 
 
-    ![library](../../docs/exported_library_files.png)
+    ![library](./docs/exported_library_files.png)
     
-    the .blend file that they are generated from can be found [here](../../assets/advanced/advanced.blend)
+    the .blend file that they are generated from can be found [here](../../examples/bevy_gltf_blueprints/basic/assets/advanced.blend)
 
 - the above only applies to collections that have **instances** in your main scene!
     if you want a specific collection in your library to always get exported regardless of its use, you need to add 
     a **COLLECTION** (boolean) custom property called ```AutoExport``` set to true
     > not at the object level ! the collection level !
 
-    ![force-export](../../docs/force_export.jpg)
+    ![force-export](./docs/force_export.jpg)
 
     It will get automatically exported like any of the "in-use" collections.
 
 - you can also get an overview of all the exported collections in the export menu
 
-    ![exported collections](../../docs/exported_collections.png)
+    ![exported collections](./docs/exported_collections.png)
 
 #### Process
 
 This is the internal logic of the export process with blueprints 
 
-![process](../../docs/process.svg)
+![process](./docs/process.svg)
 
 ie this is an example scene...
 
-![](../../docs/workflow_original.jpg)
+![](./docs/workflow_original.jpg)
 
 and what actually gets exported for the main scene/world/level
 
-![](../../docs/workflow_empties.jpg)
+![](./docs/workflow_empties.jpg)
 
 all collections instances replaced with empties, and all those collections exported to gltf files as seen above
 
+
+## Development 
+
+- since the code has now been split up into multiple modules, to make your life easier, I highly recomend (if you are using vscode like me) to use 
+[this](https://marketplace.visualstudio.com/items?itemName=JacquesLucke.blender-development) excellent extension , works easilly and fast , even for the latest 
+versions of Blender (v4.0 as of this writing)
+- this [article](https://polynook.com/learn/set-up-blender-addon-development-environment-in-windows) might also help out 
+(easy enough to get it working on linux too)
+
 ## License
 
 This tool, all its code, contents & assets is Dual-licensed under either of

tools/gltf_auto_export/__init__.py

@@ -1,46 +1,203 @@
-#TODO: this is not actually in use yet, just use the gltf_auto_export.py file
 bl_info = {
-    "name": "Test glTF/glb auto-export",
+    "name": "gltf_auto_export",
     "author": "kaosigh",
-    "version": (0, 1),
+    "version": (0, 5, 4),
     "blender": (3, 4, 0),
     "location": "File > Import-Export",
     "description": "glTF/glb auto-export",
     "warning": "",
-    "wiki_url": "",
+    "wiki_url": "https://github.com/kaosat-dev/Blender_bevy_components_workflow",
-    "tracker_url": "",
+    "tracker_url": "https://github.com/kaosat-dev/Blender_bevy_components_workflow/issues/new",
     "category": "Import-Export"
-    }
+}
-
 import bpy
+import os
 
-from .gltf_auto_export import TEST_AUTO_OT_gltf
+from bpy.app.handlers import persistent
-from .gltf_auto_export import deps_update_handler
+from bpy.props import (IntProperty)
-from .gltf_auto_export import save_handler
-from .gltf_auto_export import get_changedScene
-from .gltf_auto_export import set_ChangedScene
 
 
-# Only needed if you want to add into a dynamic menu
+from . import helpers
+from .internals import (SceneLink,
+                        SceneLinks,
+                        CollectionToExport,
+                        CollectionsToExport,
+                        CUSTOM_PG_sceneName
+                        )
+from .auto_export import auto_export
+from .preferences import (AutoExportGltfPreferenceNames,
+                          AutoExportGltfAddonPreferences
+                          )
+from .ui.main import (GLTF_PT_auto_export_main,
+                      GLTF_PT_auto_export_root,
+                      GLTF_PT_auto_export_blueprints,
+                      GLTF_PT_auto_export_collections_list,
+                      GLTF_PT_auto_export_gltf,
+                      SCENE_UL_GLTF_auto_export,
+                      AutoExportGLTF
+                      )
+from .ui.various import (SCENES_LIST_OT_actions)
+from .helpers_scenes import (is_scene_ok)
+
+bpy.context.window_manager['changed_objects_per_scene'] = {}
+bpy.context.window_manager['previous_params'] = {}
+bpy.context.window_manager['__gltf_auto_export_initialized'] = False
+bpy.context.window_manager['__gltf_auto_export_gltf_params_changed'] = False
+
+######################################################
+""" there are two places where we load settings for auto_export from:
+- in ui/main AutoExportGLTF -> invoke
+- in auto_export.py -> auto_export
+This is a workaround needed because of the way the settings are stored , perhaps there is a better way to deal with it ? ie by calling the AutoExportGLTF operator from the auto_export function ?
+"""
+
+
+#see here for original gltf exporter infos https://github.com/KhronosGroup/glTF-Blender-IO/blob/main/addons/io_scene_gltf2/__init__.py
+@persistent
+def deps_update_handler(scene, depsgraph):
+    if scene.name != "temp_scene": # actually do we care about anything else than the main scene(s) ?
+        print("depsgraph_update_post", scene.name)
+        print("-------------")
+        changed = scene.name or ""
+
+        # depsgraph = bpy.context.evaluated_depsgraph_get()
+        if not 'changed_objects_per_scene' in bpy.context.window_manager:
+            bpy.context.window_manager['changed_objects_per_scene'] = {}
+
+        if not changed in bpy.context.window_manager['changed_objects_per_scene']:
+            bpy.context.window_manager['changed_objects_per_scene'][changed] = {}
+        
+        for obj in depsgraph.updates:
+            if isinstance(obj.id, bpy.types.Object):
+                # get the actual object
+                object = bpy.data.objects[obj.id.name]
+                bpy.context.window_manager['changed_objects_per_scene'][scene.name][obj.id.name] = object
+        
+        bpy.context.window_manager.changedScene = changed
+
+@persistent
+def save_handler(dummy): 
+    print("-------------")
+    print("saved", bpy.data.filepath)
+    if not 'changed_objects_per_scene' in bpy.context.window_manager:
+        bpy.context.window_manager['changed_objects_per_scene'] = {}
+    changes_per_scene =  bpy.context.window_manager['changed_objects_per_scene']
+
+    #determine changed parameters
+    addon_prefs = bpy.context.preferences.addons["gltf_auto_export"].preferences
+
+    prefs = {}
+    for (k,v) in addon_prefs.items():
+        if k not in AutoExportGltfPreferenceNames:
+            prefs[k] = v
+
+    previous_params = bpy.context.window_manager['previous_params'] if 'previous_params' in bpy.context.window_manager else {}
+    set1 = set(previous_params.items())
+    set2 = set(prefs.items())
+    difference = dict(set1 ^ set2)
+    
+    changed_param_names = list(set(difference.keys())- set(AutoExportGltfPreferenceNames))
+    changed_parameters = len(changed_param_names) > 0
+    # do the export
+    auto_export(changes_per_scene, changed_parameters)
+
+
+    # save the parameters
+    # todo add back
+    for (k, v) in prefs.items():
+        bpy.context.window_manager['previous_params'][k] = v
+
+    # reset a few things after exporting
+    # reset wether the gltf export paramters were changed since the last save 
+    bpy.context.window_manager['__gltf_auto_export_gltf_params_changed'] = False
+    # reset whether there have been changed objects since the last save 
+    bpy.context.window_manager['changed_objects_per_scene'] = {}
+
+def get_changedScene(self):
+    return self["changedScene"]
+
+def set_changedScene(self, value):
+    self["changedScene"] = value
+
+classes = [
+    SceneLink,
+    SceneLinks,
+    CUSTOM_PG_sceneName,
+    SCENE_UL_GLTF_auto_export,
+    SCENES_LIST_OT_actions,
+
+    AutoExportGLTF, 
+    AutoExportGltfAddonPreferences,
+
+    CollectionToExport,
+    CollectionsToExport,
+
+    GLTF_PT_auto_export_main,
+    GLTF_PT_auto_export_root,
+    GLTF_PT_auto_export_blueprints,
+    GLTF_PT_auto_export_collections_list,
+    GLTF_PT_auto_export_gltf
+]
+
 def menu_func_import(self, context):
-    self.layout.operator(TEST_AUTO_OT_gltf.bl_idname, text="glTF auto Export (.glb/gltf)")
+    self.layout.operator(AutoExportGLTF.bl_idname, text="glTF auto Export (.glb/gltf)")
-
 
 def register():
-    bpy.utils.register_class(TEST_AUTO_OT_gltf)
+    for cls in classes:
-    bpy.types.TOPBAR_MT_file_export.append(menu_func_import)
+        bpy.utils.register_class(cls)
 
