Box3D — High-Performance 3D Physics Engine for Games

Introduction

Box3D is a 3D physics engine written in C by Erin Catto, the renowned creator of Box2D. It extends the proven design principles of Box2D into three dimensions, providing fast and accurate rigid-body simulation for games, robotics, and interactive applications.

What Box3D Does

• Simulates 3D rigid-body dynamics with collision detection and response
• Supports common 3D shapes (boxes, spheres, capsules, convex hulls)
• Provides joints and constraints for articulated bodies and mechanisms
• Handles continuous collision detection to prevent tunneling
• Delivers deterministic simulation results for consistent behavior

Architecture Overview

Box3D follows a data-oriented design in pure C for maximum performance and portability. The broad phase uses a dynamic bounding volume hierarchy for spatial queries. The narrow phase computes contact manifolds using GJK and SAT algorithms. The solver uses a modern approach with warm starting and sub-stepping for stable, accurate constraint resolution.

Self-Hosting & Configuration

• Build with CMake on any platform with a C11 compiler
• Link as a static or shared library into your game engine or application
• Configure world gravity, solver iterations, and time step size at initialization
• Tune collision filtering using category and mask bits
• Sample applications included for testing and reference

Key Features

• Written in pure C for maximum portability and performance
• Data-oriented design with cache-friendly memory layouts
• Multithreaded island solving for parallel simulation
• Continuous collision detection prevents fast-moving objects from tunneling
• Created by the author of Box2D with decades of physics engine expertise

Comparison with Similar Tools

• Bullet Physics — Mature and feature-rich but complex C++ API; Box3D is simpler and C-based
• PhysX (NVIDIA) — High performance but proprietary with complex licensing; Box3D is open source
• Rapier — Rust-based physics engine; Box3D targets C for broader engine integration
• Jolt Physics — Modern C++ engine; Box3D offers a simpler C API with similar performance goals

FAQ

Q: Is Box3D related to Box2D? A: Yes. Both are created by Erin Catto. Box3D extends the design philosophy of Box2D into three dimensions.

Q: Can I use it with Unity or Unreal? A: Not directly, but the C API can be integrated as a native plugin in any engine.

Q: Is it production-ready? A: Box3D is in early development. Check the repository for current stability status.

Q: Does it support soft bodies or cloth? A: No. Box3D focuses on rigid-body dynamics. Use a dedicated solver for deformable bodies.

Sources

• https://github.com/erincatto/box3d
• https://box2d.org