glTF exporter: perf: use bytearrays

io_scene_gltf2/__init__.py

@@ -15,7 +15,7 @@
 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": (1, 4, 25),
+    "version": (1, 4, 26),
     'blender': (2, 90, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/io/exp/gltf2_io_buffer.py

@@ -22,21 +22,23 @@ class Buffer:
     """Class representing binary data for use in a glTF file as 'buffer' property."""
 
     def __init__(self, buffer_index=0):
-        self.__data = b""
+        self.__data = bytearray(b"")
         self.__buffer_index = buffer_index
 
     def add_and_get_view(self, binary_data: gltf2_io_binary_data.BinaryData) -> gltf2_io.BufferView:
         """Add binary data to the buffer. Return a glTF BufferView."""
         offset = len(self.__data)
-        self.__data += binary_data.data
+        self.__data.extend(binary_data.data)
+
+        length = binary_data.byte_length
 
         # offsets should be a multiple of 4 --> therefore add padding if necessary
-        padding = (4 - (binary_data.byte_length % 4)) % 4
-        self.__data += b"\x00" * padding
+        padding = (4 - (length % 4)) % 4
+        self.__data.extend(b"\x00" * padding)
 
         buffer_view = gltf2_io.BufferView(
             buffer=self.__buffer_index,
-            byte_length=binary_data.byte_length,
+            byte_length=length,
             byte_offset=offset,
             byte_stride=None,
             extensions=None,