AI for RPGs

Vendayan · 2002-12-05T06:59:39

It amazes me sometimes that the AI for RPG''s is so extremely limited. Perhaps I should start with a couple of examples. First Everquest. For one because just about every RPG player has played it or at least read/heard alot about it in detail. The AI in this game is very simple. An NPC has a radius around it in which it picks up events of a character/NPC moving in close. When one does move inside that radius it checks to see if it can see the subject, invisibility and line of sight are the only things I believe it considers. After it ''sees'' a target it checks as to whether or not it will attack depending on the ''faction'' system. If so the NPC closes for the kill until it gets too badly hurt and then runs. This is what we are wasting our money on!? On a better note there is Morrowind. This game has no better of a system, except for roleplaying. An NPC might in morrowing notice that a player is wearing very high quality clothing and offer a compliment. An NPC will also call for the guards if the player would be so bold as to try to sell an item to him that he stole of the merchants shelf. Although I''ve been dissapointed at times to find that I could be on the brink of death and while standing right next to a cleric whose life I had saved in a quest would sit and stare at me while I bled to death, even while he had many powerful healing spells and full mana. I would love to be part of a team that would actually take things such as this into consideration. Where every time an NPC acknowledges the presence of another player/NPC he would check a list of attributtes to that player and act on them accordingly. For instance consider the follwing scenario... Two NPC guards are walking a predefined path along the top of a castle wall. Both guards are equiped with a shield a crossbow and a longsword. The guards also know that if anything goes terribly wrong to run to the castle wizard (this would be a short script to make the gaurd ''persue'' then put the wizard in a ''catious'' state and have the wizard ''follow guard'' while the guard will ''pursue'' the threat). The guards then during their partol see an intruder climbing the walls. If this scenario happened in everquest the AI would respond like this... If the Target''s level is too much higher than mine, Ignore the threat until it attacks me. Otherwise walk in blindly with the sword (because its in my hand at the time) and fight until im down to 20% health, in which case I run straight away from the intruder, or until one of us dies. This can be done much better using a bit more event driving. I would have the NPCs first consider the opponent a bit better. They would come to a rating of some sort of the amount of threat the target seems to be judging by his appearance. An orc has moderately intimidating appearance and reputation as a race. So we will take that factor and later apply it in some way to the assessment of this individual orc. Judging by the individual orcs appearance by what it''s holding and wearing it seems to be a scout as opposed to a spell caster. So that''s average, but this orc though has another factor to consider. It has a pegged leg. This affects not only the ''fearsomeness'' of the orc but also it general speed/mobility factor, which our guards might consider if they have to run for the wizard. Given the scenario the guards decide that they might easily be able to handle this orc themselves. Of course periodically the guards will need to reconsider thier course of action. Especially when this orc turns out to be an experienced assasin and manages to take off the arm of one of the guards and then turns on the other quickly wearing him down. In everquest... the guard who had his arm taken is considered to be in critical condition so he turns and runs, although the other who is unhurt stands stupidly and continues to attack without considering his own fate or the possibe fate of his friend, who with the AI in everquest would now be being chased by an orc who blindly turned his back on the healthy guard to chase the wounded one. Another solution could be to decided that since both guards are from the same faction and fighting a common enemy that they would be good candidates to form a group to combat this orc. In group AI the NPC''s will react to events that affect their group members. When the one guard loses his arm and turns, the other who is healthy considers running as well, but instead decides to cover him by setting his movement action status to ''cover'' and keep his action status on ''attack''. Ok, now I''m not saying that this how it SHOULD be done, but just saying what I would like to see. If anyone else has any other good ideas or input throw in your 2 cents. ~Vendayan

Artificial Intelligence Programming

Started by Vendayan November 17, 2002 03:12 AM

27 comments, last by Vendayan 22 years, 2 months ago

Vendayan

Author

278

December 01, 2002 02:56 PM

Ok, I''m going to work on making a complex AI as I have been speaking of. It may take me a while because I''m currently working on a project. But I will document the research, and if GameDev would let me, I will be more than happy to write an article on what I can come up with.

