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name: 3d-building-mechanics description: "Complete Three.js building system with spatial indexing, structural physics, and multiplayer networking. Use for survival/crafting games, sandbox games, multiplayer construction, or any 3D building mechanics."

3D Building Mechanics - Advanced Skill

Complete Three.js building system with performance optimization, structural physics, and multiplayer networking.

When to Use This Skill

Use when building:

• Survival/crafting games with base building
• Creative sandbox games
• Multiplayer construction games
• Any 3D building mechanics in Three.js

Quick Start

Copyimport { SpatialHashGrid } from './scripts/spatial-hash-grid.js';
import { HeuristicValidator } from './scripts/heuristic-validator.js';
import { ClientPrediction } from './scripts/client-prediction.js';

// Set up spatial indexing
const spatialIndex = new SpatialHashGrid(10);

// Set up structural validation (Rust/Valheim style)
const validator = new HeuristicValidator({ mode: 'heuristic' });

// For multiplayer - client prediction
const prediction = new ClientPrediction(buildingSystem);

File Structure

Copyreferences/
  performance-at-scale.md    - Spatial partitioning, chunks, instancing
  structural-physics-advanced.md - Arcade vs heuristic vs realistic
  multiplayer-networking.md  - Authority models, delta sync, conflicts

scripts/
  spatial-hash-grid.js   - O(1) spatial queries for uniform distribution
  octree.js              - Adaptive spatial queries for clustered bases
  chunk-manager.js       - World streaming for large maps
  performance-profiler.js - Benchmarking utilities
  
  heuristic-validator.js - Fast stability checking (Fortnite/Rust/Valheim)
  stability-optimizer.js - Caching and batch updates
  damage-propagation.js  - Damage states, cascading collapse
  physics-engine-lite.js - Optional realistic physics
  
  delta-compression.js   - Only send what changed
  client-prediction.js   - Optimistic placement with rollback
  conflict-resolver.js   - Handle simultaneous builds
  building-network-manager.js - Complete server/client networking

Key Patterns

Spatial Indexing Decision

• <1,000 pieces: Simple array
• 1,000-5,000 uniform: SpatialHashGrid
• 1,000-5,000 clustered: Octree
• 5,000+: ChunkManager + Octree per chunk

Structural Physics Modes

• Arcade (Fortnite): Connectivity only, instant collapse
• Heuristic (Rust/Valheim): Stability %, predictable rules
• Realistic: Full stress/strain, computationally expensive

Multiplayer Authority

• Server-authoritative with client prediction
• Delta compression (only send changes)
• Conflict resolution: first-write, timestamp, or lock-based