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DigitalRuneFBX Support

This sections contains some notes about Autodesk FBX files.

This topic contains the following sections:

FBX format

Autodesk FBX (file extension .fbx) is a proprietary file format for exchanging 3D assets. FBX is currently the best choice for importing models and animations into XNA or MonoGame. However, there are several versions of the FBX format - not all versions are compatible with XNA or MonoGame!

List of FBX versions (and alternate names in brackets):

  • 6.x (FBX 2006, FBX 2009, FBX 2010)
  • 7.1 (FBX 2011)
  • 7.2 (FBX 2012)
  • 7.3 (FBX 2013)
  • 7.4 (FBX 2014)

More important than the file version is the structure of the scene in the FBX file. The structure depends on the FBX exporter and the export settings being used.

The FBX format stores the units (m, cm, inches, etc.) that are used in the scene. The default unit used by FBX is cm. Some importers ignore the unit settings and assume that 1 unit = 1 cm. Therefore it might be necessary to manually scale the model during import from cm to the correct unit.

The Autodesk FBX Converter can be used to convert 3D file formats (3DS, DAE, DXF, FBX, OBJ) and to preview models. It can also convert FBX files between different FBX versions.

Importing FBX files in XNA

According to the MSDN documentation, XNA was designed to work with assets exported with the 2006.11 version of the FBX exporter.

Importing FBX files in MonoGame

MonoGame uses Assimp to import FBX files. The current version of Assimp supports FBX version 7.1 (FBX 2011), 7.2 (FBX 2012), and 7.3 (FBX 2013).

Assimp is not as powerful as the Autodesk FBX SDK - not all FBX features are supported. Limitations:

  • A model cannot have more than one skeleton.
  • Bone names need to be unique. Bones names must not conflict with other node names.
  • If the skeleton includes non-deformation bones: Always export the skeleton in bind pose (rest pose)!
  • Assimp only reads the key frame values stored in the FBX file. It does not fully evaluate the scene for animations. This means, all bones that are animated need to be key-framed!
Tip Tip

open3mod is a 3D model viewer built using Assimp. You can check your exported models and animations using open3mod. If the model looks okay in open3mod, then MonoGame should not have any troubles loading the model.

See Also