Constants

Part of the Nodes and Scenes section of Coddy's Godot journey. Lesson 14 of 28.

Some values never change while the game runs, like a robot's top speed. Use a constant for them. It is made with const instead of var:

const SPEED = 250

Constants are written in CAPITALS, so readers see the value is fixed. To change it, edit the number where it is made.

A line that changes a constant is an error. Godot catches it before the game starts. The Console says Cannot assign a new value to a constant and names the line.

Challenge

Easy

Make the game start, with a faster robot.

Delete _ready() and the line inside it: a script cannot change a constant.
Give SPEED the value 300 where it is made, and keep it a const.

Press Play: the game starts and the robot moves left at 300 pixels a second. Then Check.

Try it yourself

extends Node2D

const SPEED = 200

func _ready():
	SPEED = 300

func _process(delta):
	position.x -= SPEED * delta

All lessons in Nodes and Scenes

1Your First Godot Game

What Is Godot?Ready Runs Once Print in Godot The Scene Tree Set a Position Move a Node Once

4Finding Nodes

The Dollar Sign Node Paths Onready Change a Color Hide and Show

2Every Frame

Process Runs Every Frame Delta Pixels per Second Move Diagonally Spin With Rotation Grow With Scale

5Project: Screensaver

Screensaver: Drift Screensaver: Side Walls

Screensaver: Top and Bottom

Screensaver: Color List

Screensaver: New Colors

3Values You Can Tune

Variables on a NodeConstantsExport Variables Vector2 Math Wrap Around the Screen Your Own Functions

Practice on your own: Godot playground