Learn C# Scripting For Unity in 15 Minutes - Part 2

Summary

In this video, Raja from Charger Games continues his 'C# in Unity' series, focusing on essential C# scripting techniques for game development. He demonstrates how to spawn game objects like a ball, manage spawn points, and trigger actions using keyboard and mouse inputs. Additionally, he explains how to use collision detection to change object colors and automate repeated object spawning with randomization. By the end, viewers will understand how to create dynamic interactions and spawn objects at random positions. The video is part of a series with more tutorials available via links in the description.

Takeaways

• 🎮 Learn C# scripting for Unity game development in a short span.
• 🌐 Part 2 of a series, check out the first part and other courses for more learning.
• 🔵 Understand how to spawn game objects in Unity using C# scripting.
• 🏐 Create a 3D object (ball), add color and a Rigidbody component for physics.
• 📍 Set up a spawn point for the game object using an empty GameObject.
• 💾 Create a GameManager object and a GameController script to handle spawning.
• 🔧 Write a function to instantiate the ball object at the spawn point's position and rotation.
• 🔄 Save the ball as a prefab for easy reuse in Unity.
• ⌨️ Implement functionality to spawn the ball when the space key is pressed.
• 🖱️ Learn to spawn the ball at the position of a mouse click on the screen.
• 🎯 Change the color of the ball upon collision with another object using a script.

Q & A

What is the main focus of this video?

The video focuses on teaching C# scripting in Unity, specifically covering essential functionalities needed for game development within 15 minutes.

What is the first task demonstrated in the video?

The first task is creating and spawning a game object (a sphere) in Unity, which is later used as a ball in the game.

How does the video explain adding color to the game object?

The video explains how to create a material and apply it to the game object by dragging and dropping the material onto the object to change its color.

What is the purpose of adding a 'rigid body' component to the ball?

Adding a 'rigid body' component enables the ball to behave according to physics, allowing it to fall when dropped into the game world.

How does the instructor demonstrate the spawning of the ball at a specific location?

The instructor creates a spawn point by making an empty game object, assigns it a position, and then writes a script that spawns the ball at that location when the game starts.

How can the ball be spawned when pressing a specific key?

The instructor modifies the script to spawn the ball when the space bar is pressed using `Input.GetKeyDown(KeyCode.Space)` inside the update function.

How does the video explain spawning the ball at the mouse click position?

The video explains converting the mouse position from screen coordinates to world coordinates and using that position to spawn the ball at the clicked location using `Camera.main.ScreenToWorldPoint(mousePos)`.

What method is used to detect collision and change the ball's color?

The method `OnCollisionEnter` is used to detect when the ball collides with another object, and the ball's color is changed using the `Renderer` component to make it red upon collision.

How is the ball set to spawn repeatedly in the game?

The `InvokeRepeating` method is used in the `Start` function to repeatedly call the `SpawnBall` function at a regular interval, allowing balls to spawn continuously.

How does the instructor randomize the spawn position of the ball?

The instructor creates random x and z values within a specified range and uses these to spawn the ball at random positions across the plane in the game.

Outlines

00:00

🎮 Unity C# Scripting Basics

Raja from Charger.Games introduces viewers to C# scripting in Unity, continuing from part 1 of his series. He covers spawning game objects, specifically a ball, and modifying its properties such as color and physics behavior with a Rigidbody component. The script 'Game Controller' is created to handle spawning, and the process of creating a prefab for the ball is detailed. The tutorial moves on to demonstrate how to spawn the ball at game start and on pressing the spacebar.

05:01

🔄 Spawning Objects on Mouse Click

The second paragraph delves into spawning objects at the position of a mouse click. It explains how to adjust the z-position of the mouse coordinates and convert screen coordinates to world coordinates for accurate object placement. A new script, 'Ball Controller', is introduced to change the color of the ball upon collision with a plane. Additionally, the use of 'InvokeRepeating' is taught to continuously spawn balls at set intervals without further user input.

