Godot 4 Crash Course #4 - Adding Meteors

Summary

This video tutorial guides viewers through creating dynamic meteor scenes in a game using Godot Engine. It covers scripting to spawn meteors at random intervals, loading and instantiating scenes, and attaching them to the scene tree. The script is enhanced to add randomness in meteor graphics, speed, direction, and rotation. The tutorial also addresses collision layers to prevent meteors from interacting with walls, ensuring a more realistic gameplay experience.

Takeaways

• 📜 The script is a tutorial on creating and managing dynamic game objects, specifically meteors, in a game environment using Godot Engine.
• 💻 The issue addressed is the manual attachment of meteors to a level scene, and the goal is to automate this process by creating a meteor every time a timer triggers.
• 🔄 A 'meteor timer' is introduced to handle the spawning of new meteors, which requires disconnecting and reconnecting signals for proper naming and functionality.
• 🌌 The process of creating a meteor involves loading a scene, instantiating it, and then attaching it to the scene tree, which is essential for dynamic object creation in Godot.
• 🔄 The script covers the steps to instantiate a meteor, including loading the meteor scene as a PackedScene, creating an instance of it, and adding it as a child to the level scene.
• 🎲 The tutorial introduces randomness to the meteor's behavior, including random positions, speeds, directions, and graphics, to enhance gameplay variety.
• 📊 A random number generator is utilized to determine the starting position, speed, and direction of the meteors, contributing to their unpredictable nature in the game.
• 🔧 The script includes a 'ready' function to set up initial conditions for the meteor, such as position, and a 'process' function to update the meteor's movement continuously.
• 🖼️ Randomization of the meteor's graphic is discussed, where a random texture is selected from a set of available images to give each meteor a unique appearance.
• 🛡️ Collision layers and masks are explained to manage which objects can interact with each other, ensuring that meteors only collide with the player and not with the game walls.
• 🛠️ The tutorial concludes with setting up collision layers for different game objects, such as players, meteors, lasers, and walls, to fine-tune the game's physics interactions.

Q & A

What is the main issue the speaker is trying to solve in the script?

The main issue is that the speaker wants to create a meteor every time a timer times out, but currently, they can only manually attach a meteor to the level scene.

What is the purpose of creating a 'meteor timer' in the script?

The 'meteor timer' is used to trigger the spawning of a new meteor every time it times out, adding randomness to the game scene.

Why does the speaker suggest disconnecting and reconnecting signals in the script?

The speaker suggests this to ensure a proper name for the method they want to call and to get rid of the previous signal function, making the code more organized and clear.

What is the significance of using a 'Packed Scene' in the script?

A 'Packed Scene' is used to store the meteor scene as a blueprint, which can then be instantiated multiple times to create actual game objects.

How does the speaker plan to manage multiple meteors in the game scene?

The speaker plans to manage multiple meteors by creating a new node called 'all meteors' and adding each new meteor as a child to this node, keeping the scene organized.

What is the purpose of the 'ready' function in the context of the meteor script?

The 'ready' function is used to run code when the meteor node is added to the scene tree, such as setting a random start position for the meteor.

Why is it necessary to create a random number generator (RNG) for the meteor's position?

The RNG is necessary to set a random start position for the meteor, ensuring that each meteor appears at a different location on the screen.

How does the speaker address the issue of meteors always spawning at the top left of the screen?

The speaker addresses this by using a random number generator to set a random X and Y position for the meteors when they are spawned.

What is the 'process' function used for in the meteor script?

The 'process' function is used to update the meteor's position continuously, giving it movement by applying a direction vector multiplied by speed and delta time.

How does the speaker intend to add more randomness to the meteor behavior?

The speaker intends to add randomness by randomizing the meteor's graphic, speed, direction, and rotation speed, making each meteor's behavior unique.

What is the final step the speaker takes to prevent meteors from colliding with the walls?

The final step is to adjust the collision layers and masks in the project settings, ensuring that meteors are on a different layer and can only collide with the player, not the walls.

