Box3D Open Source 3D Physics Engine Released
Original: Box3D, an open source 3D physics engine
Why This Matters
Open source physics engines expand options for game developers; 3D physics performance critical for large-scale game worlds.
Box3D, an open source 3D physics engine forked from Box2D, launched on GitHub June 30, 2026. Developed by a physics programmer for The Legend of California game, it adds 3D features including triangle mesh collision, height-field collision, and multi-threading support while maintaining Box2D's core architecture.
Box3D, announced June 30, 2026, is an open source 3D physics engine available on GitHub. It extends Box2D with features needed for 3D games, including triangle mesh collision, height-field collision, baked compound collision, sub-stepping solver, continuous collision detection, and wide SIMD contact solver. The engine is written in C17 and features multi-threading hooks, optional internal scheduler, large world support with doubles for position, cross-platform determinism, and recording/replay capabilities. The engine was developed out of necessity for The Legend of California, a survival game in development at Kintsugiyama since 2022 using Unreal Engine 5.0. The developer encountered issues with Unreal's native Chaos physics engine, including lack of gyroscopic torque support and erratic collision behavior when simulating large capsules falling on triangle meshes. Additionally, the game requires fast broad-phase physics for hundreds of thousands of server-side entities. Rather than modifying existing solutions like Jolt, the developer forked Rubikon-Lite, a hobby version of Valve's Half-Life: Alyx physics engine Rubikon maintained by physics programmer Dirk Gregorius. The integration worked well in Unreal, providing needed features. As development progressed, the developer aligned the 2D and 3D physics efforts, incorporating optimizations from Box2D v3.0 into the 3D engine, ultimately releasing it as open source.