Constrain draggable object to one axis

Is there a way to constrain a draggable object to one axis? I found an option to specify a dragPlane but no way to constrain to one specific axis. For context, I have a box with one manipulator on each face and I want each manipulator to be draggable on only the axis of that face (e.g. the Z+ manipulator should be draggable on only the Z-axis).

This is not possible in the viewer 2 API which is publicly released at the moment. The upcoming viewer 3 API will have more advanced options to contrain dragging.