+    bpy.types.Scene.main_scene = bpy.props.PointerProperty(type=bpy.types.Scene, name="main scene", description="main_scene_chooser", poll=is_scene_ok)
+    bpy.types.Scene.library_scene = bpy.props.PointerProperty(type=bpy.types.Scene, name="library scene", description="library_scene_picker", poll=is_scene_ok)
+
+    # setup handlers for updates & saving
     bpy.app.handlers.depsgraph_update_post.append(deps_update_handler)
     bpy.app.handlers.save_post.append(save_handler)
-    #bpy.types.TOPBAR_MT_file_export.append(menu_func_import)
-    bpy.types.Scene.changedScene = bpy.props.StringProperty(get=get_changedScene, set=set_ChangedScene)
 
+    bpy.types.WindowManager.changedScene = bpy.props.StringProperty(get=get_changedScene, set=set_changedScene)
+    bpy.types.WindowManager.exportedCollections = bpy.props.CollectionProperty(type=CollectionsToExport)
+
+    # add our addon to the toolbar
+    bpy.types.TOPBAR_MT_file_export.append(menu_func_import)
+
+    ## just experiments
+    bpy.types.Scene.main_scenes_list_index = IntProperty(name = "Index for main scenes list", default = 0)
+    bpy.types.Scene.library_scenes_list_index = IntProperty(name = "Index for library scenes list", default = 0)
+
+    """
+    mock_main_scenes = []
+    main_scenes = bpy.context.preferences.addons["gltf_auto_export"].preferences.main_scenes
+    for item_name in mock_main_scenes:
+        item = main_scenes.add()
+        item.name = item_name
+    
+    mock_library_scenes = []
+    library_scenes = bpy.context.preferences.addons["gltf_auto_export"].preferences.library_scenes
+    for item_name in mock_library_scenes:
+        item = library_scenes.add()
+        item.name = item_name"""
+
+    bpy.context.preferences.addons["gltf_auto_export"].preferences.main_scenes_index = 0
+    bpy.context.preferences.addons["gltf_auto_export"].preferences.library_scenes_index = 0
 
 def unregister():
-    bpy.utils.unregister_class(TEST_AUTO_OT_gltf)
+    for cls in classes:
+        bpy.utils.unregister_class(cls)
+
     bpy.types.TOPBAR_MT_file_export.remove(menu_func_import)
 
+    # remove handlers & co
     bpy.app.handlers.depsgraph_update_post.remove(deps_update_handler)
     bpy.app.handlers.save_post.remove(save_handler)
-    #bpy.types.TOPBAR_MT_file_export.remove(menu_func_import)
+    
-    del bpy.types.Scene.changedScene
+    del bpy.types.WindowManager.changedScene
+    del bpy.types.WindowManager.exportedCollections
+
+    del bpy.types.Scene.main_scene
+    del bpy.types.Scene.library_scene
+
+    del bpy.types.Scene.main_scenes_list_index
+    del bpy.types.Scene.library_scenes_list_index
+
+
+if "gltf_auto_export" == "__main__":
+    register()

tools/gltf_auto_export/auto_export.py

@@ -0,0 +1,154 @@
+import os
+import bpy
+import traceback
+
+from .helpers_scenes import (get_scenes, )
+from .helpers_collections import (get_exportable_collections, get_collections_per_scene)
+from .helpers_export import (export_main_scene, export_blueprints_from_collections)
+from .helpers import (check_if_blueprints_exist, check_if_blueprint_on_disk)
+from .config import scene_key
+
+"""Main function"""
+def auto_export(changes_per_scene, changed_export_parameters):
+    addon_prefs = bpy.context.preferences.addons["gltf_auto_export"].preferences
+
+    # a semi_hack to ensure we have the latest version of the settings
+    initialized = bpy.context.window_manager['__gltf_auto_export_initialized'] if '__gltf_auto_export_initialized' in bpy.context.window_manager else False
+    if not initialized:
+        print("not initialized, fetching settings if any")
+        # semi_hack to restore the correct settings if the add_on was installed before
+        settings = bpy.context.scene.get(scene_key)
+        if settings:
+            print("loading settings in main function")
+            try:
+                # Update filter if user saved settings
+                #if hasattr(self, 'export_format'):
+                #    self.filter_glob = '*.glb' if self.export_format == 'GLB' else '*.gltf'
+                for (k, v) in settings.items():
+                    setattr(addon_prefs, k, v)
+                    # inject scenes data
+                    if k == 'main_scene_names':
+                        main_scenes = addon_prefs.main_scenes
+                        for item_name in v:
+                            item = main_scenes.add()
+                            item.name = item_name
+
+                    if k == 'library_scene_names':
+                        library_scenes = addon_prefs.library_scenes
+                        for item_name in v:
+                            item = library_scenes.add()
+                            item.name = item_name
+
+
+
+            except Exception as error:
+                print("error setting preferences from saved settings", error)
+        bpy.context.window_manager['__gltf_auto_export_initialized'] = True
+
+    # have the export parameters (not auto export, just gltf export) have changed: if yes (for example switch from glb to gltf, compression or not, animations or not etc), we need to re-export everything
+    print ("changed_export_parameters", changed_export_parameters)
+    try:
+        file_path = bpy.data.filepath
+        # Get the folder
+        folder_path = os.path.dirname(file_path)
+        # get the preferences for our addon
+
+        export_blueprints = getattr(addon_prefs,"export_blueprints")
+        export_output_folder = getattr(addon_prefs,"export_output_folder")
+
+        [main_scene_names, level_scenes, library_scene_names, library_scenes] = get_scenes(addon_prefs)
+
+        print("main scenes", main_scene_names, "library_scenes", library_scene_names)
+        print("export_output_folder", export_output_folder)
+
+        # export everything everytime
+        if export_blueprints:
+            print("EXPORTING")
+            # get a list of all collections actually in use
+            collections = get_exportable_collections(level_scenes, library_scenes)
+            # first check if all collections have already been exported before (if this is the first time the exporter is run
+            # in your current Blender session for example)
+            export_blueprints_path = os.path.join(folder_path, export_output_folder, getattr(addon_prefs,"export_blueprints_path")) if getattr(addon_prefs,"export_blueprints_path") != '' else folder_path
+            export_levels_path = os.path.join(folder_path, export_output_folder)
+
+            gltf_extension = getattr(addon_prefs, "export_format")
+            gltf_extension = '.glb' if gltf_extension == 'GLB' else '.gltf'
+            collections_not_on_disk = check_if_blueprints_exist(collections, export_blueprints_path, gltf_extension)
+            changed_collections = []
+
+            print('changes_per_scene', changes_per_scene.items(), changes_per_scene.keys())
+            for scene, bla in changes_per_scene.items():
+                print("  changed scene", scene)
+                for obj_name, obj in bla.items():
+                    object_collections = list(obj.users_collection)
+                    object_collection_names = list(map(lambda collection: collection.name, object_collections))
+                    if len(object_collection_names) > 1:
+                        print("ERRROR, objects in multiple collections not supported")
+                    else:
+                        object_collection_name =  object_collection_names[0] if len(object_collection_names) > 0 else None
+                        print("      object ", obj, object_collection_name)
+                        if object_collection_name in collections:
+                            changed_collections.append(object_collection_name)
+
+            collections_to_export = list(set(changed_collections + collections_not_on_disk))
+
+            # we need to re_export everything if the export parameters have been changed
+            collections_to_export = collections if changed_export_parameters else collections_to_export
+
+            collections_per_scene = get_collections_per_scene(collections_to_export, library_scenes)
+
+            # collections that do not come from a library should not be exported as seperate blueprints
+            library_collections = [name for sublist in collections_per_scene.values() for name in sublist]
+            collections_to_export = list(set(collections_to_export).intersection(set(library_collections)))
+
+            print("--------------")
+            print("collections:               all:", collections)
+            print("collections:           changed:", changed_collections)
+            print("collections: not found on disk:", collections_not_on_disk)
+            print("collections:         to export:", collections_to_export)
+            print("collections:         per_scene:", collections_per_scene)
+
+            # backup current active scene
+            old_current_scene = bpy.context.scene
+            # backup current selections
+            old_selections = bpy.context.selected_objects
+
+            # first export any main/level/world scenes
+            print("export MAIN scenes")
+            for scene_name in main_scene_names:
+                do_export_main_scene =  changed_export_parameters or (scene_name in changes_per_scene.keys() and len(changes_per_scene[scene_name].keys()) > 0) or not check_if_blueprint_on_disk(scene_name, export_levels_path, gltf_extension)
+                if do_export_main_scene:
+                    print("     exporting scene:", scene_name)
+                    export_main_scene(bpy.data.scenes[scene_name], folder_path, addon_prefs, collections)
+
+
+            # now deal with blueprints/collections
+            do_export_library_scene = changed_export_parameters or len(collections_to_export) > 0 # export_library_scene_name in changes_per_scene.keys()
+            print("export LIBRARY")
+            if do_export_library_scene:
+                # we only want to go through the library scenes where our collections to export are present
+                for (scene_name, collections_to_export)  in collections_per_scene.items():
+                    print("     exporting collections from scene:", scene_name)
+                    print("     collections to export", collections_to_export)
+                    library_scene = bpy.data.scenes[scene_name]
+                    export_blueprints_from_collections(collections_to_export, library_scene, folder_path, addon_prefs)
+
+
+            # reset current scene from backup
+            bpy.context.window.scene = old_current_scene
+
+            # reset selections
+            for obj in old_selections:
+                obj.select_set(True)
+        else:
+            for scene_name in main_scene_names:
+                export_main_scene(bpy.data.scenes[scene_name], folder_path, addon_prefs)
+
+    except Exception as error:
+        traceback.print_stack()
+        def error_message(self, context):
+            self.layout.label(text="Failure during auto_export: Error: "+ str(error))
+
+        bpy.context.window_manager.popup_menu(error_message, title="Error", icon='ERROR')
+
+

