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Engine: state the body shape the renderer needs, and check real snapshots aga… (#41)
Requested-by: benjivers <[email protected]> Co-authored-by: benjivers <[email protected]>
4 files
changed +113
−0
src/body.test.ts added +25
| @@ -0,0 +1,25 @@ | ||
| 1 | /** | |
| 2 | * The engine's body contract, checked against this game's own snapshot rather | |
| 3 | * than one a test made up: a game that renames `alive` passes every render | |
| 4 | * test and draws every enemy as a corpse. It lives here, not in `engine/`, | |
| 5 | * because it needs the game. | |
| 6 | */ | |
| 7 | ||
| 8 | import { expect, test } from "bun:test"; | |
| 9 | import { valGame } from "./arena.ts"; | |
| 10 | import { snapshotProblems } from "./engine/body.ts"; | |
| 11 | import { newMatch } from "./match.ts"; | |
| 12 | ||
| 13 | test("every body and `me` in a real snapshot of a running match fits the contract", () => { | |
| 14 | const state = newMatch(7); | |
| 15 | const game = valGame(state, () => {}); | |
| 16 | for (let i = 0; i < 90; i++) game.step(state, 1 / 30); | |
| 17 | let bodies = 0; | |
| 18 | for (const viewer of state.players) { | |
| 19 | const seen = state.players.filter((p) => p.id === viewer.id || game.visible(state, viewer, p)); | |
| 20 | const snap = game.snapshot(state, viewer, seen) as { me: unknown; players: unknown[] }; | |
| 21 | expect(snapshotProblems(snap)).toEqual([]); | |
| 22 | bodies += snap.players.length; | |
| 23 | } | |
| 24 | expect(bodies).toBeGreaterThan(state.players.length); | |
| 25 | }); |
src/engine/arena.ts +3
| @@ -17,6 +17,9 @@ | ||
| 17 | 17 | * - Every snapshot is built for one viewer, from the bodies the game says |
| 18 | 18 | * that viewer can see. The client never learns a position it has no line |
| 19 | 19 | * of sight to. |
| 20 | * | |
| 21 | * What a snapshot's bodies and `me` must carry for the client renderer is in | |
| 22 | * `body.ts`; a game checks its real snapshot against it. | |
| 20 | 23 | */ |
| 21 | 24 | |
| 22 | 25 | export const TICK = 1 / 30; |
src/engine/body.test.ts added +14
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| 1 | /** The body contract: what it names, and what it refuses. */ | |
| 2 | import { expect, test } from "bun:test"; | |
| 3 | import { bodyProblems, meProblems } from "./body.ts"; | |
| 4 | ||
| 5 | const good = { id: "a", name: "A", x: 1, y: 2, angle: 0, alive: true, hp: 100, mate: false }; | |
| 6 | ||
| 7 | test("a well-formed body has no problems, and each missing or mistyped field is named", () => { | |
| 8 | expect(bodyProblems(good)).toEqual([]); | |
| 9 | const { alive: _, ...noAlive } = good; | |
| 10 | expect(bodyProblems({ ...noAlive, down: false })).toEqual(["body.alive should be a boolean, is undefined"]); | |
| 11 | expect(bodyProblems({ ...good, x: NaN })).toHaveLength(1); | |
| 12 | expect(bodyProblems(null)).toEqual(["body is not an object"]); | |
| 13 | expect(meProblems({ id: "a" })).toContain("me.ammo should be a number, is undefined"); | |
| 14 | }); |
src/engine/body.ts added +71
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| 1 | /** | |
| 2 | * The body a snapshot must carry, stated once. | |
| 3 | * | |
| 4 | * The client renderer (`scene.js`, `topdown.js`, `presence.js`, `gun.js`) | |
| 5 | * reads fixed fields off every body in `snap.players` and off `snap.me`. A | |
| 6 | * game that renames one — `down` for `alive` — is not refused by anything at | |
| 7 | * runtime: every enemy simply draws as a corpse. So the shape is a contract | |
| 8 | * here, and each game tests its real snapshot against it. | |
| 9 | * | |
| 10 | * Every body in `snap.players` has: | |
| 11 | * id: string who; `me` is skipped in the scene by this id | |
| 12 | * name: string the tag over the body | |
| 13 | * x, y: number where, in world units | |
| 14 | * angle: number which way it faces, radians | |
| 15 | * alive: boolean false draws a corpse | |
| 16 | * hp: number 0..100; a bar shows under 100 | |
| 17 | * mate: boolean on the viewer's side | |
| 18 | * | |
| 19 | * `snap.me` has, besides id, x, y, angle, alive and hp: | |
| 20 | * ammo: number rounds in the magazine | |
| 21 | * reloading: boolean mid-reload | |
| 22 | */ | |
| 23 | ||
| 24 | type Kind = "string" | "number" | "boolean"; | |
| 25 | ||
| 26 | const BODY: Record<string, Kind> = { | |
| 27 | id: "string", | |
| 28 | name: "string", | |
| 29 | x: "number", | |
| 30 | y: "number", | |
| 31 | angle: "number", | |
| 32 | alive: "boolean", | |
| 33 | hp: "number", | |
| 34 | mate: "boolean", | |
| 35 | }; | |
| 36 | ||
| 37 | const ME: Record<string, Kind> = { | |
| 38 | id: "string", | |
| 39 | x: "number", | |
| 40 | y: "number", | |
| 41 | angle: "number", | |
| 42 | alive: "boolean", | |
| 43 | hp: "number", | |
| 44 | ammo: "number", | |
| 45 | reloading: "boolean", | |
| 46 | }; | |
| 47 | ||
| 48 | function problems(value: unknown, shape: Record<string, Kind>, label: string): string[] { | |
| 49 | if (typeof value !== "object" || value === null) return [`${label} is not an object`]; | |
| 50 | const out: string[] = []; | |
| 51 | for (const [field, kind] of Object.entries(shape)) { | |
| 52 | const got = (value as Record<string, unknown>)[field]; | |
| 53 | if (typeof got !== kind || (kind === "number" && !Number.isFinite(got))) out.push(`${label}.${field} should be a ${kind}, is ${String(got)}`); | |
| 54 | } | |
| 55 | return out; | |
| 56 | } | |
| 57 | ||
| 58 | /** What is wrong with one body of `snap.players`; empty when it is fit to draw. */ | |
| 59 | export const bodyProblems = (body: unknown, label = "body"): string[] => problems(body, BODY, label); | |
| 60 | ||
| 61 | /** What is wrong with `snap.me`; empty when the gun and the camera can read it. */ | |
| 62 | export const meProblems = (me: unknown): string[] => problems(me, ME, "me"); | |
| 63 | ||
| 64 | /** Every problem in a snapshot's bodies and `me`. */ | |
| 65 | export function snapshotProblems(snap: { me?: unknown; players?: unknown }): string[] { | |
| 66 | const players = Array.isArray(snap.players) ? snap.players : null; | |
| 67 | return [ | |
| 68 | ...meProblems(snap.me), | |
| 69 | ...(players ? players.flatMap((p, i) => bodyProblems(p, `players[${i}]`)) : ["players is not an array"]), | |
| 70 | ]; | |
| 71 | } |