unity-physics

SKILL.md

Unity Physics (Rigidbody / PhysX)

Make objects move, collide, and detect each other with Unity 6.3 LTS's built-in 3D physics
(PhysX). Get the FixedUpdate discipline, trigger-vs-collision rules, and collision layers
right. Targets Unity 6.3 LTS (6000.3).

Unity 6.3 LTS rename: Rigidbody.velocity is now Rigidbody.linearVelocity (the old
name is deprecated). Code copied from older tutorials will warn or fail to compile.

When to use

Use when giving an object physical motion (forces, velocity, gravity), responding to
collisions or triggers, setting up collision layers/masks, raycasting for ground checks or
line-of-sight, or connecting bodies with joints.

Use when scenes/prefabs contain Rigidbody + Collider components.

When not to use: 2D physics (Rigidbody2D, Collider2D) is a separate API — adapt the
concepts but the types differ. Cross-engine feel tuning (timestep, jitter, tunnelling) →
physics-tuning. Reading input that drives movement → unity-input-system.