Web Game Engine Expert (Physics, Architecture & Game Loops)

English | Bahasa Indonesia

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<a name="english"></a>

English

Orchestration & Integration

Connects and orchestrates with relevant domain skills:

• web-3d-graphics-expert — Visual rendering layer (WebGPU, Three.js, Babylon.js, PlayCanvas).
• glsl-shader-expert — Custom gameplay shaders, damage flashes, VFX materials.
• ui-ux-pro-max — In-game HUD overlays, crosshairs, radial inventory menus, and responsive virtual touch joysticks.
• design-system-architect — Consistent game UI tokens, custom bitmap/web fonts, and health/resource bar theming.
• visual-ui-auditor — Auditing responsive canvas scaling, DPI-aware pixel ratios (window.devicePixelRatio), and HUD contrast against 3D backgrounds.
• anti-slop — Enforcing zero placeholder physics, non-jittering deterministic game loops, and complete asset lifecycles.
• webxr-ar-vr-expert — Spatial controls and VR/AR controller tracking.
• realtime-collaboration-expert — Low-latency multiplayer state synchronization (WebRTC / WebTransport).
• performance-web-vitals — Frame budgeting (16.6ms for 60fps, 8.3ms for 120fps) and eliminating Garbage Collection stalls.
• wasm-edge-computing-expert — Compiling custom Rust/C++ simulation modules to WASM.

Description

Production-grade guidance for engineering commercial-quality 2D and 3D web games running at steady 60 to 144+ FPS. Enforces strict game architectural patterns: Fixed-Timestep Accumulators with render interpolation, WebAssembly Physics Engines (Rapier 3D, Jolt Physics, Havok), Zero-GC Object Pooling to eliminate JavaScript garbage collection stutters, Entity Component System (ECS) architectures, Web Audio API 3D Spatial Sound (HRTF), and WebTransport / WebRTC low-latency netcode.

Trigger Conditions

Activate this skill when the user is:

• Developing a web-based game or physics simulation (2D or 3D).
• Integrating physics with @dimforge/rapier3d, jolt-physics, @babylonjs/havok, or @react-three/rapier.
• Building or refactoring a game loop to fix frame pacing or physics stuttering on 120Hz/144Hz monitors.
• Implementing an Entity Component System (ECS) with bitECS or miniplex.
• Designing zero-allocation object pools for projectiles, particles, or temporary math vectors.
• Adding Gamepad API, Pointer Lock mouse look, or mobile virtual touch controls.
• Integrating 3D positional audio via the Web Audio API.
• Architecting multiplayer game networking with WebTransport (QUIC datagrams) or WebRTC DataChannels.

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Modern Web Game Engine Landscape (2026)

Engine / Stack	Dimension	Physics Backend	Key Strengths
PlayCanvas Engine	3D	Ammo.js / Rapier WASM	Complete production game engine, tiny runtime (~200KB), mobile-first 60fps, built-in sound & input.
Babylon.js + Havok	3D	Havok Physics WASM	AAA physics simulation, native sub-stepping, character controllers, convex decomposition.
Three.js / R3F + Rapier / Jolt	3D	Rapier 3D (Rust) / Jolt (C++)	Modular, massive ecosystem, best for React/Vue indie games and procedural worlds.
LittleJS	2D	Built-in lightweight physics	Micro-size (<50KB), hyper-fast hybrid WebGL/2D canvas, ideal for 2D platformers & game jams.
PixiJS v8	2D	Matter.js / Rapier 2D	Next-gen WebGPU 2D rendering pipeline, thousands of animated sprites at 144 FPS.
Needle Engine	3D	PhysX / Rapier	Export directly from Unity/Blender into Three.js with full component lifecycles.

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1. The Deterministic Game Loop: Fixed-Timestep Accumulator

CRITICAL RULE: Never tie physics updates directly to requestAnimationFrame delta time. A variable delta causes non-deterministic physics, tunneling, and jitter on 120Hz/144Hz monitors.