tools/gltf_auto_export/config.py

@@ -0,0 +1 @@
+scene_key = "auto_gltfExportSettings"

tools/gltf_auto_export/helpers.py

@@ -0,0 +1,63 @@
+import os
+import bpy
+
+#####################################################
+#### Helpers ####
+
+
+
+# Makes an empty, at location, stores it in existing collection, from https://blender.stackexchange.com/questions/51290/how-to-add-empty-object-not-using-bpy-ops
+def make_empty(name, location, coll_name): #string, vector, string of existing coll
+    empty_obj = bpy.data.objects.new( "empty", None, )
+    empty_obj.name = name
+    empty_obj.empty_display_size = 1 
+    bpy.data.collections[coll_name].objects.link(empty_obj)
+    empty_obj.location = location
+    return empty_obj
+
+
+def make_empty2(name, location, collection):
+    object_data = None #bpy.data.meshes.new("NewMesh") #None
+    empty_obj = bpy.data.objects.new( name, object_data )
+    empty_obj.name = name
+    empty_obj.location = location
+
+
+    empty_obj.empty_display_size = 2
+    empty_obj.empty_display_type = 'PLAIN_AXES'   
+    collection.objects.link( empty_obj )
+    return empty_obj
+
+def make_empty3(name, location, rotation, scale, collection): 
+    original_active_object = bpy.context.active_object
+    bpy.ops.object.empty_add(type='PLAIN_AXES', location=location, rotation=rotation, scale=scale)
+    empty_obj = bpy.context.active_object
+    empty_obj.name = name
+    empty_obj.scale = scale # scale is not set correctly ?????
+    bpy.context.view_layer.objects.active = original_active_object
+    return empty_obj
+
+
+def traverse_tree(t):
+    yield t
+    for child in t.children:
+        yield from traverse_tree(child)
+
+
+def check_if_blueprints_exist(collections, folder_path, extension):
+    not_found_blueprints = []
+    for collection_name in collections:
+        gltf_output_path = os.path.join(folder_path, collection_name + extension)
+        print("gltf_output_path", gltf_output_path)
+        found = os.path.exists(gltf_output_path) and os.path.isfile(gltf_output_path)
+        if not found:
+            not_found_blueprints.append(collection_name)
+    return not_found_blueprints
+
+
+def check_if_blueprint_on_disk(scene_name, folder_path, extension):
+    gltf_output_path = os.path.join(folder_path, scene_name + extension)
+    found = os.path.exists(gltf_output_path) and os.path.isfile(gltf_output_path)
+    print("level", scene_name, "found", found, "path", gltf_output_path)
+    return found
+

tools/gltf_auto_export/helpers_collections.py

@@ -0,0 +1,97 @@
+import bpy
+from .helpers import traverse_tree
+
+# returns the list of the collections in use for a given scene
+def get_used_collections(scene): 
+    root_collection = scene.collection 
+
+    scene_objects = [o for o in root_collection.objects]
+    collection_names = set()
+    used_collections = []
+    for object in scene_objects:
+        #print("object ", object)
+        if object.instance_type == 'COLLECTION':
+            #print("THIS OBJECT IS A COLLECTION")
+            # print("instance_type" ,object.instance_type)
+            collection_name = object.instance_collection.name
+            #print("instance collection", object.instance_collection.name)
+            #object.instance_collection.users_scene
+            # del object['blueprint']
+            # object['BlueprintName'] = '"'+collection_name+'"'
+            if not collection_name in collection_names: 
+                collection_names.add(collection_name)
+                used_collections.append(object.instance_collection)
+
+    #print("scene objects", scene_objects) 
+    return (collection_names, used_collections)
+
+# gets all collections that should ALWAYS be exported to their respective gltf files, even if they are not used in the main scene/level
+def get_marked_collections(scene):
+    # print("checking library for marked collections")
+    root_collection = scene.collection
+    marked_collections = []
+    collection_names = []
+    for collection in traverse_tree(root_collection):
+        if 'AutoExport' in collection and collection['AutoExport'] == True:
+            marked_collections.append(collection)
+            collection_names.append(collection.name)
+    return (collection_names, marked_collections)
+
+# get exportable collections from lists of mains scenes and lists of library scenes
+def get_exportable_collections(main_scenes, library_scenes): 
+    all_collections = []
+    for main_scene in main_scenes:
+        (collection_names, _) = get_used_collections(main_scene)
+        all_collections = all_collections + list(collection_names)
+    for library_scene in library_scenes:
+        marked_collections = get_marked_collections(library_scene)
+        all_collections = all_collections + marked_collections[0]
+    return all_collections
+
+def get_collections_per_scene(collection_names, library_scenes): 
+    collections_per_scene = {}
+    for scene in library_scenes:
+        root_collection = scene.collection
+        for cur_collection in traverse_tree(root_collection):
+            if cur_collection.name in collection_names:
+                if not scene.name in collections_per_scene:
+                    collections_per_scene[scene.name] = []
+                collections_per_scene[scene.name].append(cur_collection.name)
+                
+    return collections_per_scene
+
+
+def get_collection_hierarchy(root_col, levels=1):
+    """Read hierarchy of the collections in the scene"""
+    level_lookup = {}
+    def recurse(root_col, parent, depth):
+        if depth > levels: 
+            return
+        if isinstance(parent,  bpy.types.Collection):
+            level_lookup.setdefault(parent, []).append(root_col)
+        for child in root_col.children:
+            recurse(child, root_col,  depth + 1)
+    recurse(root_col, root_col.children, 0)
+    return level_lookup
+
+# the active collection is a View Layer concept, so you actually have to find the active LayerCollection
+# which must be done recursively
+def find_layer_collection_recursive(find, col):
+    # print("root collection", col)
+    for c in col.children:
+        # print("child collection", c)
+        if c.collection == find:
+            return c
+    return None
+
+
+#Recursivly transverse layer_collection for a particular name
+def recurLayerCollection(layerColl, collName):
+    found = None
+    if (layerColl.name == collName):
+        return layerColl
+    for layer in layerColl.children:
+        found = recurLayerCollection(layer, collName)
+        if found:
+            return found
+

