Entity

Defined in: Entity.ts:51

An entity is a named container of components with O(1) lookups by type.

Extended by

TimerEntity

Constructors

Constructor

new Entity(name?, tags?): Entity

Defined in: Entity.ts:104

Parameters

name?

string

tags?

Iterable<string, any, any>

Returns

Entity

Properties

id

readonly id: number

Defined in: Entity.ts:54

Unique auto-incrementing ID.

key?

readonly optional key?: string

Defined in: Entity.ts:65

Stable identity key, scene-scoped. Set at spawn-time when options.key is passed to scene.spawn / entity.spawnChild; undefined otherwise. Used with scene.findByKey and as a stable id in reactive stores (e.g. a createSet<string>() persisted under "world.opened").

name

readonly name: string

Defined in: Entity.ts:56

Display name for debugging.

timeScale

timeScale: number = 1

Defined in: Entity.ts:80

Per-entity time-scale multiplier. Mirrors Scene.timeScale but scoped to this single entity: the engine composes the delta time passed to this entity’s components (and its ProcessComponent, particle emitters) as dt * scene.timeScale * entity.timeScale. 1 = normal speed, 0.5 = half speed, 0 = frozen, 2 = double speed.

Physics is deliberately NOT affected: PhysicsSystem steps a single shared Rapier world per scene under scene.timeScale only, so a rigid-body entity’s simulation cannot be individually slowed or sped up via this field. Use a kinematic body or scale velocities manually if you need per-body time control.

[TRAITS_KEY]

static [TRAITS_KEY]: Set<symbol>

Defined in: Entity.ts:52

Accessors

activeSelf

Get Signature

get activeSelf(): boolean

Defined in: Entity.ts:235

This entity’s own activeness bit — what setActive last wrote. An entity whose activeSelf is true can still be dormant, if an ancestor is not. Use isActive for the state the engine acts on.

Returns

boolean

children

Get Signature

get children(): ReadonlyMap<string, Entity>

Defined in: Entity.ts:279

Named children as a read-only map. Empty map if no children.

Returns

ReadonlyMap<string, Entity>

generation

Get Signature

get generation(): number

Defined in: Entity.ts:160

Which life of this entity is current. An EntityPool member is reused, so one object serves many lives; the counter moves on whenever a life ends, by release or by destruction. handle compares against it. Compare for equality only — a destruction cascade can advance it more than once, so it does not count lives. Written by the engine only.

Returns

number

isActive

Get Signature

get isActive(): boolean

Defined in: Entity.ts:245

Whether the entity is active: its own activeSelf and every ancestor’s. A dormant entity keeps all of its components and its place in scene.getEntities(), but drops out of queries, findEntity, findEntitiesByTag and findEntities, and its components stop updating.

Returns

boolean

isDestroyed

Get Signature

get isDestroyed(): boolean

Defined in: Entity.ts:140

True once the entity is dead — after destroy() is called, or once its scene starts tearing it down on scene exit.

Returns

boolean

isPooled

Get Signature

get isPooled(): boolean

Defined in: Entity.ts:149

True while an EntityPool owns this entity. Pool members are left out of save snapshots: a pool restores empty and refills, so whatever was in flight when the game was saved is gone on load.

Returns

boolean

parent

Get Signature

get parent(): Entity | null

Defined in: Entity.ts:274

The parent entity, or null if this is a root entity.

Returns

Entity | null

scene

Get Signature

get scene(): Scene

Defined in: Entity.ts:122

The scene this entity belongs to. Throws if the entity is not attached to a scene — which in practice only happens before scene.spawn / addChild wires it up, or after the entity is destroyed (end-of-frame flush after destroy(), or scene teardown on exit). Inside lifecycle methods (setup, component onAdd, update, and component onDestroy during destruction) this is always safe to access.

For the rare case where you genuinely need to inspect whether an entity has a scene (e.g. defensive code in systems iterating a query result), use tryScene instead.

Returns

Scene

tryScene

Get Signature

get tryScene(): Scene | null

Defined in: Entity.ts:132

The scene this entity belongs to, or null if detached.

