.FBX

Filmbox

Introduction

FBX began as the native format of Filmbox, a motion capture program by Kaydara that was later renamed MotionBuilder. Autodesk bought Kaydara in 2006 and FBX became the usual way to move models, skeletons and animation between Autodesk tools such as Maya and 3ds Max and game engines. The format is proprietary: Autodesk publishes an SDK for reading and writing it, not a specification.

The same tree of nodes can be saved in two forms, binary and ASCII text. Binary is the default and by far the more common.

Variations

FormatVariationAboutOpen
.FBXASCII FBXThe text form of FBX: the same scene nodes written as names, values and braces.Open
.FBXBinary FBXAutodesk’s scene exchange format as binary node records, the usual form of FBX.Open

Binary FBX

The usual form: a short header, then a tree of node records with typed properties, where large arrays of numbers may be zlib compressed.

The file starts with the text Kaydara FBX Binary followed by two spaces and a zero byte. A 32-bit little-endian version number, such as 7400, follows at offset 23.

ASCII FBX

The same nodes written as text, with names, comma-separated values and braces. It is larger and slower to load, and is mainly used to inspect or compare files.

The file starts with a comment line beginning ; FBX and the version, such as ; FBX 7.4.0 project file, rather than the binary signature.

Links

Software

Developers

  • ufbx, single-file C library that loads binary and ASCII FBX
  • Assimp, C++ library that imports dozens of 3D formats, FBX among them

Reference