WEBVTT

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Realistic Basics
Using Unreal Engine Blueprints

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GCC Academy

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Hello

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I am Tak Gwang-wook, in charge of the Blueprint lecture

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This time, we will create a simple function

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using Blueprint

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In this session, we will learn about the series of methods

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for designing a function through a practical example

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verifying whether the designed work works properly

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and finally completing the function

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Role and Mechanism of Collision

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This time, I will create a simple function

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using the basic blueprint theorywe learned earlier

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The function is as follows: There is a white platform

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When the player steps on this white platform

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this white platform becomes a button

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that opens the door in front of it

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To do this, we need to prepare a few things

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First, I think we need to install the door

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We'll use the asset in StarterContent for the door

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In the Content Drawer

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you will see a folder called StarterContent

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This is included when you create a project

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and you can set

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whether to install it

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If you don't have it and didn't set it

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then click this + button, and at the top

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you will see an item called

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Add Feature or Content Pack

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If you click this item, you can add

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various content items

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Among them, there is an item called Content

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If you look here, you will see Starter Content

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If you select this Starter Content

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and click Add to Project

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the StarterContent folder we saw earlier will be created

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and you can use various assets inside it

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If you look inside, there is an item called Props

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You will see various assets

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Among them, you will see an asset called SM_Door

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Let's try placing the assets

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We want to put a platform in the middle here

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 and when the player presses this platform

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we're going to make it rotate on the Z axis like this

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When we press the play button, if we play like this

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the character doesn't come out like this

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It can only move around like this

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We want to control the character directly

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and have the character press the button

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but since the character doesn't come out right now

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we need to install a system that makes the character come out

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It comes out like this because it wasn't created

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in third-person mode when it was first created

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so this system wasn't automatically installed

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To do that, first cancel

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and click the Add button

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at the top of the Content Drawer

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and then click Add Feature or Content Pack

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You've clicked on our content a little while ago

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Here, the Blueprint items

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are organized in a way that allows you

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to install multiple modes

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Even if we didn't select this

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 before creating the project

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we don't have to create the project again

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We can add them additionally like this

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We can simply click on Third Person

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and Add to Project

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and you can see that it is installed like this

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The Content Browser pops up separately

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Close it again

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and click on Content Drawer

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Now, several folders will be created

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A Characters folder, LevelPrototyping

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and a folder called Third Person will be created

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This way, it's not applied right away

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when you play

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You need to make some settings

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If you go to Edit, Project Settings

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and look on the left, you'll see Maps&Modes

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in the project items

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You can change this mode

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in the Maps&Modes item

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Here, you can change it to the Third Person mode

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we received

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Click GameModeBase

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If you look at the top

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there's an item called BP_ThirdPersonGameMode

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If you select this item

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you'll see that the ones below

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will be applied automatically

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If this is applied

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if you close the Project Settings window

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and play again

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the character will appear like this

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The point where the character appears

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is marked with this flag

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This is an actor called PlayerStart

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and this actor

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specifies where

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the character appears

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So when you play

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the character appears here

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If you move this PlayerStart location

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to the back like this

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when you play, you can see the character

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created a little further back than that location

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Then, you can see the character appear

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a little bit away from the door

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I think it's okay to put it a little bit further back

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 I'll put it a little bit further back

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If you put it like this and play, you can see that

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it starts a little bit further away

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Now we're ready

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The door and player are ready

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so let's create a button blueprint that can open the door

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Let's open Content Drawer again

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and create it inside this BP folder

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Right click, click Blueprint Class

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This time, I will inherit the actor class

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to place it at this level

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So click on the actor

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name it BP_Door

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Double click to go into the blueprint

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Again, this panel will be attached next to the level like this

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and Basic is not needed, so let's close it

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First, let's make the appearance a little simpler

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First, to express that this is a button

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on the floor

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I will create a button using a simple box

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It's not an actual button you press

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but I think it's good to think of it

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as a visual representation that says, "This is a stepping stone"

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So, if you press the + button in Components

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and search for Cube

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you can pull out a cube shape like this

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I'll click on it to pull out a cube

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This is a component that gives it a cube-shaped appearance

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It simply takes care of the appearance

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And here, there's a Static Mesh

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called Cube

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which has a square shape like this

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I will change this square shape a little bit and make it flat

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If I make it flat like this, around 0.1 on the Z-axis

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I'll make it flat like this, around 0.05

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Let's make it flat like this

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This will create a simple mark that

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the character can step on

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Next, the platform called the cube

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is not directly pressed

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I said it is not directly pressed

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but it is just indicated as a location

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where you can press

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The concept that we move the character, 
stand on this platform

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and press this platform

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is actually because there is an area

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that can detect a character

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When the character enters that space and collides

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when the overlap occurs

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it can be seen as a pressed event

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So, the important thing is that there needs to be an area

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that the character can collide with

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So, that area that can collide with the character

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and cause the character to collide

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This area is called

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Collision

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So we need to install Collision

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Likewise, if you click the + button in Components

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and search for Collision

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you can pull out various types of Collisions

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I'll choose Box Collision among them

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I'll just name it Box

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If you create a Box Collision component like this

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you can see that a shape with

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only a yellow wireframe is created

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This means the area

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It indicates the collision area

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This area can be raised

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using the size or scale

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or there is an item called Box Extent below it

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You can adjust the value using this Box Extent

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Let's adjust it a little to fit the size

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Let's set it to about 50

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and 50, 50

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Then, it will almost match the white box shape below

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And let's install it above so that it doesn't go out

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If you mark the area like this

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when the character sees this white stepping stone 
and steps on it

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the character overlaps this Collision Box

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When it recognizes that the character has entered this area

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the door will open based on that recognition

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Then, the user will think that they pressed the stepping stone

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So you can think of this area as a space that recognizes

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that the character has entered this space

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a detection space

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That's Collision

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First, let's put the appearance like this, compile it, save it

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and install it here

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I'll drag and drop the blueprint

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from the Content Drawer and place it like this

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When I place it like this, you can see that it is expressed

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together with the white platform

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and the yellow collision area

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Then, when the character comes to

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step on the platform

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let's output "Detected" just like

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we output "Hello World"

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to check whether it is detected and works well

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Go back to BP_Door

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This time, we need to create an output function

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so, we have to go to the Event Graph item at the top

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Click Event Graph

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First, Print String

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Select

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the Print String node

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I'll set it to output "Detected"

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in this Print String node

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I'll set like this

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Where should I connect this node?

