erincatto/box3d

Box3D

Box3D is a 3D physics engine for games.

Features

Collision

• Continuous collision detection
• Contact events
• Convex hulls, capsules, spheres, triangle meshes, and height fields
• Multiple shapes per body
• Collision filtering
• Ray casts, shape casts, and overlap queries
• Sensor system
• Character mover

Physics

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

System

• Data-oriented design
• Written in portable C17
• Extensive multithreading and SIMD
• Optimized for large piles of bodies
• Cross platform determinism
• Recording and replay

Samples

• Uses sokol to run with D3D11 on Windows, Metal on macOS, and OpenGL 4.5 on Linux.
• Graphical user interface with imgui.
• Many samples to demonstrate features and performance.

Building all platforms

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

Building with CMake presets (recommended)

This uses the presets in CMakePresets.json.

• 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
• Windows MinGW: cmake --preset mingw-release then cmake --build --preset mingw-release

Run the samples app (must be in the Box3D directory).

• Windows: .\build\bin\Release\samples.exe
• Linux: ./build/bin/samples
• macOS: ./build/bin/Release/samples

Building for Visual Studio

• Install Visual Studio
• Run build_vs2026.bat
• Open and build build/box3d.slnx

Building for Linux

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

Building for Xcode

• mkdir build
• cd build
• cmake -G Xcode ..
• Open box3d.xcodeproj
• Select the samples scheme
• Build and run the samples

Building for Web

• Emscripten SDK
• emcmake cmake -B build -DBOX3D_SAMPLES=OFF
• cmake --build build

Box3D uses SSE2 with WebAssembly. Define BOX3D_DISABLE_SIMD to disable SSE2.

Building and installing

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

Using Box3D in your project

The core library has no dependencies beyond the C runtime (and libm on Unix). Linking it gives you the box3d::box3d target.

I recommend to use FetchContent:

include(FetchContent)
FetchContent_Declare(box3d
  GIT_REPOSITORY https://github.com/erincatto/box3d.git
  GIT_TAG v0.1.0)
FetchContent_MakeAvailable(box3d)

target_link_libraries(my_app PRIVATE box3d::box3d)

For a vendored copy or git submodule, point add_subdirectory at it:

add_subdirectory(extern/box3d)

target_link_libraries(my_app PRIVATE box3d::box3d)

To use a copy installed with cmake --install, find the package:

find_package(box3d 0.1 REQUIRED)

target_link_libraries(my_app PRIVATE box3d::box3d)

See docs/hello.md for a minimal first program.

Compatibility

The Box3D library and samples build and run on Windows, Linux, and Mac.

You will need a compiler that supports C17 to build the Box3D library.

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

Box3D uses SSE2 and Neon SIMD math to improve performance. SIMD can be disabled by defining BOX3D_DISABLE_SIMD.

Documentation

The user manual lives in docs/ and is built with Doxygen. Enable the BOX3D_DOCS CMake option and build the doc target.

Community

• Discord

Contributing

Pull requests are currently disabled. Instead, please file an issue for bugs or feature requests. For support, please visit the Discord server.

Giving feedback

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

License

Box3D is developed by Erin Catto and uses the MIT license.

Sponsorship

Support development of Box3D through Github Sponsors.

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

LLM Usage

LLMs are used in the following areas:

• unit tests
• samples app
• migrating code between Box2D and Box3D
• build configuration
• code reviews
• benchmarking

Elsewhere all code is developed and written by me. I take responsibility for every line of code in Box2D/3D.