Have you ever wanted your NPCs to

actually remember how you treat them?

Today, we're going to build a clean,

reusable relationship system in GDO 4.5,

and you'll be able to drop into any game

in no time. Welcome back to GDAU dev

checkpoint. I ran a poll recently asking

what systems you wanted to see most, and

the relationship system won. But don't

worry, we're going to do all of them.

We're going to cover all these topics in

separate videos in the order they were

voted for. Now, creating social systems

can get messy if you hardcode them into

every single enemy or shopkeeper. So,

today we're going to build a

relationship component, a single brain

that manages friendship, hatred, and

everything in between. First, we'll

build our component. Instead of just a

script, we'll make it a scene. This lets

us drag it and drop it into any

character in our game instantly. All

right. I'm here in a brand new project.

I'm going to create a new scene. I'm

going to use other node. Just use

regular node. And I'm going to rename

this node to relationship

component.

Then I'm attach a script to this. The

green icon there. I'm going to make a

new folder. I'm going right click new

folder. Call it scripts.

And I'm going to save relationship

component GD in that and create.

Then I'm going S and save the scene in a

new folder called scenes.

Then save it. Now, let's define what a

relationship actually is. At its core,

it's just a number. We need a starting

value, a maximum value, and a way to

tell the rest of the game when that

number changes. Now, back in our

relationship component script, I'm going

to get rid of the boilerplate code.

Going to add in some signals. So, the

first signal we're going to use is going

to be called affinity changed, and it's

going to have a new amount passed into

it. The second signal we're going to

want to use is a relationship

status changed. This how we're going to

track our friend and foe status or

neutral. We're going to pass status into

that. The new amount into the affinity

change. And we need some export

variables. First one we're going to use

is current affinity.

And we're going to have that to be int.

We're going to start at 50. So neutral.

The next export variable we're going to

use is max affinity.

We're going to set that in to be 100.

So if we're at 100 or friends, then we

need a minimum affinity. So if this is

zero, we're going to be enemies. And we

also need to set the

friend and foe thresholds. So when to

become friends, when to become enemies.

So we're going to set that at 70 to be a

friend.

And for enemies, we're just going to go

to 30. So foe or enemy threshold,

set that in to 30. So it goes below 30,

we're going to be enemies. Then we need

a a function here. And we're going to

call change affinity and we're going to

change it by an amount. And int is going

to be that amount. So say if we give a

gift or if we insult them, we're going

to change that current affinity by that

amount we're passing into this function.

Well, then we also need to emit this

signal to say this happened. So affinity

changed. This is a signal. We're going

to emit it. And what we're going to emit

is the current affinity

right there. So then we need to check

for status changes. Let's check for

status change. So if current affinity

right there is greater than or equal to

our friend threshold, well we need to

change our relationship status.eit

to friend

just like that.

But if it's not if the current affinity

is

less than or equal to the enemy

threshold, well say the relationship

status has changed again to enemy.

But if it's neither of these things,

well, it's going to be right in the

middle. So the relationship status there

is going to be emitted as neutral.

Just like that. Go and save the script.

Now you've reached your first

checkpoint. Stop and look at the code

what we just wrote. Current affinity

plus equals amount. What happens if we

add a thousand to it or subtract a

thousand? We don't fix this. Your player

could have 5,000% love with a goblin or

negative infinity with the merchant

breaking your game logic. We need to

clamp it. So this variant here, clamp

value variant minimum to maximum. That's

what we want to use to clamp our

affinity. So, back in our project, right

below our current affinity here, we want

to set our current affinity

to equal a clamp. We want to set it

between a variant, which is what we want

to set to a minimum and a maximum. So,

go ahead and give that a try. Clamp our

current affinity between the max and the

min affinity. Give that a go and pause

the video now.

How'd that go? Did you get it? Let's go

and do it together. If you didn't, that

is just fine. So, all we need to put

here is our current affinity. We're

going to clamp it between our min

affinity

and our max affinity.

Just like that. Make this bigger. So, we

should also have something that says,

hey, what is our current and old

affinities?

So, our new affinity, we're just going

to print it to a debug console here.

We're going to point out our current

affinity

and that's going to be a debug check. So

you make sure this is going up and down

as intended. The key takeaway here is

always sanitize your data. Using clamp

ensures your values never escape the

boundaries you set, preventing

gamebreaking bugs later. Now for a

little bit of magic. Because we saved

our component as a scene, adding it to

an NPC is effortless. And a number in

the console is boring. So let's make

that visual. We'll add a progress bar

that updates automatically whenever our

relationship changes. Going to make this

smaller here. I'm going to create a new

scene. Scene. New scene.

It's going to be a 2D scene. I'll rename

the root node to NPC.

Go back to my 2D scene here. I'm going

to add a child node of sprite 2D.

