I need my Y arrow to be perpendicular with the object and the X arrow parallel so that the glass panels array in a straight line without having to change other values in the relative offset setting
- Select two vertices,
- Change Transformation Orientations to Normal,
- Press the add button in the Transform Orientations panel then
- Select new normal, ie Edge, in the drop down list.
- In Object mode, shift+S > Cursor to selected,
- Shift+A > Empty > Plane Axes,
- Set the constraint as shown in the figure and
- Move Empty object using added normal(Edge).