tools/gltf_auto_export/helpers_export.py

@@ -0,0 +1,149 @@
+import os
+import bpy
+from .preferences import (AutoExportGltfPreferenceNames)
+from .helpers_scenes import (generate_hollow_scene, clear_hollow_scene)
+from .helpers_collections import (recurLayerCollection)
+from .helpers import (traverse_tree)
+######################################################
+#### Export logic #####
+
+
+def generate_gltf_export_preferences(addon_prefs): 
+    # default values
+    gltf_export_preferences = dict(
+        export_format= 'GLB', #'GLB', 'GLTF_SEPARATE', 'GLTF_EMBEDDED'
+        check_existing=False,
+
+        use_selection=False,
+        use_visible=True, # Export visible and hidden objects. See Object/Batch Export to skip.
+        use_renderable=False,
+        use_active_collection= False,
+        use_active_collection_with_nested=False,
+        use_active_scene = False,
+
+        export_texcoords=True,
+        export_normals=True,
+        # here add draco settings
+        export_draco_mesh_compression_enable = False,
+
+        export_tangents=False,
+        #export_materials
+        export_colors=True,
+        export_attributes=True,
+        #use_mesh_edges
+        #use_mesh_vertices
+        export_cameras=True,
+        export_extras=True, # For custom exported properties.
+        export_lights=True,
+        export_yup=True,
+        export_skins=True,
+        export_morph=False,
+        export_apply=False,
+        export_animations=False
+    )
+        
+    for key in addon_prefs.__annotations__.keys():
+        if str(key) not in AutoExportGltfPreferenceNames:
+            #print("overriding setting", key, "value", getattr(addon_prefs,key))
+            gltf_export_preferences[key] = getattr(addon_prefs,key)
+
+    return gltf_export_preferences
+
+# find which of the library scenes the given collection stems from
+# TODO: does not seem efficient at all ?
+def get_source_scene(collection_name, library_scenes): 
+    match = None
+    for scene in library_scenes:
+        root_collection = scene.collection
+        found = False
+        for cur_collection in traverse_tree(root_collection):
+            if cur_collection.name == collection_name:
+                found = True
+                break
+        if found:
+            match = scene
+            break
+    return match
+
+# export collections: all the collections that have an instance in the main scene AND any marked collections, even if they do not have instances
+def export_collections(collections, folder_path, library_scene, addon_prefs, gltf_export_preferences): 
+    # set active scene to be the library scene (hack for now)
+    bpy.context.window.scene = library_scene
+    # save current active collection
+    active_collection =  bpy.context.view_layer.active_layer_collection
+
+    for collection_name in collections:
+        print("exporting collection", collection_name)
+        layer_collection = bpy.context.view_layer.layer_collection
+        layerColl = recurLayerCollection(layer_collection, collection_name)
+        # set active collection to the collection
+        bpy.context.view_layer.active_layer_collection = layerColl
+
+        gltf_output_path = os.path.join(folder_path, collection_name)
+
+        export_settings = { **gltf_export_preferences, 'use_active_scene': True, 'use_active_collection': True, 'use_active_collection_with_nested':True} #'use_visible': False,
+        export_gltf(gltf_output_path, export_settings)
+    
+    # reset active collection to the one we save before
+    bpy.context.view_layer.active_layer_collection = active_collection
+
+
+def export_blueprints_from_collections(collections, library_scene, folder_path, addon_prefs):
+    export_output_folder = getattr(addon_prefs,"export_output_folder")
+    gltf_export_preferences = generate_gltf_export_preferences(addon_prefs)
+    export_blueprints_path = os.path.join(folder_path, export_output_folder, getattr(addon_prefs,"export_blueprints_path")) if getattr(addon_prefs,"export_blueprints_path") != '' else folder_path
+
+    #print("-----EXPORTING BLUEPRINTS----")
+    #print("LIBRARY EXPORT", export_blueprints_path )
+
+    try:
+        export_collections(collections, export_blueprints_path, library_scene, addon_prefs, gltf_export_preferences)
+    except Exception as error:
+        print("failed to export collections to gltf: ", error)
+        # TODO : rethrow
+
+
+# export all main scenes
+def export_main_scenes(scenes, folder_path, addon_prefs): 
+    for scene in scenes:
+        export_main_scene(scene, folder_path, addon_prefs)
+
+def export_main_scene(scene, folder_path, addon_prefs, library_collections): 
+    export_output_folder = getattr(addon_prefs,"export_output_folder")
+    gltf_export_preferences = generate_gltf_export_preferences(addon_prefs)
+
+    export_blueprints = getattr(addon_prefs,"export_blueprints")
+  
+    if export_blueprints : 
+        (hollow_scene, object_names) = generate_hollow_scene(scene, library_collections)
+        #except Exception:
+        #    print("failed to create hollow scene")
+
+        # set active scene to be the given scene
+        bpy.context.window.scene = hollow_scene
+
+    gltf_output_path = os.path.join(folder_path, export_output_folder, scene.name)
+    print("       exporting gltf to", gltf_output_path, ".gltf/glb")
+
+
+    export_settings = { **gltf_export_preferences, 
+                       'use_active_scene': True, 
+                       'use_active_collection':True, 
+                       'use_active_collection_with_nested':True,  
+                       'use_visible': False,
+                       'use_renderable': False,
+                       'export_apply':True
+                       }
+    export_gltf(gltf_output_path, export_settings)
+
+    if export_blueprints : 
+        clear_hollow_scene(hollow_scene, scene, object_names)
+
+
+#https://docs.blender.org/api/current/bpy.ops.export_scene.html#bpy.ops.export_scene.gltf
+def export_gltf (path, export_settings):
+    settings = {**export_settings, "filepath": path}
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    bpy.ops.export_scene.gltf(**settings)
+
+

