ScreenFollow

Defined in: renderer/src/ScreenFollow.ts:80

Each frame, projects a world source through a camera and writes the resulting screen coord to this entity’s Transform.worldPosition.

The canonical “billboard” primitive: pair with a UIPanel (or UIRoot) on a screen-space layer using positioning: "transform" to produce UI that tracks a target entity but stays axis-aligned and constant-size regardless of camera zoom or rotation — nameplates, health bars, damage numbers, interaction prompts.

class Nameplate extends Entity {
  constructor(private readonly target: Entity, private readonly camera: CameraEntity) {
    super();
  }
  setup() {
    this.add(new Transform());
    this.add(new ScreenFollow({
      target: this.target,
      camera: this.camera,
      offset: new Vec2(0, -40),      // 40 screen px above the target
    }));
    const panel = this.add(new UIPanel({
      positioning: "transform",      // reads Transform.worldPosition
      anchor: Anchor.BottomCenter,   // pivot on the panel
    }));
    panel.text("Grunt-42", { fontSize: 11 });
  }
}

Extends

Component

Constructors

Constructor

new ScreenFollow(opts): ScreenFollow

Defined in: renderer/src/ScreenFollow.ts:86

Parameters

opts

ScreenFollowOptions

Returns

ScreenFollow

Overrides

Component.constructor

Properties

enabled

enabled: boolean

Defined in: core/dist/index.d.ts:647

Whether this component is active. Disabled components are skipped by ComponentUpdateSystem.

Inherited from

Component.enabled

entity

entity: Entity

Defined in: core/dist/index.d.ts:645

Back-reference to the owning entity. Set by the engine when the component is added to an entity. Do not set manually.

Inherited from

Component.entity

Accessors

context

Get Signature

get context(): EngineContext

Defined in: core/dist/index.d.ts:660

Access the EngineContext from the entity’s scene. Throws if the entity is not in a scene.

Returns

EngineContext

Inherited from

Component.context

scene

Get Signature

get scene(): Scene

Defined in: core/dist/index.d.ts:655

Access the entity’s scene. Throws if the entity is not in a scene. Prefer this over threading through this.entity.scene in component code.

Returns

Scene

Inherited from

Component.scene

Methods

_runCleanups()

_runCleanups(): void

Defined in: core/dist/index.d.ts:697

Internal

Run and clear all registered cleanups. Called by Entity.remove() and Entity._performDestroy() before onRemove/onDestroy.

Returns

void

Inherited from

Component._runCleanups

addCleanup()

protected addCleanup(fn): void

Defined in: core/dist/index.d.ts:691

Parameters

fn

() => void

Returns

void

Inherited from

Component.addCleanup

afterRestore()?

optional afterRestore(data, resolve): void

Defined in: core/dist/index.d.ts:711

Called after onAdd() during save/load restoration. Apply state that depends on onAdd() having run.

Parameters

data

unknown

resolve

SnapshotResolver

Returns

void

Inherited from

Component.afterRestore

fixedUpdate()?

optional fixedUpdate(dt): void

Defined in: core/dist/index.d.ts:707

Called every fixed timestep by the built-in ComponentUpdateSystem.

Parameters

dt

number

Returns

void

Inherited from

Component.fixedUpdate

listen()

protected listen<T>(entity, token, handler): void

Defined in: core/dist/index.d.ts:687

Subscribe to events on any entity, auto-unsubscribe on removal.

Type Parameters

T

T

Parameters

entity

Entity

token

EventToken<T>

handler

(data) => void

Returns

void

Inherited from

Component.listen

listenScene()

protected listenScene<T>(token, handler): void

Defined in: core/dist/index.d.ts:689

Subscribe to scene-level bubbled events, auto-unsubscribe on removal.

Type Parameters

T

T

Parameters

token

EventToken<T>

handler

(data, entity) => void

Returns

void

Inherited from

Component.listenScene

onAdd()?

optional onAdd(): void

Defined in: core/dist/index.d.ts:699

Called when the component is added to an entity.

Returns

void

Inherited from

Component.onAdd

onDestroy()?

optional onDestroy(): void

Defined in: core/dist/index.d.ts:703

Called when the component is destroyed (entity destroyed or component removed).

Returns

void

Inherited from

Component.onDestroy

onRemove()?

optional onRemove(): void

Defined in: core/dist/index.d.ts:701

Called when the component is removed from an entity.

Returns

void

Inherited from

Component.onRemove

serialize()?

optional serialize(): unknown

Defined in: core/dist/index.d.ts:709

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

Returns

unknown

Inherited from

Component.serialize

service()

protected service<T>(key): T

Defined in: core/dist/index.d.ts:677

Lazy proxy-based service resolution. Can be used at field-declaration time:

readonly input = this.service(InputManagerKey);

The actual resolution is deferred until first property access.

Type Parameters

T

T extends object

Parameters

key

ServiceKey<T>

Returns

T

Inherited from

Component.service

sibling()

protected sibling<C>(cls): C

Defined in: core/dist/index.d.ts:685

Lazy proxy-based sibling component resolution. Can be used at field-declaration time:

readonly anim = this.sibling(AnimatedSpriteComponent);

The actual resolution is deferred until first property access.

Type Parameters

C

C extends Component

Parameters

cls

ComponentClass<C>

Returns

C

Inherited from

Component.sibling

update()

update(): void

Defined in: renderer/src/ScreenFollow.ts:96

Called every frame by the built-in ComponentUpdateSystem.

Returns

void

Overrides

Component.update

use()

protected use<T>(key): T

Defined in: core/dist/index.d.ts:668

Resolve a service by key, cached after first lookup. Scene-scoped values (registered via scene._registerScoped) take precedence over engine scope. A key declared with scope: "scene" that falls back to engine scope emits a one-shot dev warning — almost always signals a missed beforeEnter hook.

Type Parameters

T

T

Parameters

key

ServiceKey<T>

Returns

T

Inherited from

Component.use