• Solution: Accumulate frame time and step physics at a fixed tick rate (e.g., 60Hz). Calculate alpha to interpolate render transforms smoothly between the previous and current physics state.

export class GameLoop {
  private accumulator = 0;
  private lastTime = performance.now();
  private readonly FIXED_TIMESTEP = 1 / 60; // 60Hz fixed physics step
  private readonly MAX_FRAME_TIME = 0.25;   // Clamp to prevent "spiral of death" during lag

  constructor(
    private updatePhysics: (dt: number) => void,
    private render: (alpha: number) => void
  ) {}

  public start() {
    this.lastTime = performance.now();
    requestAnimationFrame(this.tick);
  }

  private tick = (currentTime: number) => {
    let frameTime = (currentTime - this.lastTime) / 1000;
    this.lastTime = currentTime;

    // Clamp huge lags (e.g., user changed browser tab)
    if (frameTime > this.MAX_FRAME_TIME) {
      frameTime = this.MAX_FRAME_TIME;
    }

    this.accumulator += frameTime;

    // Execute fixed updates
    while (this.accumulator >= this.FIXED_TIMESTEP) {
      this.updatePhysics(this.FIXED_TIMESTEP);
      this.accumulator -= this.FIXED_TIMESTEP;
    }

    // Alpha is the leftover fractional progress towards the next physics step [0.0, 1.0)
    const alpha = this.accumulator / this.FIXED_TIMESTEP;
    this.render(alpha);

    requestAnimationFrame(this.tick);
  };
}

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2. High-Performance WASM Physics: Rapier & Jolt

Option A: Rapier 3D (Rust + WASM + SIMD)

Lightweight, determinism-friendly, native support in React Three Fiber (@react-three/rapier):

import { Physics, RigidBody, CuboidCollider } from '@react-three/rapier';

export function GamePhysicsWorld({ children }: { children: React.ReactNode }) {
  return (
    <Physics gravity={[0, -9.81, 0]} timeStep="vary">
      {/* Player Dynamic Capsule */}
      <RigidBody position={[0, 2, 0]} enabledRotations={[false, false, false]} colliders="ball">
        <mesh>
          <sphereGeometry args={[0.5]} />
          <meshStandardMaterial color="dodgerblue" />
        </mesh>
      </RigidBody>

      {/* Static Floor */}
      <RigidBody type="fixed">
        <CuboidCollider args={[20, 0.5, 20]} position={[0, -0.5, 0]} />
      </RigidBody>

      {children}
    </Physics>
  );
}

Option B: Jolt Physics WASM (jolt-physics)

The AAA open-source physics engine used in titles like Horizon Forbidden West. Best for massive simulations (>2,000 rigid bodies) and advanced ragdolls in vanilla Three.js or Babylon.js.

Option C: Babylon.js + Havok Physics V2 (@babylonjs/havok)

The industry standard AAA physics engine compiled to WebAssembly with SIMD acceleration. Provides native sub-stepping, character controllers, convex hull decomposition, and constraint solvers:

import {
  Scene,
  Vector3,
  MeshBuilder,
  HavokPlugin,
  PhysicsAggregate,
  PhysicsShapeType,
  PhysicsCharacterController
} from '@babylonjs/core';
import HavokPhysics from '@babylonjs/havok';

export async function initBabylonHavokPhysics(scene: Scene) {
  // 1. Initialize Havok WASM binary and plugin
  const havokInstance = await HavokPhysics();
  const havokPlugin = new HavokPlugin(true, havokInstance);
  scene.enablePhysics(new Vector3(0, -9.81, 0), havokPlugin);

  // 2. Static Ground PhysicsAggregate
  const ground = MeshBuilder.CreateGround('ground', { width: 40, height: 40 }, scene);
  const groundAggregate = new PhysicsAggregate(
    ground,
    PhysicsShapeType.BOX,
    { mass: 0, restitution: 0.1, friction: 0.8 },
    scene
  );

