I have been playing a little bit with the MPxTransform / MPxTransformMatrix. My idea it was to create a transform node with some Pre-transforms attributes, like pre transform, pre rotation, or a pre matrix.
So you can use the pre rotation in the same way you use the jointOrient attribute in joints, the preTranslate would be an offset, usseful to zero out your node (kind of change the pivot) and my idea for the preMatrix was to been able to connect an external worldMatrix and follow his transformation.
But so far, I have found some problems and I don't know how to solve them, I have been taking a look to the rockingTransform example, but it also has the same result, the transformation applied it only affects to the hierarchy and worldMatrix (as i expected) but it doesn't 'transform' the local rotation axis.
Anyone has any experience with custom transforms?