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Which event node should I connect it to?

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When it starts? When it's alive? 
Or when it overlaps with an actor?

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Of course, it's when it overlaps with an actor

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 This Collision that we created

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is related to this ActorBeginOverlap

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In other words, BeginOverlap, this node

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tells this blueprint to generate

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an event when it overlaps

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with some external actor

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How do you detect that there's an overlap?

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That's the role of this box, Collision

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When the Collision and the character overlap

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that's when

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ActorBeginOverlap occurs

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and is executed

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So if we connect the execution pin of

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this ActorBeginOverlap to Print String like this

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the Print String node will be executed

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when the actor hits the Collision

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Let's take a look

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Compile, save, come back and play

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As you can see now, there's a character like this

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Let's go to this platform

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When you go like this

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do you see the phrase "Detected" appear in the upper left?

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I'll make it a little longer

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Let's make it 10 seconds, compile, save, play again

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and move the character to the platform

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Looking at the top left corner of the mask

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you can see that it says Detected

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That means

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it's working properly

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So now we can add some functions

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to ActorBeginOverlap

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Let's delete Print String

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What are we going to do with this node?

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We're going to rotate this door on this level to open it

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Let's add a node

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Right-click and select Add Actor World Rotation

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Let's take this node out

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This node rotates the actor

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So, if you look, we need

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two data pins on the left

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One is who the target is

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If we say self now, it means BP_Door itself

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In other words, what I'm saying is that this thing itself will rotate

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This platform itself will rotate

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but we don't want that

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So what we want is this door

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so another actor

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So, we will put this other actor in a variable

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and connect that actor here

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so that it can rotate

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the external actor

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So, we're going to create a variable first

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In VARIABLES, press the + button

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00:15:48.799 --> 00:15:52.440
and name it Door

277
00:15:52.440 --> 00:15:59.640
Since we need to put the external actor in a variable

278
00:15:59.640 --> 00:16:04.880
the container that holds the actor, the data type, must be the Actor

279
00:16:04.880 --> 00:16:09.479
I'll make a big choice for the classification 
and search for Actor here

280
00:16:12.960 --> 00:16:18.039
Then, among the object types of Actor

281
00:16:18.039 --> 00:16:22.320
there is an item called Object Reference in Actor

282
00:16:22.320 --> 00:16:24.119
If you click on this item

283
00:16:24.119 --> 00:16:30.880
it will be created as a variable containing the actor class

284
00:16:30.880 --> 00:16:33.919
When we learned about data types

285
00:16:33.919 --> 00:16:38.069
we said there are two types of actor data types

286
00:16:38.069 --> 00:16:39.799
basic and user-defined data types

287
00:16:39.799 --> 00:16:41.799
This actor data type belongs to the second

288
00:16:41.799 --> 00:16:45.359
user-defined data type

289
00:16:45.359 --> 00:16:49.640
In particular, this actor is a user data type created in Unreal

290
00:16:49.640 --> 00:16:52.520
So, you can think of it as a class data type

291
00:16:52.520 --> 00:16:57.440
created in advance to contain a class called Actor

292
00:16:57.440 --> 00:17:03.159
Since we need to put a door in this variable from the outside

293
00:17:03.159 --> 00:17:08.479
let's turn on the eye or check the Instance Editable item

294
00:17:08.479 --> 00:17:12.440
to set it so that it can be pulled out

295
00:17:12.440 --> 00:17:15.960
And this Door variable should now be connected here

296
00:17:15.960 --> 00:17:19.919
We need to drag and drop it and click Get Door

297
00:17:19.919 --> 00:17:21.039
to get the variable

298
00:17:21.039 --> 00:17:23.289
Let's take this variable and connect

299
00:17:23.289 --> 00:17:25.633
this variable to Target like this

300
00:17:30.804 --> 00:17:33.320
Compile and save it, and let's take a look

301
00:17:33.320 --> 00:17:39.039
Then, if you select this blueprint and look at the Details window

302
00:17:39.039 --> 00:17:43.440
you can see a variable called Door in the middle

303
00:17:43.440 --> 00:17:46.840
This Door doesn't contain anything right now

304
00:17:46.840 --> 00:17:51.880
so you just need to assign this Door to this slot

305
00:17:51.880 --> 00:17:55.840
You can do this by clicking the None sign

306
00:17:55.840 --> 00:18:01.320
and selecting SM_Door directly

307
00:18:01.320 --> 00:18:07.080
Or, you can click the clicker button on the right

308
00:18:07.080 --> 00:18:10.286
directly select this object, and bring it in

309
00:18:14.840 --> 00:18:16.119
Like this

310
00:18:16.119 --> 00:18:17.640
Then you can see that it's been entered

311
00:18:17.640 --> 00:18:20.119
So it's been selected like this

312
00:18:20.119 --> 00:18:22.280
If you come back

313
00:18:22.280 --> 00:18:25.330
you can see that this variable

314
00:18:25.330 --> 00:18:27.840
now contains the Door actor

315
00:18:27.840 --> 00:18:31.200
We're going to add a function

316
00:18:31.200 --> 00:18:35.880
for that Door to rotate

317
00:18:35.880 --> 00:18:40.440
If you look, there's an item here

318
00:18:40.440 --> 00:18:43.140
The item below here controls

319
00:18:43.140 --> 00:18:46.119
how much it will rotate

320
00:18:46.119 --> 00:18:48.880
If you look, it says Delta Rotation

321
00:18:48.880 --> 00:18:51.280
then X, Y, and Z

322
00:18:51.280 --> 00:18:58.000
In other words, you can think of Delta as a variable value

323
00:18:58.000 --> 00:19:02.479
Delta Rotation means, "How much will it rotate?"

