Perform a raycast at the position specified by its parent event. A raycast will pick entity and trigger its EnterRayHit and LeaveRayHit events accordingly.
This action should usually be placed in an input Event suchs as FingerDown or FingerMove. The action doesn't do anything if its not in an event that has at least a 2D coordinate in its parameter A.
A simple way to think about this action is that in a FingerDown event it'll trigger the EnterRayHit event on the entity that is below the finger or mouse cursor.