Input action maps in Unity - Step-by-Step Execution

Concept Flow - Input action maps

Define Input Actions

↓

Create Input Action Map

↓

Add Actions to Map

↓

Enable Action Map

↓

Listen for Input Events

↓

Respond to Input

↓

Disable Action Map when done

Input action maps group input actions. You define actions, add them to a map, enable the map, then listen and respond to inputs.

Execution Sample

Unity

var playerActions = new InputActionMap("Player");
var jump = playerActions.AddAction("Jump", binding: "<Keyboard>/space");
jump.performed += ctx => Debug.Log("Jump pressed");
playerActions.Enable();

This code creates an input action map named 'Player', adds a 'Jump' action bound to the spacebar, listens for the jump action, and enables the map.

Execution Table

Step	Action	InputActionMap State	Event Subscription	Output
1	Create InputActionMap 'Player'	Empty map created	No subscriptions	No output
2	Add 'Jump' action with spacebar binding	Map has 1 action: 'Jump'	No subscriptions	No output
3	Subscribe to 'Jump.performed' event	Map unchanged	Jump action subscribed to event	No output
4	Enable InputActionMap	Map enabled	Subscriptions active	No output
5	Press spacebar	Map enabled	Jump.performed event triggered	Console logs 'Jump pressed'
6	Disable InputActionMap	Map disabled	Subscriptions inactive	No output

💡 InputActionMap disabled, no further input events processed

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	After Step 6
playerActions	null	Empty InputActionMap	Contains 'Jump' action	Same	Enabled	Enabled	Disabled
jump	null	null	InputAction bound to spacebar	Subscribed to performed event	Same	Same	Same

Key Moments - 3 Insights

Why do we need to enable the InputActionMap before it detects input?

The InputActionMap only listens for input when enabled, as shown in step 4 and 5 of the execution_table. Without enabling, input events won't trigger.

What happens if we add an action but don't subscribe to its events?

Adding an action alone doesn't produce output. You must subscribe to events like 'performed' to respond, as shown in step 3 and 5.

Why disable the InputActionMap after use?

Disabling stops listening to inputs and frees resources, preventing unwanted input handling, as shown in step 6.

Visual Quiz - 3 Questions

Look at the execution_table, what is the state of 'playerActions' after step 4?

A Enabled

B Empty

C Disabled

D Null

💡 Hint

Check the 'InputActionMap State' column at step 4 in the execution_table

At which step does the 'Jump.performed' event subscription happen?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Look at the 'Event Subscription' column in the execution_table

If we never call 'playerActions.Enable()', what happens when pressing spacebar?

A Console logs 'Jump pressed'

B Error thrown

C No output, input ignored

D InputActionMap disables automatically

💡 Hint

Refer to step 4 and 5 in the execution_table about enabling the map

Concept Snapshot

Input Action Maps group input actions.
Define actions and add to a map.
Subscribe to action events (e.g., performed).
Enable the map to listen for inputs.
Disable when done to stop listening.

Full Transcript

Input action maps in Unity help organize input controls. First, you create an InputActionMap, then add actions like 'Jump' with specific bindings such as the spacebar. You subscribe to events like 'performed' to respond when the input happens. Enabling the map starts listening for inputs, and disabling stops it. This process ensures your game reacts only when you want it to, keeping input handling clean and efficient.

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