Outlines

00:00

🌌 Creating Meteor Scenes with Timers

The script discusses the process of creating meteor scenes in a game via scripting and adding randomness to their appearance. The current issue is that a meteor can only be manually attached to the level scene, which is not ideal for automatic generation upon a timer's trigger. The solution involves creating a 'meteor timer' function that, when called, spawns a new meteor. The steps include loading the meteor scene into a variable, instantiating it to create a new meteor object, and then attaching this object to the level scene. The process is demonstrated in the Godot engine, where the game is still running while the editor is being used to make changes.

05:02

🚀 Randomizing Meteor Spawn and Movement

This paragraph delves into randomizing the meteor spawn positions and their movement within the game. It starts by explaining how to create a random number generator to determine the initial position of the meteor on the X and Y axes. The script then discusses adding a 'ready' function to the meteor to set a random starting position when it's added to the scene tree. The movement of the meteors is randomized by setting a 'process' function that updates the meteor's position with a direction vector and speed, multiplied by the frame's delta time for smooth motion. The paragraph also covers the mistake of using a local variable instead of a global one for speed, direction, and rotation, emphasizing the importance of variable scope in scripting.

10:03

🎲 Adding Randomization to Meteor Properties

The focus of this paragraph is on further randomizing the meteor's properties, including its graphic, speed, direction, and rotation. It explains how to set global variables for speed, rotation speed, and direction at the top of the script for use in both the 'ready' and 'process' functions. The script uses the random number generator to assign randomized values to these properties. For the meteor's graphic, it suggests picking one of the five available images at random. The rotation speed is also randomized, and the paragraph provides a clear explanation of the difference between 'rotation' and 'rotation degrees', opting for the latter for this implementation.

15:05

🖼️ Implementing Random Meteor Graphics

This paragraph covers the implementation of random graphics for the meteors by loading different textures based on a randomized path. It explains how to create a random path by combining strings and integers, and then loading the corresponding texture for the meteor's sprite. The process involves using the 'load' function to get the texture from the randomized path and then assigning it to the meteor's sprite. The paragraph also addresses the issue of meteors colliding with the game's walls, which is undesirable, and suggests a solution by adjusting the collision layers and masks to prevent these collisions.

20:07

🛡️ Setting Up Collision Layers for Game Objects

The final paragraph discusses setting up collision layers for different game objects to manage interactions effectively. It explains the importance of assigning each game object to a specific layer and configuring the layer's visibility and collision properties. The script outlines the process of renaming the layers in the project settings for better organization and then updating the layer and mask settings for the player, meteors, lasers, and level static bodies. This setup ensures that the meteors only collide with the player and not with the walls, and that lasers can collide with meteors but not with the player. The paragraph concludes with the intention to work on lasers in the subsequent part of the tutorial.

Keywords

💡Scene Creation

Scene creation refers to the process of generating a specific environment or setting within a game or interactive application. In the context of the video, scene creation is central to the theme as the script discusses creating a 'meteor scene' programmatically. The video provides a step-by-step guide on how to script the creation of a meteor scene in Godot, which is essential for adding dynamic elements like meteors to a game level.

💡Randomness

Randomness is the concept of unpredictability or lack of pattern in events. In the video, randomness is a key concept used to make the game more dynamic and less predictable by introducing variability in the appearance and behavior of meteors. The script mentions adding randomness to the meteor's speed, direction, and graphic, which contributes to the video's theme of creating engaging and varied gameplay experiences.

💡Meteor Timer

A 'meteor timer' is a game mechanic used to trigger events, such as the spawning of a meteor, after a set period of time. The script explains how to set up a timer in Godot that, upon timing out, will execute a function to create a new meteor. This concept is integral to the video's theme of automating scene elements and adding an element of surprise to the game.

💡Packed Scene

A 'packed scene' in Godot is a reference to a pre-configured scene that can be saved and reused in different parts of a game. The video script describes using a packed scene to load the meteor scene, which is then instantiated multiple times with variations to add meteors to the game level. This concept is crucial for understanding how to efficiently manage and reuse game assets.

💡Instantiate

To 'instantiate' in the context of game development means to create a new instance of a pre-defined object or scene. The script details the process of instantiating the meteor scene to spawn new meteors in the game world. This action is a fundamental part of the video's theme, demonstrating how to dynamically generate game objects in response to in-game events.

