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Defines a bone outside of any .smd source. This is useful when building animation only mdl's that would otherwise optimize out all the bones since none of them are connected to any geometry or attachment points. You can get studiomdl to dump this out using the "-definebones" command line option.

The (fixup) fields specify how the IK solver has rotated any of the bones to match the single X axis as the long axis requirement for all bones in an IK chain. All the source animations are resolved to match this new orientation.

$definebone can also be used to change the bone order of a model (for example, bone merging purposes), by specifying it before any model references and changing around the $definebone list order.

This command is run before any $hierarchy commands.


$definebone (name) (parent) (X) (Y) (Z) (xr) (yr) (zr) (fixup XR) (fixup YR) (fixup ZR)

Generating definebone lines using Crowbar

The $define bone process of crowbar. highlighted are: The definebone checkboxes in blue, The bone collapsing messages in red, and the generated definebone lines in green. (Click to enlarge)

The Crowbar Decompiling tool has a user interface for studiomdl, which also contains an automated process for writing $definebone lines.

  1. Remove all existing $definebone lines, or only the ones you want to re-write.
  2. In the "Compile" tab of Crowbar, select the "definebones" checkbox. You can decide to write everything into a qci file by checking the "Create qci file" checkbox underneath
  3. Click "Compile". This will not compile the model itself, it will only generate definebone lines. If you did not decide to write a qci file, you must copy the lines from crowbars compile-log text box and paste it into your qc file.
Note:If the compile log reads "collapsing <bonename>" followed by "Collapsed X bones", you will be missing the listed bones. Add a $bonemerge line for each missing bone.
Note:If you compile definebone lines while you already have existing definebone lines it will use the data of the existing lines, instead of reading the information from the smd or dmx file.