Download

Reactive Path Following/AI Navigation

Is Reactive Path Following or something close to it possible with Blueprints?

If you asked, “What is Reactive Path Following”, then here are some links to explain. http://www.valvesoftware.com/publications/2009/ai_systems_of_l4d_mike_booth.pdf
https://developer.valvesoftware.com/wiki/AI_Systems_of_L4D

Essentially I am trying to create an RTS style game. I’ve got to the point where I want to work on the movement for the units. The pathing in UE4 isn’t all that bad except for the part where it doesn’t work well with dynamic objects, like other units(pawns). And the built in RVO Avoidance just doesn’t cut it (it is quite buggy). Is Reactive Path Following something I should continue to pursue in blueprints or should I go with an even simpler pathing system. All I want is for the units to go to the destination (when the player clicks) using the shortest path but also avoids colliding with other units.

I’m not finding much info/guidance for AI/Pathing in UE4, so I was hoping a more knowledgeable developer could enlighten me/point me in the right direction.

It doesn’t explain much in that article about what the term means, it’s mainly a bunch of slides all titled Reactive Path Following.

By looking at the pictures though, it appears to me that they just broke the problem into smaller chunks which is perfectly fine to do. Whether you do it in Blueprints or C++ is up to you. You get short term goals along the path. But, that’s just what I’m guessing by looking at the power point, it’s very high level and without detail.

Your going to have to do it yourself no matter what scheme is used, there is no out of the box solution that will work for every game and there are tradeoff’s in all of it. In that presentation it is very specific to zombies, and there zombies can basically path over anything because they all have the ability to climb very quickly.

Hello,

I spoke with our pathfinding developers the other day about this very issue and I was informed that there is an “Avoidance/Priorty Pathing” system on the way that would allow you to set up better “buffers” to get around objects in a more natural looking way. Sorry I don’t have a solution, but it is something I wanted to let you know we were working on.

Cool. Any idea of when this might be released?

Thanks for the reply. There actually is a 2nd link that does go into a little more detail. https://developer.valvesoftware.com/...Systems_of_L4D
It is still pretty high level, but it is more than just images.

The main problem I have with AI pathing/navigation is that I just don’t even know where to begin, since there is little to no documentation. So just to create pathing with simple avoidance, could you or somebody else point me in the right direction? What should I research/look into? I am just at a complete loss as to how to do this in blueprints.

Pathing isn’t really something you would concern yourself with blueprint wise. You want your movement system to deal with that kind of thing, just setting the destination should be enough for blueprints (and perhaps dealing with an inability to complete a blocked path).

You’ll basically have to wait for the Epic guys to create a solution, or implement your own. Head on over to AIGameDev.com for more info on the various solutions (there are a great many with a great many different tradeoffs). Things like RVO, ClearPath, HPA* and the like. They’re likely not something you’d want to do without some knowledge of the requirements of the game and/or general experience of problems with the various algorithms. If you want to follow up some academic background reading, I suggest maybe starting at Prof Norm Badlers lab with Prof? N. Pelachaud at University of North Carolina, they’ve done quite a lot of work on pathing methods (look for HiDac as a start). Obviously this is an area of active research not just for games but for simulations and crowd modelling, so there’s plenty to read if you’re interested.

I also have a youtube playlist for my students: https://www.youtube.com/watch?v=Hc6kng5A8lQ&list=PL4C3D55CA4EF8578B which has a number of different algorithms and videos of how they appear etc. But thats the tip of the iceberg :slight_smile: