Godot 2d Physics

This is the reference you want open when implementing collision detection, raycasting, or trigger zones in Godot 2D. It covers the collision layer/mask mental model (what you broadcast vs. what you listen to), explains when to use Area2D signals versus move_and_collide, and includes patterns for PhysicsServer2D when you need to manage thousands of physics bodies without node overhead. The NEVER list alone is worth it: scaling CollisionShape2D nodes breaks physics, move_and_slide already factors in delta, and RigidBody2D modifications need _integrate_forces to avoid jitter. The scripts cover everything from basic setup to advanced cases like physics sub-stepping for fast projectiles and custom gravity zones.