Document exporting animation clips and setup pose at frame 0

[ziriax]

Update the README, frame 0 (or the frame specified with the -ivt argument) should contain a setup pose, Maya2glTF is not using Maya's skin binding pose information, since that turns out to be unreliable (can be locked, so going to the binding pose is not always possible unless modifying the scene)

[BigRoy]

@ziriax what was the issue with it potentially being locked? What exactly would be locked? Can you describe an example case where otherwise it would have failed?

Using the preBindMatrix from the skinCluster nodes you should be able to completely identify the bind pose matrices for the joints no matter what the frame is.

[ziriax]

Often Maya gives an error when asking to return the bind pose.

This is related to https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2015/ENU/Maya/files/GUID-D47C31C7-428F-4A54-B104-49C51F3856E5-htm.html

So we didn't bother trying to solve this, and just require our artists to make a keyframe that we consider to be the setup pose. We just read the world matrices of the joints at that frame, and reconstruct a bind pose. This always works, but might not be the same one as Maya. But that's okay, since we never use local transformations anyway, we always start from the sampled world transforms, so that artists can apply whatever constraints they desire

But yes, it might be possible to work around this. Thanks for the info!

We are currently very busy, I was actually preparing version 1.0 of this plugin, I will try to find some time to continue work on it.

That being said, PRs are always welcome, although I admit the code is not as clean as I would like it to be ;-)