tools/gltf_auto_export/helpers_scenes.py

@@ -0,0 +1,102 @@
+import bpy
+from .helpers_collections import (find_layer_collection_recursive)
+from .helpers import (make_empty3)
+
+# generate a copy of a scene that replaces collection instances with empties
+# alternative: copy original names before creating a new scene, & reset them
+# or create empties, hide original ones, and do the same renaming trick
+def generate_hollow_scene(scene, library_collections): 
+    root_collection = scene.collection 
+    temp_scene = bpy.data.scenes.new(name="temp_scene")
+    copy_root_collection = temp_scene.collection
+
+    # we set our active scene to be this one : this is needed otherwise the stand-in empties get generated in the wrong scene
+    bpy.context.window.scene = temp_scene
+
+    found = find_layer_collection_recursive(copy_root_collection, bpy.context.view_layer.layer_collection)
+    if found:
+        # once it's found, set the active layer collection to the one we found
+        bpy.context.view_layer.active_layer_collection = found
+
+    #original_names = {}
+    original_names = []
+
+    # copies the contents of a collection into another one while replacing library instances with empties
+    def copy_hollowed_collection_into(source_collection, destination_collection):
+        for object in source_collection.objects:
+            if object.instance_type == 'COLLECTION' and (object.instance_collection.name in library_collections):
+                collection_name = object.instance_collection.name
+
+                original_name = object.name
+                original_names.append(original_name)
+
+                object.name = original_name + "____bak"
+                empty_obj = make_empty3(original_name, object.location, object.rotation_euler, object.scale, destination_collection)
+                """we inject the collection/blueprint name, as a component called 'BlueprintName', but we only do this in the empty, not the original object"""
+                empty_obj['BlueprintName'] = '"'+collection_name+'"'
+                empty_obj['SpawnHere'] = ''
+
+                for k, v in object.items():
+                    empty_obj[k] = v
+            else:
+                destination_collection.objects.link(object)
+
+        # for every sub-collection of the source, copy its content into a new sub-collection of the destination
+        for collection in source_collection.children:
+            copy_collection = bpy.data.collections.new(collection.name + "____collection_export")
+            copy_hollowed_collection_into(collection, copy_collection)
+            destination_collection.children.link(copy_collection)
+
+    copy_hollowed_collection_into(root_collection, copy_root_collection)
+    
+    # objs = bpy.data.objects
+    #objs.remove(objs["Cube"], do_unlink=True)
+    return (temp_scene, original_names)
+
+# clear & remove "hollow scene"
+def clear_hollow_scene(temp_scene, original_scene, original_names):
+    # reset original names
+    root_collection = original_scene.collection
+
+    def restore_original_names(collection):
+        for object in collection.objects:
+            if object.instance_type == 'COLLECTION':
+                if object.name.endswith("____bak"):
+                    object.name = object.name.replace("____bak", "")
+        for child_collection in collection.children:
+            restore_original_names(child_collection)
+    
+    restore_original_names(root_collection)
+
+    # remove empties (only needed when we go via ops ????)
+    root_collection = temp_scene.collection 
+    scene_objects = [o for o in root_collection.objects]
+    for object in scene_objects:
+        if object.type == 'EMPTY':
+            if hasattr(object, "SpawnHere"):
+                bpy.data.objects.remove(object, do_unlink=True)
+            else: 
+                bpy.context.scene.collection.objects.unlink(object)
+            #bpy.data.objects.remove(object, do_unlink=True)
+
+    bpy.data.scenes.remove(temp_scene)
+
+
+# convenience utility to get lists of scenes
+def get_scenes(addon_prefs):
+    level_scene_names= list(map(lambda scene: scene.name, getattr(addon_prefs,"main_scenes")))
+    library_scene_names = list(map(lambda scene: scene.name, getattr(addon_prefs,"library_scenes")))
+
+    level_scene_names = list(filter(lambda name: name in bpy.data.scenes, level_scene_names))
+    library_scene_names = list(filter(lambda name: name in bpy.data.scenes, library_scene_names))
+
+    level_scenes = list(map(lambda name: bpy.data.scenes[name], level_scene_names))
+    library_scenes = list(map(lambda name: bpy.data.scenes[name], library_scene_names))
+    
+    return [level_scene_names, level_scenes, library_scene_names, library_scenes]
+
+
+def is_scene_ok(self, scene):
+    prefs = bpy.context.preferences.addons["gltf_auto_export"].preferences
+    return scene.name not in prefs.main_scenes and scene.name not in prefs.library_scenes
+

tools/gltf_auto_export/internals.py

@@ -0,0 +1,22 @@
+import bpy
+
+class SceneLink(bpy.types.PropertyGroup):
+    name: bpy.props.StringProperty(name="")
+    scene: bpy.props.PointerProperty(type=bpy.types.Scene)
+
+class SceneLinks(bpy.types.PropertyGroup):
+    name = bpy.props.StringProperty(name="List of scenes to export", default="Unknown")
+    items: bpy.props.CollectionProperty(type = SceneLink)
+
+class CUSTOM_PG_sceneName(bpy.types.PropertyGroup):
+    name: bpy.props.StringProperty()
+    display: bpy.props.BoolProperty()
+
+class CollectionToExport(bpy.types.PropertyGroup):
+    name: bpy.props.StringProperty(name="")
+
+class CollectionsToExport(bpy.types.PropertyGroup):
+    name = bpy.props.StringProperty(name="List of collections to export", default="Unknown")
+    items: bpy.props.CollectionProperty(type = CollectionToExport)
+
+

