Learn C# Scripting for Unity 15 Minutes - Part 4 - Foreach Loop, Array, Find Tags

Summary

In this Unity tutorial, Raja from Charger Games walks through C# scripting for object manipulation. The video focuses on finding game objects by tag, specifically cubes and spheres, and demonstrates how to destroy or interact with them. The tutorial covers using arrays to store multiple objects, utilizing loops for bulk operations, and implementing actions via input keys. Additionally, Raja explores how to selectively destroy objects by tags and customize interactions, such as color changes upon clicking. This video is a practical guide for game developers looking to enhance their Unity projects with C# scripting.

Takeaways

• 😀 Learn how to find and manipulate game objects in Unity using C# scripting.
• 📦 A 3D cube object is created, positioned, and a material is applied to it.
• 🔍 Game objects can be located by tag using the method `GameObject.FindWithTag` in Unity scripts.
• 🧠 Tags can be added to game objects for easier identification and interaction through scripts.
• 💥 Game objects, like the cube, can be destroyed using the `Destroy()` method after being found by tag.
• 💡 Multiple game objects can be stored in an array and managed together using `FindGameObjectsWithTag`.
• 🔄 The `foreach` loop is used to iterate through arrays of game objects, applying actions such as destruction.
• 🕹 Actions like destroying objects can be triggered by user input, such as pressing the spacebar or specific keys.
• 🎮 A new script can allow the destruction of objects when clicked, filtering based on their tag (e.g., only cubes or spheres).
• 🎨 Scripts can be applied to multiple game objects, enabling different actions depending on the object's tag, like changing color or destruction.

Q & A

What is the purpose of the video tutorial?

The purpose of the video tutorial is to teach how to script in C# for Unity, specifically focusing on how to search for and manipulate game objects within a Unity scene.

How does the script find a specific game object in the scene?

The script finds a specific game object by using `GameObject.FindWithTag` and specifying the tag of the game object, like 'cube' or 'sphere'. This allows the script to locate and interact with the object.

Why do you need to use tags for game objects in Unity?

Tags are used to categorize game objects, making it easier to identify and find multiple objects of the same type, such as all cubes or spheres. This approach is useful when you need to perform actions on a group of objects.

How can you assign a tag to a game object in Unity?

To assign a tag, select the game object, go to the 'Tag' drop-down menu, and either choose an existing tag or create a new one by clicking on 'Add Tag' and saving it.

What is the benefit of using arrays in the script when finding multiple game objects?

Arrays are useful for storing multiple game objects with the same tag. This allows the script to reference and manipulate all of them collectively, such as destroying all cubes or spheres in a scene.

How does the script destroy multiple game objects at once?

The script uses a `for each` loop to iterate through the array of game objects found with a specific tag, such as cubes, and destroys each one sequentially using the `Destroy()` function.

What is the purpose of using the `Input.GetKeyDown` method in the script?

The `Input.GetKeyDown` method is used to detect key presses. In the tutorial, pressing specific keys like 'space' or 'S' triggers the destruction of either cubes or spheres in the scene.

What is the difference between `GameObject.FindWithTag` and `GameObject.FindGameObjectsWithTag`?

`GameObject.FindWithTag` finds and returns a single game object with the specified tag, while `GameObject.FindGameObjectsWithTag` returns an array of all game objects with that tag, allowing for batch operations like destroying or modifying them.

How does the script differentiate between game objects when destroying them?

The script differentiates between game objects based on their tags. It checks the tag of the object and only destroys those with a specific tag, such as 'cube' or 'sphere'.

How can the `OnMouseDown` method be used in Unity scripting?

The `OnMouseDown` method is called when the user clicks on a game object. In the tutorial, it is used to destroy an object when clicked, but only if the object's tag matches a specified condition, such as 'cube' or 'sphere'.

