Entity

Defined in: Entity.ts:74

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:159

Parameters

name?

string

tags?

Iterable<string, any, any>

Returns

Entity

Properties

fixedUpdate?

readonly optional fixedUpdate?: undefined

Defined in: Entity.ts:129

Reserved: a subclass that declares fixedUpdate fails to compile.

There is no fixed-step entity hook either, and for the same reason. Both homes above apply: a component added to the entity, or a process on the queue that makeSceneScopedQueue() returns when the work outlives a single entity.

The slot is optional, so the compiler reports the subclass method as not assignable to type undefined rather than to type never.

id

readonly id: number

Defined in: Entity.ts:77

Unique auto-incrementing ID.

key?

readonly optional key?: string

Defined in: Entity.ts:88

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:79

Display name for debugging.

timeScale

timeScale: number = 1

Defined in: Entity.ts:103

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.

update?

readonly optional update?: undefined

Defined in: Entity.ts:116

Reserved: a subclass that declares update fails to compile.

The engine’s per-frame pass ticks the components an entity holds, so an entity method with this name is dead code. Per-frame logic belongs in a component added to the entity, or in a process on the queue that makeSceneScopedQueue() returns when the work outlives a single entity.

The slot is optional, so the compiler reports the subclass method as not assignable to type undefined rather than to type never.

[TRAITS_KEY]

static [TRAITS_KEY]: Set<symbol>

Defined in: Entity.ts:75

Accessors

activeSelf

Get Signature

get activeSelf(): boolean

Defined in: Entity.ts:286

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:334

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:211

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:296

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:195

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:200

True while an EntityPool owns this entity.

Returns

boolean

parent

Get Signature

get parent(): Entity | null

Defined in: Entity.ts:329

The parent entity, or null if this is a root entity. A child created by Entity.spawnChild reads null until that call returns, so its setup() cannot reach the parent through it.

Returns

Entity | null

scene

Get Signature

get scene(): Scene

Defined in: Entity.ts:177

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:187

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

Returns

Scene | null

Methods

_componentsInUpdateOrder()

_componentsInUpdateOrder(): Iterable<Component>

Defined in: Entity.ts:702

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>

_deactivateForDestroy()

_deactivateForDestroy(): void

Defined in: Entity.ts:860

Internal

Internal: deactivate immediately without touching activeSelf, mirroring what destroy() does per-entity. Used by Scene when it tears down every entity at once — idempotent, and safe to call in any order across a flat entity set: an entity already reached through a parent’s cascade is a no-op here.

Returns

void

_destroyOwned()

_destroyOwned(): void

Defined in: Entity.ts:749

Internal

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

Returns

void

_detachFromParent()

_detachFromParent(): void

Defined in: Entity.ts:901

Internal

Internal: detach from whatever parent this entity has, without touching children or activeness. Shared by _performDestroy, the pooled-child branch of _destroyOwned’s cascade, and EntityPool.stow, which parks a released member that picked up a parent mid-lease. Unlike removeChild, this does not resync activeness — callers that need activeSelf honoured against no parent still call setActive/_resyncActive themselves.

Returns

void

_endLife()

_endLife(): void

Defined in: Entity.ts:884

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:716

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:871

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:276

Internal

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

Parameters

owner

EntityPoolOwner

Returns

void

_performDestroy()

_performDestroy(onError?): void

Defined in: Entity.ts:919

Internal

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

Parameters

onError?

(error) => void

Returns

void

_resyncActive()

_resyncActive(): void

Defined in: Entity.ts:800

Internal

Internal: recompute effective activeness against the current parent and propagate to descendants. Called after setActive and after a re-parent.

Returns

void

_setActiveSuppressed()

_setActiveSuppressed(activeSelf): void

Defined in: Entity.ts:810

Internal

Internal: write activeSelf and park the entity as dormant without firing hooks or touching queries. Pools and dormant-parent child spawns use this to avoid transient query membership and enable hooks.

Parameters

activeSelf

boolean

Returns

void

_setKey()

_setKey(key): void

Defined in: Entity.ts:1013

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:1002

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:521

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:342

Add a named child entity. Auto-adds to parent’s scene if not already in one; a child that belongs to a different scene is rejected.

Parameters

name

string

child

Entity

Returns

void

destroy()

destroy(): void

Defined in: Entity.ts:735

Retire the entity. Leaves its queries immediately — isActive reads false and component onDisable fires right away — with the rest of teardown (onDestroy, detach from scene) deferred to the end-of-frame flush.

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:646

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:647

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:565

Get a component by class. An exact match wins; otherwise the single component assignable to cls is returned. Throws when nothing matches, and when several components are assignable to cls — use Entity.getAll for that case.

Type Parameters

C

C extends Component

Parameters

cls

ComponentClass<C>

Returns

C

getAll()

Call Signature

getAll(): Iterable<Component>

Defined in: Entity.ts:675

Get all components as an iterable, in add order.

Returns

Iterable<Component>

Call Signature

getAll<C>(cls): readonly C[]

Defined in: Entity.ts:684

Every component assignable to cls — the class itself and any subclass — in add order. The returned array is a read-only view of the entity’s index: removing a component replaces the list rather than mutating it, so a walk already in flight visits every member it started with. Adding one appends to the live list, so a walk in flight also visits a component added during it.

Type Parameters

C

C extends Component

Parameters

cls

ComponentClass<C>

Returns

readonly C[]

getChild()

getChild(name): Entity

Defined in: Entity.ts:507

Get a child by name. Throws if not found.

Parameters

name

string

Returns

Entity

handle()

handle(): EntityHandle<Entity>

Defined in: Entity.ts:244

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:597

Check if entity has a component of the given class or any subclass of it.

Parameters

cls

ComponentClass

Returns

boolean

hasTrait()

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

Defined in: Entity.ts:978

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:631

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:967

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:975

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:606

Remove the component of exactly this class. A base class is not resolved here: remove(Base) does nothing when the entity holds only a subclass, even though has(Base) is true. Remove the concrete class.

Parameters

cls

ComponentClass

Returns

void

removeChild()

removeChild(name): Entity

Defined in: Entity.ts:489

Remove a named child. Returns the detached entity.

Parameters

name

string

Returns

Entity

requireKey()

requireKey(): string

Defined in: Entity.ts:988

Return the stable key, or throw if this entity was spawned without one. Use it in the entity’s setup() or in a component’s onAdd() when the code depends on identity (e.g. reading from a createSet keyed by entity key). The spawn call assigns the key before setup() runs.

Returns

string

setActive()

setActive(active): void

Defined in: Entity.ts:318

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:952

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:410

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.

The parent link is made after the child is built: child.parent is null for the whole of its setup(), including the onAdd() of every component that setup adds, and holds the parent once this call returns. Pass the parent as a setup param when the child needs it. To have setup() read this.parent, reserve both entities in a scene.spawnBatch and call batch.addChild before batch.setup.

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:411

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:416

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:422

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:580

Get a component by class, or undefined if none matches. An exact match wins; otherwise the single component assignable to cls is returned. Throws when several are assignable — use Entity.getAll instead.

Type Parameters

C

C extends Component

Parameters

cls

ComponentClass<C>

Returns

C | undefined

tryGetChild()

tryGetChild(name): Entity | undefined

Defined in: Entity.ts:516

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

Parameters

name

string

Returns

Entity | undefined

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