tools/gltf_auto_export/preferences.py

@@ -0,0 +1,319 @@
+
+from bpy.types import AddonPreferences
+
+from bpy.props import (BoolProperty,
+                       IntProperty,
+                       StringProperty,
+                       EnumProperty,
+                       CollectionProperty
+                       )
+
+from .internals import (CUSTOM_PG_sceneName)
+
+AutoExportGltfPreferenceNames = [
+    'auto_export',
+    'export_main_scene_name',
+    'export_output_folder',
+    'export_library_scene_name',
+    'export_blueprints',
+    'export_blueprints_path',
+
+    'main_scenes',
+    'library_scenes',
+    'main_scenes_index',
+    'library_scenes_index'
+]
+
+class AutoExportGltfAddonPreferences(AddonPreferences):
+    # this must match the add-on name, use '__package__'
+    # when defining this in a submodule of a python package.
+    bl_idname = __package__
+    bl_options = {'PRESET'}
+
+    auto_export: BoolProperty(
+        name='Auto export',
+        description='Automatically export to gltf on save',
+        default=True
+    )
+    export_main_scene_name: StringProperty(
+        name='Main scene',
+        description='The name of the main scene/level/world to auto export',
+        default='Scene'
+    )
+    export_output_folder: StringProperty(
+        name='Export folder (relative)',
+        description='The root folder for all exports(relative to current file) Defaults to current folder',
+        default=''
+    )
+    export_library_scene_name: StringProperty(
+        name='Library scene',
+        description='The name of the library scene to auto export',
+        default='Library'
+    )
+    # blueprint settings
+    export_blueprints: BoolProperty(
+        name='Export Blueprints',
+        description='Replaces collection instances with an Empty with a BlueprintName custom property',
+        default=True
+    )
+    export_blueprints_path: StringProperty(
+        name='Blueprints path',
+        description='path to export the blueprints to (relative to the Export folder)',
+        default='library'
+    )
+
+    main_scenes: CollectionProperty(name="main scenes", type=CUSTOM_PG_sceneName)
+    main_scenes_index: IntProperty(name = "Index for main scenes list", default = 0)
+
+    library_scenes: CollectionProperty(name="library scenes", type=CUSTOM_PG_sceneName)
+    library_scenes_index: IntProperty(name = "Index for library scenes list", default = 0)
+
+    #####
+    export_format: EnumProperty(
+        name='Format',
+        items=(('GLB', 'glTF Binary (.glb)',
+                'Exports a single file, with all data packed in binary form. '
+                'Most efficient and portable, but more difficult to edit later'),
+               ('GLTF_EMBEDDED', 'glTF Embedded (.gltf)',
+                'Exports a single file, with all data packed in JSON. '
+                'Less efficient than binary, but easier to edit later'),
+               ('GLTF_SEPARATE', 'glTF Separate (.gltf + .bin + textures)',
+                'Exports multiple files, with separate JSON, binary and texture data. '
+                'Easiest to edit later')),
+        description=(
+            'Output format and embedding options. Binary is most efficient, '
+            'but JSON (embedded or separate) may be easier to edit later'
+        ),
+        default='GLB'
+    )
+    export_copyright: StringProperty(
+        name='Copyright',
+        description='Legal rights and conditions for the model',
+        default=''
+    )
+
+    export_image_format: EnumProperty(
+        name='Images',
+        items=(('AUTO', 'Automatic',
+                'Save PNGs as PNGs and JPEGs as JPEGs. '
+                'If neither one, use PNG'),
+                ('JPEG', 'JPEG Format (.jpg)',
+                'Save images as JPEGs. (Images that need alpha are saved as PNGs though.) '
+                'Be aware of a possible loss in quality'),
+                ('NONE', 'None',
+                 'Don\'t export images'),
+               ),
+        description=(
+            'Output format for images. PNG is lossless and generally preferred, but JPEG might be preferable for web '
+            'applications due to the smaller file size. Alternatively they can be omitted if they are not needed'
+        ),
+        default='AUTO'
+    )
+
+    export_texture_dir: StringProperty(
+        name='Textures',
+        description='Folder to place texture files in. Relative to the .gltf file',
+        default='',
+    )
+
+    """
+    export_jpeg_quality: IntProperty(
+        name='JPEG quality',
+        description='Quality of JPEG export',
+        default=75,
+        min=0,
+        max=100
+    )
+    """
+
+    export_keep_originals: BoolProperty(
+        name='Keep original',
+        description=('Keep original textures files if possible. '
+                     'WARNING: if you use more than one texture, '
+                     'where pbr standard requires only one, only one texture will be used. '
+                     'This can lead to unexpected results'
+        ),
+        default=False,
+    )
+
+    export_texcoords: BoolProperty(
+        name='UVs',
+        description='Export UVs (texture coordinates) with meshes',
+        default=True
+    )
+
+    export_normals: BoolProperty(
+        name='Normals',
+        description='Export vertex normals with meshes',
+        default=True
+    )
+
+    export_draco_mesh_compression_enable: BoolProperty(
+        name='Draco mesh compression',
+        description='Compress mesh using Draco',
+        default=False
+    )
+
+    export_draco_mesh_compression_level: IntProperty(
+        name='Compression level',
+        description='Compression level (0 = most speed, 6 = most compression, higher values currently not supported)',
+        default=6,
+        min=0,
+        max=10
+    )
+
+    export_draco_position_quantization: IntProperty(
+        name='Position quantization bits',
+        description='Quantization bits for position values (0 = no quantization)',
+        default=14,
+        min=0,
+        max=30
+    )
+
+    export_draco_normal_quantization: IntProperty(
+        name='Normal quantization bits',
+        description='Quantization bits for normal values (0 = no quantization)',
+        default=10,
+        min=0,
+        max=30
+    )
+
+    export_draco_texcoord_quantization: IntProperty(
+        name='Texcoord quantization bits',
+        description='Quantization bits for texture coordinate values (0 = no quantization)',
+        default=12,
+        min=0,
+        max=30
+    )
+
+    export_draco_color_quantization: IntProperty(
+        name='Color quantization bits',
+        description='Quantization bits for color values (0 = no quantization)',
+        default=10,
+        min=0,
+        max=30
+    )
+
+    export_draco_generic_quantization: IntProperty(
+        name='Generic quantization bits',
+        description='Quantization bits for generic coordinate values like weights or joints (0 = no quantization)',
+        default=12,
+        min=0,
+        max=30
+    )
+
+    export_tangents: BoolProperty(
+        name='Tangents',
+        description='Export vertex tangents with meshes',
+        default=False
+    )
+
+    export_materials: EnumProperty(
+        name='Materials',
+        items=(('EXPORT', 'Export',
+        'Export all materials used by included objects'),
+        ('PLACEHOLDER', 'Placeholder',
+        'Do not export materials, but write multiple primitive groups per mesh, keeping material slot information'),
+        ('NONE', 'No export',
+        'Do not export materials, and combine mesh primitive groups, losing material slot information')),
+        description='Export materials',
+        default='EXPORT'
+    )
+
+    export_original_specular: BoolProperty(
+        name='Export original PBR Specular',
+        description=(
+            'Export original glTF PBR Specular, instead of Blender Principled Shader Specular'
+        ),
+        default=False,
+    )
+
+    export_colors: BoolProperty(
+        name='Vertex Colors',
+        description='Export vertex colors with meshes',
+        default=True
+    )
+
+    export_attributes: BoolProperty(
+        name='Attributes',
+        description='Export Attributes (when starting with underscore)',
+        default=False
+    )
+
+    use_mesh_edges: BoolProperty(
+        name='Loose Edges',
+        description=(
+            'Export loose edges as lines, using the material from the first material slot'
+        ),
+        default=False,
+    )
+
+    use_mesh_vertices: BoolProperty(
+        name='Loose Points',
+        description=(
+            'Export loose points as glTF points, using the material from the first material slot'
+        ),
+        default=False,
+    )
+
+    export_cameras: BoolProperty(
+        name='Cameras',
+        description='Export cameras',
+        default=True
+    )
+
+    use_selection: BoolProperty(
+        name='Selected Objects',
+        description='Export selected objects only',
+        default=False
+    )
+
+    use_visible: BoolProperty(
+        name='Visible Objects',
+        description='Export visible objects only',
+        default=True
+    )
+
+    use_renderable: BoolProperty(
+        name='Renderable Objects',
+        description='Export renderable objects only',
+        default=False
+    )
+
+
+    export_apply: BoolProperty(
+        name='Export Apply Modifiers',
+        description='Apply modifiers (excluding Armatures) to mesh objects -'
+                    'WARNING: prevents exporting shape keys',
+        default=True
+    )
+
+    export_yup: BoolProperty(
+        name='+Y Up',
+        description='Export using glTF convention, +Y up',
+        default=True
+    )
+
+    use_visible: BoolProperty(
+        name='Visible Objects',
+        description='Export visible objects only',
+        default=False
+    )
+
+    use_renderable: BoolProperty(
+        name='Renderable Objects',
+        description='Export renderable objects only',
+        default=False
+    )
+
+    export_extras: BoolProperty(
+        name='Custom Properties',
+        description='Export custom properties as glTF extras',
+        default=True
+    )
+
+    export_animations: BoolProperty(
+        name='Animations',
+        description='Exports active actions and NLA tracks as glTF animations',
+        default=False
+    )

