---
tags: Parsing
---

# UAsset Schema - KaitaiStruct

[kaitai.io](https://kaitai.io/)

meta:
  id: uasset
  title: Unreal Engine Asset
  file-extension: uasset
  application: Unreal Engine
  endian: le
seq:
  - id: tag
    type: u4
  - id: legacy_ver
    type: s4
  - id: ue_ver
    type: s4
  - id: file_ver
    type: u4
  - id: licensee_ver
    type: u4
  - id: custom_versions
    type: custom_version_table
  - id: header_size
    type: u4
  - id: package_group
    type: encoded_string
  - id: package_flags
    type: u4
  - id: names_chunk
    type: chunk_pointer
  - id: exports_chunk
    type: chunk_pointer
  - id: imports_chunk
    type: chunk_pointer
  - id: depends_offset
    type: u4
  - id: string_assets
    type: chunk_pointer
  - id: thumbnail_offset
    type: u4
  - id: guid
    size: 16
  - id: generations
    type: generation_info_table
  - id: engine_version_saved
    type: engine_version
  - id: compression_flags
    type: u4
  - id: compressed_chunks
    type: compressed_chunk_table
  - id: package_source
    type: u4
  - type: u8 #unknown_field, This field isn't present in some older ARK mods
    if: licensee_ver >= 10
  - id: packages_to_cook
    type: string_table
  - type: s4 #texture_allocations, Legacy field that is not used anymore
    if: legacy_ver > -7
  - id: asset_registry_data_offset
    type: u4
  - id: bulk_data_start_offset
    type: u8
  - id: world_tile_info_data_offset
    type: u8
instances:
  names:
    pos: names_chunk.offset
    type: encoded_string
    repeat: expr
    repeat-expr: names_chunk.count
  imports:
    pos: imports_chunk.offset
    type: import_table_item
    repeat: expr
    repeat-expr: imports_chunk.count
  exports:
    pos: exports_chunk.offset
    type: export_table_item
    repeat: expr
    repeat-expr: exports_chunk.count
  tile_info:
    pos: world_tile_info_data_offset
    type: world_tile_info
    if: (world_tile_info_data_offset != 0)
  none_name:
    value: package_group.value
types:
  custom_version_table:
    seq:
      - id: count
        type: u4
      - id: items
        type: custom_version
        repeat: expr
        repeat-expr: count
  custom_version:
    seq:
      - id: guid
        size: 16
      - id: version
        type: u4
      - id: friendly_name
        type: encoded_string
  generation_info_table:
    seq:
      - id: count
        type: u4
      - id: items
        type: generation_info
        repeat: expr
        repeat-expr: count
  generation_info:
    seq:
      - id: export_count
        type: u4
      - id: name_count
        type: u4
  compressed_chunk_table:
    seq:
      - id: count
        type: u4
      - id: items
        type: compressed_chunk
        repeat: expr
        repeat-expr: count
  compressed_chunk:
    seq:
      - id: uncompressed_offset
        type: u4
      - id: uncompressed_size
        type: u4
      - id: compressed_offset
        type: u4
      - id: compressed_size
        type: u4
  string_table:
    seq:
      - id: count
        type: u4
      - id: items
        type: encoded_string
        repeat: expr
        repeat-expr: count
  engine_version:
    seq:
      - id: major
        type: u2
      - id: minor
        type: u2
      - id: patch
        type: u2
      - id: changelist
        type: u4
      - id: branch
        type: encoded_string
  encoded_string:
    seq:
      - id: length
        type: s4
      - id: narrow
        type: strz
        size: length
        encoding: utf8
        if: length >= 0
      - id: wide
        type: strz
        size: length * -2
        encoding: utf16
        if: length < 0
    instances:
      value:
        value: 'length < 0 ? wide.substring(0, -length - 1) : narrow.substring(0, length - 1)'
  chunk_pointer:
    seq:
      - id: count
        type: u4
      - id: offset
        type: u4
  name_index:
    seq:
      - id: index
        type: u4
      - id: instance
        type: u4
    instances:
      value:
        value: _root.names[index].value
  object_index:
    seq:
      - id: raw_value
        type: s4
    instances:
      kind:
        value: 'raw_value == 0 ? "none" : raw_value < 0 ? "import" : "export"'
      index:
        value: 'raw_value < 0 ? -raw_value - 1 : raw_value - 1'
        if: raw_value != 0
      value:
        value: 'raw_value < 0 ? _root.imports[index] : _root.exports[index]'
        if: raw_value != 0
  import_table_item:
    seq:
      - id: package
        type: name_index
      - id: class
        type: name_index
      - id: namespace
        type: object_index
      - id: name
        type: name_index
  export_table_item:
    seq:
      - id: class
        type: s4
      - id: super
        type: s4
      - id: namespace
        type: s4
      - id: name
        type: name_index
      - id: object_flags