324
00:19:02.479 --> 00:19:04.840
"How much will it rotate?"

325
00:19:04.840 --> 00:19:07.340
How much will it rotate on the X-axis, Y-axis

326
00:19:07.340 --> 00:19:09.960
and how much will it rotate on the Z-axis

327
00:19:09.960 --> 00:19:14.599
You can think of it as setting how much it will rotate

328
00:19:14.599 --> 00:19:17.479
Here's the concept

329
00:19:17.479 --> 00:19:19.212
If you select the Door actor

330
00:19:19.212 --> 00:19:22.320
and look at Rotation, there are X, Y, and Z

331
00:19:22.320 --> 00:19:28.719
You can think of it as specifying the angles of X, Y, and Z

332
00:19:28.719 --> 00:19:30.880
As you can see, what we want is this

333
00:19:30.880 --> 00:19:33.760
the arrows are X, Y, and Z

334
00:19:33.760 --> 00:19:35.880
The gizmo is based on the world

335
00:19:35.880 --> 00:19:38.329
Since we're going to rotate it based on the world

336
00:19:38.329 --> 00:19:43.357
if you look at it based on the world

337
00:19:43.357 --> 00:19:47.872
you'll see that it moves

338
00:19:47.872 --> 00:19:50.744
based on the blue arrow Z-axis

339
00:19:50.744 --> 00:19:55.944
So, you can add 90 degrees like this

340
00:19:55.944 --> 00:19:58.835
Turn it back

341
00:19:58.835 --> 00:20:04.435
and input 90 degrees only on the Z-axis

342
00:20:04.435 --> 00:20:06.905
Since they're all combined now

343
00:20:06.905 --> 00:20:10.655
I'd like to separate

344
00:20:10.655 --> 00:20:13.405
the combined Input Pin

345
00:20:13.405 --> 00:20:15.880
So, I'll right-click on the Input Pin

346
00:20:15.880 --> 00:20:20.480
Then there's an item called Split Struct Pin

347
00:20:20.480 --> 00:20:22.680
I'll select this

348
00:20:22.680 --> 00:20:27.730
Then, you can see that it's separated into X, Y, and Z

349
00:20:27.730 --> 00:20:31.928
X and Y will stay the same, and we want the Z-axis

350
00:20:31.928 --> 00:20:36.880
We can input 90 degrees on the Z-axis like this

351
00:20:36.880 --> 00:20:39.980
Then, we can connect it to

352
00:20:39.980 --> 00:20:42.218
ActorBeginOverlap like this

353
00:20:45.639 --> 00:20:47.889
Then, when the overlap occurs

354
00:20:47.889 --> 00:20:53.480
it will rotate the Door actor

355
00:20:53.480 --> 00:20:57.380
90 degrees on the Z-axis

356
00:20:57.380 --> 00:20:58.578
Let's give it a try

357
00:20:58.578 --> 00:21:00.578
Click Compile and Save

358
00:21:00.578 --> 00:21:03.799
I came back and try to click Play

359
00:21:03.799 --> 00:21:05.499
Wait

360
00:21:05.499 --> 00:21:10.040
Right now, this door is probably not going to move

361
00:21:10.040 --> 00:21:12.140
If you play, it won't move

362
00:21:12.140 --> 00:21:17.000
The reason for this is because the properties 
of this mesh are set not to move

363
00:21:17.000 --> 00:21:21.400
In other words, it's set to stationary, not moving

364
00:21:21.400 --> 00:21:24.767
If you look in the Details window

365
00:21:24.767 --> 00:21:28.080
and select this door in the Details window

366
00:21:28.080 --> 00:21:32.320
there's an item called Mobility under Transform

367
00:21:32.320 --> 00:21:34.178
This Mobility item is that

368
00:21:34.178 --> 00:21:36.639
It should be checked as Static

369
00:21:36.639 --> 00:21:38.821
What Static means is that

370
00:21:38.821 --> 00:21:43.478
this actor is set never to move

371
00:21:43.478 --> 00:21:46.778
You need to change this Static to Movable

372
00:21:46.778 --> 00:21:48.400
Then, it will be able to move

373
00:21:48.400 --> 00:21:51.450
If you press the play button in this state

374
00:21:51.450 --> 00:21:54.639
there will be a character, and I'll go to the platform

375
00:21:54.639 --> 00:21:58.639
If you step on the platform like this

376
00:21:58.639 --> 00:22:00.959
you can see that it opens

377
00:22:00.959 --> 00:22:04.709
But as you can see

378
00:22:04.709 --> 00:22:07.599
when I play and press the platform

379
00:22:07.599 --> 00:22:11.440
I don't like how it opens

380
00:22:11.440 --> 00:22:15.290
I wish it would open smoothly

381
00:22:15.290 --> 00:22:18.119
but it doesn't feel natural because it opens like this

382
00:22:18.119 --> 00:22:20.969
So, we will make this node that we created

383
00:22:20.969 --> 00:22:26.357
so that the door can open more smoothly

384
00:22:28.679 --> 00:22:30.579
So how should we do that?

