Learn X in Y minutes

# Single-line comments are written using hash symbol.
"""
  Multi-line
  comments
  are
  written
  using
  docstrings.
"""

# Script file is a class in itself and you can optionally define a name for it.
class_name MyClass

# Inheritance
extends Node2D

# Member variables
var x = 8 # int
var y = 1.2 # float
var b = true # bool
var s = "Hello World!" # String
var a = [1, false, "brown fox"] # Array - similar to list in Python,
                                # it can hold different types
                                # of variables at once.
var d = {
  "key" : "value",
  42 : true
} # Dictionary holds key-value pairs.
var p_arr = PoolStringArray(["Hi", "there", "!"]) # Pool arrays can
                                                  # only hold a certain type.

# Built-in vector types:
var v2 = Vector2(1, 2)
var v3 = Vector3(1, 2, 3)

# Constants
const ANSWER_TO_EVERYTHING = 42
const BREAKFAST = "Spam and eggs!"

# Enums
enum { ZERO, ONE , TWO, THREE }
enum NamedEnum { ONE = 1, TWO, THREE }

# Exported variables are visible in the inspector.
export(int) var age
export(float) var height
export var person_name = "Bob" # Export type hints are unnecessary
                        # if you set a default value.

# Functions
func foo():
  pass # pass keyword is a placeholder for future code

func add(first, second):
  return first + second

# Printing values
func printing():
  print("GDScript ", "is ", " awesome.")
  prints("These", "words", "are", "divided", "by", "spaces.")
  printt("These", "words", "are", "divided", "by", "tabs.")
  printraw("This gets printed to system console.")

# Math
func doing_math():
  var first = 8
  var second = 4
  print(first + second) # 12
  print(first - second) # 4
  print(first * second) # 32
  print(first / second) # 2
  print(first % second) # 0
  # There are also +=, -=, *=, /=, %= etc.,
  # however no ++ or -- operators.
  print(pow(first, 2)) # 64
  print(sqrt(second)) # 2
  printt(PI, TAU, INF, NAN) # built-in constants

# Control flow
func control_flow():
  x = 8
  y = 2 # y was originally a float,
        # but we can change its type to int
        # using the power of dynamic typing!

  if x < y:
    print("x is smaller than y")
  elif x > y:
    print("x is bigger than y")
  else:
    print("x and y are equal")

  var a = true
  var b = false
  var c = false
  if a and b or not c: # alternatively you can use &&, || and !
    print("This is true!")

  for i in range(20): # GDScript's range is similar to Python's
    print(i) # so this will print numbers from 0 to 19

  for i in 20: # unlike Python, you can loop over an int directly
    print(i) # so this will also print numbers from 0 to 19

  for i in ["two", 3, 1.0]: # iterating over an array
    print(i)

  while x > y:
    printt(x, y)
    y += 1

  x = 2
  y = 10
  while x < y:
    x += 1
    if x == 6:
      continue # 6 won't get printed because of continue statement
    prints("x is equal to:", x)
    if x == 7:
      break # loop will break on 7, so 8, 9 and 10 won't get printed

  match x:
    1:
      print("Match is similar to switch.")
    2:
      print("However you don't need to put cases before each value.")
    3:
      print("Furthermore each case breaks on default.")
      break # ERROR! Break statement is unnecessary!
    4:
      print("If you need fallthrough use continue.")
      continue
    _:
      print("Underscore is a default case.")

  # ternary operator (one line if-else statement)
  prints("x is", "positive" if x >= 0 else "negative")

# Casting
func casting_examples():
  var i = 42
  var f = float(42) # cast using variables constructor
  var b = i as bool # or using "as" keyword

# Override functions
# By a convention built-in overridable functions start with an underscore,
# but in practice you can override virtually any function.

# _init is called when object gets initialized
# This is the object's constructor.
func _init():
  # Initialize object's internal stuff here.
  pass

# _ready gets called when script's node and
# its children have entered the scene tree.
func _ready():
  pass

# _process gets called on every frame.
func _process(delta):
  # The delta argument passed to this function is a number of seconds,
  # which passed between the last frame and the current one.
  print("Delta time equals: ", delta)

# _physics_process gets called on every physics frame.
# That means delta should be constant.
func _physics_process(delta):
  # Simple movement using vector addition and multiplication.
  var direction = Vector2(1, 0) # or Vector2.RIGHT
  var speed = 100.0
  self.global_position += direction * speed * delta
  # self refers to current class instance

# When overriding you can call parent's function using the dot operator
# like here:
func get_children():
  # Do some additional things here.
  var r = .get_children() # call parent's implementation
  return r

# Inner class
class InnerClass:
  extends Object

  func hello():
    print("Hello from inner class!")

func use_inner_class():
  var ic = InnerClass.new()
  ic.hello()
  ic.free() # use free for memory cleanup

extends Node2D

var sprite # This variable will hold the reference.

# You can get references to other nodes in _ready.
func _ready() -> void:
  # NodePath is useful for accessing nodes.
  # Create NodePath by passing String to its constructor:
  var path1 = NodePath("path/to/something")
  # Or by using NodePath literal:
  var path2 = @"path/to/something"
  # NodePath examples:
  var path3 = @"Sprite" # relative path, immediate child of the current node
  var path4 = @"Timers/Firerate" # relative path, child of the child
  var path5 = @".." # current node's parent
  var path6 = @"../Enemy" # current node's sibling
  var path7 = @"/root" # absolute path, equivalent to get_tree().get_root()
  var path8 = @"/root/Main/Player/Sprite" # absolute path to Player's Sprite
  var path9 = @"Timers/Firerate:wait_time" # accessing properties
  var path10 = @"Player:position:x" # accessing subproperties

  # Finally, to get a reference use one of these:
  sprite = get_node(@"Sprite") as Sprite # always cast to the type you expect
  sprite = get_node("Sprite") as Sprite # here String gets
                                        # implicitly casted to NodePath
  sprite = get_node(path3) as Sprite
  sprite = get_node_or_null("Sprite") as Sprite
  sprite = $Sprite as Sprite

func _process(delta):
  # Now we can reuse the reference in other places.
  prints("Sprite has global_position of", sprite.global_position)

# Use onready keyword to assign a value to
# a variable just before _ready executes.
# This is a commonly used syntax sugar.
onready var tween = $Tween as Tween

# You can export NodePath, so you can assign it within the inspector.
export var nodepath = @""
onready var reference = get_node(nodepath) as Node

class_name Player extends Node2D

var hp = 10

signal died() # define signal
signal hurt(hp_old, hp_new) # signals can take arguments

func apply_damage(dmg):
  var hp_old = hp
  hp -= dmg
  emit_signal("hurt", hp_old, hp) # emit signal and pass arguments
  if hp <= 0:
    emit_signal("died")

func _ready():
  # connect signal "died" to function "_on_death" defined in self
  self.connect("died", self, "_on_death")

func _on_death():
  self.queue_free() # destroy Player on death

extends Node

var x: int # define typed variable
var y: float = 4.2
var z := 1.0 # infer type based on default value using := operator

onready var node_ref_typed := $Child as Node

export var speed := 50.0

const CONSTANT := "Typed constant."

func _ready() -> void:
  # function returns nothing
  x = "string" # ERROR! Type can't be changed!
  return

func join(arg1: String, arg2: String) -> String:
  # function takes two Strings and returns a String
  return arg1 + arg2

func get_child_at(index: int) -> Node:
  # function takes an int and returns a Node
  return get_children()[index]

signal example(arg: int) # ERROR! Signals can't take typed arguments!