How can I get the global rotation of a bone from the Blender editor? I want to constrain a bone to have only that rotation, regardless of its parent. I want it in pose mode.
I have done some testing on my own and here is the blend file. You can download it to test if that is what you are looking for. The rig is done on the left hand.
Basically, I have created an IK target for the hand so that it always points at the target you tell it to regardless how you move the arm. It works like the way you would constraint the eyes to a target.