Bevy Book

A hands-on reference for building a 2D game with Bevy 0.18 - from first window to procedural worlds, data-driven characters, collision systems, inventory, and weather effects.

Special shoutout to Febin John James — thank you for your support and contributions!

Table of Contents

Chapter 1: Getting Started with Bevy

• 1. Project Setup
  • 1.1 Create the Project
  • 1.2 Add Bevy Dependency
  • 1.3 Speed Up Compile Times
• 2. Core Architecture - Thinking in Systems
• 3. Step-by-Step Implementation
  • Step 1 - Minimal Window with Camera
  • Step 2 - Player Component (Tag Marker)
  • Step 3 - Spawn the Player (Text Placeholder)
  • Step 4 - Player Movement System
  • Step 5 - Register the Movement System
• 4. Adding Sprite Graphics
  • 4.1 Spritesheet Source
  • 4.2 Asset Directory
  • 4.3 Refactor - Separate into Modules
  • 4.4 The Player Module
• 5. Rust Concepts Quick Reference
• 6. Bevy Memory & Performance Notes
• 7. Recommended Crates for Expanding This Project
• 8. Tips for Further Improvement
• 9. Complete File Structure
• 10. Full Schedule Reference

Chapter 2: Procedural Tilemap Generation with WFC

• 1. Chapter Overview
• 2. Wave Function Collapse (WFC) - How It Works
• 3. Project Setup
• 4. Architecture Overview
• 5. Step-by-Step Implementation
  • Step 1 - Tilemap Definition
  • Step 2 - Asset Loading
  • Step 3 - Socket Definitions
  • Step 4 - Model Builder
  • Step 5 - Rules
  • Step 6 - Generator Configuration
  • Step 7 - Main Integration
• 6. Rust Concepts Introduced in This Chapter
• 7. Quick Weight Tuning Guide
• 8. Known Issues & Workarounds
• 9. Recommended Crates for Expanding Procedural Worlds
• 10. Tips for Further Improvement
• 11. Complete Layer Stack Visualization

Chapter 3: Data-Driven Characters

• 1. Chapter Overview
• 2. Project Setup
• 3. The RON Configuration File
• 4. Architecture - System Flow
• 5. Data Types
• 6. Animation Engine
• 7. Movement System
• 8. Spawn & Character Switching
• 9. Plugin Registration
• 10. Rust Concepts Introduced
• 11. Tips for Further Improvement
• 12. Recommended Crates
• 13. Spritesheet Layout Reference
• 14. Complete Component Hierarchy

Chapter 4: State Machines & Collision

• 1. Chapter Overview
• 2. Project Structure After This Chapter
• 3. Game States
• 4. Character State Machine
• 5. Architecture Refactor
• 6. Collision System
• 7. Player Collider
• 8. Debug Visualization
• 9. Y-Based Depth Sorting
• 10. Centralized Configuration
• 11. Complete Player Entity Components
• 12. Rust Concepts Introduced
• 13. Controls Summary
• 14. Known Issues & Tips
• 15. Recommended Crates

Chapter 5: Inventory & Camera

• 1. Chapter Overview
• 2. Project Structure After This Chapter
• 3. Inventory System
• 4. Camera System
• 5. World Scale Changes
• 6. Updated main.rs
• 7. Centralized Config - Full State
• 8. Rust Concepts Introduced
• 9. Controls Summary (Cumulative)
• 10. Tips for Further Improvement
• 11. Recommended Crates

Appendix A: Building a Rain System

• Step 1: Set Up the Weather Module
• Step 2: Create the Weather State
• Step 3: Make It Rain - Spawning Raindrops
• Step 4: Move and Clean Up Raindrops
• Step 5: Darken the Screen
• Step 6: Slow the Player
• Step 7: Spawn Puddles
• Reference: Z-Ordering Cheat Sheet
• Challenges: Take It Further