Outlines

00:00

🎮 Introduction to C# Scripting in Unity

In this introductory section, Raja from Charger Games introduces the video, part of a tutorial series on learning C# scripting for Unity. The goal is to teach how to search and find objects in a scene. The example focuses on creating a cube, applying a material, and then manipulating it through C# scripts. Raja demonstrates how to find and interact with objects in a Unity scene, such as changing the cube's color or destroying it.

05:00

🧩 Using Tags to Identify and Find Game Objects

This section focuses on tagging game objects to easily locate them within the scene. Raja explains how to create and assign tags to objects like cubes and spheres. He demonstrates how to find game objects using the 'FindGameObjectsWithTag' method, store them in an array, and then manipulate or destroy them through a loop. The tutorial covers the usage of arrays to store multiple game objects and how to traverse through them using a foreach loop to apply actions like destruction.

10:02

🌀 Destroying Game Objects by Pressing Keys

In this section, Raja introduces how to destroy game objects by pressing specific keys. Using Unity’s Input system, the script detects key presses (like the spacebar for cubes and the 'S' key for spheres) and destroys the respective objects. The tutorial showcases how to set up different key bindings to control various actions on objects, allowing users to selectively interact with different groups of game objects based on their tags.

15:04

🖱️ Destroying Game Objects with Mouse Clicks

Raja explains how to destroy game objects through mouse clicks. A new script called 'Destroyer' is introduced, which uses the 'OnMouseDown' method to detect clicks on objects. Based on their tags (either 'cube' or 'sphere'), the script destroys the clicked object. This method demonstrates how to interact with objects individually while ensuring that only certain tagged objects are affected.

🎨 Performing Different Actions on Multiple Objects with a Single Script

The final section of the video showcases how to perform various actions on different objects using the same script. Raja describes how the 'Destroyer' script can be modified to apply different behaviors depending on the tag of the object. For example, clicking on cubes could turn them red, while clicking on spheres could turn them green. This flexibility allows for dynamic interactions with multiple objects using a unified code structure. The video concludes with a call to action for viewers to apply the learned concepts in their own projects.

Keywords

💡GameObject

A GameObject is the fundamental building block of objects in Unity. In the script, it refers to the objects like cubes and spheres that are placed in the scene and can be manipulated. The tutorial shows how to create and manipulate these objects in code.

💡Tag

Tags are labels that can be assigned to GameObjects in Unity to categorize them. The video demonstrates how to use tags like 'Cube' and 'Sphere' to identify and interact with specific objects programmatically, such as finding or destroying all objects with a certain tag.

💡FindGameObjectsWithTag

This method in Unity is used to find all GameObjects that have been assigned a specific tag. The tutorial explains how to use it to search for multiple objects, such as all cubes in a scene, and perform actions on them, like destruction.

💡Script

A script in Unity is a C# file that contains code to control the behavior of GameObjects. In the video, a script named 'GameManager' is created to manage the behavior of various objects, such as finding and destroying them using tags and arrays.

💡Destroy

The 'Destroy' function in Unity is used to remove a GameObject from the scene. In the video, the script demonstrates how to destroy specific GameObjects, like cubes or spheres, either when the game starts or when a certain key is pressed.

💡Array

An array is a collection of elements stored in a single variable. In the tutorial, arrays are used to store multiple GameObjects, such as all cubes or spheres in the scene, allowing the script to loop through and perform actions on each one.

💡ForEach Loop

A 'ForEach' loop is a control structure that iterates over elements in a collection, such as an array. The video demonstrates how to use a ForEach loop to cycle through all GameObjects in an array (e.g., cubes) and apply actions like destruction.

💡Material

Materials in Unity define the appearance of a GameObject’s surface, including color and texture. The tutorial shows how to apply a material to a GameObject, like a cube, to change its color to black, enhancing its visual appeal.

💡Input.GetKeyDown

This Unity method detects when a key is pressed. In the tutorial, the 'Input.GetKeyDown' function is used to trigger actions, such as destroying all cubes when the space key is pressed, or destroying all spheres when the 'S' key is pressed.

💡Empty GameObject

An empty GameObject is a GameObject without a physical form that can still hold components and scripts. In the video, an empty GameObject is created to act as the Game Manager, holding a script that controls various actions within the game.

