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Scripting & the Node Lifecycle

A script attached to a node gives it behavior by overriding engine callbacks. The script extends the node's type and becomes that node.

Core lifecycle callbacks

• _ready() — called once when the node and its children have entered the scene tree; do setup, cache node references here.
• _process(delta) — called every rendered frame; delta is seconds since last frame. Use for non-physics per-frame logic (UI, timers, input polling). Frame-rate dependent, so scale by delta.
• _physics_process(delta) — called at a fixed rate (default 60 Hz) in sync with the physics engine; do movement and physics here for deterministic behavior.
• _input(event) / _unhandled_input(event) — receive input events.
• _enter_tree() / _exit_tree() — when the node is added/removed from the tree.

A first script

Attach a script to a node, then in _process/_physics_process read input and move it; in _ready grab references (@onready var sprite = $Sprite2D). Build behavior from these callbacks plus signals for events.

Pausing & process modes

Setting get_tree().paused = true pauses the game. Each node's process mode decides how it behaves while paused: INHERIT (default), PAUSABLE (stops when paused), ALWAYS (keeps running — for pause menus), or DISABLED. This lets a pause menu stay interactive while gameplay freezes — set the menu's process mode to ALWAYS.

Frame vs physics

Rule of thumb: movement/physics → _physics_process (fixed timestep, deterministic); visuals/UI/other → _process. Mixing them up causes jittery or frame-rate-dependent gameplay.