I'm going use the GDO icon that comes

with every project as my character. We

also want our new relationship component

in here. the relationship component

scene. We're going to drag and drop that

onto NPC. Now we have it on our NPC.

What we're also going to do is add a

progress bar to see the results. So add

child node NPC, which means the progress

bar so we can see how friendly or faux

we are. Now with the progress bar

selected, I'm going to go over to the

inspector here. I'm going turn off the

percentage. I'm going to set the current

value to 50. So neutral and go down to

layout. set the custom minimum size to

100 on the X so we can see it. I'm going

change the anchor presets to center.

Now I'm going to go into my window here

and zoom in a bit. I'm going use my move

tool. I'm going to drag this straight

up.

There we go. Right above our character's

head. And we're click on our root node

at PC. We're going to add a new script.

We're going to put it in our scripts

folder. Make sure scripts open scripts

create. I'll make this bigger. I'll go

ahead and delete this boiler plate code.

Once that's gone, I'll make this smaller

again so I add some onesies. I need a

relationship component reference. I'm

going to click and drag and hold down

control and drop that. Now I have that

in my script. And I also need the

progress bar. Click, drag, controll,

drop. All right, now I have those. I'm

going make it bigger. Enter down a

couple times. I'm going to create the

ready function

right there. And then I may click pass

real quick as a placeholder. Enter down

a couple times and create a function.

It's going to be called on affinity

changed.

And then we're going to take in a new

value into this function. New val.

And then what this is going to do is

change the progress bar

value

with a new value.

So when this function is called, it's

going to change our progress bar. Then

back in our ready function, we need to

commit to this signal from the ready

function

in the relationship component. The

signal we want to commit to is the

affinity changed. and we want to

connect. And we want to connect with our

function we just wrote on affinity

changed. Now we have the brain and the

visuals. Let's create a fake interaction

to test it. We'll bind the space bar to

give a gift and escape to insult them.

Our component also shouts out friend or

enemy whenever the value crosses those

lines. Let's make our NPC listen to it.

Now we're going to go back to our NPC

script and save it. and the NPC scene.

We also need to save that. And back in

our NPC script and create a new function

underneath on affinity changed. That's

going to be on status changed.

Our new status for our friend or foe.

Now we're going to use we'll just print

out to the console as well. So our

current status

is going to be

our new status.

It helps if you do a underscore in

between. There we go. And then after

that, well, we want a simple visual

feedback so we can see on the screen

what's happening as well. So if new

status

is ren,

well, we're going to change the progress

bar to green. We just do progress bar

modulate

and we're going to change the color to

green.

Just like that. And then well for enemy

of course I'm going to use red. So enemy

progress bar

modulate

to red.

There we go. And also if for neutral

neutral usually runs the gray gambit. So

we'll do the progress part. Modulate

colors gray.

There we go. Notice going to connect

this function to our relationship

component. So back in our ready

function, I'm going to connect the

relationship component, the relationship

status

relationship status changed function.

Connect that to our new function of pod

status changed

and save that. Now we add some input

function here. So underneath the on

status change, we're going to do an

input event function to listen for our

space bars and our escapes. So if event

is action pressed, there we go. We want

to look for UI except that's going to be

our space bar. By default, GDO has a UI

accept in it already, so we don't have

to set that up. So space bar. Now if

that's pressed well this is going to be

the give gift.

There we go. Then we need to change our

relationship component change affinity

change affinity

to 10. And then well if we press escape

we want to do the opposite. So the vent

is action pressed. The cancel is the

escape one. Here I cancel. There we go.

And then we want to set that to be the

it's going to usually the escape button

escape button. And if we do that, well,

we want to print insulted,

right? But we also want to change our

relationship component. Change affinity.

And we want to do that to minus 10.

We're going to go and save that. Make

this smaller. Go back to our 2D scene.

I'm going to zoom out here. I'm going

grab the NPC. Use the move tool. And

this is our viewport window. I'm going

to drag our NPC to the middle so we can

see them. Save. We're in the current

scene.

All right. Now, I'm going to drag up so

we can see the console. I'll press

spacebar. And we go up up. Now we're a

friend. We go up up to 100. Then we stay

at 100. Then escape. Back down. Down.

Down. Now we're neutral. We're back to

gray. Now we're red. Enemies. Down.

Down. tab. Now we stay at zero. And just

like that, you have a fully functional

relationship component. The beauty of

this is that the NPC script doesn't need

to know how the math works. It just

tells the component add 10, remove 10,

and the component handles the signals,

the clamping, and the logic.

You can drag this specific node onto a

shopkeeper to determine prices or a

quest giver to unlock secrets. It's

completely reusable.

expanding this, we can take this a step

further and use resources to give our

NPC specific likes or dislikes. So, you

can't just spam the same gift over and

over. Let me know in the comments if

that's something you'd be interested in.

Now, if you found this helpful at all or

fun, leave a comment what your GDO game

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