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‫Hello and welcome.

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‫In this lecture, we're going to be getting at eye to followers and navigate around the world, avoiding

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‫obstacles and just generally being a little bit of an annoying nuisance.

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‫Let's dive in and see how this is possible.

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‫So the next most obvious, obvious piece of the puzzle that we need to sort out here is getting our

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‫eye to move towards us.

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‫It's no good them just standing there.

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‫They also need to move and then they'll need to shoot.

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‫First of all, let's figure out how we can do movement.

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‫Now, when you're moving with eye needs to know about obstacles, it needs to do something called pathfinding

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‫because say, I'm hiding down in this corridor here and it wants to get to me.

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‫It needs to know that it can't just move through the wall.

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‫It's going to need to plan its route to come around the obstacles and come towards me.

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‫Now, the way this typically works in games in general and specifically here in Unreal is that we generate

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‫a mesh which tells us where is walkable within a level and then using various algorithms, one of which

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‫is called a star path finding.

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‫You can navigate on this mesh and create a route plan and the AI then uses this route plan to move along.

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‫So that's the kind of outline of the process.

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‫Fortunately, a lot of that is done for us.

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‫We don't have to code this from scratch.

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‫So what we need to do is, first of all, be able to see the nav mesh.

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‫And at the moment we can't see enough mesh partially because there isn't one.

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‫So what we need to do is look in our placed actors window here, or so we go to window and look for

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‫placed place actors.

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‫We need to search for a nav mesh and we're looking for the nav mesh bounds volume.

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‫Now this creates a volume, a kind of box, and everything within that box is going to be checked for

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‫how navigable it is, basically, whether it's flat or whether it's not too steep.

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‫Basically where there's a wall, you can't go through walls, you can't walk over walls because they're

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‫too steep.

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‫So if we drag in a nav mesh bounds volume and just bring it here and just put it slightly through the

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‫floor so that this allows the floor to be part of that navigation calculation, then what we've got

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‫to do is enable the visibility of NAV meshes.

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‫You can do this by clicking on the show button in the top left of your viewport and then clicking on

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‫navigation or using the shortcut.

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‫P So I'm going to use the shortcut.

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‫P And selecting well, you don't even have to select the bounds volume.

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‫You can instantly see this green mesh has appeared within the bounds volume which is telling us this

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‫is a walkable area.

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‫So if we had our enemy within this area and his target was also within the area, then it could find

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‫a path along this mesh.

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‫Now let's have a look at what happens if we move this to where there's an obstacle.

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‫You can see that the mesh kind of cuts out around this obstacle.

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‫So what we actually want to do is have this volume encompass the whole of our level and you could choose

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‫not to or just do it in certain segments, but the easiest way is just to increase the bounds of this

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‫volume, which you can do.

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‫If you go over to the details pane on the right, there's the brush settings and you can change the

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‫size of the brush like so you can see we can make it larger, we can make it wider and it goes red when

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‫it's being recalculated.

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‫You can see it's doing that building nav mesh and the larger it's going to be, the harder it is going

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‫to be to build a nav mesh longer it's going to take.

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‫But you can see that this is working.

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‫It's cutting out the corridors.

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‫It's cutting out the obstacles that we can't walk around.

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‫The second part of this puzzle is having our eye able to do its rooting algorithms on this mesh.

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‫Now, let's go ahead and open the BP shooter eye control, because I want to show you something that

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‫is in here.

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‫I'm going to open up the full blueprint editor here and have a look here.

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‫There is a component called the path following component.

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‫That component is responsible for finding an F mesh and then basically allowing us to create paths and

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‫follow them and move along them automatically.

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‫So we don't have to build any of that functionality in.

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‫All we have to do is use a function that's available on our AI controller.

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‫If you go and search for the AI controller H and look for the move to function, then let's do move

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‫to with an open brackets.

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‫Then there's a couple of options here.

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‫We've got a one takes a move to request.

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‫There are some other options here too, but they actually go by a different name.

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‫Now, in later versions of Unreal, we've got move to actor and we've got move to location, which have

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‫the same distinction as our setting focus.

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‫You can set focus to something that's moving like an actor, or you can set focus to a specific destination

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‫such as a waypoint in your patrol route, for example, might be a move to location.

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‫So I'd like you to have a go at attempting a move to as your challenge.

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‫So get a nav mesh in your scene, make it cover as much of the scene as you need to for you to be able

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‫to move around and have the.

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‫I follow you in all locations and then call that move to either move to act or move to a location.