Highlights

Introduction to Learn C# Scripting for Unity tutorial series.

Learning how to search and find different objects from a scene.

Creating a new 3D object named 'cube' and resetting its position.

Applying a black material to the cube for visual enhancement.

Creating a new C# script named 'game manager'.

Attaching the script to a new empty game object named 'game manager'.

Using 'GameObject.FindWithTag' to find objects with a specific tag.

Adding a 'cube' tag to the cube object for identification.

Writing code to find and destroy the cube object with the 'cube' tag.

Duplicating and positioning multiple cube objects in the scene.

Creating a new sphere object and applying a red material.

Adding a 'sphere' tag to the sphere object.

Duplicating and distributing sphere objects across the scene.

Finding and storing references to multiple objects with tags.

Using a for-each loop to destroy all objects with a specific tag.

Destroying all cubes when the space key is pressed.

Destroying all spheres when the 's' key is pressed.

Creating a 'destroyer' script to handle object destruction on mouse click.

Attaching the 'destroyer' script to all game objects for conditional destruction.

Changing the script to destroy spheres instead of cubes by altering the tag check.

Conclusion and call to action for feedback and suggestions for future tutorials.

Transcripts

hey there this is raja from charger

games and welcome back to another video

this is another part of my learn c sharp

scripting for unity tutorial

so in this video as well within short

time we're gonna learn a lot of new

things

so let's get started learning without

wasting any time

so first of all in this video we're

going to learn how we can search and

find

different objects from our scene all

right so as you can see here i can

simply go ahead and create a new 3d

object

and we're going to name it a cube i'm

gonna reset its position

and then i'm gonna position it right so

that i can see it in the scene

now i'm gonna go to my materials folder

and as you can see i already have

created this materials from previous

tutorials

so i can simply drag and drop this black

material right here on the cube

to make it look good and if you don't

have materials created you can simply go

ahead and right click

create and from here you can go to this

material to create a new material

all right so now that we have this cube

now

let's say we want to create a script and

from the script if we want to find the

cube

and do then do something with the cube

let's say we want to change its color or

we want to destroy it

so it doesn't matter wherever we have

this cube

we want to find it from our script and

then do something with it

so for that first of all we're gonna go

ahead and create a new script

i'm gonna create this new c sharp script

and i'm gonna name this one

game manager

okay now i'm gonna create a new

empty game object where we gonna attach

our script so

because this script is the is a generic

script that will

work on our whole game that's why we're

not gonna attach it to any particular

game object

okay so we're gonna create an empty game

object and we're gonna name this one

game manager or game controller anything

that you want

and then i'm gonna drag and drop the

game manager script onto our game

controller

then simply double click to open it in

visual studio

alright now let's try to find out how we

are going to

find the cube so we are going to use a

method called

object dot search or game object

find game objects with tag okay so

let's say in this seed we can add a tag

called cube to this cube and then from

our script we're gonna

find the game object which has this cube

tag

attached and that's how we're gonna find

this game object all right

so in order to add a tag you can select

your cube

and from the tag as you can see

currently it doesn't have any tag

so from here you can select this cube

tag now in my case this cube tag is

already created but in your case you can

go to add tag

and suppose you didn't have this text so

you can simply remove them

and then you can simply click on plus

and from here

select cube and click on save so now as

you can see i have a new tag

created now i can select my cube and

from the tag

select the cube tag okay so now it has

the cube tag attached so now let's go

back to our script

and your script here we gonna say

game object cube

equals game object dot find with

tag and for the tag we're gonna say q

and this is what you need to write

exactly same as it is written in your

tag otherwise this is not gonna work

so this code will find the game object

which has the cube tag attached and give

us access to it

inside this cube variable so now let's

say i want to destroy the cube

so for that i'm going to simply say

destroy

cube all right so this

is what it will do whenever our game

runs this will simply destroy the cube

and as you can see here we have the cube

tag attached now when i click on play

you will see immediately the key will

get destroyed

but you will probably say that we can

already do it

using destroy function we can simply add

a destroy function to this cube and

