PC Desync/Resync issues (Husk fireballs, zeds warping when attacking)

[hunter_hunted]

Looking at the code, it seems zeds force a net update/resync when they do a special move/attack.

This is likely the cause of at least 2 very annoying common gameplay affecting issues in online play.


1. Zeds teleport just as they attack:

https://youtu.be/HHYYb6MxUhE

https://youtu.be/tJpHxVNmUoU

All zeds do this when playing online/multiplayer, even when connected alone to a dedicated server hosted on the same machine.



2. Husk fireball desync:
https://youtu.be/wlP69cEgc44

In this example the gorefiend is ahead of where it looks, so the fireball misses serverside but hits it clientside since the fireball attack is forcibly synced but the walking of the gorefiend isn't.

This happens most commonly when a husk shoots through a crowd, but this is the simplest example I've managed to capture.



I don't know what causes the zeds location to be out of sync in the first place, but as it happens even on a locally hosted server it's obviously not network connection related.

For reference, these exact same issues seem to be present in other unreal engine games. For example, in Fortnite which uses UE4, the zombies currently warp forwards/resync when they get under your crosshairs.



(While I'm at it - why is bloat bile spawned by AI not removed from the projectiles list when it's destroyed such as by end of wave cleanup?)

 

[s5yn3t]

That whole warping, rubberbanding is what i was complaining for over a year now.

but i can't recall husk fireball hitting you instead of the gorefiend... Unless you played in an over 100 ping server.

 

[s5yn3t]

Foster Parent

 

[hunter_hunted]

but i can't recall husk fireball hitting you instead of the gorefiend... Unless you played in an over 100 ping server.

Sorry, I've reclarified - it happens with big groups of zeds mostly - just turned out to be a gorefiend in the simplest example I've managed to capture.
As with the other, seems to be regardless of ping (I don't tend to play on servers above 40-60 ping).
Another example: https://youtu.be/k26lsFYa-Mw

The opposite case also happens sometimes, where the fireball visually hits you but does no damage or knockback (because it already did damage/knockback to a zed in it's path or such):
https://youtu.be/Q29sLyCRUq4

 

[s5yn3t]

The opposite case also happens sometimes, where the fireball visually hits you but does no damage or knockback (because it already did damage/knockback to a zed in it's path or such):
https://youtu.be/Q29sLyCRUq4

this i can confirm and does happen quite often (also on 34-60 ping servers)

To the point where there's a group of people standing in the doorway, gets hit by a fireball but no damage was dealt... Good way to get startled tho

 

[Foster Parent]

I can ask, though that looks different from my experience. BTW, what code are you looking at?

 

[hunter_hunted]

I can ask, though that looks different from my experience.

Every time a zed gets in range for a moving/lunge attack in MP their feet slide forwards suddenly right at the start of the attack animation.
Most noticeable with bloats/fps, but happens with every moving attack to some extent as far as I can tell (Seems to be the ones with bUseRootMotion set in the animgroup?)

Found a surprisingly easy replication.
Join local server, login as admin, use 'admin enablecheats' then 'admin spawnai fleshpound' and watch the warping issue.
Compare this with offline using 'enablecheats' and 'spawnai fleshpound' where it moves more naturally.

Needed a few tries to get the same attack and a FP that didn't spawn enraged, but here's the comparison:

This is a FP warping forwards during his initial attack while connected to a server running on my PC:
https://youtu.be/6ZW1H4u5YN8

This is the same initial attack in solo offline:
https://youtu.be/JTLMQOmT29Y

If I freeze frame at the moment the gloves get their red glow, the SP FP is here:
https://i.imgur.com/zBZBjLq.jpg
But the MP FP is far closer:
https://i.imgur.com/ZlLxtJj.jpg

This is because it spent the previous 3 frames (only 50ms worth at 60 fps) sliding/warping forwards.
The online FP then plays the leap animation while stood in one spot already next to me, whereas the solo FP actually leaps towards me.

BTW, what code are you looking at?

Looking again I'm not so sure now. I had assumed the force update in ReplicateSpecialMove of KFSpecialMoveHandler.uc was re-syncing some out of place motion drift, but the above example seems to indicate the problem is the AI's position is being transitioned to the end point of the motion far too early/quickly when viewed as a client in online and not solo.

