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Dwarf Fortress => DF Dwarf Mode Discussion => Topic started by: darkhog on December 10, 2023, 05:10:20 pm

Title: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: darkhog on December 10, 2023, 05:10:20 pm

Wasn't sure where to put it since it's neither a suggestion, nor a bug report, just some ideas. So one of the biggest FPS death causes is pathfinding, especially when stuff like clown armies, undead body parts and so on are concerned, which goes back to the number of creatures trying to pathfind each frame. But wouldn't putting a hard limit on the total number of creatures on the map at the same time solve FPS death, at least when large amounts of creatures are concerned? Or, at the very least, putting a limit on the amount of creatures that can actually pathfind every frame, others being frozen in time until it's their "turn".


//edit: Another cause for the FPS death seems to be creatures stuck on trees or other inaccessible locations - would making them able to jump off, even if it would injure them help reduce chances of FPS death from such occurrences?

Title: Re: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: Bumber on December 10, 2023, 07:06:59 pm

Quote from: darkhog on December 10, 2023, 05:10:20 pm

So one of the biggest FPS death causes is pathfinding

Nope. (http://www.bay12forums.com/smf/index.php?topic=180561.0)

Title: Re: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: Telgin on December 10, 2023, 07:08:52 pm

Pathfinding itself actually doesn't cause much performance hit, outside of pathological conditions like flowing water causing the connectivity map to recalculate frequently.  Putnam did a lot of profiling to confirm that.

Citizens are supposed to be able to climb down from getting stranded now, so that should be better than it was at one point.  Animals still get stuck in trees, but I don't think they contribute much to FPS since they don't do much but randomly wander.  I think there are still some outstanding issues like having strange moods in burrows that can cause FPS to tank if a dwarf can't reach an item they want.

That said, reducing the number of creatures will always help.  I'm pretty sure the number of fort citizens has an outsized impact since they do more than things like animals, but I'm not sure if sapient creatures like goblins or random cavern civilization creatures have the same impact as dwarves despite having no meaningful relations or other things to calculate.  For all I know the game does the calculations and just does nothing with them.

I am curious if it's practical to amortize unit calculations though, like half of the units "thinking" on A frames and the other half on B frames.  The game may even do this for all I know, since you'll occasionally notice dwarves pursuing some task for a while after it's meaningless, like station orders, before abruptly changing to something else a few frames later.  The complex interactions between units probably make this hard to do in practice too.

One thing that would definitely help some people is fixing the fact that you can get hundreds of cavern people on your map.  I don't know if it's just a problem with agitating them and getting unending ambushes, or if they just accumulate over time no matter what.  I'm also not sure if they start accumulating or showing up before the caverns are revealed.

Title: Re: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: anewaname on December 12, 2023, 05:14:36 pm

Minor points (not intended to take away from what has already been covered):

Spoiler (click to show/hide)

How often a re-path is attempted and the distance to the target is important to recognizing when pathfinding is a problem.

So, most creatures stuck in trees don't cause heavy FPS loss because their re-path attempt ends in a few tiles and they do not attempt to re-path that often (citizens will idle for some time when stuck and kids will even Play, and will not enter climb mode until they enter combat or hit starvation/dehydration). Previous DF versions had a problem with pets and pet-locked doors, because pets attempt to re-path very often to their owner and the re-path distance to the owner could become long, and it would fail immediately and restart.

Creatures that cause big FPS hits are the ones that attempt to re-path often over long-distances, like FBs who are willing to re-path hundreds of tiles through different caverns to get into your fort. They will test all the possible paths to create a couple hundred tile path, then be interrupted and need to re-path. Flying creatures can also do horrible things to FPS in the right circumstances.

Title: Re: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: brewer bob on December 13, 2023, 10:14:28 am

Quote from: anewaname on December 12, 2023, 05:14:36 pm

Flying creatures can also do horrible things to FPS in the right circumstances.

The upside of this FPS drop on certain maps is that you get an early warning that the kea menace has arrived.

Title: Re: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: darkhog on December 13, 2023, 01:47:49 pm

Still, if there's a hard limit on the number of creatures on the map at once, there's a less of a possibility that any of those things happen. It would be reasonably high to not affect the gameplay too much, but also low enough to improve the things.

Also another thing would be to limit how often creatures could repath, the lower FPS (as percentage of max FPS), the tighter the limit. IMO having a creature, including a megabeastm stuck is preferable to unplayable FPS.

Title: Re: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: Putnam on December 21, 2023, 06:27:53 pm

Quote from: Bumber on December 10, 2023, 07:06:59 pm

Quote from: darkhog on December 10, 2023, 05:10:20 pm

So one of the biggest FPS death causes is pathfinding

Nope. (http://www.bay12forums.com/smf/index.php?topic=180561.0)

Yeah, fair response, but the primary cause of fort FPS issues is still... number of creatures. So the title question's a valid one. And the answer is basically just "yes", straight-up.

Quote from: darkhog on December 13, 2023, 01:47:49 pm

Still, if there's a hard limit on the number of creatures on the map at once, there's a less of a possibility that any of those things happen. It would be reasonably high to not affect the gameplay too much, but also low enough to improve the things.

Also another thing would be to limit how often creatures could repath, the lower FPS (as percentage of max FPS), the tighter the limit. IMO having a creature, including a megabeastm stuck is preferable to unplayable FPS.

Yeah, this is something I've sorta-kinda considered. Making your units who are stuck in a tree explicitly try to climb around instead of just path failing and posting to the errorlog about it is a sort of "step one" of this, there's a flag in there now that makes this happen and adding more "chill out with the panic pathing" stuff might just generally be a good idea. While slow FPS reduction over time isn't a pathfinding problem, sudden drops to the single digits usually is. The thread I made there was using "FPS death" to mean the general complaint of "slow, inevitable decline in game speed", which pathfinding is not really a party in at all.

Title: Re: Would a hard limit on total number of creatures present in any fort fix FPS💀?
Post by: Pillbo on December 21, 2023, 08:58:33 pm

It seems like flying is often brought up as a problematic issue in general. Has there be any thought put into ways to address the way flying currently works? I'd be interested in seeing the results of profiling flying creatures behavior.

Edit - limiting creatures in some way will likely have to be part of the updates to adv mode since you can't really even go into a lot of cities or pits without the game becoming unplayable. So maybe that kind of change will work out for fort mode too.