10:01

🎰 Randomizing Spawn Locations

In the final paragraph, Raja teaches how to randomize the spawn location of objects over a defined area. The focus is on creating a random x and z position for spawning within certain limits. The 'Game Controller' script is updated to include randomization, and the 'Start' function is modified to repeatedly call the spawn function at random positions. The video concludes with a prompt for viewers to apply these lessons to their own game projects and to explore more courses for in-depth learning.

Keywords

💡C# Scripting

C# scripting refers to writing code in the C# programming language to control the behavior of elements within Unity, a popular game development engine. In the video, C# scripting is used to create functionalities such as spawning objects, handling inputs, and controlling game logic.

💡Unity

Unity is a game development engine that allows developers to build 2D and 3D games. In the video, Unity is used as the platform where C# scripts are applied to create and manipulate game objects like spheres (balls) and manage game components such as the game manager.

💡Game Object

A game object is any object within a Unity scene, such as a character, item, or environmental element. The video demonstrates how to create and manage a game object, specifically a sphere (ball), which can be manipulated through scripting to spawn, move, and change properties.

💡Rigid Body

A rigid body is a Unity component that enables physics-based behavior, such as gravity and collisions, for a game object. In the video, a rigid body is added to the sphere so that it can interact with the game world physically, allowing it to fall when the game starts.

💡Prefab

A prefab is a pre-configured game object in Unity that can be reused and instantiated multiple times in a scene. In the video, the ball object is saved as a prefab so that it can be spawned dynamically during the game whenever needed, rather than existing statically in the scene.

💡Instantiate

Instantiate is a function in Unity that creates a new instance of a game object. The video shows how this function is used to spawn balls at different points in the game, creating dynamic gameplay where objects appear based on user input or automatically over time.

💡Spawn Point

A spawn point is a designated location in a Unity scene where game objects can be created or 'spawned.' The video explains how to create an empty game object and set its position as a spawn point, from which new balls will appear during the gameplay.

💡Update Function

The Update function in Unity runs once per frame and is commonly used for checking player inputs or continuously updating game elements. In the video, the Update function is used to detect when the player presses a key (e.g., spacebar) or clicks the mouse to spawn new balls.

💡Collision

A collision in Unity refers to when two game objects with physical properties interact, such as when a ball hits the ground. In the video, the OnCollisionEnter function detects when the ball collides with another object, triggering a color change to indicate the collision event.

💡Invoke Repeating

Invoke Repeating is a Unity function that repeatedly calls a specified function at defined intervals. In the video, this function is used to automatically spawn new balls at regular time intervals, demonstrating how game mechanics can be automated through scripting.

Highlights

Introduction to the video series focusing on C# scripting in Unity within 15 minutes, highlighting that this is part 2 of the series and advising viewers to check out part 1 for a complete understanding.

Demonstration of spawning a 3D object (a sphere) in Unity, including adding color and rigid body physics to the object, and the steps needed to create and apply materials in Unity.

Setting up a spawn point in Unity using an empty game object and assigning it a visible icon, then using this spawn point as a reference for object instantiation.

Explanation of creating a C# script named `GameController` to manage game logic, including public references to the ball object and the spawn point.

Implementation of the `SpawnBall` function using the `Instantiate` method to create a copy of the ball object at a specified position and rotation, emphasizing the use of `Quaternion.identity` for default rotation.

Creating a prefab from the ball object to allow for reuse and efficient object spawning, and updating the script to instantiate the ball from the prefab.

Triggering the spawn function in Unity's `Start` method to automatically spawn the ball when the game begins, and verifying that the functionality works as expected.

Modifying the script to spawn the ball using keyboard input (space key), utilizing Unity's `Input.GetKeyDown` method to handle user interactions.

Changing the script to spawn the ball at the mouse click position by converting screen coordinates to world coordinates using `Camera.main.ScreenToWorldPoint`, ensuring accurate placement in the game world.