385
00:22:30.579 --> 00:22:33.879
It would be good to rotate it little by little

386
00:22:33.879 --> 00:22:35.800
in every frame

387
00:22:35.800 --> 00:22:43.479
OK, then, let's connect this node to the tick

388
00:22:43.479 --> 00:22:44.729
Maybe 90 degrees

389
00:22:44.729 --> 00:22:47.520
Since it will rotate 90 degrees every frame

390
00:22:47.520 --> 00:22:49.170
let's untie this

391
00:22:49.170 --> 00:22:51.620
Since it will rotate 90 degrees every frame

392
00:22:51.620 --> 00:22:53.240
 it seems like it will rotate a lot

393
00:22:53.240 --> 00:22:56.040
Let's make it move slowly

394
00:22:56.040 --> 00:23:00.960
1 degree per frame

395
00:23:00.960 --> 00:23:04.759
Let's see what happens
I'll compile and save

396
00:23:04.759 --> 00:23:07.109
If we play it

397
00:23:07.109 --> 00:23:10.299
it looks like

398
00:23:10.299 --> 00:23:13.299
it's working fine

399
00:23:13.299 --> 00:23:15.839
It looks like it's working fine

400
00:23:15.839 --> 00:23:17.589
but there's a problem here

401
00:23:17.589 --> 00:23:20.389
You can see that the door is rotating

402
00:23:20.389 --> 00:23:23.119
even though we haven't stepped on the platform

403
00:23:23.119 --> 00:23:27.169
We want it to move when we step on the platform

404
00:23:27.169 --> 00:23:31.520
It should move when we step on it, 
but it's moving even though we're not stepping on it

405
00:23:31.520 --> 00:23:35.279
So, we need to add a little more functionality

406
00:23:35.279 --> 00:23:39.529
We need to add a function to set whether or not

407
00:23:39.529 --> 00:23:44.434
this character has stepped on this platform

408
00:23:44.434 --> 00:23:47.838
Let's try this

409
00:23:47.839 --> 00:23:52.686
In the blueprint, how do we tell

410
00:23:52.686 --> 00:23:55.217
if we stepped on the button or the character

411
00:23:55.217 --> 00:23:58.673
stepped on it?

412
00:23:58.673 --> 00:24:01.923
I'm going to create a Boolean variable

413
00:24:01.923 --> 00:24:07.440
 I will create a container that can hold and be false

414
00:24:07.440 --> 00:24:11.339
and when ActorBeginOverlap when there's a collision 
or when they stepped on it

415
00:24:11.339 --> 00:24:16.839
we can change that variable to true

416
00:24:16.839 --> 00:24:19.919
to indicate that it's open

417
00:24:19.919 --> 00:24:24.064
We will make this Rotation node

418
00:24:24.064 --> 00:24:27.364
operate based on the result

419
00:24:27.364 --> 00:24:29.600
of that variable

420
00:24:29.600 --> 00:24:32.050
So, first, we need to create a variable

421
00:24:32.050 --> 00:24:34.900
So I will click the + button on VARIABLES

422
00:24:34.900 --> 00:24:40.000
and name it isOpen

423
00:24:40.000 --> 00:24:43.538
It's going to contain the information, "Is it open?"

424
00:24:43.538 --> 00:24:48.753
So, I'm going to make the data type Boolean

425
00:24:48.753 --> 00:24:51.901
There's no need to make this variable public

426
00:24:51.901 --> 00:24:54.401
We just need to have the information inside

427
00:24:54.401 --> 00:24:56.839
so I don't think it's necessary to open it

428
00:24:56.839 --> 00:24:59.139
I'm going to deactivate

429
00:24:59.139 --> 00:25:02.842
this basic value by compiling and saving

430
00:25:02.842 --> 00:25:07.192
In other words, it's not open

431
00:25:07.192 --> 00:25:10.760
it's notified that it's not open as deactivated

432
00:25:10.760 --> 00:25:13.810
When ActorBeginOverlap is executed

433
00:25:13.810 --> 00:25:17.559
that is, when a collision occurs, and an event occurs

434
00:25:17.559 --> 00:25:24.519
we need to set it to check the isOpen variable like this

435
00:25:24.519 --> 00:25:29.984
How do we do this? 
When we bring in the isOpen variable

436
00:25:29.984 --> 00:25:33.239
we've only brought in Get isOpen so far

437
00:25:33.239 --> 00:25:39.004
This time, we're going to select Set isOpen like this

438
00:25:39.004 --> 00:25:41.854
So, we will connect the ActorBeginOverlap execution pin

439
00:25:41.854 --> 00:25:47.239
to the Set execution pin

440
00:25:47.239 --> 00:25:53.320
And we're going to check the isOpen of this Set node

441
00:25:53.320 --> 00:25:57.870
Then, when the ActorBeginOverlap event occurs

442
00:25:57.870 --> 00:26:03.318
that is, when the character collides with Collision, execute it

443
00:26:03.318 --> 00:26:09.668
What kind of execution? Set the Set isOpen variable

444
00:26:09.668 --> 00:26:16.040
How? I added a function to set it to check

445
00:26:16.040 --> 00:26:22.850
Let's check if it's working properly

446
00:26:22.850 --> 00:26:25.200
using the Print node

447
00:26:25.200 --> 00:26:27.679
Let's put these guys down

448
00:26:27.679 --> 00:26:31.975
and say

449
00:26:36.399 --> 00:26:42.640
"It's open" here
If it works properly

450
00:26:42.640 --> 00:26:46.290
isOpen will be checked

451
00:26:46.290 --> 00:26:50.890
and the phrase "It's open" will be printed

452
00:26:50.890 --> 00:26:51.920
Let's check it out

453
00:26:51.920 --> 00:26:57.000
Let's compile, save, play

454
00:26:57.000 --> 00:26:58.550
and go to the platform

455
00:26:58.550 --> 00:27:05.237
If we go to the platform like this 
and step on it, "It's open" will appear

456
00:27:05.237 --> 00:27:10.959
Then, we can see that it's working properly

457
00:27:10.959 --> 00:27:14.009
So what we need to do from now on is

458
00:27:14.009 --> 00:27:19.311
Instead of continuing this function

459
00:27:19.311 --> 00:27:23.361
that rotates the Add Actor World Rotation statement

