How To Make A 2D Shooter

Gamepad stick dead zone. Default: 0.125 (if configured in the action).

cameraSize

float

No

Orthographic size. The default depends on your world scale; start with that 5 for many 2D setups.

cameraZ

float

No

Camera Z position. Default: -10 for typical 2D scenes.

Code Example

using UnityEngine; using UnityEngine.InputSystem;

[RequireComponent(typeof(Rigidbody2D))] public class PlayerMovement2D: MonoBehaviour { [Header("Movement")] [SerializeField] private float speed = 6.0f;

[Header("Input")] [SerializeField] private string inputActionName = "Move";

private Rigidbody2D rb; private Vector2 moveInput;

private InputAction moveAction;

private void Awake() { rb = GetComponent<Rigidbody2D>();

// Assumes you assigned an InputActionAsset via PlayerInput OR created one in code. // If using PlayerInput, you can fetch the action from PlayerInput.actions. var playerInput = GetComponent<PlayerInput>(); if (playerInput == null) { Debug.LogError("PlayerMovement2D requires a PlayerInput component on the same GameObject."); enabled = false; return; }

moveAction = playerInput.actions[inputActionName]; if (moveAction == null) { Debug.LogError($"InputAction '{inputActionName}' not found in InputActionAsset."); enabled = false; return; }

// Bind callbacks to capture input as it happens. moveAction.performed += OnMove; moveAction.canceled += OnMove; }

private void OnDestroy() { moveAction.performed -= OnMove; moveAction.canceled -= OnMove; }

private void OnMove(InputAction.CallbackContext context) { // ReadValue<Vector2>() expects the action to be configured as a Vector2 control type. moveInput = context.ReadValue<Vector2>(); }

private void FixedUpdate() { // Apply in FixedUpdate for stable physics movement. Vector2 velocity = moveInput * speed; rb.velocity = velocity; } } Response Format

{ "project": { "renderingMode2D": true, "camera": { "projection": "Orthographic", "orthographic": true, "transformPositionZ": -10 }, "player": { "components": ["PlayerInput", "Rigidbody2D", "PlayerMovement2D"] } }, "input": { "inputActionName": "Move", "expectedValueType": "Vector2", "bindings": [ { "source": "Keyboard", "controls": ["W", "A", "S", "D"] }, { "source": "Gamepad", "controls": ["LeftStick"] } ] }, "movement": { "speed": 6.0, "applicationLoop": "FixedUpdate", "movementVectorMapping": { "x": "left/right", "y": "down/up" } } } Notes & Best Practices

• Input system value type must match code: ReadValue<Vector2>() requires the Move action to be configured for Value Type = Vector2; otherwise you’ll read zeroes or get binding warnings.

• Physics timing: set velocity FixedUpdate() when using Rigidbody2D to avoid frame-rate-dependent movement.

• Camera consistency: keep the camera orthographic and lock its Z position; changing orthographic size alters world-to-screen scale and affects perceived speed.

• Sprite pivot/import: ensure sprites have consistent pivot points (often bottom-center for ground movement) and avoid mixed pivots that make

• Sprite import scale: in the sprite import settings, keep it Pixels Per Unit consistent across sprites. If one sprite uses 100 PPU and another uses 16, collisions and movement alignment will drift.

• Screen-to-world mapping: for aiming and spawning later, cache Camera.main and rely on Camera.ScreenToWorldPoint the correct z value (usually -camera.transform.position.z for 2D).

• Input System lifecycle: enable/disable the PlayerInput component (or the action map) when pausing or switching scenes. If you leave actions enabled, callbacks keep updating moveInput.

• Edge cases: guard against missing PlayerInput or null values Rigidbody2D at edit time to prevent runtime nulls.

2D Launch Checklist (Unity project + Input System)

Use this checklist to verify the project is in a clean state before adding weapons, enemies, or shooting logic.

Check

Target value / setting

Where

Project type

2D template or equivalent (2D physics enabled)

Unity Editor

Render mode

The camera is set to orthographic.

Camera component

Camera transform

Z position constant (commonly -10 )

Camera transform

Rigidbody

Player uses Rigidbody2D

Player GameObject

Physics plan

Gravity scale set intentionally ( 0 for top-down, 1 for platformer)

Rigidbody2D

Player input driver

Player has PlayerInput with an InputActionAsset

Player GameObject

Move action

Value Type = Vector2, action name matches code (e.g., Move )

Input Actions asset

Movement timing

Apply movement in FixedUpdate

Movement script

No mixed pivots

Sprite pivots aligned for consistent collision/movement

Sprite Import settings

Related sections

• Input System action maps and rebinding (for supporting keyboard + gamepad)

• 2D physics movement tuning (drag, friction, gravity scale)

• Camera-based world coordinates (for mouse aiming and projectile spawn positions)

With a clean camera, consistent sprite import settings, and movement input wired through the Input System, the next chapter can focus on adding aim direction and projectile spawning using the same input pipeline.

End of chapter one. 4 more chapters in the full book.