Managing inputs in Unity can quickly become unwieldy, especially when dealing with multiple devices and input schemes. This guide explores a modular approach using ScriptableObjects to manage device-specific icons, decouple input events, and enable dependency injection for flexibility.

Goals

  • Ease of Management: Simplify handling device-specific input icons.
  • Decoupling: Avoid relying on a centralized input manager.
  • Flexibility: Use ScriptableObjects for modular and reusable input definitions.

Drawbacks

  • InputActionDefinition OnInput returns a CallbackContext that can have any information
  • Subscribers have to assume the CallbackContext has the info they need (ex. a Vector2)

Steps

Follow these steps to implement this architecture:

  1. Setup Input Actions: Open a Unity InputAction asset and configure the necessary inputs.
  2. Create InputActionDefinitions: For each input, create an InputActionDefinition ScriptableObject.
  3. Add a PlayerInput Component: Attach a PlayerInput component to a GameObject in the scene.
  4. Set to Invoke Unity Events: Configure the PlayerInput component’s behavior to Invoke Unity Events.
  5. Bind Input Definitions: Assign an InputActionDefinition to trigger the Fire() method for each input action.
  6. Inject Inputs Where Needed: In future components, reference the appropriate InputActionDefinition assets to handle inputs.

Architecture Diagram

Below is a high-level architecture diagram of this setup:

classDiagram class ScriptableObject class InputActionDefinition { +name : string +keyboardIcon : Sprite +gamepadIcon : Sprite +touchIcon : Sprite +OnInput : Action~InputAction.CallbackContext~ +Fire() void +GetIcon() Sprite } ScriptableObject <|-- InputActionDefinition InputActionDefinition -- Move.asset : Create SO InputActionDefinition -- Jump.asset : Create SO Move.asset <.. PlayerController : References Jump.asset <.. PlayerController : References class PlayerController { +InputActionDefinition OnMove +InputActionDefinition OnJump +Move() void +Jump() void } class PlayerInput { } note for PlayerController "Pass in the desired definition assets.
Use their OnInput event." note for PlayerInput "Set behavior to invoke Unity Event.
Match the InputActions with
the related InputActionDefinition"

Example PlayerInput Component

player-input.webp

Example Implementation

Here’s a simple example of how input handling might look in your script:

//PlayerController.cs

[SerializeField] InputActionDefinition OnMove;
[SerializeField] InputActionDefinition OnJump;

private void Start()
{
    OnMove.OnInput += HandleMove;
    OnJump.OnInput += HandleJump;
}

private void HandleMove(InputAction.CallbackContext ctx) {
    Vector2 movement = ctx.ReadValue<Vector2>();
    // Movement Logic
}

private void HandleJump(InputAction.CallbackContext ctx) {
    if (ctx.started) {
        // Jump Logic
    }
}