Input action maps in Unity - Mini Project: Build & Apply

Input Action Maps in Unity

📖 Scenario: You are creating a simple Unity game where the player can move a character using keyboard inputs. To manage these inputs cleanly, you will use Input Action Maps, which help organize input controls.

🎯 Goal: Build a Unity script that sets up an Input Action Map for player movement and reads input values to move the character.

📋 What You'll Learn

Create an Input Action Map called playerActions with an action move

Add a Vector2 binding to move for keyboard WASD keys

Create a variable moveInput to store the current movement input

Print the moveInput value each frame to see the input

💡 Why This Matters

🌍 Real World

Input Action Maps help organize player controls in games, making it easier to manage different input devices and actions.

💼 Career

Game developers use Input System features like action maps to create flexible and maintainable input handling in professional Unity projects.

1

Create the Input Action Map and move action

Create an InputActionMap called playerActions and add an InputAction called move with type Value and control type Vector2.

Unity

# Your code here to create playerActions and move action

Hint

Use new InputActionMap("Player") to create the map and AddAction to add the move action.

2

Add WASD keyboard bindings to the move action

Add a composite binding of type 2DVector to the move action with these parts: up bound to W, down to S, left to A, and right to D keys on the keyboard.

Unity

using UnityEngine.InputSystem;

InputActionMap playerActions = new InputActionMap("Player");
InputAction move = playerActions.AddAction("move", InputActionType.Value, "");
move.expectedControlType = "Vector2";

# Add 2DVector composite binding with WASD keys to move action

Hint

Use AddCompositeBinding("2DVector") and chain With calls for each direction.

3

Enable the action map and read input

Enable the playerActions map and create a Vector2 variable called moveInput. Use move.ReadValue<Vector2>() to update moveInput each frame inside an Update method.

Unity

using UnityEngine.InputSystem;
using UnityEngine;

InputActionMap playerActions = new InputActionMap("Player");
InputAction move = playerActions.AddAction("move", InputActionType.Value, "");
move.expectedControlType = "Vector2";

move.AddCompositeBinding("2DVector")
    .With("up", "/w")
    .With("down", "/s")
    .With("left", "/a")
    .With("right", "/d");

Vector2 moveInput;

void Start()
{
    // Enable the action map
}

void Update()
{
    // Read move input value
}

Hint

Call playerActions.Enable() in Start() and update moveInput in Update().

4

Print the move input value each frame

Add a Debug.Log statement inside the Update method to print the current moveInput value.

Unity

using UnityEngine.InputSystem;
using UnityEngine;

InputActionMap playerActions = new InputActionMap("Player");
InputAction move = playerActions.AddAction("move", InputActionType.Value, "");
move.expectedControlType = "Vector2";

move.AddCompositeBinding("2DVector")
    .With("up", "/w")
    .With("down", "/s")
    .With("left", "/a")
    .With("right", "/d");

Vector2 moveInput;

void Start()
{
    playerActions.Enable();
}

void Update()
{
    moveInput = move.ReadValue();
    // Your code here to print moveInput
}

Hint

Use Debug.Log(moveInput); inside Update() to see the input values in the console.

Practice

1.

What is the main purpose of an Input Action Map in Unity's Input System?

easy

A. To handle audio playback

B. To render graphics on the screen

C. To store game settings permanently

D. To group related input actions for easier management

Solution

1. Step 1: Understand what Input Action Maps do

   Input Action Maps group related input actions, like movement or UI controls, to organize inputs.

2. Step 2: Compare with other options

   Rendering graphics, storing settings, and audio playback are unrelated to input action maps.

3. Final Answer:

   To group related input actions for easier management -> Option D

4. Quick Check:

   Input Action Maps = Group inputs [OK]

Hint: Remember: Action maps group inputs logically [OK]

Common Mistakes:

• Confusing input maps with graphics or audio systems
• Thinking action maps store data permanently
• Assuming action maps handle rendering

2.

Which of the following is the correct way to enable an InputActionMap named playerControls in C#?

?

easy

A. playerControls.Activate();

B. playerControls.Start();

C. playerControls.Enable();

D. playerControls.Run();

Solution

1. Step 1: Recall the method to enable input action maps

   The correct method to enable an InputActionMap is Enable().

2. Step 2: Verify other options

   Start(), Activate(), and Run() are not valid methods for InputActionMap.

3. Final Answer:

   playerControls.Enable(); -> Option C

4. Quick Check:

   Enable() activates input maps [OK]

Hint: Use Enable() to start input action maps [OK]

Common Mistakes:

• Using Start() instead of Enable()
• Confusing method names with other Unity components
• Forgetting to enable the action map before use

3.

Given the following code snippet, what will be the output when playerControls is enabled and the player presses the jump button?

var playerControls = new PlayerInputActions();
playerControls.Player.Jump.performed += ctx => Debug.Log("Jump pressed");
playerControls.Player.Enable();
// Player presses jump button

medium

A. Jump pressed

B. No output

C. NullReferenceException

D. Jump pressed twice

Solution

1. Step 1: Understand event subscription and enabling

   The code subscribes to the Jump action's performed event and enables the Player action map.

2. Step 2: Predict output on jump button press

   When the jump button is pressed, the subscribed lambda logs "Jump pressed" once.

3. Final Answer:

   Jump pressed -> Option A

4. Quick Check:

   Subscribed event triggers log once [OK]

Hint: Enabling action map triggers subscribed events [OK]

Common Mistakes:

• Forgetting to enable the action map
• Expecting multiple logs without multiple subscriptions
• Confusing event names or missing subscription

4.

What is wrong with this code snippet that tries to disable an input action map?

var controls = new PlayerInputActions();
controls.Player.Disable();
controls.Player.performed += ctx => Debug.Log("Action performed");

medium

A. The event subscription is on the action map instead of a specific action

B. Disable() method does not exist on InputActionMap

C. You cannot disable an action map before subscribing to events

D. The code should call Enable() before Disable()

Solution

1. Step 1: Check event subscription target

   The code subscribes to performed on controls.Player, which is an InputActionMap, not an InputAction.

2. Step 2: Understand correct subscription

   Events like performed belong to InputActions, e.g., controls.Player.Jump.performed, not the whole map.

3. Final Answer:

   The event subscription is on the action map instead of a specific action -> Option A

4. Quick Check:

   Subscribe events on actions, not maps [OK]

Hint: Subscribe events on actions, not action maps [OK]

Common Mistakes:

• Subscribing events on InputActionMap instead of InputAction
• Confusing Disable() method availability
• Assuming order of Enable/Disable affects subscription

5.

You want to switch between two control schemes, Keyboard and Gamepad, during gameplay using input action maps. Which approach correctly handles this switch?

?

hard

A. Use only one action map and ignore control schemes

B. Disable the current action map and enable the other action map

C. Create new input actions every time you switch

D. Enable both action maps at the same time

Solution

1. Step 1: Understand control scheme switching

   Switching control schemes means activating one input action map and deactivating the other to avoid conflicts.

2. Step 2: Evaluate options

   Enabling both maps causes input conflicts; creating new actions wastes resources; ignoring schemes loses flexibility.

3. Final Answer:

   Disable the current action map and enable the other action map -> Option B

4. Quick Check:

   Switch by toggling action maps [OK]

Hint: Toggle action maps to switch control schemes [OK]

Common Mistakes:

• Enabling multiple action maps causing input conflicts
• Recreating actions unnecessarily
• Ignoring control scheme differences