How to Store AI Knowledge about the Game-World for AI Decision Making

by Visulth   Last Updated October 18, 2019 00:13 AM - source

I have a game-world with a fair amount of AI that have some Senses, like vision, hearing, touch, smell, etc.

But I'm not sure how to put that information in a single place for the individual AI to then iterate over it and make a decision.

For example, each sense (emitter and receiver) currently returns a structure called a Stimulus with information like position, direction, stimulus type (sight, sound, smell, etc), npc type (human, animal, monster, etc), and so on.

And currently, the monster AI just have a hard-coded hierarchy of preference - touch (e.g., damage events) > sight > sound > smell, so if you fire a gun it'll try to follow that noise but if he then sees you, he'll switch to tracking you visually and forget about the noise.

However, this isn't very robust. It doesn't deal with repeated damage events or one player kiting or stale stimuli vs new stimuli very well. Ideally I'd want to use some sort of utility evaluation so that I can get more complex and dynamic behaviour out and I can fix edge cases where it feels like the AI isn't interacting right (e.g., ignoring stimuli that it shouldn't be).

I'm not sure how to approach that implementation. Should I just have an array of every stimulus the AI encounters and loop over that every tick? But then how do I prune that list since it'd get very large very quickly and might contain really old stimuli (currently the AI only has one "target stimuli" and new stimuli go through that hierarchy of preference before being either discarded or replacing the target stimuli).

(As a side note, this GDC Talk about Creating the Living, Breathing World of Hitman has provided some great information about how they deal with Knowledge, but I wasn't able to discern how they store it and iterate through multiple Knowledge fields of a single AI and so on).

(I'd also love any advice on the Knowledge/Stimulus data structure itself; to be modular enough to hold different types of information, instead of having a bunch of unused fields; say how a sound might need only type and direction, but a visual stimulus might only need type and position and so on)

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