Original subtitles

0 Welcome to hit detection. 1

Basically, hit detection means that the enemy, when it gets hit by a projectile, it needs to be notified. 2

Hey, wait a second. 3

I have been hit. 4

Let's find out how this works. 5

So if I run the scene and we think this is a projectile and this is the enemy, if we move the projectile 6

through the enemy, then a hit was detected in the output. 7

Of course, multiple projectiles will yield multiple hit detected results. 8

This is important because if the enemy does not directly detect the player, but the player hits the 9

enemy, then the enemy should retaliate. 10

Let's see how this is done. First, 11

as you can see, there is no player, actually just the bullet. 12

And the bullet has a mesh instance which is not so relevant just for visual purposes, but it has an 13

area. 14

And this is important because this is how the collision will happen. 15

It has monitoring turned on and there is a collision shape which is a capsule shape. 16

Please note that the collision shape is a little bigger than the projectile. 17

This is just for the demo purposes to make it easier to use. 18

Now let's see about the bullet. 19

By the way, please note that the area 20

has on body_entered and this signal is getting triggered in the bullet. 21

So basically the bullet script is quite simple. 22

It just detects if a body entered the area, it gets the parent of that object and then if the object 23

has the method called register hit. 24

In this case, for example, the AI would have implemented this method, then it calls it. 25

If not, nothing happens. 26

Now let's look at the AI. 27

So here the actual collision happens in the kinematic body by just having the body in the bullet. 28

We will not get the register hit, which is a level above it. 29

So of course this get parent needs to be used. 30

By the way, pro tip, make sure you have the same structure for the enemies as for the players because 31

you have a generic projectile. 32

Then, 33

in some cases this might be at the body level, in some other cases it might be at the parent level. 34

And then you have to implement either checks for just the body if it has this register hit or the parent 35

and the body and it will get messy. 36

So make sure you have the same structure for every object that needs to receive a projectile. 37

But in this case is the higher level. 38

So here is just a register hit and of course it will print hit detected. 39

Then this can be later included in the AI's decision system and tell: Hey, please attack the player now 40

or retreat or whatever. 41

So basically this is the hit detection. Now that we have covered how to deal if sensors, state machines. 42

Let's head over to the last part of the course, which is the actual project. I'll see you in there!