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The AI Systems of "Left 4 Dead" [pdf]

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Re: The AI Systems of "Left 4 Dead" [pdf]

#31

Post by fafner »

TillE wrote: post #2

scribd is "unable to display this document", and the download button doesn't even work. Just link the original. http://www.valvesoftware.com/publications/2009/ai_systems_of...

The link is to the original. The scribd link is to the side and is automatically added by HN.

(I never really liked scribd and with pdf.js it's clearly obsolete)

Re: The AI Systems of "Left 4 Dead" [pdf]

#33

Post by robotmay »

arethuza wrote: post #12
ddorian43 wrote: post #7

Earlier quoted context omitted.

play multiplayer?

I only ever play multiplayer (mostly Halo 4 these days) - any time I try Campaign I find the AI rather boring and predictable. I don't know if the Halo series are bad for this or not.

Yeah, it's not anything amazing from my experience. I've heard the FEAR games had decent AI, as well as Far Cry.

If we're not talking FPS then I've been impressed by the AI in XCOM. God damn those bastards are hard work.

Re: The AI Systems of "Left 4 Dead" [pdf]

#34

Post by jfb »

fafner wrote: post #31
TillE wrote: post #2

scribd is "unable to display this document", and the download button doesn't even work. Just link the original. http://www.valvesoftware.com/publications/2009/ai_systems_of...

The link is to the original. The scribd link is to the side and is automatically added by HN. (I never really liked scribd and with pdf.js it's clearly obsolete)

For PDFs at least, scribd seems purely parasitic.

Re: The AI Systems of "Left 4 Dead" [pdf]

#37

Post by xhrpost »

gmaslov wrote: post #18
ccozan wrote: post #17

That's hardly AI. It's just algorithms. Parametrized, using a probability distribution to randomize the environment, user programmed algorithms. EDIT: Well, if this AI in game development, then so be it. But it's still not AI in the generic way, IMHO. To downvoters: I didn't contest the fact that they don't work. I do enjoy this games a lot and I praise the programmers that make such games work.

Ah, yes. The perennial curse of AI: as soon as it works, it's not called AI anymore ;-)

If I remember correctly, people used to criticize IBM's Deep Blue for not being "real" AI because it just basically brute-forced a ton of possible play paths in the chess game. Someone then said: "Saying that Deep Blue doesn't really think is like saying an airplane doesn't really fly because it doesn't flap its wings."

Re: The AI Systems of "Left 4 Dead" [pdf]

#38

Post by opminion »

ccozan wrote: post #17

That's hardly AI. It's just algorithms. Parametrized, using a probability distribution to randomize the environment, user programmed algorithms. EDIT: Well, if this AI in game development, then so be it. But it's still not AI in the generic way, IMHO. To downvoters: I didn't contest the fact that they don't work. I do enjoy this games a lot and I praise the programmers that make such games work.

The intro of http://openlibrary.org/works/OL16095031W/Artificial_Intellig... discusses the variety of definitions.

Re: The AI Systems of "Left 4 Dead" [pdf]

#39

Post by supar »

adriancooney wrote: post #6

The climbing sequence is particularly impressive but maybe a tad excessive in my opinion but. I count six operations, two of which seem to computationally intensive due to their trial-and-error approach. I can see the reasoning behind it if the AI is climbing a physics props but surely map data could be retrieved relative to position and save all that ray tracing (if that's the correct term)?

Not sure what you mean by "map data". You can certainly have a list of props that are in the way and have them as a mesh. It's certainly easier if you have only one prop, but you have to account for that they may stack together in any way- and suddently the geometry configuration becomes non-trivial again.

Re: The AI Systems of "Left 4 Dead" [pdf]

#40

Post by danso »

I love this game, one of the last FPSes I still play other than Team Fortress 2...unfortunately, like TF2, it's not very playable unless everyone in the round is amenable to being a team player. The multiplayer deathmatch allows one team to take the role of monsters, who have the backing of the zombie horde to make up for lack of guns. Playing it really provides some interesting insights to how the AI effectively functions, by slowly getting the human players to come unglued, either by targeting stragglers or letting the best players get too overconfident and move ahead of the team. Of course, all deathmatch games have this dynamic but it's very explicit in L4D, mostly because it's impossible for one human or monster player to singlehandedly own the opposing team in the way that an ace player can miraculously wipe out a team in Counter-Strike.

edit: The AI controlled human players is extremely competent, maybe the best bot players yet created. But they do show their limitations in multiplayer...among their weaknesses: they're too willing to sacrifice their healthpacks for an injured teammate, and will almost always try to help an incapacitated player no matter how hopeless his/her cause. Real humans can be total assholes, but in some situations its best for the team to leave a straggler behind, especially if the enemy has set up an ambush for the rescuers.

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