~Vendayan

"Never have a battle of wits with an unarmed man. He will surely attempt to disarm you as well"~Vendayan

Timkin

864

December 01, 2002 05:35 PM

quote:
Original post by Sigloxx
(I think they actually use one physical server per zone, though, and each zone contains usually less than 150 players and roughly 1000 NPCs..

FYI: For those that are interested, each EQ world server is (unless recent changes have been made within the last year) comprised of 22 physical machines running as a cluster. Each machine handles several zones so the player count for a machine was several thousand during EQs peak of subscription (and at peak times). The average zone had only a hundred or so NPCs maximum, although some zones would have several hundred (and some would have less than a hundred).

Cheers,

Timkin

[edited by - Timkin on December 1, 2002 6:38:09 PM]

Sigloxx

122

December 02, 2002 04:12 AM

quote:
Original post by Timkin

FYI: For those that are interested, each EQ world server is (unless recent changes have been made within the last year) comprised of 22 physical machines running as a cluster. Each machine handles several zones so the player count for a machine was several thousand during EQs peak of subscription (and at peak times). The average zone had only a hundred or so NPCs maximum, although some zones would have several hundred (and some would have less than a hundred).

Cheers,

Timkin

[edited by - Timkin on December 1, 2002 6:38:09 PM]

Not wishing to develop as it's a bit off topic, but just wanted to correct a few things - not sure what your info source is?
Each machine indeed covers several zones, contrarily to what I had wrotten earlier. Each server comprises 171 zones, and the maximum total number of NPCs is certainly more than 30 000 (the numbers you mentionned seem ok for the 51 original everquest zones, but in add ons almost all zones have over 200 NPCs). And more importantly, the maximum number of player per server (not per machine ) is a few thousands (2 years ago servers were crashing when reaching 2500 to 3500 players, or when some zones were geting over 300 players (new server releases, the "newbie" zones were overpopulated), nowadays they seem more stable, but even at peak times after new add on releases the most popular servers don't go above 3000 or so players/server.

EDIT : I noticed in another post that you have been playing Everquest too. About the number of NPCS per zone, arena has zero, erud s crossing, Solusek Temple and Erudin palace (and maybe a few other city zones, Oggok, Halas, Qeynos catacombs, Kaladim North and South, neriak foreign quarters) have less than 100 NPC up at max. Many of EQ clasic zones have more than 200 (Everfrost, revamped PoH, the various karanas, etc..). In Kuniark, Droga for instance has probably over 400 mobs -though it becomes harder to tell even for a tracker -, Nurga about the same, and most outdoor zones have quite over 200. The smallest zone I can think of is howling stones with something like 150 mobs (Karnor is roughly the same too). The distribution of player per machine seems well done (I noticed one machine was having Rivervale+Lesser Faydark+Solusek B++one or 2 other, as far as I remember, meaning the machine covers zones of various popularity and made for different levels of players). For the player population by server, it's been harder to tell since Luclin's release, but the number of servers slightly increased, and I don't think the number of subscribers increased much?

quote:
Original post by Vendayan

Ok, I'm going to work on making a complex AI as I have been speaking of. It may take me a while because I'm currently working on a project. But I will document the research, and if GameDev would let me, I will be more than happy to write an article on what I can come up with.

~Vendayan

Good luck, will be very interesting to see your ideas developed that way

. Thinking a bit about it at the moment too actually (though not for a classic RPG, just some kind of virtual world).

David Antonini.

[edited by - sigloxx on December 2, 2002 5:32:22 AM]

David Antonini.

Timkin

864

December 03, 2002 12:03 AM

quote:
Original quote by Sigloxx
not sure what your info source is?

