API reference

The classes and methods scripts use most. For how they fit together, see Behaviours and Gameplay recipes.

Object	Highlights
Behaviour	start, update(dt), fixed_update(dt), on_trigger_enter/exit(other), on_collision_enter/exit(other), on_destroy; helpers game_object, name, transform, character, rigidbody, vehicle, props, prop, find, find_all, destroy, get_component; timers after(seconds) { }, every(seconds) { }, tween(seconds, ease: :smooth) { |t| }, cancel_timers
GameObject	name, tag, tag?, props, alive?, destroy, visible / visible=, behaviours, parent, children, transform, character, rigidbody, vehicle, get_component(Klass), add_component(Klass, speed: 2.0), tint(=) (multiplies its colors: [1.0, 0.5, 0.5]), animation (its own clips, see Animator), animation_offset(=) (seconds a spawned copy's animations run ahead of the original's)
Transform	position(=), local_position(=), rotation(=) (Euler degrees), rotate, look_at, translate, scale(=), forward, right, up
CharacterController	move(velocity), jump(speed), grounded?, velocity
Rigidbody	velocity(=), add_impulse(vector)
Vehicle	drive(throttle:, steering:, brake:, handbrake:), stop, speed (m/s, signed), velocity
Physics	raycast(origin, direction, max_distance = 1000, ignore = nil) → {object:, point:, normal:, distance:} or nil
Input	axis(:horizontal / :vertical), down?(:space), pressed?, released?, action?(:jump), action_pressed?; mouse: mouse_x, mouse_y, mouse_dx, mouse_dy, mouse_wheel, mouse_down?(:left), mouse_pressed?, mouse_released?, mouse_locked=; gamepad: gamepad?, gamepad_axis(:left_x), gamepad_down?(:a), gamepad_pressed?, gamepad_released?; text (typed this frame); touch_controls= (the on-screen stick and buttons of a phone)
Time	delta, fixed_delta, elapsed, frame, scale(=) (0 pauses the game)
Scene / Camera	Scene.find(name), Scene.find_all(tag), Scene.objects, Camera.main, Camera.screen_ray(x, y) → [origin, direction], Camera.fov(=) (degrees), Camera.motion_blur(=) (0..1: the picture streaks away from its center, as when moving fast)
SceneScript	setup, find, find_all, find! (see Setting a level up in Ruby)
Scene.spawn	Scene.spawn("Bullet", position: v, rotation: euler, physics: true) copies a prefab = true template (hidden and inert in the game) with its physics and scripts; copies of animated characters move like the original
Particles	Particles.burst(position, count:, color:, alpha:, glow:, direction:, spread:, speed:, life:, size:, gravity:, image:, spin:) → how many were added, Particles.count, Particles.clear
Animation	Animation.names, play(name, loop: true, speed: 1.0, restart: false), pause(name), stop(name), playing?(name), time(name), duration(name), seek(name, seconds)
Animator	game_object.animation (or animation in a behaviour): play(name, loop: true, speed: 1.0, fade: 0.0, restart: false), mix(name, weight: 1.0, loop: true, speed: 1.0), unmix, pause, follow_scene(fade: 0.0), clip, playing?, time
Network	host(port: 7777, name:, visible: true, room: false), join(address, port: 7777) / join(room: "K7QM3P"), relay=, room, search, searching?, stop_search, games, discovery_port=, leave, online?, connecting?, host?, id, peers, port, emit(name, data = nil, to: :all / :host / id), on(name) { \|data, from\| }, on_connect, on_fail, on_disconnect, on_join { \|peer\| }, on_leave { \|peer\| }, spawn(template, owner: Network.id, position:, rotation:), allow_spawn(*templates) (see Multiplayer)
NetworkSync	A behaviour: add_component(NetworkSync, owner: peer_id, key: "name"), mine?, owner, key, assign(owner:, key:)
Save	Save.get(key, default = nil), Save[key], Save[key] = value (numbers, texts, true/false), Save.delete(key), Save.clear, Save.keys
Audio	Audio.play(:jump, volume:, pitch:), Audio.music(:theme, loop: true, volume: 0.7), Audio.stop_music, Audio.music_pitch = 1.2, Audio.music_volume = 0.5 (change them every frame for an engine's drone), Audio.volume = 0.8 (files in sounds/)
UI / Debug / Game	UI.text(str, x:, y:, size:, color:, alpha:, align:), UI.rect(x:, y:, width:, height:, color:, alpha:, radius:), UI.image(name, x:, y:, width:, height:), UI.button(label, x:, y:, width:, height:) → clicked?, UI.text_field(value, x:, y:, width:, height:, max_length:) → the new value, UI.width, UI.height, UI.text_width(str, size:), Debug.log/warn/error, Game.quit, Game.load_scene("level2") (scenes/level2.glb; "main" is scene.glb; Ruby globals survive), Game.scene_name, Game.title
GameMenu	A behaviour: title screen, pause menu and end screen. GameMenu.instance, show(:pause), resume, restart, finish("You win!"), open?, screen, screens (:title, :pause, :over, and the game's own), button_box(index); GameMenu::Screen.new(heading:, options:, back:), add_option(label, index:) { }; settings title, start_open (see Gameplay recipes)
Vector3	Vector3.new(x, y, z), Vector3.zero, one, up, down, left, right, forward, back; arithmetic, dot, cross, length, normalized, clamped(max_length = 1.0), lerp, flat, with(y: 0), distance_to, approx?, to_a

Script errors are logged with a backtrace and only disable the failing behaviour; the game keeps running. Assigning transform.position to a physics object teleports it (moving bodies also stop); changing its rotation keeps its velocity. Vehicle wheel meshes must have their rotation applied (axle along X).