parseGlb static method

GltfResult parseGlb(Uint8List glbData)

Parses a GLB binary buffer.

Implementation

static GltfResult parseGlb(Uint8List glbData) {
  // GLB header: magic(4) + version(4) + length(4) = 12 bytes
  final magic = ByteData.sublistView(
    glbData,
    0,
    4,
  ).getUint32(0, Endian.little);
  if (magic != 0x46546C67) {
    throw const FormatException('Invalid GLB magic number');
  }

  // Chunk 0: JSON
  final jsonLength = ByteData.sublistView(
    glbData,
    12,
    16,
  ).getUint32(0, Endian.little);
  final jsonString = utf8.decode(glbData.sublist(20, 20 + jsonLength));

  // Chunk 1: Binary (optional)
  Uint8List? binBuffer;
  if (glbData.length > 20 + jsonLength + 8) {
    final binOffset = 20 + jsonLength;
    final binLength = ByteData.sublistView(
      glbData,
      binOffset,
      binOffset + 4,
    ).getUint32(0, Endian.little);
    binBuffer = glbData.sublist(binOffset + 8, binOffset + 8 + binLength);
  }

  final json = jsonDecode(jsonString) as Map<String, dynamic>;
  return _parse(json, binBuffer);
}