  // 3. Dynamic Rigid Body (Crate)
  const crate = MeshBuilder.CreateBox('crate', { size: 1.5 }, scene);
  crate.position.set(0, 5, 0);
  const crateAggregate = new PhysicsAggregate(
    crate,
    PhysicsShapeType.BOX,
    { mass: 10, restitution: 0.3, friction: 0.5 },
    scene
  );

  // 4. Kinematic Character Controller with slope limit and step handling
  const playerCapsule = MeshBuilder.CreateCapsule('playerCapsule', { radius: 0.5, height: 1.8 }, scene);
  playerCapsule.position.set(0, 1, 0);
  
  const characterController = new PhysicsCharacterController(
    playerCapsule.position,
    {
      capsuleHeight: 1.8,
      capsuleRadius: 0.5,
      maxSlope: Math.PI / 4, // 45 degree slope climbing limit
      stepHeight: 0.3
    },
    scene
  );

  return { havokPlugin, groundAggregate, crateAggregate, characterController };
}

Physics Best Practice: ALWAYS use primitive colliders (Sphere, Box, Capsule) for moving dynamic bodies. NEVER use Trimesh (triangle mesh) for dynamic objects; Trimesh should only be used for static world terrain.

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3. Zero-GC Memory Management & Object Pooling

CRITICAL RULE: In games, memory allocation (new Vector3(), new Bullet()) inside the tick loop triggers V8 Garbage Collection (GC) pauses every few seconds, dropping frames from 60 to 45 FPS.

• Scratch Object Reuse: Create scratch variables once at module level.

  // BAD: Allocates a new vector every frame
  const dir = new THREE.Vector3().subVectors(target, source).normalize();
  
  // GOOD: Reuses module-level scratch vector
  const _scratchVec = new THREE.Vector3();
  _scratchVec.subVectors(target, source).normalize();
  

• Generic Object Pool:

export class ObjectPool<T> {
  private pool: T[] = [];
  constructor(
    private factory: () => T,
    private reset: (item: T) => void,
    initialSize = 50
  ) {
    for (let i = 0; i < initialSize; i++) {
      this.pool.push(this.factory());
    }
  }

  public acquire(): T {
    return this.pool.length > 0 ? this.pool.pop()! : this.factory();
  }

  public release(item: T): void {
    this.reset(item);
    this.pool.push(item);
  }
}

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4. Input Management: Pointer Lock & Gamepad API

// 1. First-Person / Third-Person Mouse Look
export function setupPointerLock(canvas: HTMLCanvasElement, onLook: (dx: number, dy: number) => void) {
  canvas.addEventListener('click', () => {
    if (document.pointerLockElement !== canvas) {
      canvas.requestPointerLock();
    }
  });

  window.addEventListener('mousemove', (e) => {
    if (document.pointerLockElement === canvas) {
      onLook(e.movementX, e.movementY);
    }
  });
}

// 2. Gamepad API with Deadzone Normalization
export function pollGamepad(deadzone = 0.15) {
  const gamepads = navigator.getGamepads ? navigator.getGamepads() : [];
  const gp = gamepads[0];
  if (!gp) return null;

  const filterAxis = (val: number) => (Math.abs(val) > deadzone ? val : 0);

  return {
    moveX: filterAxis(gp.axes[0]),
    moveY: filterAxis(gp.axes[1]),
    lookX: filterAxis(gp.axes[2]),
    lookY: filterAxis(gp.axes[3]),
    buttonJump: gp.buttons[0]?.pressed ?? false,
    buttonAction: gp.buttons[1]?.pressed ?? false
  };
}

