135 lines
4.1 KiB
Markdown
135 lines
4.1 KiB
Markdown
# OpenSpec Change: enterprise-gaming-game-loop
|
|
|
|
- **Change ID**: enterprise-gaming-game-loop
|
|
- **Package**: `@suaveplan/game-loop`
|
|
- **Category**: gaming/engine
|
|
- **Target path**: `gaming/engine/game-loop`
|
|
- **Status**: PROPOSED
|
|
- **Date**: 2026-04-24
|
|
- **Reference spec**: `/mnt/s/web/suaveplan/enterprise/game-loop.md`
|
|
|
|
---
|
|
|
|
## Summary
|
|
|
|
Deliver `@suaveplan/game-loop` on the genesis branch from scratch at enterprise quality. The package provides a fixed-timestep game loop with tick scheduling — the heartbeat that drives `@suaveplan/ecs` world updates and all time-sensitive gameplay systems. The loop implements the classic "fix your timestep" accumulator pattern: unlimited render interpolation alpha with a capped fixed physics step, lag compensation, frame-time smoothing, and panic detection. Genesis adds structured errors, injectable clock and AbortSignal cancellation, OTel frame-time histograms, and deterministic test harness via FakeClock.
|
|
|
|
---
|
|
|
|
## Current-state audit (genesis)
|
|
|
|
Package does not exist on genesis yet — fresh build.
|
|
|
|
---
|
|
|
|
## Available workspace deps on genesis
|
|
|
|
| Package | Role |
|
|
|---|---|
|
|
| `@suaveplan/error` (`workspace:^`) | `GameLoopError`; `GAME_LOOP.*` error codes |
|
|
| `@suaveplan/types` (`workspace:^`) | `Clock` injectable |
|
|
| `@suaveplan/events` (`workspace:^`) | `loop:tick`, `loop:panic`, `loop:stop` events |
|
|
| `zod` (`catalog:forms`) | `GameLoopOptions` schema |
|
|
| `@opentelemetry/api` (`catalog:observability`) | Frame-time histogram, tick counter |
|
|
|
|
---
|
|
|
|
## Public API surface
|
|
|
|
```ts
|
|
function createGameLoop(options: GameLoopOptions): GameLoop
|
|
|
|
interface GameLoopOptions {
|
|
fixedStep: number // ms per physics tick, e.g. 16.666
|
|
maxFrameTime?: number // ms cap to prevent spiral of death, default 250
|
|
onTick: (dt: number) => void
|
|
onRender?: (alpha: number) => void
|
|
clock?: Clock
|
|
logger?: LoggerLike
|
|
}
|
|
|
|
interface GameLoop {
|
|
start(signal?: AbortSignal): void
|
|
stop(): void
|
|
readonly isRunning: boolean
|
|
readonly tickCount: number
|
|
readonly fps: number // rolling average over last 60 frames
|
|
readonly frameBudgetMs: number
|
|
}
|
|
|
|
// Scheduler — attach one-shot or recurring callbacks to loop ticks
|
|
function createTickScheduler(loop: GameLoop): TickScheduler
|
|
|
|
interface TickScheduler {
|
|
scheduleOnce(cb: () => void, afterTicks?: number): ScheduledHandle
|
|
scheduleEvery(cb: () => void, everyTicks: number): ScheduledHandle
|
|
cancel(handle: ScheduledHandle): void
|
|
}
|
|
|
|
type ScheduledHandle = number & { readonly __brand: 'ScheduledHandle' }
|
|
```
|
|
|
|
### Error codes
|
|
|
|
```ts
|
|
type GameLoopErrorCode =
|
|
| 'GAME_LOOP_ALREADY_RUNNING'
|
|
| 'GAME_LOOP_NOT_RUNNING'
|
|
| 'GAME_LOOP_PANIC'
|
|
| 'GAME_LOOP_INVALID_STEP'
|
|
```
|
|
|
|
---
|
|
|
|
## New additions for genesis
|
|
|
|
1. **Accumulator + interpolation alpha** — `alpha = accumulator / fixedStep` passed to `onRender` for smooth rendering between physics steps.
|
|
2. **Panic detection** — if `accumulator > maxFrameTime * 3` the loop fires `loop:panic` event and clamps accumulator.
|
|
3. **FakeClock integration** — `clock` option accepts `FakeClock` from `@suaveplan/testing`; tick advances deterministically in tests.
|
|
4. **OTel** — `game_loop.frame_time_ms` histogram, `game_loop.tick_total` counter, `game_loop.fps` gauge.
|
|
5. **AbortSignal** — `start(signal)` — loop exits cleanly when signal fires.
|
|
|
|
---
|
|
|
|
## File layout
|
|
|
|
```text
|
|
gaming/engine/game-loop/
|
|
package.json
|
|
tsconfig.json
|
|
vitest.config.ts
|
|
src/
|
|
index.ts
|
|
error-codes.ts
|
|
constants/
|
|
index.ts
|
|
types/
|
|
common.ts
|
|
common.md
|
|
core/
|
|
game-loop/
|
|
game-loop.ts
|
|
game-loop.md
|
|
game-loop.types.ts
|
|
game-loop.test.ts
|
|
index.ts
|
|
tick-scheduler/
|
|
tick-scheduler.ts
|
|
tick-scheduler.md
|
|
tick-scheduler.types.ts
|
|
tick-scheduler.test.ts
|
|
index.ts
|
|
utils/
|
|
frame-stats.ts
|
|
frame-stats.md
|
|
frame-stats.test.ts
|
|
tests/
|
|
integration.test.ts
|
|
```
|
|
|
|
---
|
|
|
|
## Impact
|
|
|
|
**Downstream**: `@suaveplan/ecs` world.tick() is driven by this loop; `@suaveplan/r3f-*` rendering uses interpolation alpha. Prerequisites: `@suaveplan/error`, `@suaveplan/types`, `@suaveplan/events`.
|