Qu3e
A lightweight, fast, and simple 3D physics engine in C++ designed for games, supporting only box collision for ease of use.
What is Qu3e?
qu3e is a lightweight, fast, and simple 3D physics engine written in C++ for game development. It specializes in rigid body simulation with box-only collision detection, offering an easy-to-use API that minimizes learning time and code complexity. The engine solves the need for a straightforward physics solution without the overhead of larger, more feature-rich libraries.
Game developers, especially those working on 3D games in C++ who need a simple, performant physics engine without external dependencies. It's also suitable for learners interested in understanding physics engine internals due to its commented codebase.
Developers choose qu3e for its minimalism, speed, and ease of integration—it's dependency-free, portable, and designed to be simple to use while still providing essential physics features. Its focus on box collision keeps the API clean and the learning curve low compared to more complex engines.
Overview
Lightweight and Simple 3D Open Source Physics Engine in C++
Use Cases
Best For
- Prototyping 3D games quickly with basic physics
- Educational projects to learn physics engine internals
- Games where box-shaped collision primitives are sufficient
- Embedded or resource-constrained environments needing a lightweight physics library
- Indie developers seeking a simple, fast physics solution without bloat
- Integrating physics into custom C++ game engines with minimal overhead
Not Ideal For
- Games requiring diverse collision shapes beyond boxes, such as spheres or capsules
- Projects needing continuous collision detection to prevent object tunneling
- Simulations where precise energy conservation is critical, due to Baumgarte stabilization issues
- Large-scale environments that require built-in multi-threading for performance scaling
Pros & Cons
Pros
The README demonstrates an easy-to-use interface with q3BodyDef and q3BoxDef for creating rigid bodies, minimizing learning time and code complexity.
It relies only on standard C headers like cassert and cmath, making it highly portable and easy to integrate across platforms without external library hassles.
Includes islanding, sleeping, and a dynamic AABB tree broad phase, as listed in the features, to efficiently manage CPU usage in physics simulations.
Supports collision layers, axis locking, and custom memory allocation via q3Alloc/q3Free, allowing fine-grained control over simulation behavior.
Cons
Only supports box collision; the README explicitly states no spheres or capsules are available, restricting use in games with varied geometries.
Uses Baumgarte stabilization, which the README admits adds extra energy and has trouble simulating zero restitution, affecting collision realism.
Lacks continuous collision detection, manifold reduction, and multi-threading—discussed as future additions but not implemented, limiting performance and accuracy.
Open Source Alternative To
Qu3e is an open-source alternative to the following products:
ODE (Open Dynamics Engine) is an open-source physics engine for simulating rigid body dynamics, commonly used in robotics, games, and virtual reality applications.
Havok is a middleware software suite primarily used for physics simulation, animation, and visual effects in video games and other interactive applications.
Bullet is an open-source real-time physics simulation library primarily used for video games and visual effects, known for its collision detection and rigid body dynamics.
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