Luny Semantics Shmemantics

LunyScript and LunyEngine strive to provide consistent, relatable semantics while avoiding terms that are too technical or too vague. But it also borrows semantics from engines where it makes the most sense.

The idea is to fix game engines' inconsistencies and to more strictly follows C# / .NET naming guidelines in hope of a standardization (long term). Events that already happened use past tense (-ed). Ongoing events use present tense (-ing). Some exceptions: Consistently scheduled events (On.Heartbeat, On.FrameUpdate) and once-only events (On.Ready).

Object Lifecycle Events

These are the object lifecycle events which can run blocks. All object-specific events use the On.* prefix. The table shows how they map to object lifecycle events in the most popular game engines:

LunyScript	Unity	Godot	Unreal
On.Created	Awake	_init	InitializeComponent
On.Ready	Start	_ready	BeginPlay
On.Enabled	OnEnable	_enter_tree	OnComponentActivated
On.Disabled	OnDisable	_exit_tree	OnComponentDeactivated
On.Heartbeat	FixedUpdate	_physics_process	TickComponent
On.FrameUpdate	Update	_process	TickComponent
On.FrameLateUpdate	LateUpdate	N/A	TickComponent
On.Destroyed	OnDestroy	N/A (manual)	UninitializeComponent
On.Collision(2D).Started	OnCollisionEnter(2D)	body_entered	OnComponentHit
On.Collision(2D).Continuing	OnCollisionStay(2D)	N/A (manual)	N/A (manual)
On.Collision(2D).Ended	OnCollisionExit(2D)	body_exited	N/A (manual)
On.Trigger(2D).Entered	OnTriggerEnter(2D)	area_entered	OnComponentBeginOverlap
On.Trigger(2D).Staying	OnTriggerStay(2D)	N/A (manual)	N/A (manual)
On.Trigger(2D).Exited	OnTriggerExit(2D)	area_exited	OnComponentEndOverlap

Note

The "heartbeat" may seem unusual. It's where every engine has issues: FixedUpdate .. uh, what is 'fixed' here? Is Update() broken?? And _physics_process is also misleading: it's not just about physics.

The concept of a heartbeat is simple and relatable: It happens at a steady rate, mostly. But it can also "skip a beat" (not run in a frame), or have an "extra beat", even "race" (run multiple time per frame).

Global Events

Global (external) events use the When.* prefix, in contrast to the On.* events which target a specific object. This list isn't exhaustive or complete but should provide an overview of the most common global events that can run blocks:

LunyScript	Unity	Godot	Unreal
When.Input.Action.Started	started	N/A	Started
When.Input.Action.Performed	performed	N/A	Triggered
When.Input.Action.Continuing	performed	N/A	Ongoing
When.Input.Action.Ended	canceled	N/A	Canceled/Completed
When.Scene.Loaded	SceneManager.sceneLoaded	N/A (tree_entered on root)	OnLevelLoaded
When.Scene.Unloaded	SceneManager.sceneUnloaded	N/A	OnLevelUnloaded
When.Quitting	OnApplicationQuit	_notification(NOTIFICATION_WM_CLOSE_REQUEST)	EndPlay (Reason: Quit)

LunyEngine Observer Events

These events are used by implementations of ILunyEngineObserver. You will probably not write an observer yourself, but you will likely see those methods in code and callstacks.

Event	Description
OnEngineStartup	Application launched, after LunyEngine initialization
OnEngineFrameBegins	Every frame, before Heartbeat/FrameUpdate
OnEngineHeartbeat	Fixed timestep, 0-n times per frame
OnEngineFrameUpdate	Frame update
OnEngineFrameLateUpdate	Runs after frame update
OnEngineFrameEnds	Every frame, after all frame events
OnEngineShutdown	Application quitting

LunyEngine Service Events

Very similar events are used by implementations of LunyEngineServiceBase providing engine "services" - feature-level APIs.

Event	Description
OnServiceInitialize	Application launched, during LunyEngine initialization
OnServiceStartup	After LunyEngine and all services' initialization
OnServiceFrameBegins	Before frame update
OnServiceHeartbeat	Before object's heartbeat
OnServiceFrameUpdate	Before object's frame update
OnServiceFrameLateUpdate	Before object's frame late update
OnServiceFrameEnds	After frame update completed
OnServiceShutdown	Application quitting