I’m happy to announce the release of a new open source 3D physics engine called Box3D. I’ve been working on this project for a few years now, but it represents over 20 years of experience writing physics engines for games. Read more here: https://box2d.org/posts/2026/06/announcing-box3d/

box2d.org

Announcing Box3D :: Box2D

I’m happy to announce the release of Box3D, an open source 3D physics engine. It is now available on GitHub. Box3D repository You can think of Box3D as a fork of Box2D, extended with many features needed for 3D games. Some additions: Triangle mesh collision Height-field collision Baked compound collision The core architecture of Box3D remains almost identical to Box2D. C API All library source is C17 Sub-stepping solver Continuous collision Graph coloring for large islands Wide SIMD contact solv

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Erin Catto @erin_catto@mastodon.gamedev.place

· 2mo ago

New blog post. Box3D is getting faster. https://box2d.org/posts/2026/07/simd-for-collision/

box2d.org

Erin Catto @erin_catto@mastodon.gamedev.place

· 1mo ago

I added a new experimental rigid body character mover to Box2D. https://www.youtube.com/watch?v=MWnTQUKUc0s

Erin Catto @erin_catto@mastodon.gamedev.place

· 3mo ago

Pushing Box3D to the limit. A pyramid with 16290 boxes. Stabilized by contact recycling.
https://www.youtube.com/watch?v=vG4HOKcQFxM

Erin Catto @erin_catto@mastodon.gamedev.place

· 4mo ago

I added a new feature to Box2D that lets you record the physics simulation in your game and then play it back in a replay viewer. This can be used to debug your simulation and includes recording of ray casts and other queries. The system makes use of determinism to exactly reproduce the simulation from your game. This feature also brings the possibility of deterministic rollback. Here's the blog post which also links to a video showing the feature in action.

https://box2d.org/posts/2026/06/replay/

box2d.org

Erin Catto @erin_catto@mastodon.gamedev.place

· 3mo ago

Large world support is coming to Box2D v3.2. Uses doubles for body positions but all math is done in relative coordinates using single precision. Around 3% performance loss.
https://www.youtube.com/watch?v=RwQrQafZU6Y