Using Helper Object Axis As Reference Vector
Instead of entering the Reference Vector in an Input Value node, we can query the Z axis of a scene object. This will make the animation of the effect even easier since we could just pick any object to acquire the value.
Select the Vector InputValue used as reference and change its type to InputObject.
Create a Point helper in the scene and pick it as the reference object in the InputObject node.
Select the InputObject node and press [O] and[b][u] [T][/u][/b] to insert an Object > PropertyQuery operator.
The default output is set to Pos, but we will want the object's Z axis.
The bold “T” is confounded in tutorial 1 (shouldn’t it be an “E” ?)
Also you forgot the normalize after the propertyQuery in the description.