destroy directly

why do we need to add tag and all these

things so for that i want to say that

let's say there are a lot of objects in

the scene and all of them have different

tag attached

let's say there we have cubes spheres

and cylinders

from there you can simply select all the

cubes because they have the cube tag

attached

and from there you can simply go ahead

and delete them okay so let's see how we

can do that with a better example

so in this case first of all here we

have the cube so i'm going to simply

duplicate the cube

and position it here here somewhere like

this

duplicate it another time position it

here here

so now we have three cubes the same way

we're going to create a new sphere game

object

3d game object sphere all right

and now i'm going to simply go to my

materials tab

and add this red material to the sphere

okay just to make it look a little bit

pretty so here we have our sphere we can

position it

somewhere like this all right now we're

gonna go to our tags

click on add tag from here we're gonna

create a new tag

called sphere all right now we're gonna

select our sphere

and select the sphere tag from here so

now we have a sphere with the sphere tag

attached

and cube with the cube tag attached now

the same way i'm gonna simply duplicate

my sphere and move it around the scene

so that we can distribute it at

different places on the scene

and use them or destroy them or do

anything that you want with them

so now as you can see we have three

cubes and three spheres on the scene

now we need to find out a way so that we

can find out all the cubes

and do something with them and then to

find out a way so that we can find all

the spheres

and do something with them so till now

we have learned how we can only find

one single game object now we're gonna

learn how we can find

multiple different game objects with tag

and how we can store them

so let's say i want to find all the

cubes in the scene

and then store them somewhere for that

we need to create an array

okay so here we are creating a single

variable to store a single object

but if we want to store multiple game

objects then we need to create something

called an

array to create an array of game objects

here we can write game object then a

pair of square brackets

and then we're gonna say cubes okay so

this is an array which will store our

cubes

the same way we're gonna say game object

period of square brackets

and then spheres okay so this is an

array that will store

our spheres so now inside the start

function

instead of writing this what you're

gonna do is we're gonna write

cubes equals game object

dot find game objects with tag

so here we're not going to use the game

object we're going to say

find game objects with text so that we

can find

multiple game objects alright and here

we can write

cube so now what we'll do is

it will simply go to the scene and find

all the game objects

that have this cube tag attached it will

find them

and it will store them inside these

cubes array

and then we can destroy them using a for

each loop

okay so this destroy function will not

work here here we need to use something

called

a for each loop okay so what this will

do is

this will go to the array and search for

each of the game objects

and destroy all of them one by one by

one

so let's see how we can use the forage

loop to use the forage loop we need to

write

for each need to write

game object g in

cubes okay now you can

rename this d to anything you can name

it c you can name it a you can name it

uh cube or anything it doesn't really

matter

so what this will do is this will search

for

all the elements in the cube okay or

this will traverse through all the

elements of this cubes array

let's say we have three cubes on the

scene so this array contains

reference to three of those cubes now

this

forage loop will refer or traverse to

three of those cubes and every time it

finds the

first second and third cube it will

store its reference inside this g

variable

and then we can do anything that we want

using the g variable

so in this case we simply want to say

destroy

g dot game object okay so let's say

it finds the first element in the cube's

array

then it will store the first element

inside g and then it will destroy the g

that is the first element then it will

traverse the second element

store it inside g then destroy secondary

limit

and this way it will keep on going so

here what we are doing is

we are traversing through all the

elements

that are stored inside this cubes array

and destroying them

one by one by one all right now instead

of doing this in the start let's see how

we can do it

when we press a key so inside the update

we're gonna say

if input dot get

key down here we're going to say key

code

dot space now you have used these things

a lot of times in the previous tutorial

so

you should not face any problems here so

whenever we press the space key

let's cut this code

and paste it here so whenever we press

the space button on our keyboard

we want to travel through all the cubes

that we have in the scene

and destroy all of them one by one by

one