460
00:27:23.361 --> 00:27:28.000
in this event called Tick

461
00:27:28.000 --> 00:27:33.850
we can add a function that says

462
00:27:33.850 --> 00:27:38.974
Do this only when isOpen is true

463
00:27:38.974 --> 00:27:42.119
depending on the situation of this isOpen variable

464
00:27:42.119 --> 00:27:43.710
Now, let's add

465
00:27:43.710 --> 00:27:48.000
a conditional expression

466
00:27:48.000 --> 00:27:50.800
when this Tick event occurs

467
00:27:50.800 --> 00:27:53.720
We learned about the node called Branch earlier

468
00:27:53.720 --> 00:27:54.894
Branch

469
00:28:01.040 --> 00:28:03.140
Using the Branch node

470
00:28:03.140 --> 00:28:05.577
we connect the Branch from this Tick

471
00:28:09.210 --> 00:28:13.360
Depending on the result of this 
conditional expression of this Branch

472
00:28:13.360 --> 00:28:19.440
if it's true or false, we execute something

473
00:28:19.440 --> 00:28:24.890
Our conditional expression is that when this isOpen

474
00:28:24.890 --> 00:28:30.000
the variable becomes True and open

475
00:28:30.000 --> 00:28:33.400
So, we drag and drop this variable

476
00:28:33.400 --> 00:28:37.250
to Get isOpen

477
00:28:37.250 --> 00:28:42.093
and connect it to this Condition like this

478
00:28:42.093 --> 00:28:46.343
Then, if isOpen is true

479
00:28:46.343 --> 00:28:47.743
the value contained in isOpen

480
00:28:47.743 --> 00:28:51.359
if it's true, True

481
00:28:51.359 --> 00:28:53.509
Iff it's true, the True execution pin

482
00:28:53.509 --> 00:28:59.119
and if it's false, the False execution pin will be activated

483
00:28:59.119 --> 00:29:02.919
When isOpen is true

484
00:29:02.919 --> 00:29:06.679
what do we do when it's open? 
We said that it'll rotate

485
00:29:06.679 --> 00:29:10.229
So, we can connect the True pin here like this

486
00:29:13.796 --> 00:29:17.484
Easy, right? 
Since we don't have to do anything when it's False

487
00:29:17.484 --> 00:29:19.479
I don't think we need to connect anything

488
00:29:19.479 --> 00:29:23.029
Let's compile and save in this state and check it out

489
00:29:23.029 --> 00:29:27.039
If you play, the door won't move in its current state

490
00:29:27.039 --> 00:29:35.479
The reason is that the value of Is Open is False now

491
00:29:35.479 --> 00:29:38.329
 If you go to the platform

492
00:29:38.329 --> 00:29:42.799
and make the isOpen variable true, it will move

493
00:29:42.799 --> 00:29:44.479
Let's go

494
00:29:44.479 --> 00:29:47.880
It opens

495
00:29:47.880 --> 00:29:49.799
It opens

496
00:29:49.799 --> 00:29:54.699
If you play again and have your character approach the platform

497
00:29:54.699 --> 00:29:59.239
you can see that it moves like this

498
00:29:59.239 --> 00:30:02.139
Okay? There's another problem here

499
00:30:02.139 --> 00:30:05.200
You can see that the door keeps rotating

500
00:30:05.200 --> 00:30:12.876
It should stop when it turns 90 degrees

501
00:30:12.880 --> 00:30:18.380
If the Z value of this Door's Rotation value

502
00:30:18.380 --> 00:30:24.440
is greater than 90 degrees, it should stop

503
00:30:24.440 --> 00:30:28.200
Right? I'll do that here

504
00:30:28.200 --> 00:30:31.900
While it's spinning

505
00:30:31.900 --> 00:30:35.440
here we will create another conditional expression

506
00:30:35.440 --> 00:30:39.397
Branch

507
00:30:39.397 --> 00:30:43.479
Branch, what's the conditional expression?

508
00:30:43.479 --> 00:30:49.559
If the Z value of the Door is greater than 90, right?

509
00:30:49.559 --> 00:30:51.959
That is, this Door

510
00:30:51.959 --> 00:30:54.239
I'll get the Door variable

511
00:30:54.239 --> 00:30:59.200
Get Door, this Door is this Door

512
00:30:59.200 --> 00:31:03.679
We're going to get the Rotation value

513
00:31:03.679 --> 00:31:08.520
That is, we will get the Rotation Z value in the Transform

514
00:31:08.520 --> 00:31:11.620
So we're going to pull it out like this

515
00:31:11.620 --> 00:31:15.599
and among the properties, functions, 
or values ​​that this Door variable has

516
00:31:15.599 --> 00:31:20.640
we're going to say, Get, get, what?

517
00:31:20.640 --> 00:31:26.239
Actor Rotation

518
00:31:26.239 --> 00:31:32.933
that is, get the rotation value of the actor

519
00:31:32.933 --> 00:31:37.080
Then we've got the rotation value of this Door

520
00:31:37.080 --> 00:31:39.320
That information is now stored here

521
00:31:39.320 --> 00:31:42.679
Likewise, you can subtract the return value

522
00:31:42.679 --> 00:31:47.760
but in this case, the values ​​are all X, Y, and Z

523
00:31:47.760 --> 00:31:49.880
So, we only need to get the Z value here

524
00:31:49.880 --> 00:31:52.030
So right-click here

525
00:31:52.030 --> 00:31:55.200
and click Split Struct Pin

526
00:31:55.200 --> 00:31:57.719
and it will be released right away

527
00:31:57.719 --> 00:32:02.840
We only need to compare this value among these

528
00:32:02.840 --> 00:32:09.760
So if this value, this Z value now is greater than 90 degrees

529
00:32:09.760 --> 00:32:12.919
 So right-click

530
00:32:12.919 --> 00:32:13.960
Greater

531
00:32:13.960 --> 00:32:17.239
 Bring up the Greater comparison operator

532
00:32:17.239 --> 00:32:20.640
And put this Z value above the comparison operator