Returns

Scene | null

Methods

_componentsInUpdateOrder()

_componentsInUpdateOrder(): Iterable<Component>

Defined in: Entity.ts:564

Internal

Internal: components in the order ComponentUpdateSystem calls them — ascending updatePriority, ties in add order. Identical to getAll() until a component declares a priority. The sorted array is replaced, not mutated, when a component is added or removed, so a pass already iterating it finishes over the old order; a component added mid-pass first runs next frame. The map iterator on the default path is live, so there a component added mid-pass can run in the same pass.

Returns

Iterable<Component>

_destroyOwned()

_destroyOwned(): void

Defined in: Entity.ts:609

Internal

Internal: destroy for real, skipping the pool redirect. Used by the owning pool when it disposes, and by the cascade below.

Returns

void

_endLife()

_endLife(): void

Defined in: Entity.ts:721

Internal

Internal: end this life so handles taken during it stop resolving. The subtree follows, because it is released or destroyed with this entity. Called by EntityPool when a lease ends; destruction goes through _markDestroyed instead.

Returns

void

_invalidateUpdateOrder()

_invalidateUpdateOrder(component): void

Defined in: Entity.ts:578

Internal

Internal: a component was added or its updatePriority was written. Switches the entity onto the sorted update path once any component leaves the default priority, and drops the cached order so the next update pass rebuilds it.

Parameters

component

Component

Returns

void

_markDestroyed()

_markDestroyed(): void

Defined in: Entity.ts:708

Internal

Internal: mark the entity destroyed without queueing it. Called by Scene during teardown so every entity reads isDestroyed === true before any component onDestroy runs, and by _destroyOwned. Idempotent, and the one place a destruction ends a life.

Returns

void

_markPooled()

_markPooled(owner): void

Defined in: Entity.ts:225

Internal

Internal: mark the entity as a pool member. Called by EntityPool when it constructs one.

Parameters

owner

EntityPoolOwner

Returns

void

_performDestroy()

_performDestroy(): void

Defined in: Entity.ts:733

Internal

Internal: perform actual destruction — remove all components and clear state. Called by Scene during endOfFrame flush.

Returns

void

_resyncActive()

_resyncActive(): void

Defined in: Entity.ts:652

Internal

Internal: recompute effective activeness against the current parent and propagate to descendants. Called after setActive, after a re-parent, and once per restored root when a snapshot finishes rebuilding the hierarchy.

Returns

void

_setActiveSuppressed()

_setActiveSuppressed(activeSelf): void

Defined in: Entity.ts:663

Internal

Internal: write activeSelf and park the entity as dormant without firing hooks or touching queries. Used by snapshot restore, which must hold every restored entity inert until the parent links are back — the single _resyncActive per root afterwards fires each hook exactly once.

Parameters

activeSelf

boolean

Returns

void

_setKey()

_setKey(key): void

Defined in: Entity.ts:836

Internal

Internal: assign the stable identity key. Called by Scene._registerKey during spawn. Throws if the entity already has a key — keys are immutable for an entity’s lifetime.

Parameters

key

string

Returns

void

_setScene()

_setScene(scene, callbacks): void

Defined in: Entity.ts:825

Internal

Internal: set the scene and callbacks. Called by Scene.spawn().

Parameters

scene

Scene | null

callbacks

EntityCallbacks | null

Returns

void

add()

add<C>(component): C

Defined in: Entity.ts:444

Add a component instance. Returns the component for chaining.

Type Parameters

C

C extends Component

Parameters

component

C

Returns

C

addChild()

addChild(name, child): void

Defined in: Entity.ts:284

Add a named child entity. Auto-adds to parent’s scene if not already in one.

Parameters

name

string

child

Entity

Returns

void

afterRestore()?

optional afterRestore(data, resolve): void

Defined in: Entity.ts:799

Called after components are restored during save/load. Rebuild non-serializable state here.

Parameters

data

unknown

resolve

SnapshotResolver

Returns

void

destroy()

destroy(): void

Defined in: Entity.ts:595

Retire the entity. For an ordinary entity that means deferred destruction, with the real cleanup at end of frame.