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5. 3D Spatial Positional Audio (Web Audio API)

export class SpatialAudioManager {
  private ctx = new AudioContext();
  private listener = this.ctx.listener;

  public updateListenerPosition(pos: { x: number; y: number; z: number }, forward: { x: number; y: number; z: number }, up = { x: 0, y: 1, z: 0 }) {
    if (this.listener.positionX) {
      this.listener.positionX.value = pos.x;
      this.listener.positionY.value = pos.y;
      this.listener.positionZ.value = pos.z;
      this.listener.forwardX.value = forward.x;
      this.listener.forwardY.value = forward.y;
      this.listener.forwardZ.value = forward.z;
      this.listener.upX.value = up.x;
      this.listener.upY.value = up.y;
      this.listener.upZ.value = up.z;
    }
  }

  public createSpatialSound(audioBuffer: AudioBuffer, pos: { x: number; y: number; z: number }) {
    const source = this.ctx.createBufferSource();
    source.buffer = audioBuffer;

    const panner = this.ctx.createPanner();
    panner.panningModel = 'HRTF'; // High-fidelity Head-Related Transfer Function
    panner.distanceModel = 'inverse';
    panner.refDistance = 1;
    panner.maxDistance = 1000;
    panner.rolloffFactor = 1;
    panner.positionX.value = pos.x;
    panner.positionY.value = pos.y;
    panner.positionZ.value = pos.z;

    source.connect(panner);
    panner.connect(this.ctx.destination);
    source.start();
  }
}

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6. Modern Multiplayer Networking: WebTransport vs WebRTC

For fast-paced real-time action games:

• Avoid WebSockets for player movement: WebSockets use TCP. When a packet is lost, TCP pauses delivery of all subsequent packets (Head-of-Line blocking), causing massive lag spikes.
• Use WebTransport (QUIC) or WebRTC DataChannels:
  • Unreliable, unordered datagrams for continuous movement updates (x, y, z, vx, vy, vz).
  • Reliable streams for critical state transitions (damage, weapon fire, chat, player joined).
• Client-Side Prediction & Reconciliation:
  1. Client immediately simulates movement locally upon keypress and stores input history with tick numbers.
  2. Server processes input at fixed 20Hz-60Hz and replies with authoritative position.
  3. Client reconciles authoritative state and replays unacknowledged inputs to avoid input lag.

Sovereign Execution, Token Efficiency & Invariants

Dimension	Sovereign Mandate & Deterministic Contract
Frontier Model Cascade	Medium / High (GPT-5.6 Sol Medium, Gemini 4 Argon, Claude Sonnet 5.5 High, Grok 4.7 High Fast)
Availability Fallback	Gemini 4 Argon/Pro -> Gemini 3.8 Flash; Claude Opus 5.5 -> Claude Opus 4.6 (Zero unhandled missing-model errors)
KV-Cache & Token Protocol	Pin static instructions & schemas at prompt prefix (kv-cache-prefix-optimizer); pass surgical CONTEXT_MAP.md slices (<250 tokens/call) during Swarm Fan-Out
SaaT CLI & MCP Dispatch	CLI: vibes skill exec web-game-engine-expert <audit|eval|verify|generate|blueprint> / MCP: vibes_skill_dispatch, vibes_ast_query, vibes_compile_cache, vibes_optimize_budget, vibes_verify_gate
NFR & Anti-Slop Invariants	P99 API Gateway Latency < 85ms, OpenAPI 3.1 / TypeSpec strict schema parity, RFC 9457 Problem Details error contracts, Idempotency-Key enforcement; 100% complete zero-placeholder output verified via node scripts/check-anti-slop.js --strict

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<a name="bahasa-indonesia"></a>

Bahasa Indonesia

Integrasi Orkestrasi

Terhubung dan mengorkestrasi skill domain yang relevan:

