doc22940 / box2d

Box2D is a 2D physics engine for games

Build Status

Box2D

Box2D is a 2D physics engine for games.

Contributing

Please do not submit pull requests with new features. Instead, please file an issue first for discussion. For bugs, I prefer detailed bug reports over pull requests.

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 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

Documentation

• Manual
• subreddit
• Discord server

License

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