Episode 3 Scripts Predefined and Input Methods

Hello guys, this is Vivek Sharma and welcome to the third episode of this game development

series on C-sharp-corner.com. In this video we will learn how we can add scripts to our project, we will learn about

basic predefined methods in Unity, vectors and input methods in Unity. So without wasting any further time, let's get started

So to begin with, first of all we will create a new folder inside our assets panel

We are going to rename it as scripts. And then we are going to create a new script inside the scripts folder

And let's rename it as dino script. Double click on it to open it up inside our text editor

I am using Visual Studio over here. Over here as you can see we have two pre-given methods

First is start. Another one is update. Start method is called only once in the beginning of the game

And update method is called on each and every frame continuously. So now let me give a brief of what we want to achieve over here

We want our dinosaur to keep moving in the x direction continuously and our dinosaur

to jump in the y direction whenever somebody hits the left mouse button or touches the screen

And we are going to achieve it by adding velocity in the x direction continuously and y direction occasionally

Velocity is a physics component and to assess that we will be needing a rigid body or a

a rigidbody2d in our case as we are creating a 2d game

So first of all, we will be declaring a private variable of type rigidbody2d and let's call it dino body

So now what we wanna do is get reference to the original rigidbody2d attached to our dinosaur and use it here So to do that I gonna write dino body equal to get component Rigidbody2d

This will get the component Rigidbody2d attached to our dinosaur gameobject. Remember that I'm writing this inside the start method because I want this to be called

only once whenever the game starts. Now we wanna move our dinosaur and for that let's learn a new concept called vector

So, generally, vectors are of two types, vector 2 and vector 3

Vector 2 contains two parameters, one is x value, another one is y value

And vector 3 contains three values, value in x, value in y and value in z

You can use vector 2 whenever you have two inputs x and y and can use vector 3 whenever

you have three inputs x, y and z. But also, in vector 3, if you leave the third value empty or assigns it equal to 0, it starts

to work as vector 2. So over here in our script what I'm gonna do is create a new variable of type

float and call it x velocity. This is going to be the velocity of our dinosaur in the x direction

and to move our dinosaur I will be adding velocity to our dino body. To do that I will write dino

body dot velocity equal to vector 3 or vector 2 if you want velocity in x direction and velocity

in y direction and of course this is a 2d game that's why I'm not gonna use the z value

so the velocity in x is going to be the variable we just declared which is x velocity but we

don't want to make any changes to the velocity in the y direction when the dinosaur is moving

constantly so over here for velocity in y direction I will use dino body We will get back to unity We click on dino player

Click on add component to add a new component. We'll search for dino script

We'll add that. And over here we can see an empty field for x velocity

I will give it a value of 5. And then I will hit play

And now as we can see our dinosaur is not just falling. it's also moving in the x direction. Now I will go back to my sprites folder and

will add two more sprites, one for the enemy and another one to create a ground

I will drag the ground sprite to the hierarchy panel and will change its size

to make it look like a ground. By the way you can also achieve it by going to the

inspector panel and changing the values inside the transform section. Now I will

quickly rename this to ground and now I will go back to the inspector panel. We

click on add component and we'll add a box collider and a rigid body to this as well but now if i hit

play what we see is our ground is also falling down and this is definitely something we don't

want to achieve so to fix this inside the rigid body 2d we will change the body type from dynamic

to kinematic and now if we hit play our ground is not falling and our dinosaur is moving in the

x direction perfect now comes the second phase of our dinosaurs movement so now

what we want to do is move our dinosaur in the y direction whenever somebody

clicks the left mouse button or taps on the screen so to do that first of all we

will create a new variable of type float and call it y velocity this is going to be the velocity of our dinosaur in the y direction and now inside the update method I gonna put a condition that if there is a left mouse button click or a tap then do this task

So over here I'm gonna write if input dot get mouse button down zero

Then add velocity to our dinosaur in the y direction over here

I have used zero as the parameter for get mouse button down because zero represents the left mouse button

if we write 1 it represents the right mouse button and if we write 2 it represents the

middle mouse button but we are going to use 0 for now and inside this if condition I'm going to write

dynobody.velocity equal to new vector 3 velocity in x and velocity in y this time velocity in y

is going to be y velocity and the velocity in x is going to be an unordered velocity

So that's why I'm gonna use dino body.velocity.x over here I will go back to unity click on dino player

And then over here we have another open field for y velocity

I'm gonna change its value to 5 And now as we can see our dinosaur is moving in the x direction

And whenever we hit the left mouse button it goes into the y direction

But here is a catch If it keeps on clicking the left mouse button our dinosaur starts to fly

And this is definitely not what we want to achieve. So in the next tutorial, we will try to fix this and we will be adding some enemies for

our dinosaur. So till then, goodbye, have fun and don't forget to follow and subscribe because the

best is to come