Secret identities in Dwarf Fortress (2017)

https://ojs.aaai.org/index.php/AIIDE/article/view/12963

by Tomte • 3 years ago

111 35 3 years ago

ojs.aaai.org

73737373735• 3 years ago

I wish there was a more technical explanation on how the various Dwarf Fortress algorithms work. The major thing I still can't wrap my head around yet is how the dwarves/NPCs schedule tasks and balance that with their needs.

Somewhere I saw a blog post about Prison Architect, a game inspired by and with similar mechanics to Dwarf Fortress, that described one aspect of the task system:

Instead of giving NPCs task lists, tasks are assigned to objects - say, a door that is not installed yet. The door would contain the instructions: "(1) move me to location [x,y] (2) install me at my current location", and idle NPCs would lookup objects with fitting tasks to their abilities/priorities and then execute the instructions.

But how to combine this with needs is unclear to me, I would love to see a good explanation of this. Here is the insane list of needs a Prison Architect NPC has: https://github.com/originalfoo/Prison-Architect-API/blob/mas..., and Prison Architect, while already displaying emergent behavior, seems to still only have a fraction of the detail and complexity and emergence that Dwarf Fortress has.

All the hype is about neural networks now, but these don't display this kind of emergent, social and constructive behavior, resource awareness and https://en.wikipedia.org/wiki/Homeostasis that these NPCs can.

coumbaya• 3 years ago

I don't know if this is this specific system in DF, but there is a recent video by Game Makers toolkit explaining The Sims AI which is kinda similar regarding objetcs and needs, pretty interesting https://youtu.be/9gf2MT-IOsg

73737373735• 3 years ago

Thank you! This makes me wonder why there is no open source implementation of/framework for such a mechanic (or why i haven't heard of one) yet - it seems to be the (potential) basis of many games - one other popular game using it is Rimworld.

Also, why games like Minecraft have not long implemented such smart and interesting NPCs yet!

cpeterso• 3 years ago

This video is a nice introduction to “Utility AI” systems and includes examples from games like The Sims and Total War. (The Sims section starts around time 6:50.)

https://youtu.be/p3Jbp2cZg3Q

A utility system is basically a codification of Maslow’s hierarchy: the system continuously re-evaluates possible behaviors’ utility functions and then chooses the top-scoring behavior.

https://en.m.wikipedia.org/wiki/Utility_system

hinkley2• 3 years ago

At this point I think some transparency would be good. One of the complaints about the game is how as time goes on the simulation gets more and more detailed and eventually the game just grinds to a halt.

A little more visibility into how all of this stuff works, and someone might be able to suggest that there's an algorithm that does this or that bit with a much lower order of complexity. A few of those and you can let a game run maybe twice as long.

minsc_and_boo• 3 years ago

If it's any consolation, a big CPU suck is friend-or-foe checks being done by characters on everyone in sight, in every tick. That came out last year-ish and making smaller taverns can (slightly) improve processing.

polytely2• 3 years ago

for more behind the scenes stuff on Dwarf Fortress I recommend listening to the occasional 'bay12 talks' podcast episodes hosted by BlindIRL (long time dwarf fortress streamer) he periodically talks with Tarn, and more recently Putnam (longtime modder and first external programmer on DF) about the state of the game and asks them player questions.

https://youtu.be/BY4jwUuvy4E

73737373735• 3 years ago

Unfortunately these interviews tend to be full with fun anecdotes, but tend to lack technical details

RugnirViking• 3 years ago

there is a menu in the game where you can see all the tasks that are scheduled in the queue including stuff like "wash self" and "replace clothing", with targets and who is currently assigned. I believe personal tasks like "have a mental breakdown" are spawned already assigned and locked in to the dwarf they are relevant to. iirc its the (j)obs manager, the same place you assign automated orders like making more beds/beer if the stockpile ever has less than 4 etc

asfarley• 3 years ago

Based on your description, you could describe “need fulfillment” as a task associated with the NPC object. Then you just maintain your original operations while adding NPCs to your object list.

serf• 3 years ago

But how to combine this with needs is unclear to me, I would love to see a good explanation of this.

some inefficient ways off the top of my head: create a threshold filter on the object with logic something like "only agents with need > X allowed", or iterate through the agents until you find one with the greatest need score that is pertinent to the object, or a combination of the two to reduce the list size that must be iterated. sprinkle in agent range from object and specific traits preferably before the list generation to further reduce iterations needed.

i've thought about all of this a lot because i'm addicted to games with agency and emergent behavior. rimworld is a lot of fun in that regard because it's easy to jump into modding it, which makes agency experimentation a lot of fun.

m463• 3 years ago

lol, bladder/bowels right up there.

