EKI NPC AI

[Dan_Incognito]

Hey everyone.

 

Ok so i have been using EKI One to pathfind for my NPC's and it works great but what i would like to know is can i use EKI One to script an NPC to attack the player? now im aware that shooting the enemy needs raycasting but can i handle enemy and player health scripts in EKI such as detect hits and kill the enemy or player when the health hits zero? Or do i have to code a class for the enemys and player first? Hope that all makes sense. Thanks in advance guys.

[Pixel Perfect]

Well EKI One is effectively a path finding and advanced AI solution based around hierarchical Finite State Machine technology with all the tools to support that. So although it's effectively a separate engine it would still be scripted in the same way as you would script an FSM within your game engine.

 

If it's not obvious what you need to do then you probably need to read up on designing AI with Finite State Machines as you need to have a good understanding of the fundamentals of State design.

 

You will indeed require classes for your NPCs which your AI can interface with and because Eki One supports a perception system you can rely on the AI for being aware of when the enemy is in sight and take appropriate action.

 

Your AI could chose the target for instance and pass that data to an NPC class 'targetEnemy' procedure passing the ident of the enemy. The function would then handle the raycast and subsequent shot if accurate targeting of the enemy is required, otherwise just run a random outcome as to whether the enemy is hit or not weighted perhaps by the distance between the two.

 

If hit call the targets decrementHealth procedure and if that results in the enemy's death, its own class instance would handle that (play the death animation, update the AI so it can be removed from the simulation etc).

 

There is a natural separation between the NPC AI and the game play logic. In theory the game play logic could be handled by EKI One too as it supports VirtualAgents which are not tied to a character as such and can be used for producing AI Directors which act at a higher level.

 

Just remember that the more you do in EKI One the more info you will need to pass between your engine and EKI One and the subsequent configuration of suitable data items for this. Some things might be better handled in your own engine even though theoretically they can be done in EKI One. I guess its a fight between ease of design (EKI One has great tools to aid this) and the complexity of the interface between EKI One and your game.

 

There are no definite answers, there are many ways of doing this. It helps to make a list of all the things that need to take place in order to aid the design of these types of systems and of course, unless you have a lot of previous experience of AI design, assume you will learn as you go and accept that you will probably redesign it many times with hindsight before arriving at a final solution.

 

Maybe some of the other people using EKI One might have some further input/insight on this.

[Dan_Incognito]

Thanks Pixel Perfect, i appreciate the help!

[Dan_Incognito]

One other thing you may be able to help with. I wanted to navmesh the desert highway map but i got an error saying the navmesh generator ran out of memory and i should try to reduce the number of allocated voxels. Could anyone help me with this please, thank you Sorry for adding another question but how can i get say the tunnels map into EKI to navmesh it? Thanks again guys and sorry for all the questions

[Pixel Perfect]

Generating nav meshes for large areas can work out quite expensive memory wise. When you get errors like this you really need to alter your configuration settings or decide if you need to generate a nav mesh for the entire area.

 

The nav mesh settings can be accessed for the Configuration setting button when editing the level in the Configurator and defaults to the following:

 

 

Increasing the Cell Size should help reduce the memory footprint as will increasing the size of merged regions but this is at the expense of the resolution of the navigation area. You need to play around with the settings to get a feel for how they affect the outcome of the nav mesh and associated memory usage.

 

You might also concider creating multiple nav meshes. Ones with small cell size but limited area for areas where this might be required such as built up areas and ones that cover large open areas with increased cell size. You can switch between nav meshes freely in your AI implementation.

 

With regard to the tunnel map, if this has any private assets (i.e. locked in a password protected pak file) then you won't be able to export it to EKI One. You need to have full access to all assets referenced in the sbx file for this to work. Otherwise it should work ok, like any other level.