Introduction of a `BallController` script to detect collisions using the `OnCollisionEnter` method and change the ball's color on impact, showcasing a dynamic reaction to game events.

Usage of `InvokeRepeating` in Unity to repeatedly call the `SpawnBall` function at specified intervals, enabling automated and consistent spawning without user input.

Adding randomization to the ball spawn positions by creating a random `Vector3` for the spawn point, using Unity's `Random.Range` method for generating values within specified boundaries.

Ensuring that multiple balls spawn at different positions on the plane by specifying maximum x and z values in the `GameManager` and dynamically adjusting the spawn points.

Optimization tip: Using prefabs and scripts to control object behavior and automate gameplay mechanics, demonstrating how to scale this technique for more complex projects.

End of the tutorial with a summary of techniques covered: object instantiation, keyboard and mouse input handling, collision detection, color changes, and automated spawning, encouraging viewers to explore further courses on C# and Unity for deeper learning.

Transcripts

hey everyone this is raja from charger

games and welcome back to this video

so in this video we're going to learn

about c sharp scripting in unity

in just 15 minutes now this is part 2 of

my c sharp in 15 minutes series

so if you haven't checked the first part

yet make sure to check that out

and you can check out all my other

courses and videos from the links in the

descriptions below

so with that being said we have a lot to

cover and

let's get started so in this video we're

going to learn about a lot of

useful c-sharp scripting functionalities

that we can use while building games in

unity

now we have to cover a lot of things

within this short time so we're going to

go really fast

so let's get started so first of all

we're going to learn how we can spawn a

game object

in unity so in order to spawn a game

object first of all i'm going to go

ahead and create a new 3d object

a sphere i'm going to rename this one to

ball now i'm going to add a color to it

so inside my materials i have this

colors

if you want to create a material you can

go to right click create

and new material from here this way

and i have this material here i'm going

to literally drag and drop it

right here so now as you can see our

ball has this color

now i'm gonna go and add a rigid body to

it so i'm gonna go to add component

physics and i'm gonna add a rigid body

component to it

now if you click on play

and if i drag my ball up as you can see

it falls down because now it has the

rigid body attached to it

so now what we're gonna do is whenever

our game starts we want to simply

spawn this ball we don't want it to be

here at the beginning but whenever we

start the game we have to spawn the ball

so in order to do that we also need a

spawn point where we actually want to

spawn our wall

so here i'm going to click on create an

empty game object

and i'm going to name this one spawn

point

and from the icons first of all let's go

ahead and

reset its position now from the icons

i'm going to select an icon for it

like this so that we can see where it is

and i'm going to drag and

move it upwards somewhere like this so

this is the point

from where our ball will spawn so this

is our spawn point

now here i'm gonna go ahead and create

an empty game object and i'm gonna name

this one

game manager and this is what we're

gonna do all our experiments on

in this video and here inside my scripts

folder i'm gonna right click

and create a new c sharp script and i'm

gonna name this one

game controller

alright

so game controller so i'm gonna select

my game manager and drag and drop my

game controller over it

now i'm gonna double click to open it in

visual studio

all right so now we have to spawn a

object in order to spawn an object first

of all we need to create

a public game object not game controller

public game object ball

so this ball object will store the ball

reference to our ball game object

next we need a public transform

spawn point so this is the position

where we are going to spawn our object

all right so now here

we're going to create a new function

we're going to call it void

spawn ball

and inside the spawnvolt function we're

going to spawn our ball

and for that we're gonna write

instantiate and what do we want to

instantiate

we want to instantiate the ball game

object and at which position

we want to associate at spawn point dot

position

and which rotation we want we want

quaternion

dot identity all right so we want to

spawn our ball at this position with

this rotation that means with zero

rotation

so now let's go ahead and save this

script go back to unity here in unity

before we can use it we need to save our

ball as a prefab so that we can reuse it

so inside my assets folder i'm gonna go

ahead and create a new folder

and i'm gonna call this one prefab now

inside the prefabs folder i'm gonna drag

