explodorama / files / src / ui / scenes.ts
scenes.ts
| 1 | import { generateScene, type Scene, type SceneKind } from '../sim/demo' |
| 2 | |
| 3 | /** |
| 4 | * Scenes for the demo and the dialogs' clips, made in a Web Worker (sim/scene-worker.ts) so the |
| 5 | * page never waits on one (PLAN.md §13c). Where a worker can't be made, on the page instead. |
| 6 | */ |
| 7 | let worker: Worker | null = null |
| 8 | try { |
| 9 | worker = new Worker(new URL('../sim/scene-worker.ts', import.meta.url), { type: 'module' }) |
| 10 | } catch { |
| 11 | worker = null |
| 12 | } |
| 13 | |
| 14 | let nextId = 0 |
| 15 | const waiting = new Map<number, { kind: SceneKind; seed: number; done: (scene: Scene | null) => void }>() |
| 16 | worker?.addEventListener('message', (e: MessageEvent<{ id: number; scene: Scene | null }>) => { |
| 17 | waiting.get(e.data.id)?.done(e.data.scene) |
| 18 | waiting.delete(e.data.id) |
| 19 | }) |
| 20 | // A worker that fails (a script that wouldn't load) answers nothing: what waits on it, and all |
| 21 | // after, is made here. |
| 22 | worker?.addEventListener('error', () => { |
| 23 | worker = null |
| 24 | for (const { kind, seed, done } of waiting.values()) done(generateScene(kind, seed)) |
| 25 | waiting.clear() |
| 26 | }) |
| 27 | |
| 28 | /** A scene of `kind` from `seed`, when it is ready; null if none was found. */ |
| 29 | export function makeScene(kind: SceneKind, seed: number): Promise<Scene | null> { |
| 30 | if (!worker) return Promise.resolve(generateScene(kind, seed)) |
| 31 | const id = nextId++ |
| 32 | return new Promise((resolve) => { |
| 33 | waiting.set(id, { kind, seed, done: resolve }) |
| 34 | worker!.postMessage({ id, kind, seed }) |
| 35 | }) |
| 36 | } |