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

• Install CMake
• Ensure CMake is in the user PATH
• Run create_sln.bat
• Open and build build/box2d.sln

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

• Install Emscripten
• Run emcmake cmake -B build -DBOX2D_VALIDATE=OFF -DBOX2D_UNIT_TESTS=OFF -DBOX2D_SAMPLES=OFF -DCMAKE_BUILD_TYPE=Release
• Run emmake make -C build
• The JavaScript and WebAssembly bindings will be in build/bin/

Box2D can be used in web browsers and Node.js via WebAssembly:

import Box2D from './box2d_bindings.js';

// Initialize Box2D
const box2d = await Box2D();

// Create a world with gravity
const world = new box2d.World(0, -10);

// Create a ground body
const ground = new box2d.Body(world, 0, -10, box2d.BodyType.staticBody);
box2d.ShapeFactory.createBox(ground, 50, 10);

// Create a dynamic body
const body = new box2d.Body(world, 0, 4, box2d.BodyType.dynamicBody);
box2d.ShapeFactory.createBox(body, 1, 1, 1.0, 0.3);

// Run simulation
world.step(1/60, 4);
console.log(body.getPosition());

TypeScript definitions are included for full type safety.

• Install CMake
• Add Cmake to the path in .zprofile (the default Terminal shell is zsh)
  • export PATH="/Applications/CMake.app/Contents/bin:$PATH"
• 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 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