This function can be used to retrieve the angle of the given camera. The return value will be between 0 and 360. Note that this function is only valid for cameras created using camera_create_view() or for those added in the room editor.
Argument Description camera_id The unique camera ID value returned when you created the camera
var ang =
if ang != 0
The above code retrieves the angle of the camera assigned to view port and then checks this to see if it matches the given value. If it does not then the view camera is set to that angle.