Urho3D tries to use existing file formats whenever possible, and define custom file formats only when absolutely necessary. Currently used custom file formats are:
Model geometry and vertex morph data byte Identifier "UMDL" uint Number of vertex buffers For each vertex buffer: uint Vertex count uint Vertex element mask (determines vertex size) uint Morphable vertex range start index uint Morphable vertex count byte Vertex data (vertex count * vertex size) uint Number of index buffers For each index buffer: uint Index count uint Index size (2 for 16-bit indices, 4 for 32-bit indices) byte Index data (index count * index size) uint Number of geometries For each geometry: uint Number of bone mapping entries uint Bone mapping data, Maps geometry bone indices to global bone indices for HW skinning. May be empty, in this case identity mapping will be used. uint Number of LOD levels For each LOD level: float LOD distance uint Primitive type (0 = triangle list, 1 = line list) uint Vertex buffer index, starting from 0 uint Index buffer index, starting from 0 uint Draw range: index start uint Draw range: index count uint Number of vertex morphs (may be 0) For each vertex morph: cstring Name of morph uint Number of affected vertex buffers For each affected vertex buffer: uint Vertex buffer index, starting from 0 uint Vertex element mask for morph data. Only positions, normals & tangents are supported. uint Vertex count For each vertex: uint Vertex index Vector3 Position (if included in the mask) Vector3 Normal (if included in the mask) Vector3 Tangent (if included in the mask) Skeleton data uint Number of bones (may be 0) For each bone: cstring Bone name uint Parent bone index starting from 0. Same as own bone index for the root bone Vector3 Initial position Quaternion Initial rotation Vector3 Initial scale float 4x3 offset matrix for skinning byte Bone collision info bitmask. 1 = bounding sphere 2 = bounding box If bounding sphere data included: float Bone radius If bounding box data included: Vector3 Bone bounding box minimum Vector3 Bone bounding box maximum Bounding box data Vector3 Model bounding box minimum Vector3 Model bounding box maximum Geometry center data For each geometry: Vector3 Geometry center
byte Identifier "UANI" cstring Animation name float Length in seconds uint Number of tracks For each track: cstring Track name (practically same as the bone name that should be driven) byte Mask of included animation data. 1 = bone positions 2 = bone rotations 4 = bone scaling uint Number of keyframes For each keyframe: float Time position in seconds Vector3 Position (if included in data) Quaternion Rotation (if included in data) Vector3 Scale (if included in data)
Note: animations are stored using absolute bone transformations. Therefore only lerp-blending between animations is supported; additive pose modification is not.
byte Identifier "USHD" short Shader type (0 = vertex, 1 = pixel) short Shader model (3) uint Number of constant parameters For each constant parameter: cstring Parameter name byte Register index byte Number of registers uint Number of texture units For each texture unit: cstring Texture unit name byte Sampler index uint Bytecode size byte Bytecode
byte Identifier "USHD" short Shader type (0 = vertex, 1 = pixel) short Shader model (4) uint Vertex element mask (0 for pixel shaders) uint Number of constant parameters For each constant parameter: cstring Parameter name byte CBuffer index uint Start byte offset in CBuffer uint Byte size uint Number of texture units For each texture unit: cstring Texture unit name byte Sampler index uint Bytecode size byte Bytecode
byte Identifier "UPAK" or "ULZ4" if compressed uint Number of file entries uint Whole package checksum For each file entry: cstring Name uint Start offset uint Size uint Checksum The compressed data for each file is the following, repeated until the file is done: ushort Uncompressed length of block ushort Compressed length of block byte Compressed data
byte Identifier "ASBC" byte Bytecode, produced by AngelScript serializer