Update Loops

• Update(): Every frame

• FixedUpdate(): Fixed timestep (physics)

• LateUpdate(): After all Updates
  

Physics & Collisions

• OnCollisionEnter(): First contact

• OnCollisionStay(): During contact

• OnCollisionExit(): Contact ends

• OnTriggerEnter(): Enter trigger zone

• OnTriggerStay(): Inside trigger

• OnTriggerExit(): Exit trigger

Rendering & Visibility

• OnBecameVisible(): Enters camera view

• OnBecameInvisible(): Exits all views

• OnRenderObject(): After camera render

• OnWillRenderObject(): Before camera render

• OnGUI(): UI/Debug rendering

Application Flow

• OnApplicationFocus(): Window focus

• OnApplicationPause(): App pause/resume

• OnApplicationQuit(): Before app closes

Input & Interaction

• OnMouseEnter(): Mouse enters collider

• OnMouseOver(): Mouse stays over collider

• OnMouseExit(): Mouse leaves collider

• OnMouseDown(): Mouse click on collider

• OnMouseUp(): Mouse release on collider

• OnMouseDrag(): Mouse drag on collider

Editor & Development

• OnDrawGizmos(): Draw debug in Scene view

• OnDrawGizmosSelected(): Draw when selected

• OnValidate(): After inspector value change

CRITICAL Pro Tips:

• Awake() runs before ANY Start() - perfect for manager initialization

• Never reference other objects in Awake() - they might not be ready

• Physics ONLY in FixedUpdate()

• Camera follow in LateUpdate()

• OnEnable/OnDisable for event subscriptions

• Input handling belongs in Update()

• OnValidate() for inspector value validation

• Use OnDrawGizmos() for debug visualization

• OnMouseOver() only works with colliders

Common Pitfalls:

• Running physics in Update()

• Initializing dependencies in wrong order

• Missing OnDisable() cleanup

• Heavy calculations in OnGUI()

• Forgetting collider requirement for mouse events

• Not handling OnApplicationPause() on mobile

• Using OnMouseDrag() for UI elements