Constants

Part of the Nodes and Scenes section of Coddy's Godot journey. Lesson 14 of 27.

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

The game does not start, because the script changes the constant SPEED. Fix it:

Keep SPEED a constant.
Make the robot move left at 300 pixels a second.

Try it yourself

extends Node2D

const SPEED = 200

func _ready():
	SPEED = 300

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

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

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: 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