Dura2D is an educational 2D physics engine developed under SOHNE. Instead of hiding the machinery behind an API, it is built to expose how game physics actually works: how bodies integrate, how contacts are solved, and how collision detection scales.
It runs natively on Linux, macOS, and Windows, and in the browser through WebAssembly.
Features
- Constraint-based solver: joints and contacts are resolved as constraints, which keeps stacks and articulated bodies stable.
- Warm starting: solver impulses are carried over between frames, so the solution converges in fewer iterations.
- Dynamic AABB tree: broad-phase collision detection stays fast as the number of bodies grows.
Tech
- C++ for the engine core
- CMake (3.26+) as the build system
- Emscripten for the WebAssembly / HTML5 build
- GitHub Actions CI on Ubuntu, macOS, and Windows
What I learned
- Why constraint-based dynamics beats naive impulse resolution once bodies start stacking.
- How warm starting exploits temporal coherence to make an iterative solver practical in real time.
- How a dynamic AABB tree turns collision detection from a quadratic scan into a logarithmic query.
- Shipping the same C++ codebase to native platforms and the web with CMake and Emscripten.
Study references that shaped the engine: Pikuma’s Game Physics course, Ming-Lun "Allen" Chou’s Game Physics series, Box2D, and Jason Gregory’s Game Engine Architecture.