A pool member is retired by going back to its pool instead — its pool owns its lifetime and destroys it only when the pool itself is disposed. That keeps destroy() usable from the places retirement is actually decided: a collision handler, an update, an event listener, all of which see a plain Entity and hold no pool reference.

Returns

void

emit()

Call Signature

emit(token): void

Defined in: Entity.ts:521

Emit a typed event on this entity. Bubbles to the scene.

Parameters

token

EventToken<void>

Returns

void

Call Signature

emit<T>(token, data): void

Defined in: Entity.ts:522

Emit a typed event on this entity. Bubbles to the scene.

Type Parameters

T

T

Parameters

token

EventToken<T>

data

T

Returns

void

get()

get<C>(cls): C

Defined in: Entity.ts:472

Get a component by class. Throws if not found.

Type Parameters

C

C extends Component

Parameters

cls

ComponentClass<C>

Returns

C

getAll()

getAll(): Iterable<Component>

Defined in: Entity.ts:550

Get all components as an iterable, in add order.

Returns

Iterable<Component>

getChild()

getChild(name): Entity

Defined in: Entity.ts:430

Get a child by name. Throws if not found.

Parameters

name

string

Returns

Entity

handle()

handle(): EntityHandle<Entity>

Defined in: Entity.ts:193

Capture a reference that expires with this entity’s current life, read back through .current.

class Turret extends Entity {
  private target?: EntityHandle<Enemy>;

  onSpotted(enemy: Enemy) { this.target = enemy.handle(); }

  update() {
    const enemy = this.target?.current;   // undefined once that enemy is gone
    if (enemy) this.aimAt(enemy);
  }
}

Take a handle whenever pooled entities are involved — a member can be retired from anywhere, so a stored plain reference goes stale silently. A plain reference is fine for entities that live as long as the scene, or when the code storing the reference also controls when the entity goes away.

A handle taken outside a live life never resolves: on a pool member (or an entity under one) whose pool is not currently lending it out, or on an entity that is destroyed or sits under a destroyed ancestor. In all of those the caller is holding a reference from a life that is already over.

Returns

EntityHandle<Entity>

has()

has(cls): boolean

Defined in: Entity.ts:488

Check if entity has a component of the given class.

Parameters

cls

ComponentClass

Returns

boolean

hasTrait()

hasTrait<T>(token): this is Entity & T

Defined in: Entity.ts:802

Check if this entity’s class implements a given trait. Acts as a type guard.

Type Parameters

T

T

Parameters

token

TraitToken<T>

Returns

this is Entity & T

on()

on<T>(token, handler): () => void

Defined in: Entity.ts:506

Subscribe to a typed event on this entity. Returns an unsubscribe function.

Type Parameters

T

T

Parameters

token

EventToken<T>

handler

(data) => void

Returns

() => void

onAcquire()?

optional onAcquire(…args): void

Defined in: Entity.ts:785

Per-reuse reset, called by EntityPool every time the entity is handed out — including the first time, right after setup(). Its parameters become the pool’s acquire(...) arguments, so a bullet that needs a position and a direction declares onAcquire(x: number, y: number, dir: Vec2).

A pooled class must declare this hook: nothing else resets the state the entity kept while dormant. Declare an empty one if there is genuinely nothing to reset. It runs on a fully active entity, and must be synchronous and non-overloaded — the pool derives acquire’s signature from it, and a set of overloads keeps only the last.

Parameters

args

…unknown[]

Returns

void

onRelease()?

optional onRelease(): void

Defined in: Entity.ts:793

Called by EntityPool when the entity is released, before it goes dormant. Optional even for pooled classes: turning components off is the job of onDisable, so this is for game-level cleanup — dropping a target reference, clearing a listener registered outside setup().

Returns

void

remove()

remove(cls): void

Defined in: Entity.ts:493

Remove a component by class.

Parameters

cls

ComponentClass

Returns

void

removeChild()

removeChild(name): Entity

Defined in: Entity.ts:412

Remove a named child. Returns the detached entity.