• web-3d-graphics-expert — Lapisan visual rendering (WebGPU, Three.js, Babylon.js, PlayCanvas).
• glsl-shader-expert — Shader kustom untuk efek visual, kilatan luka, dan partikel game.
• ui-ux-pro-max — Overlay HUD dalam game, crosshair, menu inventaris radial, dan joystick virtual sentuh responsif.
• design-system-architect — Desain token UI game yang konsisten, font bitmap/web kustom, dan tema bar health/stamina.
• visual-ui-auditor — Audit visual penskalaan canvas responsif, pixel ratio sadar-DPI (window.devicePixelRatio), dan kontras HUD terhadap latar 3D.
• anti-slop — Penegakan fisika bebas placeholder, game loop deterministik tanpa jitter, dan siklus hidup aset lengkap.
• webxr-ar-vr-expert — Kontrol spasial dan pelacakan kontroler VR/AR.
• realtime-collaboration-expert — Sinkronisasi state multiplayer real-time (WebRTC / WebTransport).
• performance-web-vitals — Manajemen frame budget (16.6ms untuk 60fps) dan pencegahan Garbage Collection stall.
• wasm-edge-computing-expert — Kompilasi modul simulasi C++/Rust kustom ke WebAssembly.

Deskripsi

Panduan produksi untuk merekayasa game web komersial 2D dan 3D dengan target stabil di 60 hingga 144+ FPS. Menerapkan arsitektur game modern: Fixed-Timestep Accumulator dengan interpolasi render, Physics Engine berbasis WebAssembly (Rapier 3D, Jolt Physics, Havok), Zero-GC Object Pooling untuk mencegah lonjakan Garbage Collector JavaScript, arsitektur ECS (Entity Component System), Audio Spasial 3D Web Audio API (HRTF), dan Netcode WebTransport / WebRTC berlatensi rendah.

Kondisi Pemicu

Aktifkan skill ini ketika pengguna:

• Membangun game web atau simulasi fisika (2D maupun 3D).
• Mengintegrasikan mesin fisika @dimforge/rapier3d, jolt-physics, @babylonjs/havok, atau @react-three/rapier.
• Memperbaiki ketidakteraturan fisika atau stuttering pada monitor 120Hz/144Hz.
• Mengimplementasikan ECS (Entity Component System) dengan bitECS atau miniplex.
• Mendesain Object Pool tanpa alokasi memori berulang untuk proyektil, peluru, atau partikel.
• Mengintegrasikan kontrol Gamepad API, Pointer Lock (mouse look), atau kontrol sentuh virtual mobile.
• Menambahkan audio spasial 3D menggunakan Web Audio API.
• Merancang arsitektur multiplayer real-time menggunakan WebTransport atau WebRTC.

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Prinsip Inti Rekayasa Game Web

1. Fixed-Timestep Accumulator Loop (Wajib):

   • Jangan pernah menjalankan komputasi fisika langsung pada delta waktu requestAnimationFrame. Perubahan refresh rate monitor (60Hz, 120Hz, 144Hz) akan merusak konsistensi fisika.
   • Akumulasikan waktu frame dan jalankan langkah fisika pada tick tetap (misal 60Hz), lalu hitung alpha untuk menginterpolasikan posisi render grafis secara mulus.

2. Mesin Fisika WASM (Rapier / Jolt / Havok):

   • Gunakan Rapier 3D (Rust WASM + SIMD) untuk Three.js/R3F.
   • Gunakan Jolt Physics untuk simulasi skala besar ribuan objek dinamis.
   • Gunakan Babylon.js + Havok Physics V2 (@babylonjs/havok) untuk simulasi kelas AAA:

   import { Scene, Vector3, MeshBuilder, HavokPlugin, PhysicsAggregate, PhysicsShapeType, PhysicsCharacterController } from '@babylonjs/core';
   import HavokPhysics from '@babylonjs/havok';
   
   export async function inisialisasiFisikaHavok(scene: Scene) {
     const havokInstance = await HavokPhysics();
     const havokPlugin = new HavokPlugin(true, havokInstance);
     scene.enablePhysics(new Vector3(0, -9.81, 0), havokPlugin);
   
