Unity Scripting Order Reference

Called when the script instance is loaded. Runs before any Start functions. Use for self-initialisation.

Timing: Once, when the script instance is loaded

void Awake() {
    rb = GetComponent<Rigidbody>();
}

Called when the object becomes active. Runs after Awake on first enable.

Timing: Each time the object becomes active

void OnEnable() {
    EventManager.OnDamage += HandleDamage;
}

Called before the first frame update, after all Awake calls. Use for cross-references between objects.

Timing: Once, before the first frame update

void Start() {
    target = FindObjectOfType<Player>();
}

Called at a fixed interval (default 0.02s / 50Hz). Use for physics, raycasts, and rigidbody forces.

Timing: Every fixed timestep (default 0.02s / 50Hz)

void FixedUpdate() {
    rb.AddForce(Vector3.up * jumpForce);
}

Called during physics step when triggers overlap.

Timing: During physics step when triggers overlap

void OnTriggerEnter(Collider other) {
    if (other.CompareTag("Player")) {
        Collect();
    }
}

Called during physics step on collision.

Timing: During physics step on collision

void OnCollisionEnter(Collision col) {
    if (col.relativeVelocity.magnitude > 5f) {
        TakeDamage();
    }
}

Called on mouse interaction with colliders.

Timing: On mouse interaction with colliders

void OnMouseDown() {
    isSelected = true;
}

Called once per frame. Use for input, non-physics movement, timers, game logic.

Timing: Once per frame

void Update() {
    transform.Translate(input * speed * Time.deltaTime);
}

Called after all Update functions. Use for camera follow, post-processing transforms.

Timing: Once per frame, after all Update calls

void LateUpdate() {
    cam.position = target.position + offset;
}

Called when renderer becomes visible/invisible to any camera.

Timing: When renderer visibility changes

void OnBecameVisible() {
    enabled = true;
}
void OnBecameInvisible() {
    enabled = false;
}

Called before/after camera renders the scene. Camera component only.

Timing: Before/after camera renders the scene

void OnPreRender() {
    // Set up before rendering
}
void OnPostRender() {
    // Clean up after rendering
}

Called after camera renders. Use for custom rendering (GL.Begin etc).

Timing: After camera renders

void OnRenderObject() {
    mat.SetPass(0);
    GL.Begin(GL.LINES);
    // draw custom geometry
    GL.End();
}

Called for IMGUI rendering. Can be called multiple times per frame. Legacy; avoid in new projects.

Timing: Multiple times per frame (legacy)

void OnGUI() {
    GUI.Label(rect, "Score: " + score);
}

Resumes after Update, before LateUpdate.

Timing: After Update, before LateUpdate

IEnumerator Example() {
    yield return null;
    // runs next frame after Update
}

Resumes after FixedUpdate.

Timing: After FixedUpdate

IEnumerator Example() {
    yield return new WaitForFixedUpdate();
    // runs after next FixedUpdate
}

Resumes after rendering is complete.

Timing: After rendering is complete

IEnumerator Example() {
    yield return new WaitForEndOfFrame();
    // runs after rendering
}

Resumes after n seconds of game time.

Timing: After n seconds of game time

IEnumerator Example() {
    yield return new WaitForSeconds(2f);
    // runs after 2 seconds
}

Called when the object becomes inactive. Pair with OnEnable.

Timing: When the object becomes inactive

void OnDisable() {
    EventManager.OnDamage -= HandleDamage;
}

Called when the object is destroyed. Use for final cleanup.

Timing: When the object is destroyed

void OnDestroy() {
    SavePlayerData();
}

Called when the application is about to quit.

Timing: When the application is about to quit

void OnApplicationQuit() {
    SaveAllData();
}