Parameters

name

string

Returns

Entity

requireKey()

requireKey(): string

Defined in: Entity.ts:811

Return the stable key, or throw if this entity was spawned without one. Use inside component setup() when the component depends on identity (e.g. reading from a createSet keyed by entity key).

Returns

string

serialize()?

optional serialize(): unknown

Defined in: Entity.ts:796

Return a JSON-serializable snapshot of this entity’s custom state. Used by the save system.

Returns

unknown

setActive()

setActive(active): void

Defined in: Entity.ts:267

Turn the entity on or off without destroying it. Descendants follow: a child of a dormant entity is dormant whatever its own activeSelf says.

Components whose effective enabled-ness flips get onDisable / onEnable. Per-component enabled flags are left alone, so a component you disabled by hand stays disabled after the entity comes back.

bullet.setActive(false);                    // hidden, updates skipped
bullet.get(Transform).setPosition(x, y);
bullet.setActive(true);                     // back in play, no respawn

An entity with a RigidBodyComponent must be moved through rb.setPosition(x, y) instead — physics owns the transform of a dynamic body and overwrites a direct Transform write on the next frame.

Parameters

active

boolean

Returns

void

setup()?

optional setup(params): void

Defined in: Entity.ts:770

Optional setup method. Called by scene.spawn(Class, params) after the entity is wired to its scene, so components can access services. Override in subclasses — do NOT use the constructor for component setup.

Parameters

params

unknown

Returns

void

spawnChild()

Call Signature

spawnChild(name, options?): Entity

Defined in: Entity.ts:337

Spawn a new entity in this entity’s scene and add it as a named child. Combines scene.spawn(...) + this.addChild(name, ...) in one call — the idiomatic way to compose entity trees (logical root + visual body

UI sibling + …).

Mirrors the overload shape of Scene.spawn: pass an Entity subclass (with optional setup params), a Blueprint, or omit for an anonymous base Entity.

this.spawnChild("body", EnemyBody, { color: 0xff6b6b });
this.spawnChild("hp", EnemyHealthBar);

Parameters

name

string

options?

SpawnOptions

Returns

Entity

Call Signature

spawnChild<E>(name, Class, …rest): E

Defined in: Entity.ts:338

UI sibling + …).

Mirrors the overload shape of Scene.spawn: pass an Entity subclass (with optional setup params), a Blueprint, or omit for an anonymous base Entity.

this.spawnChild("body", EnemyBody, { color: 0xff6b6b });
this.spawnChild("hp", EnemyHealthBar);

Type Parameters

E

E extends Entity

Parameters

name

string

Class

() => E

rest

…ClassSpawnArgs<E>

Returns

E

Call Signature

spawnChild<P>(name, blueprint, params, options?): Entity

Defined in: Entity.ts:343

UI sibling + …).

Mirrors the overload shape of Scene.spawn: pass an Entity subclass (with optional setup params), a Blueprint, or omit for an anonymous base Entity.

this.spawnChild("body", EnemyBody, { color: 0xff6b6b });
this.spawnChild("hp", EnemyHealthBar);

Type Parameters

P

P

Parameters

name

string

blueprint

Blueprint<P>

params

P

options?

SpawnOptions

Returns

Entity

Call Signature

spawnChild(name, blueprint, options?): Entity

Defined in: Entity.ts:349

UI sibling + …).

Mirrors the overload shape of Scene.spawn: pass an Entity subclass (with optional setup params), a Blueprint, or omit for an anonymous base Entity.

this.spawnChild("body", EnemyBody, { color: 0xff6b6b });
this.spawnChild("hp", EnemyHealthBar);

Parameters

name

string

blueprint

Blueprint<void>

options?

SpawnOptions

Returns

Entity

tryGet()

tryGet<C>(cls): C | undefined

Defined in: Entity.ts:483

Get a component by class, or undefined if not found.

Type Parameters

C

C extends Component

Parameters

cls

ComponentClass<C>

Returns

C | undefined

tryGetChild()

tryGetChild(name): Entity | undefined

Defined in: Entity.ts:439

Get a child by name, or undefined if not found.

Parameters

name

string

Returns

Entity | undefined