533
00:32:20.640 --> 00:32:25.520
elow this, you can decide how much it will be greater than

534
00:32:25.520 --> 00:32:28.080
You can put a general number

535
00:32:28.080 --> 00:32:30.885
but for now, you can just put

536
00:32:30.885 --> 00:32:33.960
the number 90 here

537
00:32:33.960 --> 00:32:40.520
Then, if this Z value is greater

538
00:32:40.520 --> 00:32:43.520
than 90 degrees

539
00:32:43.520 --> 00:32:47.119
it will be established like this

540
00:32:47.119 --> 00:32:49.869
The result value is now connected

541
00:32:49.869 --> 00:32:51.760
to this Branch like this

542
00:32:51.760 --> 00:32:57.719
Then, if this result value is greater than 90 degrees, 
it should stop

543
00:32:57.719 --> 00:32:59.479
It should stop

544
00:32:59.479 --> 00:33:03.840
If the Z value of Door is greater than 90 degrees

545
00:33:03.840 --> 00:33:05.080
it will proceed with the True value

546
00:33:05.080 --> 00:33:12.479
At that time, we change the isOpen variable back to False

547
00:33:12.479 --> 00:33:15.919
If we changed it

548
00:33:15.919 --> 00:33:21.679
we said this Tick event would occur every frame

549
00:33:21.679 --> 00:33:24.320
When it occurs again

550
00:33:24.320 --> 00:33:30.679
is the isOpen variable inactive? Is it False?

551
00:33:30.679 --> 00:33:34.440
Then, it will say that it should not go to True but to False

552
00:33:34.440 --> 00:33:35.799
and will not do anything

553
00:33:35.799 --> 00:33:37.559
In other words, it will stop

554
00:33:37.559 --> 00:33:40.479
All of this will stop

555
00:33:40.479 --> 00:33:43.200
So, I'm going to do this here

556
00:33:43.200 --> 00:33:46.650
I will bring in the isOpen variable

557
00:33:46.650 --> 00:33:51.039
and open the Set isOpen mode

558
00:33:51.039 --> 00:33:56.119
So, when it's greater than 90 degrees when it's true

559
00:33:56.119 --> 00:34:03.219
I will run it to deactivate the isOpen variable

560
00:34:03.219 --> 00:34:05.719
That's what we did

561
00:34:05.719 --> 00:34:07.919
Done?

562
00:34:07.919 --> 00:34:09.359
Then, let's take a look again

563
00:34:09.359 --> 00:34:11.719
Let's test it here

564
00:34:11.719 --> 00:34:15.869
Let's print "It is now stopped"

565
00:34:15.869 --> 00:34:22.479
through Print String

566
00:34:22.479 --> 00:34:25.320
If this works well

567
00:34:25.320 --> 00:34:27.270
isOpwen will be deactivated

568
00:34:27.270 --> 00:34:32.000
and "It is stopped" will be printed

569
00:34:32.000 --> 00:34:33.559
Then, it must have worked well

570
00:34:33.559 --> 00:34:35.119
We'll know

571
00:34:35.119 --> 00:34:37.058
Let's say "It is stopped"

572
00:34:41.454 --> 00:34:45.559
about 10 times for a long time

573
00:34:45.559 --> 00:34:48.309
Right now, "Open" and "It is opened"

574
00:34:48.309 --> 00:34:50.239
are set to 2 seconds

575
00:34:50.239 --> 00:34:55.320
so that it will disappear quickly, so let's set it to 10 seconds

576
00:34:55.320 --> 00:34:59.479
If you compile, save, and play again

577
00:34:59.479 --> 00:35:03.059
pressing a button like this

578
00:35:03.059 --> 00:35:07.119
will stop with the message "It is opened"

579
00:35:07.119 --> 00:35:08.640
This time, it's finished

580
00:35:08.640 --> 00:35:10.840
After it's fully opened and over 90 degrees

581
00:35:10.840 --> 00:35:13.200
you can see that "It is stopped" is printed

582
00:35:13.200 --> 00:35:17.559
and the door naturally stops

583
00:35:17.559 --> 00:35:24.799
Then, this time, I think the opening speed is a little slow

584
00:35:24.799 --> 00:35:28.559
so I'll look for something suitable

585
00:35:28.559 --> 00:35:31.080
Right now, it's 1

586
00:35:31.080 --> 00:35:34.760
so let's create a variable

587
00:35:34.760 --> 00:35:36.599
to modify it externally

588
00:35:36.599 --> 00:35:39.199
So, I'll click on VARIABLES

589
00:35:39.199 --> 00:35:41.852
and create a variable

590
00:35:41.852 --> 00:35:48.080
I'll name it Speed

591
00:35:48.080 --> 00:35:55.520
I'll make sure the value is Float and up to the decimal point

592
00:35:55.520 --> 00:36:03.960
Then, I'll extract this variable with Get Speed ​​

593
00:36:03.960 --> 00:36:06.960
​​and put the variable

594
00:36:06.960 --> 00:36:09.280
into Delta Rotation like this

595
00:36:09.280 --> 00:36:11.440
Click on Compile and Save

596
00:36:11.440 --> 00:36:16.960
For now, we should set the default value for Speed ​​to 1

597
00:36:16.960 --> 00:36:21.440
And I'll check Instance Editable

598
00:36:21.440 --> 00:36:25.440
so that it can be modified externally

599
00:36:25.440 --> 00:36:31.000
Click on Compile and Save
This time, when you go outside

600
00:36:31.000 --> 00:36:33.199
it's not this Door

601
00:36:33.199 --> 00:36:35.599
and if you click on this Blueprint

602
00:36:35.599 --> 00:36:39.565
the Blueprint we created, you can see that there are items

603
00:36:39.565 --> 00:36:42.039
that can be set up to the Door Speed

604
00:36:42.039 --> 00:36:45.479
It's currently at 1, but I'll make it faster

605
00:36:45.479 --> 00:36:47.080
How about 10?