I worked as a guide for quite some time, although I gave it up to write my thesis.

quote:
Original quote by Sigloxx
Each server comprises 171 zones

Okay, I did make the distinction between World Servers and physical machines (servers). You are thinking of a World Server when you are quoting 171 zones per server (eg: Karana Server, Innoruuk Server). Each World server is actually a cluster of physical machines: when last I was involved with CS it was 22 machines per world server, as I noted above.

As to the number of mobs per zone... I''m going by data collected from ShowEQ (packet sniffer). If you have contradictory data I''d be interested to know its source. As I said above though, I wasn''t talking about every zone, but rather the `average zone''.

Cheers,

Timkin

Leecho0

122

December 03, 2002 01:01 AM

I''ve got one question, why can''t the client computer handle some of the computations? the server just has to be the database of the world.

on a side note, why are RPG''s still number based? They started RPG''s with numbers only because there were no better way to simulate combat. There has to be a more exciting way to fight than subtracting numbers.

FritzMar

140

December 03, 2002 10:30 AM

there are basicly two ways to handle the battle thing

1st) you use numbers and you do the same as every one else

in my opioin the battles are are done ''using numbers'' that way because that is the best way to represent somthing in the computer and its one of the fastest for sure.

2nd) you could make the battle more like a fighting game aka ''mortal combat'' ''teken'' ''vf'' but then since you need to represnt damage to a charater in the rpg you still need to use numbers to store data its no fun if you hit the guy every time and he is kill do to random button mashing

0))))))>|FritzMar>

krez

443

December 03, 2002 12:36 PM

quote:
Original post by Leecho0
on a side note, why are RPG''s still number based? They started RPG''s with numbers only because there were no better way to simulate combat. There has to be a more exciting way to fight than subtracting numbers.

everything in computers is numbers (compute r, it''s not just a clever name), there is no way around it...

--- krez ([email="krez_AT_optonline_DOT_net"]krez_AT_optonline_DOT_net[/email])

Kylotan

10,513

December 04, 2002 02:03 PM

quote:
Original post by Leecho0
I''ve got one question, why can''t the client computer handle some of the computations? the server just has to be the database of the world.

Because clients cheat.

quote:
on a side note, why are RPG''s still number based? They started RPG''s with numbers only because there were no better way to simulate combat. There has to be a more exciting way to fight than subtracting numbers.

Sigloxx

122

December 05, 2002 06:59 AM

quote:
Original post by Timkin

As to the number of mobs per zone... I''m going by data collected from ShowEQ (packet sniffer). If you have contradictory data I''d be interested to know its source. As I said above though, I wasn''t talking about every zone, but rather the `average zone''.

Cheers,

Timkin

Ah ok. Well my own experience is just as an ex-addicted EQ player having played trackers and pullers at most levels(in several dungeons I can actually just count the mobs as I know where they spawn and roam), so I''d rather trust showEQ

. I must admit I am pretty surprised by a 100 NPC/world zone number though. I had seen some listings obtained by showEQ, showing usually the various type of mobs along with their level range and hitpoints, but never found a list giving the actual number of NPC up at the same time. Illya''s bestiary gives the different "type" of mobs per zone. Of course all the named aren''t up at the same time. But for common mobs there are usually several occurences of them (if not a lot). In a zone like Ak''Annon, wich seems to me to be a rather average populated zone for classic EQ, Illya''s lists 123 different type of mobs, and there are no placeholders or rare spawns. Considering that many of these mobs exist in several occurences (a clockwork merchant, a cockwork cleaner, etc..), the actual number of NPCs up at the same time should probably be around 200+. That''s why I was intrigued by your numbers

.
Whatever the exact average number is anyway, the number of NPCs per world server is way higher than the max number of player per world server that the machines can deal with (even with 1000 mobs per zone it means 17 000+ mobs per world server, when world servers tend to crash with 3000+ players logged on).

Regards,

David Antonini.

David Antonini.

AI for RPGs

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