and drop my ball right here

so now we can reuse this ball anytime

that you want so

i'm gonna go ahead and deactivate this

ball from the scene

then i'm gonna select my game manager

and as you can see it has a slot for

ball i'm gonna drag and drop my ball

from the prefab folder here

and for the spawn point i'm gonna drag

and drop the spawn point right here so

we have the ball and the spawn point

and now we need to open up game

controller and inside the start we need

to say

spawn ball so we are calling this

function in the start

now let's go back and now if i click on

play when the game starts

our ball spawns and anytime when i

restart the game

the ball keeps spawning just like this

so now let's learn how we can spawn the

ball when we press a button on our

keyboard

so let's open up our script and here

inside the update i'm going to say if

input dot get key down

key code dot space so that means

whenever we press the space button

we simply want to call the spawn ball

function

all right now i'm going to comment this

one out

and now whenever i press the space

button the ball will be spawned so let's

go back to unity

and every time i press the space button

as you can see a new ball spawns

and it keeps spawning like this so what

we can do is i can go to my plane and if

you don't have this plane you can simply

go to

create 3d object plane and create a new

plane

and i'm going to select my plane and

from the x rotation i'm going to give it

a rotation of let's say 10

or minus 10 all right just like this

so now you will see whenever i click on

play i press base button

and a new world spawns and it falls down

all right

so now we're gonna learn how we can

click our mouse on at a point

and spawn the ball at that position on

our screen so let's see how we can do

that so open up our script

and here inside the update function we

need to say if

input dot get mouse button down 0

that means if we are pressing the left

mouse button then first of all we need

to get the mouse position so here we're

going to say

vector vector3 mouse pose

equals input dot mouse position

all right next we need to do what we

need to do is we need to change the z

position of our mouse so into say mouse

mouse pose dot z equals

5 f all right or let's say 10 f

then we need to say vector 3 spawn

position so this is the position where

you're going to actually spawn

equals camera dot main dot

screen to world point and here we're

going to write

mouse pose so here we are converting our

mouse position which is in screen

coordinates

to this one that is world coordinate so

in order to use any position we need to

convert it to word coordinates otherwise

we cannot spawn the objects at the

correct position

so now that we have got the position we

need to spawn our ball at this position

so to do that i am going to simply copy

this spawn ball code

place it here and instead of this spawn

pointed position

here we're going to say spawn pose

all right so this is the spawn position

that we have calculated from our

calculations

so let's go back to unity so now you

will see whenever i click my mouse

the ball gets spawned at that point so

this is how we have learned how to

spawn a ball at any point where we click

our mouse

all right so now we're gonna learn how

to change the color of the balls when

they collide with this plane

so for that here we're gonna create

another new script we're going to call

this one

ball controller then i'm going to go to

my prefabs folder

select my ball go to add component

scripts and add the ball controller

script to it all right

now i'm going to double click on it now

here what we need to do is we need to

check when our ball is colliding with

the plane

for that we're going to call the void on

collision

enter function so this function gets

called automatically whenever our ball

collides

with any other object so whenever our

ball collides with any other object we

need to simply change the color of the

ball

in order to change the color of the ball

we're going to say get

component renderer and this will give us

access to the renderer component of our

ball

dot material dot color

equals color dot red so whenever our

ball collides with the plane or any

other game object

we can simply go and change its color to

color.red

you can simply go ahead and change it to

color.green or color.blue

i'm going to simply go ahead and make it

red so now let's save this and go back

to unity

now you will see i can spawn my balls at

any point and whenever they fall down

they actually become red

so now you can see i can spawn my balls

at any position and whenever they fall

down

they automatically change the color and

they become red so our code is working

okay so now we're gonna learn how to

call this spawn ball functions

repeatedly again and again

so that we don't have to do anything and

this function will get called again and

again and the balls will get spawned

again and again

