io_scene_gltf2/io/exp/gltf2_io_buffer.py

   1 # SPDX-FileCopyrightText: 2018-2021 The glTF-Blender-IO authors
   2 #
   3 # SPDX-License-Identifier: Apache-2.0
   4
   5 import base64
   6
   7 from ...io.com import gltf2_io
   8 from ...io.exp import gltf2_io_binary_data
   9
  10
  11 class Buffer:
  12     """Class representing binary data for use in a glTF file as 'buffer' property."""
  13
  14     def __init__(self, buffer_index=0, initial_data=None):
  15         self.__data = bytearray(b"")
  16         if initial_data is not None:
  17             self.__data = bytearray(initial_data.tobytes())
  18         self.__buffer_index = buffer_index
  19
  20     def add_and_get_view(self, binary_data: gltf2_io_binary_data.BinaryData) -> gltf2_io.BufferView:
  21         """Add binary data to the buffer. Return a glTF BufferView."""
  22         offset = len(self.__data)
  23         self.__data.extend(binary_data.data)
  24
  25         length = binary_data.byte_length
  26
  27         # offsets should be a multiple of 4 --> therefore add padding if necessary
  28         padding = (4 - (length % 4)) % 4
  29         self.__data.extend(b"\x00" * padding)
  30
  31         buffer_view = gltf2_io.BufferView(
  32             buffer=self.__buffer_index,
  33             byte_length=length,
  34             byte_offset=offset,
  35             byte_stride=None,
  36             extensions=None,
  37             extras=None,
  38             name=None,
  39             target=binary_data.bufferViewTarget
  40         )
  41         return buffer_view
  42
  43     @property
  44     def byte_length(self):
  45         return len(self.__data)
  46
  47     def to_bytes(self):
  48         return self.__data
  49
  50     def clear(self):
  51         self.__data = b""
  52
  53     def to_embed_string(self):
  54         return 'data:application/octet-stream;base64,' + base64.b64encode(self.__data).decode('ascii')