tools/gltf_auto_export/ui/main.py

@@ -0,0 +1,387 @@
+import bpy
+from bpy.types import Operator
+from bpy_extras.io_utils import ExportHelper
+from bpy.props import (BoolProperty,
+                       IntProperty,
+                       StringProperty,
+                       EnumProperty,
+                       CollectionProperty
+                       )
+
+from ..preferences import (AutoExportGltfAddonPreferences, AutoExportGltfPreferenceNames)
+from ..helpers_scenes import (get_scenes)
+from ..helpers_collections import (get_exportable_collections)
+######################################################
+## ui logic & co
+
+class AutoExportGLTF(Operator, AutoExportGltfAddonPreferences, ExportHelper):
+    """test"""
+    bl_idname = "export_scenes.auto_gltf"
+    bl_label = "Apply settings"
+    bl_options = {'PRESET', 'UNDO'}
+
+    # ExportHelper mixin class uses this
+    filename_ext = ''
+
+    filter_glob: StringProperty(
+            default='*.glb;*.gltf', 
+            options={'HIDDEN'}
+    )
+
+    will_save_settings: BoolProperty(
+        name='Remember Export Settings',
+        description='Store glTF export settings in the Blender project',
+        default=True
+    )
+
+    # Custom scene property for saving settings
+    scene_key = "auto_gltfExportSettings"
+
+    def save_settings(self, context):
+        # find all props to save
+        exceptional = [
+            # options that don't start with 'export_'  
+            'main_scenes',
+            'library_scenes'
+        ]
+        all_props = self.properties
+        export_props = {
+            x: getattr(self, x) for x in dir(all_props)
+            if (x.startswith("export_") or x in exceptional) and all_props.get(x) is not None
+        }
+        # we add main & library scene names to our preferences
+        main_scenes = list(map(lambda scene_data: scene_data, getattr(bpy.context.preferences.addons["gltf_auto_export"].preferences,"main_scenes")))
+        library_scenes = list(map(lambda scene_data: scene_data, getattr(bpy.context.preferences.addons["gltf_auto_export"].preferences,"library_scenes")))
+
+        export_props['main_scene_names'] = list(map(lambda scene_data: scene_data.name, getattr(bpy.context.preferences.addons["gltf_auto_export"].preferences,"main_scenes")))
+        export_props['library_scene_names'] = list(map(lambda scene_data: scene_data.name, getattr(bpy.context.preferences.addons["gltf_auto_export"].preferences,"library_scenes")))
+        self.properties['main_scene_names'] = export_props['main_scene_names']
+        self.properties['library_scene_names'] = export_props['library_scene_names']
+        context.scene[self.scene_key] = export_props
+
+      
+    def apply_settings_to_preferences(self, context):
+        # find all props to save
+        exceptional = [
+            # options that don't start with 'export_'  
+            'main_scenes',
+            'library_scenes'
+        ]
+        all_props = self.properties
+        export_props = {
+            x: getattr(self, x) for x in dir(all_props)
+            if (x.startswith("export_") or x in exceptional) and all_props.get(x) is not None
+        }
+        addon_prefs = bpy.context.preferences.addons["gltf_auto_export"].preferences
+
+        for (k, v) in export_props.items():
+            setattr(addon_prefs, k, v)
+
+
+    def execute(self, context):     
+        if self.will_save_settings:
+            self.save_settings(context)
+        # apply the operator properties to the addon preferences
+        self.apply_settings_to_preferences(context)
+
+        return {'FINISHED'}    
+    
+    def invoke(self, context, event):
+        settings = context.scene.get(self.scene_key)
+        print("settings", settings)
+        self.will_save_settings = False
+        if settings:
+            print("loading settings in invoke AutoExportGLTF")
+            try:
+                for (k, v) in settings.items():
+                    print("loading setting", k, v)
+                    setattr(self, k, v)
+                self.will_save_settings = True
+
+                # Update filter if user saved settings
+                if hasattr(self, 'export_format'):
+                    self.filter_glob = '*.glb' if self.export_format == 'GLB' else '*.gltf'
+
+                # inject scenes data
+                if hasattr(self, 'main_scene_names'):
+                    main_scenes = bpy.context.preferences.addons["gltf_auto_export"].preferences.main_scenes
+                    main_scenes.clear()
+                    for item_name in self.main_scene_names:
+                        item = main_scenes.add()
+                        item.name = item_name
+
+                if hasattr(self, 'library_scene_names'):
+                    library_scenes = bpy.context.preferences.addons["gltf_auto_export"].preferences.library_scenes
+                    library_scenes.clear()
+                    for item_name in self.library_scene_names:
+                        item = library_scenes.add()
+                        item.name = item_name
+
+            except (AttributeError, TypeError):
+                self.report({"ERROR"}, "Loading export settings failed. Removed corrupted settings")
+                del context.scene[self.scene_key]
+
+
+        for (k, v) in self.properties.items():
+            print("PROPERTIES", k, v)
+
+        addon_prefs = bpy.context.preferences.addons["gltf_auto_export"].preferences
+
+      
+
+        [main_scene_names, level_scenes, library_scene_names, library_scenes]=get_scenes(addon_prefs)
+        collections = get_exportable_collections(level_scenes, library_scenes)
+
+        try:
+            # we save this list of collections in the context
+            bpy.context.window_manager.exportedCollections.clear()
+            #TODO: add error handling for this
+            for collection_name in collections:
+                ui_info = bpy.context.window_manager.exportedCollections.add()
+                ui_info.name = collection_name
+        except Exception as error:
+            self.report({"ERROR"}, "Failed to populate list of exported collections/blueprints")
+     
+
+
+        wm = context.window_manager
+        wm.fileselect_add(self)
+        return {'RUNNING_MODAL'}
+        # return self.execute(context)
+
+    def draw(self, context):
+        pass
+
+class GLTF_PT_auto_export_main(bpy.types.Panel):
+    bl_space_type = 'FILE_BROWSER'
+    bl_region_type = 'TOOL_PROPS'
+    bl_label = ""
+    bl_parent_id = "FILE_PT_operator"
+    bl_options = {'HIDE_HEADER'}
+
+    @classmethod
+    def poll(cls, context):
+        sfile = context.space_data
+        operator = sfile.active_operator
+
+        return operator.bl_idname == "EXPORT_SCENES_OT_auto_gltf"
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False  # No animation.
+
+        sfile = context.space_data
+
+
+class GLTF_PT_auto_export_root(bpy.types.Panel):
+    bl_space_type = 'FILE_BROWSER'
+    bl_region_type = 'TOOL_PROPS'
+    bl_label = "Auto export"
+    bl_parent_id = "GLTF_PT_auto_export_main"
+    #bl_options = {'DEFAULT_CLOSED'}
+
+    @classmethod
+    def poll(cls, context):
+        sfile = context.space_data
+        operator = sfile.active_operator
+        return operator.bl_idname == "EXPORT_SCENES_OT_auto_gltf"
+
+    def draw_header(self, context):
+        sfile = context.space_data
+        operator = sfile.active_operator
+        self.layout.prop(operator, "auto_export", text="")
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False  # No animation.
+
+        sfile = context.space_data
+        operator = sfile.active_operator
+
+        layout.active = operator.auto_export
+        layout.prop(operator, 'will_save_settings')
+        layout.prop(operator, "export_output_folder")
+
+        # scene selectors
+        row = layout.row()
+        col = row.column(align=True)
+        col.separator()
+
+        source = bpy.context.preferences.addons["gltf_auto_export"].preferences
+
+        rows = 2
+
+        # main/level scenes
+        layout.label(text="main scenes")
+        layout.prop(context.scene, "main_scene", text='')
+
+        row = layout.row()
+        row.template_list("SCENE_UL_GLTF_auto_export", "level scenes", source, "main_scenes", source, "main_scenes_index", rows=rows)
+
+        col = row.column(align=True)
+        sub_row = col.row()
+        add_operator = sub_row.operator("scene_list.list_action", icon='ADD', text="")
+        add_operator.action = 'ADD'
+        add_operator.scene_type = 'level'
+        #add_operator.source = operator
+        sub_row.enabled = context.scene.main_scene is not None
+
+        sub_row = col.row()
+        remove_operator = sub_row.operator("scene_list.list_action", icon='REMOVE', text="")
+        remove_operator.action = 'REMOVE'
+        remove_operator.scene_type = 'level'
+        col.separator()
+
+        #up_operator = col.operator("scene_list.list_action", icon='TRIA_UP', text="")
+        #up_operator.action = 'UP'
+        #col.operator("scene_list.list_action", icon='TRIA_DOWN', text="").action = 'DOWN'
+
+        # library scenes
+        layout.label(text="library scenes")
+        layout.prop(context.scene, "library_scene", text='')
+
+        row = layout.row()
+        row.template_list("SCENE_UL_GLTF_auto_export", "library scenes", source, "library_scenes", source, "library_scenes_index", rows=rows)
+
+        col = row.column(align=True)
+        sub_row = col.row()
+        add_operator = sub_row.operator("scene_list.list_action", icon='ADD', text="")
+        add_operator.action = 'ADD'
+        add_operator.scene_type = 'library'
+        sub_row.enabled = context.scene.library_scene is not None
+
+
+        sub_row = col.row()
+        remove_operator = sub_row.operator("scene_list.list_action", icon='REMOVE', text="")
+        remove_operator.action = 'REMOVE'
+        remove_operator.scene_type = 'library'
+        col.separator()
+
+
+      
+class GLTF_PT_auto_export_blueprints(bpy.types.Panel):
+    bl_space_type = 'FILE_BROWSER'
+    bl_region_type = 'TOOL_PROPS'
+    bl_label = "Blueprints"
+    bl_parent_id = "GLTF_PT_auto_export_root"
+
+    @classmethod
+    def poll(cls, context):
+        sfile = context.space_data
+        operator = sfile.active_operator
+
+        return operator.bl_idname == "EXPORT_SCENES_OT_auto_gltf" #"EXPORT_SCENE_OT_gltf"
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False  # No animation.
+
+        sfile = context.space_data
+        operator = sfile.active_operator
+
+        layout.prop(operator, "export_blueprints")
+        layout.prop(operator, "export_blueprints_path")
+
+class GLTF_PT_auto_export_collections_list(bpy.types.Panel):
+    bl_space_type = 'FILE_BROWSER'
+    bl_region_type = 'TOOL_PROPS'
+    bl_label = "Blueprints: Exported Collections"
+    bl_parent_id = "GLTF_PT_auto_export_blueprints"
+    bl_options = {'DEFAULT_CLOSED'}
+
+    @classmethod
+    def poll(cls, context):
+        sfile = context.space_data
+        operator = sfile.active_operator
+
+        return operator.bl_idname == "EXPORT_SCENES_OT_auto_gltf" #"EXPORT_SCENE_OT_gltf"
+
+    def draw(self, context):
+        layout = self.layout
+        layout.use_property_split = True
+        layout.use_property_decorate = False  # No animation.
+
+        sfile = context.space_data
+        operator = sfile.active_operator
+        addon_prefs = bpy.context.preferences.addons["gltf_auto_export"].preferences
+
+        for collection in bpy.context.window_manager.exportedCollections:
+            row = layout.row()
+            row.label(text=collection.name)
+
+class GLTF_PT_auto_export_gltf(bpy.types.Panel):
+    bl_space_type = 'FILE_BROWSER'
+    bl_region_type = 'TOOL_PROPS'
+    bl_label = "Gltf"
+    bl_parent_id = "GLTF_PT_auto_export_main"
+    bl_options = {'DEFAULT_CLOSED'}
+
+    @classmethod
+    def poll(cls, context):
+        sfile = context.space_data
+        operator = sfile.active_operator
+
+        return operator.bl_idname == "EXPORT_SCENES_OT_auto_gltf" #"EXPORT_SCENE_OT_gltf"
+    
+    def draw(self, context):
+        preferences = context.preferences
+        addon_prefs = preferences.addons["gltf_auto_export"].preferences
+        layout = self.layout
+
+        sfile = context.space_data
+        operator = sfile.active_operator
+
+        #preferences = context.preferences
+        #print("ADDON PREFERENCES ", list(preferences.addons.keys()))
+        #print("standard blender gltf prefs", list(preferences.addons["io_scene_gltf2"].preferences.keys()))
+        # we get the addon preferences from the standard gltf exporter & use those :
+        addon_prefs_gltf = preferences.addons["io_scene_gltf2"].preferences
+
+        #addon_prefs = preferences.addons["gltf_auto_export"].preferences
+
+        # print("KEYS", operator.properties.keys())
+        #print("BLAS", addon_prefs.__annotations__)
+        #print(addon_prefs.__dict__)
+        for key in addon_prefs.__annotations__.keys():
+            if key not in AutoExportGltfPreferenceNames:
+                layout.prop(operator, key)
+     
+
+    
+
+class SCENE_UL_GLTF_auto_export(bpy.types.UIList):
+    # The draw_item function is called for each item of the collection that is visible in the list.
+    #   data is the RNA object containing the collection,
+    #   item is the current drawn item of the collection,
+    #   icon is the "computed" icon for the item (as an integer, because some objects like materials or textures
+    #   have custom icons ID, which are not available as enum items).
+    #   active_data is the RNA object containing the active property for the collection (i.e. integer pointing to the
+    #   active item of the collection).
+    #   active_propname is the name of the active property (use 'getattr(active_data, active_propname)').
+    #   index is index of the current item in the collection.
+    #   flt_flag is the result of the filtering process for this item.
+    #   Note: as index and flt_flag are optional arguments, you do not have to use/declare them here if you don't
+    #         need them.
+    def draw_item(self, context, layout, data, item, icon, active_data, active_propname):
+        ob = data
+        # draw_item must handle the three layout types... Usually 'DEFAULT' and 'COMPACT' can share the same code.
+        if self.layout_type in {'DEFAULT', 'COMPACT'}:
+            # You should always start your row layout by a label (icon + text), or a non-embossed text field,
+            # this will also make the row easily selectable in the list! The later also enables ctrl-click rename.
+            # We use icon_value of label, as our given icon is an integer value, not an enum ID.
+            # Note "data" names should never be translated!
+            #if ma:
+            #    layout.prop(ma, "name", text="", emboss=False, icon_value=icon)
+            #else:
+            #    layout.label(text="", translate=False, icon_value=icon)
+            layout.label(text=item.name, icon_value=icon)
+            #layout.prop(item, "name", text="", emboss=False, icon_value=icon)
+        # 'GRID' layout type should be as compact as possible (typically a single icon!).
+        elif self.layout_type == 'GRID':
+            layout.alignment = 'CENTER'
+            layout.label(text="", icon_value=icon)
+
+