so this is it let's save this go back to

unity

and see how our code is working

so as you can see our code is uh

attached to the manager

and now if i click on play you will see

here we have all the different things

and only the cubes will get destroyed

when i press the space key

so three two one space and as you can

see all the cubes got destroyed

because all the cubes had this cube

tag attached okay now let's see how we

can do the same thing for the spheres

so let's go to our game manager

and now we're going to say

here the same way first of all we need

to store the reference of the spheres

so here we're gonna say spheres

equals game object not game controller

game object dot find

game objects with tag and make sure to

write

objects and not object i'm saying it

again and again

and here we're going to say spheres

sphere actually so now we have access to

all the spheres inside this sphere array

now the same way we need to use a

foreign loop

and do the same thing so inside the

update we're going to say if

input dot get key down

input the get key down key code dot

let's say i'm gonna say s

so whenever we press the s key on our

keyboard we're going to do the same

thing so let's copy the forage loop

paste it here and instead of writing

cubes

here we're going to simply write spheres

all right so now what we'll do is it

will

get access to each and every sphere that

is

stored inside this spheres array and

then it will destroy all of them

one by one by one whenever we press the

s

key on our keyboard so let's see how

that works let's go back to unity

and now whenever we're gonna press the s

key on our keyboard

the spheres will get destroyed and

whenever we press the

space button the cubes will get

destroyed so maximize and play

click on play and now i'm going to press

the

s key and as you can see all the spheres

got destroyed

i'm going to press the space key and all

the cubes got destroyed

so this way you can use these features

to

find and search multiple game objects on

the scene

and destroy any of them that you want

anytime

now let's see how we can do some more

cool things using this tag functionality

so let's say we have already learned how

we can simply click on any object and

destroy it

now let's say i want to destroy certain

object

and i want to simply save other objects

and

don't destroy them so let's say i click

on the cubes

and i want to i want to destroy the

cubes but i click on the spheres

but i don't want to destroy the spheres

and we want to actually

write the same code and do the do both

of things together

all right so to do that here i'm gonna

create a new script

and i'm gonna name this one destroyer

and inside the destroyer script what

you're gonna do is we're gonna first of

all check

void on mouse down

so this function will be called whenever

our mouse will be clicked

over this object then we're gonna check

if

this dot gameobject.tag

equals cube

only then we gonna say destroy

gameobject

otherwise we're not gonna destroy the

game object all right so let's see how

that works

so now we're gonna select all of our

game objects and we're gonna add the

destroyer

script to all of them so let's say here

i'm gonna select my cubes

and my spheres all of them together by

pressing the shift key so select the

first one

press the shift key select the last one

and then drag and drop the destroyer

script here

and as you can see all of them will have

the destroyer script attached

all right and we're gonna attach it to

our first cube as well so it has a

description script to it

now let me click on play

and you will see whenever i click on the

spheres nothing happens but whenever i

click on the

cubes they get destroyed all right so

the same script is attached to all of

the game objects

but only the cubes are getting destroyed

the spheres are not

now we can also go ahead and change the

script anytime

so let's say i simply change this to

sphere

and as soon as i do that and go back to

unity

now you will see it will completely be

changed now whenever i go ahead and

click on it

you will see now i can click on the

cubes but they will not get destroyed

but if i click on the spheres they will

get destroyed

okay so just by writing this simple code

and this simple

tag test we can do a lot more things so

we can attach the same script to

multiple game objects

and let's say we click on we run the

game and whenever we click on the cubes

we want to turn them red and whenever we

click on the spheres

we return them green so we can write one

single script

attach them to all the game objects and

perform different actions on them

depending on the different things that

you do

so this is it this is all i wanted to

show you in this video i hope you really

enjoyed and learned a lot of new things

so go ahead and use these skills in your

new projects

so let me know in the comments if you

like this video and what do you want to

see in the next tutorial

and if you if this video helped you

please hit the like button so that i can

make more videos like this

so thank you so much for watching this

is raja from charger games

and i'm gonna see you in this next video

soon