     // Batas lantai statis
     const lantai = MeshBuilder.CreateGround('lantai', { width: 40, height: 40 }, scene);
     new PhysicsAggregate(lantai, PhysicsShapeType.BOX, { mass: 0, friction: 0.8 }, scene);
   
     // Objek kotak dinamis
     const kotak = MeshBuilder.CreateBox('kotak', { size: 1.5 }, scene);
     kotak.position.set(0, 5, 0);
     new PhysicsAggregate(kotak, PhysicsShapeType.BOX, { mass: 10, restitution: 0.3 }, scene);
   
     // Character Controller dengan batas kemiringan (slope) dan tangga
     const pemain = MeshBuilder.CreateCapsule('pemain', { radius: 0.5, height: 1.8 }, scene);
     const controller = new PhysicsCharacterController(
       pemain.position,
       { capsuleHeight: 1.8, capsuleRadius: 0.5, maxSlope: Math.PI / 4, stepHeight: 0.3 },
       scene
     );
   
     return { havokPlugin, controller };
   }
   

   • Hindari penggunaan mesh collider (Trimesh) pada objek bergerak; selalu gunakan primitif (Bola, Kotak, Kapsul).

3. Manajemen Memori Zero-GC:

   • Pembuatan objek baru (new Vector3(), objek peluru) setiap frame memicu Garbage Collection di browser yang menyebabkan frame drop berkala.
   • Daur ulang objek menggunakan pola Object Pooling dan gunakan kembali variabel scratch statis.

4. Kontrol Responsif:

   • Manfaatkan Pointer Lock API untuk kontrol kamera first-person / third-person dengan movementX dan movementY.
   • Gunakan Gamepad API dengan deadzone filter untuk mendukung controller konsol (PlayStation, Xbox).

5. Audio Spasial 3D (HRTF):

   • Hubungkan AudioListener ke transformasi kamera, dan hubungkan suara ke PannerNode dengan model panning 'HRTF' untuk audio 3 dimensi realistis berdasarkan jarak dan arah.

6. Netcode Modern (WebTransport):

   • Jangan gunakan WebSocket (TCP) untuk posisi pergerakan pemain karena rentan terhadap Head-of-Line blocking.
   • Gunakan WebTransport (datagram UDP over QUIC) atau WebRTC DataChannels disertai Client-Side Prediction dan Server Reconciliation.

Matriks Eksekusi Berdaulat, Efisiensi Token & Invarian

Dimensi	Mandat Berdaulat & Kontrak Deterministik
Kaskade Model Frontier	Medium / High (GPT-5.6 Sol Medium, Gemini 4 Argon, Claude Sonnet 5.5 High, Grok 4.7 High Fast)
Invarian Fallback Ketersediaan	Gemini 4 Argon/Pro -> Gemini 3.8 Flash; Claude Opus 5.5 -> Claude Opus 4.6 (Bebas gagal saat model belum tersedia/kuota penuh)
Protokol Hemat Token & KV-Cache	Kunci instruksi & skema statis di prefix awal (kv-cache-prefix-optimizer); kirim potongan CONTEXT_MAP.md (<250 token/panggilan) saat Fan-Out
Eksekusi SaaT CLI & MCP	CLI: vibes skill exec web-game-engine-expert <audit|eval|verify|generate|blueprint> / MCP: vibes_skill_dispatch, vibes_ast_query, vibes_compile_cache, vibes_optimize_budget, vibes_verify_gate
Invarian NFR & Anti-Slop	Latensi P99 API < 85ms, paritas skema ketat OpenAPI 3.1 / TypeSpec, kontrak error RFC 9457 Problem Details, penegakan Idempotency-Key; kode 100% tuntas tanpa placeholder diverifikasi melalui node scripts/check-anti-slop.js --strict