606
00:36:47.080 --> 00:36:49.431
I'll play it when it's like this

607
00:36:49.431 --> 00:36:51.479
If I go like this

608
00:36:51.479 --> 00:36:53.719
it's too fast, right?

609
00:36:53.719 --> 00:36:56.440
Let's just make it around 3

610
00:36:56.440 --> 00:36:59.240
You'll see it open

611
00:36:59.240 --> 00:37:01.799
if you play it

612
00:37:01.799 --> 00:37:06.000
If you think it's too fast, you can decrease it further

613
00:37:06.000 --> 00:37:12.479
You can even decrease it to 0.5

614
00:37:12.479 --> 00:37:17.119
You'll see it open slowly like this

615
00:37:17.119 --> 00:37:19.334
 I adjusted the speed of the door

616
00:37:19.334 --> 00:37:21.560
using the Speed ​​variable

617
00:37:21.560 --> 00:37:26.680
So, I created a function so that a constant value

618
00:37:26.680 --> 00:37:29.464
increases every frame

619
00:37:29.807 --> 00:37:33.649
Delta Second

620
00:37:34.239 --> 00:37:37.920
But this function has a fatal error

621
00:37:37.920 --> 00:37:41.040
It is not an error at this point

622
00:37:41.040 --> 00:37:44.560
on the PC you are playing on

623
00:37:44.560 --> 00:37:48.800
However, learning about the delta second concept

624
00:37:48.800 --> 00:37:55.439
will help you realize this mod has a huge error

625
00:37:55.439 --> 00:37:58.680
Let's learn about delta second

626
00:37:58.680 --> 00:38:00.760
First, let's say there are two PCs

627
00:38:00.760 --> 00:38:04.119
Let's say that two players, Cheol-soo and Young-hee

628
00:38:04.119 --> 00:38:07.959
are playing a racing game with two computers

629
00:38:07.959 --> 00:38:11.760
This race game is designed so that

630
00:38:11.760 --> 00:38:14.560
each frame reads 1 meter

631
00:38:14.560 --> 00:38:17.640
Let's say Cheol-soo's computer is a bit better

632
00:38:17.640 --> 00:38:21.199
so it takes 0.25 seconds to read one frame

633
00:38:21.199 --> 00:38:23.800
And in the case of Young-hee's computer

634
00:38:23.800 --> 00:38:29.160
if it takes 0.5 seconds

635
00:38:29.160 --> 00:38:33.400
when 1 second passes, Cheol-soo's PC will have read 4 times

636
00:38:33.400 --> 00:38:37.680
and every time it reads a frame, it will move 1 meter each

637
00:38:37.680 --> 00:38:41.479
so that Cheol-soo will have moved 4 meters

638
00:38:41.479 --> 00:38:47.239
Young-hee's PC will read two frames per second

639
00:38:47.239 --> 00:38:49.040
Since it reads 0.5 seconds per frame

640
00:38:49.040 --> 00:38:52.540
it will read 1m per frame

641
00:38:52.540 --> 00:38:54.400
and 1m per frame

642
00:38:54.400 --> 00:38:56.550
so as a result, it will move 2m

643
00:38:56.550 --> 00:38:59.199
in 1 second

644
00:38:59.199 --> 00:39:04.719
In other words, Yeong-hee will always lag behind Cheol-soo

645
00:39:04.719 --> 00:39:08.880
This means that the result of the running game will differ

646
00:39:08.880 --> 00:39:13.199
depending on whether the PC is good or bad

647
00:39:13.199 --> 00:39:16.839
This will cause unfairness

648
00:39:16.839 --> 00:39:19.800
So the method used is

649
00:39:19.800 --> 00:39:21.756
right here, delta seconds

650
00:39:21.756 --> 00:39:26.280
That is, the displacement time is applied

651
00:39:26.280 --> 00:39:30.430
It multiplies the time to read one frame

652
00:39:30.430 --> 00:39:32.800
and maintains it at a certain time

653
00:39:32.800 --> 00:39:37.200
In other words, it forces the movement to be 1m

654
00:39:37.200 --> 00:39:39.040
when 1 second has passed

655
00:39:39.040 --> 00:39:43.000
So for each frame

656
00:39:43.000 --> 00:39:50.000
Cheol-soo multiplies a fixed amount of time 
by a slightly smaller number, 0.25

657
00:39:50.000 --> 00:39:53.600
and Young-hee's computer multiplies it by 0.5

658
00:39:53.600 --> 00:39:55.400
which is a slightly different

659
00:39:55.400 --> 00:39:58.900
Cheol-soo and Young-hee's computers multiply

660
00:39:58.900 --> 00:40:01.182
slightly different amounts of time

661
00:40:01.182 --> 00:40:05.032
In the end, these two players

662
00:40:05.032 --> 00:40:08.682
can get the same result

663
00:40:08.682 --> 00:40:12.359
of moving 1m in 1 second

664
00:40:12.359 --> 00:40:16.759
Then, it won't be unfair to either of them

665
00:40:16.759 --> 00:40:20.809
Multiplying this Speed ​​value by the value of the time

666
00:40:20.809 --> 00:40:25.719
to read this frame, called delta seconds

667
00:40:25.719 --> 00:40:29.019
fixes the overall time

668
00:40:29.019 --> 00:40:31.519
This is the most basic element in programming

669
00:40:31.519 --> 00:40:33.669
the most basic element

670
00:40:33.669 --> 00:40:37.920
in creating real-time content

671
00:40:37.920 --> 00:40:39.570
So I'm going to do that

672
00:40:39.570 --> 00:40:43.070
So if you right-click in this blank space

673
00:40:43.070 --> 00:40:52.501
and search for displacement time, Get World delta Seconds

