Jitter Physics 2
[](https://github.com/notgiven688/jitterphysics2/actions/workflows/jitter-tests.yml)
[](https://www.nuget.org/packages/Jitter2/)
[](https://discord.gg/7jr3f4edmV)
Jitter Physics 2, the evolution of [Jitter Physics](https://github.com/notgiven688/jitterphysics), is an impulse-based dynamics engine with a semi-implicit Euler integrator. It is a fast, simple, and dependency-free engine written in C# with a clear and user-friendly API.
📦 The official **NuGet** package ([changelog](https://jitterphysics.com/docs/changelog)) can be found [here](https://www.nuget.org/packages/Jitter2), the *double precision* version [here](https://www.nuget.org/packages/Jitter2.Double).
---
▶️ Try the interactive demo and explore the docs at **[jitterphysics.com](https://jitterphysics.com/docs/introduction.html)**.
There is also a tiny demo available for the [Godot engine](other/GodotDemo) 🎮.
---
## Getting Started
Jitter is cross-platform. The `src` directory contains four projects:
| Project | Description |
|------------------|------------------------------------------------------------|
| Jitter2 | The main library housing Jitter2's functionalities. |
| JitterDemo | Features demo scenes rendered with OpenGL, tested on Linux and Windows. |
| JitterBenchmark | The setup for conducting benchmarks using BenchmarkDotNet. |
| JitterTests | Unit tests utilizing NUnit. |
To run the demo scenes:
- Install [.NET 10 SDK](https://dotnet.microsoft.com/download/dotnet/10.0)
- `git clone https://github.com/notgiven688/jitterphysics2.git`
- `cd ./jitterphysics2/src/JitterDemo && dotnet run -c Release`
JitterDemo uses [GLFW](https://www.glfw.org/) for accessing OpenGL and managing windows, and [cimgui](https://github.com/cimgui/cimgui) for GUI rendering. The project contains these native binaries in precompiled form.
## Features
- [x] Compile time option for double precision.
- [x] Optional cross-platform deterministic solver mode for reproducible simulation.
- [x] Speculative contacts (avoiding the bullet-through-paper problem).
- [x] A variety of constraints and motors (AngularMotor, BallSocket, ConeLimit, DistanceLimit, FixedAngle, HingeAngle, LinearMotor, PointOnLine, PointOnPlane, TwistAngle) with support for softness.
- [x] A sophisticated deactivation scheme with minimal cost for inactive rigid bodies (scenes with 100k inactive bodies are easily achievable).
- [x] Edge collision filter for internal edges of triangle meshes.
- [x] Substepping for improved constraint and contact stability.
- [x] Generic convex-convex collision detection using EPA-aided MPR.
- [x] "One-shot" contact manifolds using auxiliary contacts for flat surface collisions.
- [x] Efficient compound shapes.
- [x] Easy integration of custom shapes. Integrated: Box, Capsule, Cone, Convex Hull, Point Cloud, Sphere, Triangle, Transformed.
- [x] Soft-body dynamics!
## Documentation
Find the [documentation here](https://notgiven688.github.io/jitterphysics2).
## Credits
Grateful acknowledgment to Erin Catto, Dirk Gregorius, Erwin Coumans, Gino van den Bergen, Daniel Chappuis, Marijn Tamis, Danny Chapman, Gary Snethen, and Christer Ericson for sharing their knowledge through forum posts, talks, code, papers, and books.
Special thanks also to the contributors of the predecessor projects JigLibX and Jitter.
## Contribute 👋
Contributions of all forms are welcome! Feel free to fork the project and create a pull request.
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Fast · Lightweight · Pure C# · MIT License
Jitter Physics 2
An impulse-based 3D rigid-body physics engine for .NET —
zero native dependencies, runs anywhere .NET runs.
Zero Dependencies
Pure C# with no native DLLs, no P/Invoke. Runs on any platform that supports .NET 8 or later.
Impulse-Based Dynamics
Semi-implicit Euler integrator with sub-stepping for stable, stiff simulations at interactive frame rates.
Deterministic Solver
Optional cross-platform deterministic mode for reproducible simulations.
Massive Sleeping Worlds
Deactivation system keeps large simulations fast — 100k+ inactive bodies have near-zero per-frame cost.
Speculative Contacts
Prevents tunneling at high velocities without the overhead of continuous collision detection.
Rich Constraints
BallSocket, Hinge, Prismatic, Universal Joint, Linear & Angular Motor, Spring, Distance Limit, and more.
Convex & Mesh Shapes
Box, Capsule, Sphere, Cone, Cylinder, ConvexHull, PointCloud, and TriangleMesh — unified GJK/MPR pipeline.
Float or Double Precision
Compile-time precision switch — the same API and source code works with either
float or double.Soft-Body Dynamics
Cloth, ropes, and deformable bodies coexist alongside rigid bodies in the same simulation world.
Interactive Web Demo
Run the physics engine live in your browser — no install required.
Hello World Tutorial
Set up a project and simulate your first falling box in minutes.
Teapot Stacking
Load convex hull meshes and simulate a tower of Utah teapots.
Documentation
Dive into bodies, shapes, constraints, and the broad-phase tree.
API Reference
Full generated reference for every public type in Jitter2.
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