Elevators in Unity

Objective: Create an elevator which can be summoned by the player to go up and down if they have 8 coins, with a light indicating elevator status.

Player summons elevator and goes up and back down, noting the light on the panel changes color.

The hierarchy window is as shown below. The key features for an elevator are the Lift, which contains the Elevator and two destination points, and the Elevator_Panel, which has the Call_Button.

Hierarchy showing Lift and Elevator_Panel structure.

The Elevator_Panel is a cuboid with a box colliders with a trigger, and ElevatorPanel C# script components, see below. Note the is trigger box collider is large enough and positioned to detect the Player standing in front of the panel. A rigidbody is not needed as the Character Controller physics on the Player is used.

Elevator Panel components

The Call_Button is a child of the Elevator_Panel with the components below, notably the mesh renderer and its associated material.

Call_Button components.

The ElevatorPanel script on the Elevator_Panel requires several variables shown below. The Elevator object is assigned in void Start(), as is the MeshRenderer of the Call_Button, both are null checked.

Variable assignment in ElevatorPanel script.

Void update checks every frame to see if the E key is pressed while the player is standing next to the panel with the required coins. If all these are true it accesses the CallElevator method on the Elevator script.

The _atElevator bool is set to true if the player enters the box collider trigger using the OnTriggerEnter method below. The _coinsCollected by the player is also retrieved from other using GetComponent to call the CoinCount method on the Player script .

OnTriggerEnter method on ElevatorPanel script.

The CointCount method on the Player script is shown below, and returns the number of _coins collected by the player.

CoinCount method on Player script.

If the player leaves the trigger an OnTriggerExit method sets the _atElevator bool to false.

OnTriggerExit method on ElevatorPanel script.

Finally a public void ButtonPressed() method is used to toggle the color of the button between red and green and is called from the Elevator script. The Elevator is a cuboid with a two box colliders, one with a trigger, and Elevator C# script components, see below. Note the is trigger box collider is large enough and positioned to detect the Player standing on the elevator.

Elevator components

The Elevator script on Elevator requires several variables to store the _pointsA & B between which the elevator moves, its current _target, its _speed, a bool to know if the Player is _onElevator, and _elevatorPanel to provide access to the ElevatorPanel script. The_elevatorPanel is assigned in void Start(), and _target is set to _pointA.

Variable assignment on the Elevator script.

Every frame void update checks to see if the Player is _onElevator and has pressed the E key, in which case it calls the CallElevator method to set the elevator destination depending on its current location. The _elevatorPanel.ButtonPressed function changes the the color of the Call_Button on the Elevator_Panel if the elevator is not in route.

CallElevator method in Elevator script.

A void FixedUpdate method is used to move the Elevator to the current _target using Vector3.MoveTowards. Once it reaches the _target, the _target is set to null until the player activates it.

FixedUpdate method in Elevator script.

Similar to the ElevatorPanel script, OnTriggerEnter and Exit are used in the Elevator script to detect when the Player, i.e. other, is _onElevator, but also control the parent of the Player. To provide smooth animation the Player needs to be a child of the Elevator when the elevator is moving, but not while off the elevator.

OnTriggerEnter and OnTriggerExit script on Elevator script.

This code in the Player, Elevator, and ElevatorPanel scripts controls elevator function providing smooth animation.