to do that we're gonna use something

called invoke repeating

all right so here inside the start

function

we're going to write invoke repeating

which helps us to call any function

repeatedly so first of all within a

string

we need to we need to write the name of

the function exactly as it is

so i'm going to go ahead and select my

spawn ball

and copy this and here i'm going to

paste

spawn ball all right so now

after that for the second parameter we

need to write after how many seconds we

want to start calling

so let's say after one second we want to

start calling and then we need to

mention

after how many seconds we're going to

repeatedly call it so let's say here i

pass

2f so that means it will call this

function

every two seconds so after every two

seconds this invoke repeating function

will get called

and the balls will be instantiated so

this is the code we need to write to

repeatedly call this

function again and again so let's save

this and go back to unity

and here if i click on play

now you will see i'm not doing anything

i'm not clicking my mouse or

pressing my space button but all the

balls are falling again and again one by

one one after one

and they are just going down all right

so our code is working

but as you can see all of them are

actually spawning at the

same position so they are not changing

their position they are

all falling at the spawn point so now

we're gonna learn how we can actually

randomize the position

and spawn them at any point that we want

to so if you select our spawn point as

you can see this is positioned here

so we need to find a random point over

this plane

so what we can do is we can get a random

position of x between this

which is about 2.87 so let's say 2.60 so

let's say

minus 3 so we need to spawn it between

minus x minus 3 to positive 3 in the x

axis all right and for the

z axis we're going to say from positive

3

to negative 3 all right so

anywhere within this point we want to

spawn this object

okay so now we need to go back to our

game controller script and here

as you can see this is the spawn ball

and we need to find a way so that we can

randomly spawn this ball

so here inside the spawn volt function

what you can do

is float

random x so this would be the random x

spawn point

equals random dot range

so at which range we want to spawn our

value

or spawn our ball so for that here going

to create two new

variables public float

max x and public float

max z so this will be the points which

will which we will use to randomly spawn

this

so here we're going to write random

range minus

max x comma max x

and for the second value we're going to

write random

z equals random dot range

minus max z comma max

z so now this will return us a random

value

between these two values okay and we're

going to use that random value

to spawn our ball so here we're going to

simply copy this code

and paste it here and here we're going

to write

vector3 random

spawn pose this is a new variable equals

new vector3 and for the x value we're

going to write

random x for the y value we're going to

write 10

f and for the z value we're going to

write

random z that we have already calculated

so now what will happen is this will

create a random spawn position

and now inside the instantiate function

instead of this we need to simply write

random spawn pose

all right so this way it is creating a

random x position

it is creating a random z position and

this is creating a random vector3

position which is

taking the random x and z and finally we

are instantiating our ball

in this random spawn point and now as

you can see in our start function we are

repeatedly calling this spawn ball

function so every time this gets called

this function gets called and the ball

will be instantiated at a random

location

over our plane so let's save this and go

back to unity

and see how it's working so now if i

click on play

you will see after some time a random

ball is getting generated

but the balls are as you can see all

spawning at the same point

and that's because we have not mentioned

the maximum x and z positions yet

so let's go to game manager as you can

see max x and max c is empty

so here i'm gonna write three and here

i'm write three as well

so now if i click on play now you will

see

all the balls are falling down at a

random value over our plane

and all of them are falling down so this

is how our random code is working

so thank you so much for watching this

video i hope you really enjoyed and

learned a lot of new things

so go ahead and apply this in your own

games so if you want to learn more about

c-sharp and unity by building a lot of

example games like 2d endless runner 3d

endless runner

and all that kind of stuff you can check

out all my courses from the links in the

description below so you can go to the

description take the courses and learn a

lot so thanks so much for watching make

sure to subscribe and i'm going to see

you in the next videos

you