Training Stream - Advanced AI - May 12th, 2015

[MieszkoZ]

Just to quickly touch on the questions that have not been answered.

Also, I’d like to hear about his experience with regard to cover systems and the like.

This is a topic for a long conversation. But the way I’d see implementing a system like that in UE4 would be to use HotSpots (that are not currently available) that would define each cover as hotspot’s slot, in combination with EQS to tell good covers from bad covers. This could be used for both static and dynamic covers, cut if someone did static (like in Gears of War) I’d also do a fair amount of precomputing to cache cover-to-cover visibility data for example.

If possible it would be nice to cover the area of spatial LODing of AI. Basically handling AI at scale with persistence, over large distances. Maybe general thoughts on higher level system organisation and delegation from manager classes.

We don’t support AI LOD-ing our ot of the box, and this is another topic for a long conversation. I’d look through all the AI Wisdom and Game AI Pro books (lot’s of good stuff there!).

In the stream demonstrating techniques used for the kite demo, there was a short explanation about a dynamic nav-mesh system that built tiles on the fly as needed. How far off is this from being integrated and ready to use?

It ships with 4.8, it works great in 4.8 prev 2 build and we’ll record a short video showing how to use it.

Something I asked about on the last stream, but just wanted to ask : any plans to implement a BT node/construct to allow choosing of tasks based on some weighted probability function? Currently it seems really hard to work around the priority-based structure when you want to introduce some randomness into the behaviour. At the moment I have a sequence which starts with a task used to make the randomized choice, followed by a selector which decorates each child with a test to see if that particular task was the one chosen. It’s very ugly!

Utility- or probability based selectors are on the todo list and I’d very much like to get them in this year.

There is an option for Debug under the Dominant Sense in AIPerceptionComponent. How to use that?

Not sure… can’t find it in 4.8 so we probably removed it!

I know there is a system within Unreal Engine called Pawn Action. It makes sense, but my question is what you think about using to create a Task/Planner system? Have you attempted to expand on this or what is your uses for it?

That’s actually one of the goals. The whole idea for pawn actions (that I’m currently redoing and will refer to as Gameplay Tasks, or in case of AI the AI Tasks) is that it’s an interface between AI’s body and all sorts of sources of “logic”. Logic in this case could be Behavior Trees, level scripting, AI “reactions” (like hit reactions), or any kind of externally implemented AI “brains” (like HTN, FSM, GOAP, etc).

How would I use the Pathing System of UE4 with procedural generated content? Is there a way to generate a navmesh at runtime or generate a navmesh on my own and pass it to the navigation system?

There’s no way to have UE4’s navigation system use a hand-created navmesh. However with some C++ skill you could implement your own navmesh class (derived from RecastNavMesh) that could do that. We do support custom navigation types.

In terms of just having navmesh with procedurally created content all you need to do is to configure your navmesh to be runtime-dynamic, which means namesh will generate on runtime when new navmesh-relevant gets introduced, or old actors modified (transformed, destroyed).

How are scores from multiple EQS tests combined to give the final item score? Just summed? Is there any control over this?

A test scores get normalized across all items tested, and then the normalized score of each item is multiplied by test’s weight. There are ways to specify values to normalized against via UI.