Box2D is a 2D physics engine for games.

• Continuous collision detection
• Contact events
• Convex polygons, capsules, circles, rounded polygons, segments, and chains
• Multiple shapes per body
• Collision filtering
• Ray casts, shape casts, and overlap queries
• Sensor system

• Robust Soft Step rigid body solver
• Continuous physics for fast translations and rotations
• Island based sleep
• Revolute, prismatic, distance, mouse joint, weld, and wheel joints
• Joint limits, motors, springs, and friction
• Joint and contact forces
• Body movement events and sleep notification

• Data-oriented design
• Written in portable C17
• Extensive multithreading and SIMD
• Optimized for large piles of bodies

• OpenGL with GLFW
• Graphical user interface with imgui
• Many samples to demonstrate features and performance

• Install CMake
• Install git
• Ensure these run from the command line

The presets in CMakePresets.json give one build flow on every platform and are picked up automatically by Visual Studio, VS Code, and CLion (open the folder and choose a preset). From the command line:

• Windows: cmake --preset windows then cmake --build --preset windows-release
• Linux: cmake --preset linux-release then cmake --build --preset linux-release
• macOS: cmake --preset macos then cmake --build --preset macos-release

Use the *-debug build presets for a debug build (not recommended for the replay viewer). The presets use the default native toolchain (the installed Visual Studio on Windows, Make on Linux, Xcode on macOS), so no specific compiler version is required.

• Install Visual Studio
• Run build_vs2026.bat for Visual Studio 2026, or use the windows preset above for other versions
• Open and build the generated solution in the build folder

• Run build.sh from a bash shell
• Results are in the build sub-folder

• mkdir build
• cd build
• cmake -G Xcode ..
• Open box2d.xcodeproj
• Select the samples scheme
• Build and run the samples

• mkdir build
• cd build
• cmake ..
• cmake --build . --config Release
• cmake --install . (might need sudo)

The samples app doubles as a viewer for Box2D recordings (.b2rec files). Any preset above builds it. Pass a recording on the command line to open it directly:

• Windows: build\bin\Release\samples.exe path\to\session.b2rec
• Linux: build/bin/samples path/to/session.b2rec
• macOS: build/bin/Release/samples path/to/session.b2rec

On Windows you can also drag a .b2rec file onto samples.exe. The viewer runs from any directory. Without an argument, open a recording from the Replay menu. See docs/recording.md for how to make a recording.

The Box2D library and samples build and run on Windows, Linux, and Mac.

You will need a compiler that supports C17 to build the Box2D library.

You will need a compiler that supports C++20 to build the samples.

Box2D uses SSE2 and Neon SIMD math to improve performance. This can be disabled by defining BOX2D_DISABLE_SIMD.

• Manual
• Migration Guide

• Discord

Please do not submit pull requests. Instead, please file an issue for bugs or feature requests. For support, please visit the Discord server.

Please file an issue or start a chat on discord. You can also use GitHub Discussions.

Box2D is developed by Erin Catto and uses the MIT license.

Support development of Box2D through Github Sponsors.

Please consider starring this repository and subscribing to my YouTube channel.

• Beef bindings - https://github.com/EnokViking/Box2DBeef
• C++ bindings - https://github.com/HolyBlackCat/box2cpp
• WASM - https://github.com/Birch-san/box2d3-wasm