Little Physics

Little Physics is a Unity ECS physics package for large-scale simulations. Pause or speed up the simulation, use dynamic, static, kinematic, and trigger bodies, and tune LOD for simulation accuracy. A spatial map limits object-to-object collisions to a volume you define. The package supports directional and radial gravity, friction, and custom job interfaces for collision detection and linecasts.

With ECS, Burst, and multithreading, it can handle on the order of 1,000,000 entities. It suits low-determinism workloads such as crowds, liquids, and particles — not highly deterministic simulations.

Features

• Deep simulation tuning — separate fixed and variable settings for different simulation profiles
• LOD — up to four levels with per-level limits
• Time control — pause, slow down, or speed up (0, 1, 2, or 4 time scale)
• Body types — dynamic, static, kinematic, and triggers
• Gravity — directional and radial
• Friction and surface collisions — every dynamic body is tested against surfaces each frame
• Substeps — split a fixed update into 1–4 substeps for better penetration handling and stability
• Collision detection and linecast — hook into the pipeline via public job interfaces and system groups.

Requirements

• Unity 6000.0 or newer.
• com.unity.entities 1.4.8 (required). Declared in package.json and installed through the Package Manager.
• Sample scenes also require com.unity.entities.graphics and com.unity.inputsystem.