💡Scene Tree

The 'scene tree' in Godot represents the hierarchy of nodes that make up a game's scene. The video script discusses attaching newly created meteor instances to the scene tree, which is essential for integrating them into the game world. Understanding the scene tree is key to the video's narrative of constructing and managing game scenes programmatically.

💡Collision

In game development, 'collision' refers to the interaction between two objects when they come into contact with each other. The script mentions handling collisions between the meteor and the game's walls, which is an important aspect of the video's theme of creating interactive and responsive game environments. The video also discusses modifying collision layers to prevent meteors from interacting with walls, which is crucial for fine-tuning gameplay.

💡Signal

A 'signal' in Godot is an event that a node can emit to communicate with other nodes. The video script explains how to use signals, specifically the 'timeout' signal from a timer, to trigger the creation of a meteor. This concept is central to the video's theme of creating interactive and event-driven game mechanics.

💡Random Number Generator

A 'random number generator' is a tool used to produce a sequence of numbers that cannot be reasonably predicted better than by a random chance. The script uses a random number generator to determine the starting position, speed, and direction of meteors, which is essential for adding unpredictability to the game's meteor behavior, aligning with the video's theme of creating randomized game elements.

💡Layer and Mask

In Godot, 'layers' and 'masks' are used to define which objects can interact with each other in a game. The video script discusses setting up collision layers and masks to control which objects can collide with meteors, such as ensuring that meteors do not collide with walls. This concept is vital for the video's theme of fine-tuning game interactions and collision mechanics.

💡Sprite2D

A 'Sprite2D' in Godot is a node used to display a 2D image or animation. The script mentions updating the texture of a Sprite2D to randomize the meteor graphics, which is a key part of the video's theme of adding visual variety to the game. This concept is important for understanding how to dynamically change the appearance of game objects.

Highlights

Creating scenes via script and adding randomness to them for dynamic gameplay.

Issue of manually attaching meteors to the level scene and the need for an automated solution.

Introduction of the meteor timer to automate meteor creation.

Steps to load a scene using a packed scene and the load function.

Creating an instance of the meteor scene using the instantiate method.

Attaching the meteor node to the scene tree using add child.

Organizing meteors under a parent node for better scene management.

Adding randomness to meteor spawn positions using a random number generator.

Calculating the display width dynamically to accommodate different window sizes.

Updating meteor positions with random X and Y coordinates for varied spawn locations.

Adding movement to meteors with a process function and delta time for smooth motion.

Randomizing meteor speed, rotation, and direction for unpredictable behavior.

Using global variables for speed, rotation speed, and direction to maintain consistency.

Implementing collision layers and masks to control interactions between objects.

Assigning specific layers and masks to differentiate between player, meteors, walls, and lasers.

Ensuring meteors collide with the player but not with walls for realistic gameplay.

Randomizing meteor graphics by selecting a random texture from a set of images.

