I rotated the cube in edit mode, is there a way to apply the selected face(yellow one) normal direction as the empty’s Z (or X, Y) direction?
The standards in blender are a bit cumbersome, I think. That is why there are some addons. I think easy align is quite good.
It might be easier just adding a new empty
- Go into Edit mode on Cube.
- Select face
- Press Shift+Numpad 7
- Shift Right-click on face to pop 3D cursor there
- Go back to Object mode
- Shift + A … add Empty
- In the Options bottom left change it’s orientation to 3D Cursor or View
- Press one of your standard numpad view keys to get back to normality
And if for some reason you absolutely have to have the rotation applied to an existing Empty, then just do as above, turn on the Copy Attributes addon, Select your original empty, shift select the newly rotated empty and hit Ctrl+C and copy rotation.
Those are exactly the answers I was looking for, thanks!