674
00:40:52.501 --> 00:40:53.848
this node will appear

675
00:40:56.343 --> 00:40:58.793
This Delta Second is different for each PC

676
00:40:58.793 --> 00:41:00.683
It varies depending on the situation

677
00:41:00.683 --> 00:41:05.083
Since this is information that the engine calculates and sends

678
00:41:05.083 --> 00:41:08.260
you can just take it and use it

679
00:41:08.260 --> 00:41:10.460
So you need to multiply this Delta Seconds

680
00:41:10.460 --> 00:41:13.670
by this Speed ​​value

681
00:41:13.670 --> 00:41:15.825
So, Multiply

682
00:41:18.735 --> 00:41:22.750
Multiply this Speed ​​value by this Delta Seconds

683
00:41:22.750 --> 00:41:26.700
and connect this multiplied result

684
00:41:26.700 --> 00:41:30.959
to Delta Rotation like this

685
00:41:30.959 --> 00:41:35.759
This way, the fairness between devices will not be violated

686
00:41:35.759 --> 00:41:37.245
Let's play

687
00:41:40.040 --> 00:41:42.048
Now, if you press the pedal

688
00:41:46.364 --> 00:41:50.329
it will probably not seem to be moving

689
00:41:52.840 --> 00:41:56.840
but if you press F8 and come out

690
00:41:56.840 --> 00:41:59.590
very slightly

691
00:41:59.590 --> 00:42:03.800
You can see it keep going up

692
00:42:03.800 --> 00:42:06.150
That means it is moving

693
00:42:06.150 --> 00:42:09.950
The reason it's so small is because 
by multiplying by the delta second

694
00:42:09.950 --> 00:42:12.100
the number moving per frame

695
00:42:12.100 --> 00:42:14.245
has become very low

696
00:42:14.245 --> 00:42:18.295
So now, we need to increase

697
00:42:18.295 --> 00:42:20.800
this Speed ​​value a lot

698
00:42:20.800 --> 00:42:22.550
It had become very low at 0.5

699
00:42:22.550 --> 00:42:25.850
This time, I'll increase it a bit to around 10

700
00:42:25.850 --> 00:42:28.826
If you play it

701
00:42:28.826 --> 00:42:31.426
It's a bit faster than before

702
00:42:31.426 --> 00:42:32.520
We need to go a bit faster

703
00:42:35.490 --> 00:42:38.021
Let's put it at around 100

704
00:42:38.021 --> 00:42:41.160
If you play it

705
00:42:41.160 --> 00:42:46.577
the result is the same in that 
it opens when you step on the pedal

706
00:42:46.577 --> 00:42:49.985
but to ensure fairness between devices

707
00:42:49.985 --> 00:42:52.885
we applied something called delta second

708
00:42:52.885 --> 00:42:55.635
which is different from the current system

709
00:42:55.635 --> 00:42:59.085
So now, when you run this function on this PC or another

710
00:42:59.085 --> 00:43:04.066
it will move the same way

711
00:43:04.066 --> 00:43:07.877
So, I created a simple function

712
00:43:07.877 --> 00:43:10.377
to open a door using blueprints

713
00:43:10.377 --> 00:43:12.520
Thank you

714
00:43:12.520 --> 00:43:15.684
Now, let's summarize what we learned

715
00:43:16.648 --> 00:43:17.898
Role of Collision and How It Works
Automatic Door
Implement automatic door function that opens by rotating when you step on the step
Drag SM_Door asset from StarterContent - Props and place it in the world

716
00:43:17.898 --> 00:43:19.148
Create a BP folder - Create a BP_Door blueprint inheriting the Actor class and place it in the level

717
00:43:19.148 --> 00:43:20.398
Blueprint Scripting
Add a Cube component using the +Add component in the component window
Add a Box Collision component for collision with the character

718
00:43:20.398 --> 00:43:21.598
Testing collision detection using Print String node in [Event ActorBeginOverlap]

719
00:43:21.598 --> 00:43:22.298
Set up the door rotation
Use the Add Actor World Rotation node to operate
Create a Door variable that contains the object to rotate and connect it to the Target input pin

720
00:43:22.298 --> 00:43:22.998
Connect the Event Tick node to the Add Actor World Rotation node, then set the Delta Rotation Z value
Create the isOpen variable, then select the Boolean data type

721
00:43:22.998 --> 00:43:23.648
Connect the Event Tick node to the Add Actor World Rotation node, then set the Delta Rotation Z value
Create the isOpen variable, then select the Bool

722
00:43:23.648 --> 00:43:24.348
Set the isOpen variable to be activated when ActorBeginOverlap is executed
Set the door to rotate only when the isOpen variable is True

723
00:43:24.348 --> 00:43:25.070
Set the door to stop rotating when the Rotation Z value of SM_Door is greater than 90

724
00:43:25.070 --> 00:43:25.815
Control door rotation speed
Create a variable, name it Speed, and select Float data type

725
00:43:25.815 --> 00:43:26.568
Drag the Speed ​​variable to the graph window, select Get Speed, and connect it to the Delta Rotation Z pin
Enable Instance Editable to enable external modification

726
00:43:26.568 --> 00:43:27.568
Delta Second
Understanding Frames
If the code moves a certain distance per frame, the distance will vary depending on the performance of the device

727
00:43:27.568 --> 00:43:28.568
The game path will vary depending on the device specifications, which is unfair

728
00:43:28.568 --> 00:43:29.568
Delta Second
To ensure fairness between devices, apply the displacement time Delta Second, the time it takes to read 1 frame
If you apply Delta Second, you can adjust it to move the same distance simultaneously

729
00:43:29.568 --> 00:43:30.518
Apply Delta Seconds
Create Get World delta Seconds node
Create Multiply and connect Speed ​​and Get World Delta Seconds nodes

730
00:43:30.518 --> 00:43:31.485
Connect Multiply result to Delta Rotation Z pin
Check that the door rotation speed changes depending on the Speed ​​value