name: building-mechanics
description: Three.js 3D building system with spatial indexing, structural physics, and multiplayer networking. Use when creating survival games, sandbox builders, or any game with player-constructed structures. Covers performance optimization (spatial hash grids, octrees, chunk loading), structural validation (arcade/heuristic/realistic physics modes), and multiplayer sync (delta compression, client prediction, conflict resolution).

3D Building Mechanics

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

Quick Start

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

// Spatial indexing for fast queries
const spatialIndex = new SpatialHashGrid(10);
spatialIndex.insert(piece, piece.position);
const nearby = spatialIndex.queryRadius(position, 15);

// Structural validation (Rust/Valheim style)
const validator = new HeuristicValidator({ mode: 'heuristic' });
validator.addPiece(piece);
const canPlace = validator.validatePlacement(newPiece);

Reference Files

Read these for detailed implementation guidance:

• references/performance-at-scale.md - Spatial partitioning, chunk loading, instancing, LOD
• references/structural-physics-advanced.md - Arcade vs heuristic vs realistic physics
• references/multiplayer-networking.md - Authority models, delta sync, conflict resolution

Scripts

Performance (references/performance-at-scale.md)

• scripts/spatial-hash-grid.js - O(1) queries for uniform distribution
• scripts/octree.js - Adaptive queries for clustered bases
• scripts/chunk-manager.js - World streaming for large maps
• scripts/performance-profiler.js - Benchmarking utilities

Structural Physics (references/structural-physics-advanced.md)

• scripts/heuristic-validator.js - Fast validation (Fortnite/Rust/Valheim modes)
• scripts/stability-optimizer.js - Caching and batch updates
• scripts/damage-propagation.js - Damage states, cascading collapse
• scripts/physics-engine-lite.js - Optional realistic physics

Multiplayer (references/multiplayer-networking.md)

• scripts/delta-compression.js - Only send changed state
• scripts/client-prediction.js - Optimistic placement with rollback
• scripts/conflict-resolver.js - Handle simultaneous builds
• scripts/building-network-manager.js - Complete server/client system

Key Patterns

Spatial Indexing Selection

Physics Mode Selection

• Arcade (Fortnite): Connectivity only, instant collapse, best for combat
• Heuristic (Rust/Valheim): Stability %, predictable, best for survival
• Realistic: Full stress/strain, expensive, best for engineering sims

Multiplayer Pattern

Server-authoritative with client prediction. Use delta compression for sync.