What we’ve done in the editor for now is just put together the resources that we want to use in the game and organize them. But how do we make things happen ? How does the player interact with the world ? How do I set score ? All this will need code to happen.
For this purpose Godot uses its own scripting language GDscript which takes a lot from Python. It is made to be simple to learn, readable, and is delivered with a lot of predefined classes that fasten the game development. It doen’t need compilation and is dynamically typed. Of course, this is not made to speed up rendering but make it so easy to use that it’s worth the choice. Most of the optimisation is done in the engine and GDscript gives a lot of performance improvement over Python in the game context. But for those who need more C++ can be used.To read this chapter, it is better to have some basic knowledge of some programming concepts. You may find courses about python in our manual.
The most part of the code structure is given by Godot itself. Scripts will be attached to nodes and extends the class this node is based on. We will just need to define what is specific to the game : mostly variables and functions.
Variables are explicitely declared :
Use the keyword var to declare the variable. For GDscript is dynamically typed, no need to define if it is an integer or a string or whatever. This will be done when a value is given.
of course you can affect a default value at the beginning
var speed = 100
or at any time in any function
speed = 100
GDscript comes up with standard types (like int, float, string, bool, null, array, dictionary…) but also has some specific related to common maths calculation in a game (such as Rect2, Vector2, Vector3…) and some engine (as Color, Image, Object, InputEvent…). It is not really the purpose of this manual to describe then intensively. Get help in Godot inline reference as described below.Note there can also been constant define with const keyword instead of var.
We sometimes export the variable in the script. This way, the variable will be displayed in the inspector. This is a good practice coders should apply for important variables. It helps non-coders and game designer to test several value and improve the game play without risking to break all the code. We’ll demo that soon.
export var speed = 100
To declare a function you simply need to use the func keyword like this :
If you had a look at python, see there is no def, no self which is considered as implied. At the opposite, conditions, while or for loop are really similar.
func function_name() :
function magic here
Predefined Godot function begin with an underscore. For example the default _ready() displayed in any new script as we’ll soon see.
# Initialization here
Of course, as our script extends the base class, each function is a method of a class and might be called as a member.
var player = get_node("player")
Enough words and let’s see the process of adding a script.
extends Node2Dand a
_ready()function that we’ll customize. The Inspector displays resource property like path and name.
_readyfunction, delete pass and add instead
print("test"). Save the script and play the game or the scene. This will this play the game but also display the Debuggerand the output. If everything is good, «test» should appear in the Output window.
_readyfunction. So we get this :
print("in score function") #jus add this to see if everything works
# Initialization here
print("no label node")
If a node named Label is found, the first message is displayed. Which is good. On the other way, change the label name to match your need. Finally, we need to know how to set the text in the game. If you have no idea of what to use just go to the Helptab, in the Search in Classes column, look for Label. Click on it to display all the method available for that class. On top we have a Public Methods, especially on called set_text(), which looks appropriate. Click on it to display details which say simply «set the label text». It could be worse. Let’s use it and play :
print("no label node")
var obstacles = var spawn_ofs = 1000
export var spawn_distance = 500
var obs = preload("res://pipes_random.scn").instance()
spawn_ofs += spawn_distance add_child(obs)
printt("obstacle spawn at ", obs.get_pos())
First we declare our variable : obstacles and spawn_distance. See that we added export keyword before the second variable. This will make it displayed in the Inspector to let the game or level designer play with the value and equilibrate the game, without having to open the script file.
Then we added a function which preloads the scene containing the buildings and instantiate them. We set the position of the new instance in a Vector2 using a variable for x value. We then update values for next instance and add the instance as child of the select node.
Our function will be used as the bat will move. So that is now what we have to do.
// show autoload
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