when using handle --use-euler-rotation Y-up flips to Z+ axis

[wave-electron]

@kcoley When using the --use-euler-rotation handle the Y-Up flips to Z+ axis. I've included the input GLTF for with and without euler handle.

using_euler_Y-up-Flips+Z.zip

[wave-electron]

@kcoley To fix the orientation, I did the following. I haven't check all cases.

# under line 453 added  
 UsdGeom.SetStageUpAxis(self.stage, UsdGeom.Tokens.z)

# Changed 
       #return (usd_node.AddRotateXYZOp(opSuffix='rotate'), convert_rotation)
        return (usd_node.AddRotateZXYOp(opSuffix='rotate'), convert_rotation)

The rotations are about jittery, and its got a gimbal lock... but I'm slightly closer to result I want than before!

[wave-electron]

@kcoley I just checked and that workaround is not going to work for all cases. One temporary solution would be to add handle for switching between the Up-axis from Y -> Z. But with the jitter and gimbal lock still an issue its not usable animation in any case.

[kcoley]

@wave-electron I see. I need to find out what is causing the jittering to occur. It could be an issue with my interpolation code in Animation. As for the rotation, I saw an answer posted in the USD forums that might provide another workaround. Another thought would be to use animated transform matrices for rotation and see if that works per key frame