        type: u4
      - id: serial_size
        type: u4
      - id: serial_offset
        type: u4
      - id: force_export
        type: u4
      - id: not_for_client
        type: u4
      - id: not_for_server
        type: u4
      - id: guid
        size: 16
      - id: package_flags
        type: u4
      - id: not_for_editor_game
        type: u4
    instances:
      properties:
        pos: serial_offset
        #size: serial_size
        type: property
        repeat: until
        #repeat-expr: 1
        repeat-until: _.has_value == false or _index == 2
  property:
    seq:
      - id: name
        type: name_index
      - id: type
        type: name_index
        if: has_value
      - id: size
        type: u4
        if: has_value
      - id: index
        type: u4
        if: has_value
      - id: value
        if: has_value
        size: size
        type:
          switch-on: type.value
          cases:
            '"ObjectProperty"': object_index
            '"NameProperty"': name_index
            '"FloatProperty"': f4
            '"DoubleProperty"': f8
            '"BoolProperty"': u1
            '"ByteProperty"': u1
            '"IntProperty"': s4
            '"UInt32Property"': u4
            '"StrProperty"': encoded_string
            '"StringProperty"': encoded_string
            '"TextProperty"': text_property
            '"StringAssetReference"': encoded_string
            '"AssetObjectProperty"': encoded_string
            '"StructProperty"': encoded_string
            '"ArrayProperty"': encoded_string
            '"Guid"': guid
            '"Vector"': vector
            '"Vector2D"': vector_2d
            '"Rotator"': rotator
            '"Quat"': quat
            '"Color"': u4
            '"LinearColor"': linear_color
            '"Box"': box
            '"IntPoint"': encoded_string
            _: unknown_property
    instances:
      has_value:
        value: name.value != _root.none_name
  text_property:
    seq:
      - id: flags
        type: u4
      - id: history_type
        type: s1
      - id: namespace
        type: encoded_string
      - id: key
        type: encoded_string
      - id: source_string
        type: encoded_string
  unknown_property:
    instances:
      value:
        value: ("<unsupported type " + _parent.type.value + ">")
  world_tile_info:
    seq:
      - type: u8 #unknown_field
      - id: bounds
        type: box
      - id: layer_name
        type: encoded_string
      - type: u4 #unknown_field
      - type: u4 #unknown_field
      - type: u4 #unknown_field
      - id: streaming_distance
        type: s4
      - id: distance_streaming_enabled
        type: u2
  box:
    seq:
      - id: min
        type: vector
      - id: max
        type: vector
      - id: is_valid
        type: u2
  vector:
    seq:
      - id: 'x'
        size: 4
      - id: 'y'
        size: 4
      - id: 'z'
        size: 4
  vector_2d:
    seq:
      - id: 'x'
        size: 4
      - id: 'y'
        size: 4
  int_point:
    seq:
      - id: 'x'
        type: s4
      - id: 'y'
        type: s4
  rotator:
    seq:
      - id: 'a'
        size: 4
      - id: 'b'
        size: 4
      - id: 'c'
        size: 4
  quat:
    seq:
      - id: 'w'
        size: 4
      - id: 'x'
        size: 4
      - id: 'y'
        size: 4
      - id: 'z'
        size: 4
  guid:
    seq:
      - id: bytes
        size: 16
  linear_color:
    seq:
      - id: 'r'
        size: 4
      - id: 'g'
        size: 4
      - id: 'b'
        size: 4
      - id: 'a'
        size: 4
  struct_property:
    params:
      - id: inside_array
        type: bool
    seq:
      - id: name
        type: name_index
      - id: value
        if: has_value
        type:
          switch-on: name.value
          cases:
            '"ObjectProperty"': object_index
            '"NameProperty"': name_index
            '"FloatProperty"': f4
            '"DoubleProperty"': f8
            '"BoolProperty"': u1
            '"ByteProperty"': u1
            '"IntProperty"': s4
            '"UInt32Property"': u4
            '"StrProperty"': encoded_string
            '"StringProperty"': encoded_string
            '"TextProperty"': text_property
            '"StringAssetReference"': encoded_string
            '"AssetObjectProperty"': encoded_string
            '"StructProperty"': encoded_string
            '"ArrayProperty"': encoded_string
            '"Guid"': guid
            '"Vector"': vector
            '"Vector2D"': vector_2d
            '"Rotator"': rotator
            '"Quat"': quat
            '"Color"': u4
            '"LinearColor"': linear_color
            '"Box"': box
            '"IntPoint"': encoded_string
            _: unknown_property
    instances:
      has_value:
        value: name.value != _root.none_name