[Dan_Incognito]

Thanks for the advice with the tunnel map i notice it has no hight map so by not having that i can't load the sbx file :/

[Pixel Perfect]

Ah ok, there is no terrain on that map is there. Does the loader fail then, I can't remember off hand if I catered for that and I don't have the code on this PC. You will need to check (and possibly modify) the code or conversely add a small terrain as a workaround

[Dan_Incognito]

i'll add some terrain onder the model and the try to import it. thanks for your help i really appreciate it

[Pixel Perfect]

That's a good workaround as you can constrain the nav mesh to the immediate area around the tunnel complex and as it's a closed system paths will only ever exist within it anyway.

 

Good luck with your development. It's really great to see people using EKI One.

[Dan_Incognito]

Thanks! If i could just ask one more thing, this kinda touchs on what i asked before about the AI but could i code the AI for enemys and such using EKI and export it to leadwerks the same way as the navmesh?

[Pixel Perfect]

Yes, but perhaps it's worth elaborating a bit here on how the EKI One - Leadwerks (or any other game engine for that matter) interface works so people who are unfamiliar with it get a better idea of what does what.

 

Although EKI One generates a nav mesh for your Leadwerks level; it does so within the EKI One sandbox and deploys this data to the EKI One AI engine. All path finding is carried out within the AI engine and only the details of the movement passed to your Leadwerks engine in the form of velocity data (direction and speed) and animation data (what the current animation type should be) at each iteration of your game loop. So your Leadwerks engine never knows anything about the nav mesh as this is all handled for it by EKI One.

 

Likewise, AI designed within the EKI One configurator and tested against your imported level in the Sandbox will be run and executed in real time within the EKI One AI engine, not your Leadwerks engine. So in order to get anything to happen in Leadwerks you need to develop the interface between the AI engine and your Leadwerks engine such that when the AI makes a decision, pertinent data is passed back to Leadwerks to enable the out come of that decision.

 

So you could imagine a situation where your AI is running and your NPCs are in attack mode. Under this simulation they will attack the player on sight. The AI uses line of sight (perception) to determine when each enemy NPC can see you and under that circumstance informs your game engine that it wants NPC n to fire at the player. For this to happen you must have a command interface between EKI One's AI engine and Leadwerks, The actual sequence of the NPC attacking the player will be controlled by your NPC class and will drive all the necessary animation sequences, the AI will simply trigger this action.

 

So to summarize, the decision to carry out events will be decided by the AI running in the EKI One engine whilst the mechanisms to actually make these events happen reside within code in your game engine. The AI engine passes instructions to the game engine whilst the game engine carries these out and provides feedback to the AI engine. So if your Player is hit, the player class could pass back the details of where it was hit back to the AI engine. It would then update your health and possibly decide you have died in which case, come the next iteration of the game loop the AI will send an instruction to enact the player death sequence. Another scenario might have the players health controlled by it's own game engine class and it would enact it's death itself, simply passing back the fact the player had died to EKI One.

 

The exact balance between what is done on the EKI One side and what is handled on the Leadwerks side is for you to decide.

[Dan_Incognito]

Ok so let me see if iv got this right so if i create the class for the NPC AI in EKI is that something i then implement into my leadwerks project folder or do i need to figure a way of running EKI alongside leadwerks to manage the AI? sorry if im not getting it right away

 

Just wanted to add something. can design my maps in leadwerks and the do the rest of the game work in EKI such as the AI? i watched the youtube vid on pathfinding with EKI and leadwerks but some points don't seem clear to me. thanks again for the help

[Pixel Perfect]

The EKI One AI engine is started from within your own game engine code and utilises the data from the EKI One project you test and deploy. It then uses a comms system to communicate between the AI engine and your game engine. That interface and the data items to be exchanged have to be defined both in EKI One and in your game engine.

 

I am currently working on a simple example of this type of interface for Leadwerks and this will be released for people to work from. It will demo the fundamentals of the interface. But each individual using EKI One will need to adapt this into their own game engines and expand this to work as they need it to. I cannot preempt their requirements as there is no fixed game engine framework in Leadwerks to work with; as Leadwerks is just a game engine API and people are free to write their engines however they see fit.

[Dan_Incognito]

cool, thanks for all your help