Transcripts

welcome back in this part we are going

to create scenes via script and add

Randomness to them basically the issue

we have at the

moment we want to create a meteor every

time the timer times out or triggers but

this we cannot do while we do have a

meteor scene we can only manually attach

it to the level scene and I think doing

all of this in practice is much better

here we are back in G do and at the

moment we do have a meteor scene and

this one works perfectly fine but inside

of the level we can only ever attach a

meteor to it and this happens manually

now we could create multiple meteors by

simply duplicating this node and then we

would have a couple but that doesn't

really solve the issue because we want

to create a new meteor every time the

timer times out this time I to be a bit

more specific and to be clear about this

one let's name it to metor

timer and with that on the right when we

are calling the signal I want to

disconnect all of the signals and click

on okay and then reconnect them because

with that we get a proper name for the

method we want to call you don't have to

do that but I think it makes a bit more

sense also we want to get rid of the

previous signal

function cool so with that we have a

meteor timer timeout function and in

there we want to spawn a whole new

meteor and for that we will need a

couple of steps but now though let me

simply keep pass in here step number

one we have to load the scene and this

we can store in a separate variable

let's call it meteor uncore scene and

for the data type we need a packed scene

to assign this one a value we will need

a function that is called load and if if

we are calling that Gau gives us a whole

bunch of things we could be loading now

in our case we want to have the meteor

TSN make sure to get the right ending

here we do not want to import the script

we want to import the entire scene if I

now press enter good do should be happy

and let me expand the code window to see

everything a bit better next up then we

want to create an instance of this

meteor scene every time this method

triggers and for that I want to create

another variable let's simply call this

one the

meteor and now to create an instance of

the scene we want to have the meteor

scene the one we just created and then

called the instantiate method on it the

way you want to think about all of this

the meteor scene we importing in the

beginning is the blueprint while the

meteor we are creating via instantiate

is going to be the actual building or

car we are creating from that blueprint

so that would be part number two create

and instance that's one more thing that

we need because at the moment we do have

a note that we could work with inside of

the level scene but that isn't enough we

also have to attach the Noe to the level

or rather let's call it the scene

tree and this you can do via ADD child

and then add the meteor and that is all

we need if I now run the code

code you can see in the top left we have

a meteor that is

entering also what you can do if I go

back to gdo while the game is still

running if I bring it up again you can

see we have the game still running

perfectly fine and I can move around

what you can do while the game is

running you can look back at the editor

and then in the scene Tre you can see

remote and local local is what you have

in the editor but if you click on remote

you can see what is actually going on in

real time in the game and there you can

see we adding a whole bunch of area 2D

notes all of those are meteors that are

created via the

timer which is a really good sign so we

know this is working cool although you

can see all of this is a bit badly

organized and to keep all of this a bit

more manageable I want to create another

note

2D which I am going to call all

meteors then I can also get rid of the

meteor we have created

earlier and then when I am adding the

child I do not want to add the child to

the parent note so the note with the

script at the moment I want to add it to

the meteors and for that I can simply

drag and drop the meteors note in there

and then add a DOT and a child if I now

run all of this again we cannot see the

meteor anymore because I deleted this

one but we can still see the meteos in

the top and if I go to remote and expand

level we can see meteors and this one

keeps on growing so that is pretty good

perfect if you want to create an

instance of a scene via code you need

these three steps you have to load a

scene you have to create an instance and

finally you have to attach the note to

the scene tree or to some other note

inside of the scene tree although this

at the moment still isn't amazing

because all of the meteors are always in

the top left to fix that I want to work

inside of the meteor script at the

moment we only have a basic function for

when a body enters this one we can just

ignore it's not too important instead I

want to run some code when we are adding

this node to the scene tree which I can

do via the ready function and just to

make sure that this is working let's

print meteor was added to the scene if I

now run all of this again we can see

that we have meteor was added to the

scene

along with a collision with the wall and

by the way in case you are wondering the

Collision we're getting right now is a

collision between the meteor and the

walls so this is what triggers the

signal we are going to fix that in just

a second actually but for now don't

worry too much about

it so back inside of the meteor I want

to get a random position for that meteor

when it is being spawned and for that we

have to create a random number generator

and stored inside of a variable let's

call it RNG for random number generator

and the data type for this one is going

to be a random number

generator so I am going to create this

one via the semicolon equal sign and

then the method to actually create a

random number generator you want to add

new with that we have a random number

generator and this we want to use to set

this start position for that first of

all we will need the width of the

display so bar width now you could

simply add 1280 in here because that is

the number we have said earlier so if

you go to project project settings and

window this is the number we are working

with right now but this isn't

particularly elegant because the player

might change the window size we might go

to full screen or you might have chosen

a different number instead we want to

get this number dynamically and to get

that you need get viewport then you want

to get visible

rectangle and on that we want to have

the size also let me expand the code

windows so we can see what's going on

size is an attribute so this one doesn't

need to be called now with all of that

let me print what we're getting via

whift it's not exactly what we need if I

now run this again we can see we get

1280 by 720 now on this I I want to use

indexing because I only really care

about the first value which would be the

width if I now run this

again we are getting 1280 or the width

of the window from that we can create

another variable let's call this one

random X and to create a random number

you want to first of all get the random

number generator and then call the

method from it the one that I'm going to

use for this one is Rand I range or

short for random integer range which is

asking has to go from a number to a

number and then the return value is

going to be an integer I want to go from

zero to my whift and then we can print

the outcome So Random X run the code

again and we should be getting a number

between 0 and 1280 and that looks about

right we now have a random X position

but on top of that I also want to have a

random I position although this one is

quite a bit easier once again we can

reuse the the random number generator

and I want to get Rand I

range I want to go

from1 100 to let's say 50 actually

should

be50 once we have those two numbers we

can update the position of the meteor

right away which we can set via a vector

2 that has a random X and a random y

value if I now run all of this again we

well cannot see anything okay my mistake

basically what is happening is we are

creating meteors on top of the window

and since those aren't moving we cannot

see anything but that we can fix quite

easily all we have to do is add a

funcore process with Delta we can simply

update the position once again an area

todde unfortunately doesn't have a move

and slide method so I want to get a

vector 2 with a Direction but now this

can simply be zero and 1.0

this then I want to multiply with some

kind of speed so the meteor isn't too

slow let's say for now 400 and finally

all of this needs to be multiplied with

Delta and now if we run this

again we should be getting meteors

coming from the top and going down and

this is looking really good that is

going to cover the basics of a meteor

but we can add a bit more Randomness

which is going to be your

exercise I want you guys to randomize

the meteor graphic speed and direction

what I mean by meteor graphic is that

inside of the meteor Graphics folder we

have five images in total and when we

are creating the meteor pick one of

those at random after that also rotate

the meteor by a random speed should be

quite a bit to work on so pause the

video now and see how far you

get all right back inside of

Gau I first off I want to add a few more

comments because after the start

position I also want to have speed

rotation and the direction could be in

here as well you do have to be careful

with these numbers because the position

we could set inside of the ready

function but for Speed rotation and

direction we have to reuse all of those

variables inside of the process function

because and there for example the speed

would be necessary as a consequence we

couldn't create a VAR speed for example

inside of the ready function because it

wouldn't be available inside of the

process function so instead what we are

going to do is create a VAR speed all

the way at the top as a global variable

which has to be an integer and by

default we actually don't have to set

anything if you keep it like this it's

totally fine and also while we are here

I want to set VAR rotation speed which

is an integer and finally I want to have

VAR bar let's call it a Direction undor

X and this one should be a floating

point value because for direction. X we

want to have this value for which we do

want to have floating Point values next

up we have to create actual random

values for speech I want to have the

random number generator and then give it

a Rand I range the numbers here are

fairly subjective I find that 200 to 500

are reasonably okay and after we have

that we can replace the 400 with this

speed so now if we are running all of

this nothing seems to be

happening and I can tell you why I made

the exact mistake I told you not to do

this should not be a VAR because that

way we are creating a local variable

inside of this function we instead want

to

overwrite this speed Global variable

inside of the function that way we can

reuse it inside of process so now if I

run this

again there we go this is working much

better and now the meteors move at a

randomized speed bit hard to see but

this is much better cool this works well

and just to be precise here when you're

creating VAR and a keyword then you are

creating a local variable inside of a

function however if you don't leave the

keyword and you create a variable before

that in the global scope then you're

overwriting that variable that way you

can overwrite the variable in one

function and use it in another function

silly mistake sorry about that so next

up we can work on direction. X and we

only care about the X Direction because

Y is always going to be one now the

value for this one is going to be RNG

and importantly we want to have Rand F

range because we want to have floating

Point values that go from -1 all the way

to one these are the values we then want

to use for the vector 2 for the

direction so this one can be Direction

dox and now if I run this again we

should be having meteors that move a bit

more randomly and that feels

significantly

better perfect finally we want to have a

rotation speed and for that we have to

update our rotation speed first of all

so this happens in the same way rotation

speed is going to be rng. Rand

I range for the values I went with 40 to

100 once again entirely subjective just

play around with the numbers and to

actually Implement these values I want

to get rotation or rotation

degrees the difference between the two

is that Rotation by itself Works in