    Bladder 9  
    Bowels 9   
    Sleep 8    
    Food 8   
    Safety 7   
    Hygiene 7
    Exercise 6  
    Family 6   
    ...

I found it interesting that maslow's heirarchy of needs shows much more detailed heirarchy: "physiological", "safety", "belonging and love", "social needs" or "esteem", "self-actualization" and "transcendence"

...and the physiological needs are broken down further and slightly differently:

    Physiological needs include:

    Air
    Water
    Food
    Heat
    Clothes
    Urination
    Excretion
    Shelter[2]
    Sleep

https://en.wikipedia.org/wiki/Maslow's_hierarchy_of_needs

chaostheory• 3 years ago

Instead of giving NPCs task lists, tasks are assigned to objects - say, a door that is not installed yet.

I believe that’s how Will Wright designed The Sims too

sk0g• 3 years ago

Have you heard of Goal-Oriented Action Planning (GOAP)? I've tried implementing it from scratch and it's really easy to get interesting, emergent behaviour. It can also be difficult to debug however, or reason about why things are happening -- or how to make things you want actually happen. I have a feeling commercial products would have much better tooling to ease some of those pains.

73737373735• 3 years ago

I've seen this great video about it! https://www.youtube.com/watch?v=PaOLBOuyswI

noirscape• 3 years ago

Basically when you make a task in dwarf fortress that requires a character in the game to do something, it gets added to a global jobs list.

Dwarves will, assuming they don't have other jobs at the time, pick a job from that list as long as they're allowed to do so by their labor selections + workshop availability (if that is possible). Do note that this doesn't actually account for pathfinding or if the job is even possible. The game will gladly tell you over and over that a job is being cancelled if for whatever reason the items needed for it are inaccessible/don't exist. Just a small note.

If the dwarf in question has no current jobs, the first priority will be for them to check their needs and try to fulfill them. Needs more or less are in two categories - "essential" and "non-essential". Non-essential needs used to be more obvious - it was the On Break part of a dwarfs schedule. Basically every once in a while, a dwarf goes "On Break", effectively making them unable to do anything except take care of their essential needs. Nowadays it's a set of activities derived from the unique identity of the dwarf (On Break doesn't exist anymore) - religious dwarves will want to play, while dwarves that seek musical entertainment will try to do so with a musical instrument.

Essential needs on the other hand are things like drinking/eating and sleeping. These pretty much come in two degrees, "want" to do and "need" to do. Want to do means the dwarf will immediately get a job to fulfill the need once the criteria are hit - if a dwarf gets hungry while hauling a rock, they'll grab a bite to eat after. When a need progresses to "need to do", it just will straight up interrupt any non-need job they're currently doing[0] (the game even tells you this) and create a new job to do it. Its how a dwarf will fall asleep on the spot if they're extremely tired.

Mental breakdown and tantrums are similarly "essential" needs, just with their own triggers that can't be interrupted by the player.

[0]: With the notable exception of military duties, which is one of the reasons militias in Dwarf Fortress have to be on a rotating schedule - dwarves will not eat or drink if they're on active duty, no matter what. They will sleep in a barracks though.

greatfilter251• 3 years ago

The early-access game Shadows of Doubt also has extensive secret-knowledge mechanics which must be carefully managed, with the additional complication that it ideally wants to keep in sync the knowledge of the player and the player character.

I had an opportunity to play it for a few hours. It's not perfect - it didn't always keep up with my deductions, and on one instance it leaked unknown info via the UI - but on the whole it succeeded at a convincing mechanic.

ehnto2• 3 years ago

It's a very good immersive-sim on top of that.

It has some tempo management to work through I think, sometimes crimes are too obvious to solve and others are essentially dead ends unless you brute force your way to the info you need (which means talking to every NPC randomly or fingerprinting the whole city). And as you said, sometimes you have made a deduction, like who someone is thus linking their other details, but it's not relfected in the UI.

Secret identities in Dwarf Fortress (2017)

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