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‫You decide which inn begin play to get the AI chasing us.

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‫So pause the video and have a go.

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‫Okay.

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‫Welcome back.

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‫Let's give this a shot.

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‫So first things first.

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‫We're going to have I'm going to be using a move to actor and we're going to have to set the goal actor.

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‫So let's go over to our shooter I controller CP and in there begin play we can do move to actor and

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‫we've got an actor already the player -- which we've got from the last lecture and let's just have

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‫a look.

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‫Are there any other useful properties here?

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‫We've got an acceptance radius.

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‫At the moment it has no acceptance radius.

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‫Basically it gets as close as it possibly can.

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‫I think that might be a little bit encroaching.

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‫I'm going to give it an acceptance radius of two meters, so it will try to get within two meters of

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‫us.

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‫So let's go ahead and build that.

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‫And once that's complete, go over into the engine.

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‫And let's have a look.

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‫I'm going to not expand the bounce volume here just to give you a taste of why we need the bounce volume

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‫in the first place.

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‫So let's start off with an alt p.

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‫And here we are.

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‫We're on the nav mesh and this guy has moved towards us automatically.

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‫But if I leave that nav mesh, he can no longer get any closer to me because he can't find the route.

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‫He can't find a way of getting to me.

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‫So what we're going to do is we in fact, I'm not sure that was what's actually going on here, because

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‫probably what's happening is that he's getting within the acceptance radius of me and they're not trying

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‫again.

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‫So one way to check that would be to just remove this acceptance radius and recompile and then we can

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‫go over and see if that's what's going on.

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‫So yeah, he comes right up to me if I move away.

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‫Well, he basically forgot that command.

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‫So what we want to do is do this in tic, because basically once he reaches me, he gives up on the

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‫idea of chasing me.

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‫So let's move this over to tic.

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‫This isn't the ideal way to do it, but that's what we're going to do.

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‫Just for now, I'm going to copy the signature of Tic from actor H, and I know that it goes in the

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‫public section, so I'm going to create a public section at the top.

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‫Copying the signature, make it an override, just safety, and then implement it over in the C++ and

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‫move our move actor in to tick and the acceptance radius still of two metres that's try this now and

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‫obviously it's complaining that we don't have a player -- over there.

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‫So let's go and make sure we're getting hold repeating this line that gets hold of the first player

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‫-- over in attic as well.

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‫And now we should be able to test it out properly, do an alt pig into the world.

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‫He comes and gets us within two meters.

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‫I move away from him and I'll look at that.

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‫He's not even aiming at me properly this time, but he is trying to follow along.

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‫But as soon as I leave that nav mesh, he no longer knows how to find me.

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‫So let's fix that up, shall we?

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‫We're going to go to an nav mesh bounce volume.

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‫If I can select it.

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‫There we go.

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‫And then we want to really zoom out here to try and encompass the whole of our level.

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‫It looks a bit janky on the outside this level, but that's just the way things often work, is that

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‫you build the level to be viewed from the inside, not from the outside.

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‫So let's make this much wider.

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‫Let's make it much taller so that it encompasses all of the level and just drag it out so that all the

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‫extents of the level here are covered.

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‫Just make it a little bit wider, a little bit longer too, and just make sure all of this is encompassed

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‫fully.

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‫And you can see the green has appeared as it's calculated the nav mesh.

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‫And let's just make sure that the nav measure is going down low enough that it's covering the lowest

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‫extents of our map seems to be covering it now.

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‫So if we go ahead and we can hide and nav mesh now that we have set it all up and we can do an alt p

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‫to go ahead and play and he can find us and follow us pretty much anywhere that we go within this level.

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‫You can see that our trusted loyal servant is following along behind us wherever we choose to go.

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‫He is just tailing us and trailing us, which is very annoying.

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‫But he is able to do that.

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‫Well, some stuff.

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‫So in this lecture we have seen how we can create our NAV measures and how we can use them to get our

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‫air to follow us around the level.

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‫Next lecture we're going to loop back around to this aming fix the bug and check line of sight so that

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‫we don't necessarily always chase the player around.

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‫See there.

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‫And I've just noticed one silly little mistake that I have made here, which is that I'm not calling

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‫to super colon colon tic.

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‫So that is actually why when you sometimes you get these weird unexplained bugs, if you're not calling

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‫to super, then things don't always work as expected.

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‫That's why the focus had stopped working, because essentially we had disabled tic on a high controller,

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‫which is no good.

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‫If you enable that, then everything should work as normal with the setting focus.