glTF exporter: Allow to call a pre and post callbacks

Thanks jjcasmar!

io_scene_gltf2/__init__.py

@@ -15,7 +15,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (1, 3, 30),
+    "version": (1, 3, 31),
     'blender': (2, 90, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',
@@ -485,6 +485,8 @@ class ExportGLTF2_Base:
             bpy.path.ensure_ext(self.filepath,self.filename_ext)))[0] + '.bin'
 
         user_extensions = []
+        pre_export_callbacks = []
+        post_export_callbacks = []
 
         import sys
         preferences = bpy.context.preferences
@@ -500,7 +502,13 @@ class ExportGLTF2_Base:
                 extension_ctors = module.glTF2ExportUserExtensions
                 for extension_ctor in extension_ctors:
                     user_extensions.append(extension_ctor())
+            if hasattr(module, 'glTF2_pre_export_callback'):
+                pre_export_callbacks.append(module.glTF2_pre_export_callback)
+            if hasattr(module, 'glTF2_post_export_callback'):
+                post_export_callbacks.append(module.glTF2_post_export_callback)
         export_settings['gltf_user_extensions'] = user_extensions
+        export_settings['pre_export_callbacks'] = pre_export_callbacks
+        export_settings['post_export_callbacks'] = post_export_callbacks
 
         return gltf2_blender_export.save(context, export_settings)
 

io_scene_gltf2/blender/exp/gltf2_blender_export.py

@@ -39,7 +39,15 @@ def save(context, export_settings):
 
     __notify_start(context)
     start_time = time.time()
+    pre_export_callbacks = export_settings["pre_export_callbacks"]
+    for callback in pre_export_callbacks:
+        callback(export_settings)
+
     json, buffer = __export(export_settings)
+
+    post_export_callbacks = export_settings["post_export_callbacks"]
+    for callback in post_export_callbacks:
+        callback(export_settings)
     __write_file(json, buffer, export_settings)
 
     end_time = time.time()