radians while rotation degree Works in

well degrees I tend to prefer degrees

but that's entirely subjective

all we have to do to this one is add the

rotation speed and don't forget to

multiply it with Delta

time and now I can run all of this again

and we are getting random movement well

rotation so that's looking pretty good

very happy and now finally to make all

of this look a bit better when we are

going to the level and the meteor timer

we can reduce the weight time quite a

bit I find 0 .25 is much better and with

that we are getting considerably more

meteors you could probably even lower

the number a bit more let's go with

0.2 but once again this is a number you

can just play around

with and well this is not looking too

bad the last thing we have to work on is

that when when we have a meteor we also

want to have a random graphic if you

look at the graphics folder there on the

meteors we have six different meteors in

total and I want to pick a random

graphic from that this probably was the

most difficult part of the exercise so I

hope it worked out I want to create a

random

texture and for that first of all we

will need a randomized path which has to

be a string and just to get one path

from these folders you can simply drag

in one of the files and then we get let

me expand all of this then we get the

path and ultimately all I want to do is

to randomize this one to be between 1

and six which is actually fairly easy so

first of all I'm going to split these

two strings so we can add something in

between and to combine different strings

all you have to do is to add a value in

between via plus the value that I want

to add is is going to be random number

generator with Rand I range the value

here should be between 1 and six finally

gdau is a bit picky about combining

different data types right now we are

trying to combine a string with an

integer which gdau doesn't like but we

can account for that by converting the

string to an integer via the string

function and with that we are going to

get a random path all we have to do now

is to load the graphic for this

particular path for that if I go back to

the normal view I want to first of all

get this Sprite 2D which I can do by a

dollar sign and Sprite 2D and on there I

want to update the texture so how can I

get this attribute and well the easiest

way is to hover over the attribute in

the inspector and there you can see we

have the texture and the value we have

to assign is a texture to the object but

step by step first of all we want to

have a texture and assign a new value

now to create a texture to object all we

need is load and then load the path we

have just created this is going to

return the object we need and with that

we can actually get rid of the value we

have set by default because we're going

to add something random anyway and now

if I run all of this we should be seeing

different kinds of meteors and that is

looking really good

Perfect all right finally there's one

more thing that I do want to do if I go

back to the level scene at the moment We

have basically walls around the entire

level and the player can collide with

them but also the meteors are colliding

with them which is not ideal and because

of that if I run the code again we get

all of these messages that a static body

2D has entered the area 2D of the meteor

which I really don't want so ideally I

want the meteor to ignore these wordss

entirely and that you can do fairly

easily so if I go to the meteor there we

have collision and in there we have a

layer and we have a mask the way this

system works is that every physics

object is on a layer and it can see

whatever is on a mask for example right

now the meteor is on layer one and it

can see all of the other physics objects

which are also on this layer at the

moment every single physics object is on

layer one and can only see mask one so

everything can see everything else but

now watch what happens if I set this to

a two then if I run the code again the

meteors are not going to collide with

anything simply because none of the

physics object is on the second

layer however if I set the player on

this layer so under Collision I want the

player to be on Layer Two if I now run

this again the meteors can can see the

player again so we get the function back

and this is much

better although this system can get very

complex so simply working with numbers

isn't great instead what you usually do

is you go to project project settings

and in there we have under layer names

2D physics and there can give each layer

a name in my case for the names usually

layer one is player for me Layer Two in

this case I want to be meteor layer

three is going to be walls and layer

four is going to be

laser and with that we have to make

quite a few updates so let's go through

it step by step first of all we have the

player itself and the player should only

be on layer one which is for the player

the player then should not be able to

see itself however it should be able to

see the meteors and the wals but it

cannot see the lasers those we haven't

worked on yet but that's going to come

later next up the meteor metors the

meteors should not be on the player

layer instead they should be on layer

number two and they can only see the

player and they should also be able to

see the lasers after that we have the

lasers and the lasers under the

Collision should be on layer three four

actually and they should be able to see

not the player but they should be able

to see the

meteors finally we have the level

because in the level

we have the four static bodies those

also need to be updated because at the

moment they can only see layout one

which is the player that's a good start

but they shouldn't be the player

themselves they should instead be on

layer three and this by the way you have

to do with all of them so this is a

system you want to set up early

otherwise it can get a bit

tedious so with that we should have all

of the collisions set up properly

which means now the player can still

collide with the meteors that is looking

good but the meteors cannot collide with

the walls and later on once we get

lasers we can also make sure that the

lasers collide with the meteors for now

I'm pretty confident that this is going

to work next up we'll work on the lasers