Box2D-optimized

This project is currently in alpha, work in progress

Box2D is a 2D physics engine for games, developed and maintained by Erin Catto.

Box2D-optimized is a Box2D fork that aims to offer improved perfromance and scalability, while maintining a similar API and feature set. This library merges commits from upstream Box2D regularly in order to be up to date.

A collection of various benchmarks and graphs showcasing the performance improvement can be found in the box2d-benchmarks repository.

There are a lot of under-the-hood changes in order to achieve this stated speedup, which are described in my dissertation for optimizing Box2D: optimizing-box2d

Contributing

Feel free to open issues for bugs and discussions or make pull requests.

License

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

Box2D-optimized is developed by Manolis Tsamis and also uses the MIT license.

Box2D

The rest of the Box2D README is copied here for convinience

Features

Collision

• Continuous collision detection
• Contact callbacks: begin, end, pre-solve, post-solve
• Convex polygons and circles
• Multiple shapes per body
• One-shot contact manifolds
• Dynamic tree broadphase
• Efficient pair management
• Fast broadphase AABB queries
• Collision groups and categories

Physics

• Continuous physics with time of impact solver
• Persistent body-joint-contact graph
• Island solution and sleep management
• Contact, friction, and restitution
• Stable stacking with a linear-time solver
• Revolute, prismatic, distance, pulley, gear, mouse joint, and other joint types
• Joint limits, motors, and friction
• Momentum decoupled position correction
• Fairly accurate reaction forces/impulses

System

• Small block and stack allocators
• Centralized tuning parameters
• Highly portable C++ with no use of STL containers

Testbed

• OpenGL with GLFW
• Graphical user interface with imgui
• Extensible test framework
• Support for loading world dumps

Building

• Install CMake
• Ensure CMake is in the user PATH
• Visual Studio: run build.bat from the command prompt
• Otherwise: run build.sh from a bash shell
• Results are in the build sub-folder
• On Windows you can open box2d.sln

Building Box2D - Using vcpkg

You can download and install Box2D using the vcpkg dependency manager:

• git clone https://github.com/Microsoft/vcpkg.git
• cd vcpkg
• ./bootstrap-vcpkg.sh
• ./vcpkg integrate install
• ./vcpkg install box2d

The Box2D port in vcpkg is kept up to date by Microsoft team members and community contributors. If the version is out of date, please create an issue or pull request on the vcpkg repository.

Note: vcpkg support is not provided by the Box2D project

Building for Xcode

• 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 testbed scheme
• Edit the scheme to set a custom working directory, make this be in box2d/testbed
• You can now build and run the testbed

Installing using CMake

You can use the CMake install feature to deploy the library to a central location that can be accessed using:

find_package(box2d REQUIRED)
target_link_libraries(mytarget PRIVATE box2d)

You can build and install the library and docs using this command sequence (requires Doxygen):

mkdir build
cd build
cmake -DBOX2D_BUILD_DOCS=ON ..
cmake --build .
cmake --build . --target INSTALL

On Windows this tries to install in Program Files and thus requires admin privileges. Alternatively you can target another directory using something like this:

mkdir build
cd build
cmake -DBOX2D_BUILD_DOCS=ON -DCMAKE_INSTALL_PREFIX="C:/packages" ..
cmake --build .
cmake --build . --target INSTALL

Documentation

• Manual
• reddit
• Discord

Sponsorship

Support development of Box2D through Github Sponsors