MHX version confusion

Several bug reports have recently been concerned with strange errors when importing MHX files into Blender: missing bones, etc. The reason is that the exported file uses a version of MHX which is incompatible with the importer. MHX does not change as rapidly as it used to, but it is still not quite stable; new features may require new language constructs. One of the main advantages with a custom import language is that both the export and import side can be modified when the need arises. The price for this is that such modifications lead to inconsistencies unless the export and import sides use the same version.

Several versions of the MHX importer are currently available: in the nightly builds, in alpha 5, and in Blender distributions from www.graphicall.org. To make things worse, Blender 2.5x is still in alpha stage and the python API is changing, although less rapidly than during the spring. This causes a lot of confusion, and it is difficult for me to fix if the versions I use work flawlessly.

In order to synch the exported MHX files with the importer, version checking is now strictly enforced. Starting with MHX version 0.13, there is an error if the MHX file and the importer do not have the same version number. You can override this behavior by deselecting the Enforce version option during import, but you do so at your own risk.

Updates 2010.07.25:

MHX updated for Blender 2.5.3 beta.

The first official Blender 2.5 beta was released a few days ago, and can be fetched from www.blender.org. There were quite a few last minute name-changes that broke the MHX importer. These have now been fixed, but compatibility with earlier builds from graphicall.org is lost. On the other hand, I expect that this beta can be a stable platform for the MHX importer until the next beta is released.

Problems with hair import

The particle hair import also stopped working on the Blender beta. After a bugfix hair curves can now be imported, but the resulting hair is nonsense. The problem is in Blender. Hair strands in Blender used to be described in global coordinates, but not any more, and the flag which controls the coordinate system (ParticleSystem.global_hair) is read-only. If anyone knows how to specify global hair coordinates, I would like to know.