tools/gltf_auto_export/ui/various.py

@@ -0,0 +1,85 @@
+
+import bpy
+from bpy.types import Operator
+
+class SCENES_LIST_OT_actions(Operator):
+    """Move items up and down, add and remove"""
+    bl_idname = "scene_list.list_action"
+    bl_label = "List Actions"
+    bl_description = "Move items up and down, add and remove"
+    bl_options = {'REGISTER'}
+
+    action: bpy.props.EnumProperty(
+        items=(
+            ('UP', "Up", ""),
+            ('DOWN', "Down", ""),
+            ('REMOVE', "Remove", ""),
+            ('ADD', "Add", "")))
+    
+
+    scene_type: bpy.props.StringProperty()#TODO: replace with enum
+
+    def invoke(self, context, event):
+        print("INVOKE", self.scene_type, "gltf_auto_export")
+        source = bpy.context.preferences.addons["gltf_auto_export"].preferences
+        target_name = "library_scenes"
+        target_index = "library_scenes_index"
+        if self.scene_type == "level":
+            target_name = "main_scenes"
+            target_index = "main_scenes_index"
+        
+        target = getattr(source, target_name)
+        idx = getattr(source, target_index)
+
+        try:
+            item = target[idx]
+        except IndexError:
+            pass
+        else:
+            if self.action == 'DOWN' and idx < len(target) - 1:
+                item_next = target[idx + 1].name
+                target.move(idx, idx + 1)
+                source[target_index] += 1
+                info = 'Item "%s" moved to position %d' % (item.name, source[target_index] + 1)
+                self.report({'INFO'}, info)
+
+            elif self.action == 'UP' and idx >= 1:
+                item_prev = target[idx - 1].name
+                target.move(idx, idx - 1)
+                source[target_index] -= 1
+                info = 'Item "%s" moved to position %d' % (item.name, source[target_index] + 1)
+                self.report({'INFO'}, info)
+
+            elif self.action == 'REMOVE':
+                info = 'Item "%s" removed from list' % (target[idx].name)
+                source[target_index] -= 1
+                target.remove(idx)
+                self.report({'INFO'}, info)
+
+        if self.action == 'ADD':
+            new_scene_name = None
+            if self.scene_type == "level":
+                if context.scene.main_scene:
+                    new_scene_name = context.scene.main_scene.name
+            else:
+                if context.scene.library_scene:
+                    new_scene_name = context.scene.library_scene.name
+            if new_scene_name:
+                item = target.add()
+                item.name = new_scene_name#f"Rule {idx +1}"
+
+                if self.scene_type == "level":
+                    context.scene.main_scene = None
+                else:
+                    context.scene.library_scene = None
+
+                #name = f"Rule {idx +1}"
+                #target.append({"name": name})
+
+                source[target_index] = len(target) - 1
+                info = '"%s" added to list' % (item.name)
+                self.report({'INFO'}, info)
+        
+        return {"FINISHED"}
+
+