I couldn't reproduce the issue in recording a demo during solo, though I don't know if that would be enough to trigger the same replication stuff as online.
(Demo recorded online just shows FP teleporting to me then running through me and generally warping around, much like the post-match zeds after a defeat while a new map is loading)


Edit: The bloat bile mine thing I was referring to is that PostBeginPlay of KFProj_BloatPukeMine.uc adds to the PTT_PukeMine pool if( InstigatorController != none || IsAIProjectile() ) but the Destroyed event only checks if( InstigatorController != none ) when removing.
I was wondering if this could be related to the common bug of people being hit by invisible puke mines during trader time.

 

[Foster Parent]

I mentioned this to the right people. They are aware that it can happen but usually it is not so pronounced. There are not many reports of it from players. More latency / ping can make it worse. Also, background processes. In testing, some use a real-time security software that hits performance to make it more obvious. Are you using anything like that?

BTW, thanks for the detailed steps and vids.

 

[hunter_hunted]

No real time security or anything and occurs the same for me and those I play with regardless of ping ( that latest comparison was connected to a server running on the same PC so sub-15 ping and no packet loss ).

I'm using a high-end PC with mid range settings to avoid even the chance of performance concerns - Generally a solid 62 fps with no hitching.
As shown above, the zed moves normally in singleplayer - it's just in the client/server version that this happens.

Others I play with see the same thing, but usually avoid it by keeping distance or put it down to general 'lag' or even don't know any different as they're used to fast zed speeds on HoE.
The animation itself plays fine, and at the right time, but the zed location transition isn't in sync with the animation at all which can lead to you getting instantly boxed in in multiplayer, where the same situation would give you time to move if it happens in singleplayer.

The same occurs if I see a zed gets close to another player in multiplayer - The zed warps from maximum attack range into touching them range right as the attack animation begins.

I first reported it myself back in June last year on the steam forums but it's probably not reported more because it always happens and everyone either accepts it as how the game works or assumes it's already reported much like the bloat mines that hit people during trader time or the aiming direction not updating fast enough in zed time for projectiles.

 

[hunter_hunted]

Captured some more examples during gameplay.
Does indeed appear to be worse if there's lots of zeds around, but happens every time for me even in quiet situations such as 1 zed left.

This one shows it happening to another player, plus HP bar teleports at the first frame of the attack animation:
https://youtu.be/LORTct2p8LM

Unsure if related, but this odd lag when a player got grabbed is very similar to the motion of the zeds (goes too far before snapping back if there's any lag at all)
https://youtu.be/U-2jAy8XvNo

And other examples:
https://youtu.be/X39QoMTidtA
https://youtu.be/AfYCsppMgj4
https://youtu.be/d52qGXeMFos

 

[s5yn3t]

Foster Parent

 

[Foster Parent]

Foster Parent

Ja, KittenMittens passed it on this morning. We're having a look. Though, hasn't it been the same for both games, since forever?

 

[s5yn3t]

Ja, KittenMittens passed it on this morning. We're having a look. Though, hasn't it been the same for both games, since forever?

by both games you also reffer to kf1.. right?
My memory of the 1st one is faded, but one thing that i remember is that it had everything working solidly... except for hit registration (especially with med darts that show green smoke from a player hit, but have no effect )

kf2 atm suffers from these nonsenses that this man recorded for longer than desired.... might also add that bloat needs a bit of tweaking, since he just snipes you with bloatbile the moment you driveby him before his puke animation can catch on to the dmg already dealt.
not only is it cheap but also unrealistic when he pukes so instantaniously. I meen look at how spiter works in l4d2, it takes time to prep the acid and then launch it.
Also speaking of prep, zeds insta jumping to clear an obstacle (especially in the zones where it makes no sense) slightly hinder the flow of the gameplay. Would be nice if they had a bit of time for them to jump like a normal humanoid entity would, with bending knees and launching upwards... or even vaulting for more agile specimens.

Sorry if i've gone offtopic ^^, just something i wanted to adress for a long time.

 

[hunter_hunted]

might also that bloat needs a bit of tweaking, since he just snipes you with bloatbile the moment you driveby him before his puke animation can catch on to the dmg already dealt.

Bloat is probably the most noticeable since his head isn't straight during the puking, you can see him warp towards you easier at the start of the animation.
Most of my videos just happen to be fleshpounds because they're the zeds that tend to make it close enough to do the attacks in regular gameplay and more of their attacks are moving so it's easier to replicate.
Seen it with pretty much every zed, but most are tricky to replicate (requires agro swap or such to allow you to get close enough to a walking trash zed, otherwise it starts sprinting before it can do the leap on HoE)

I've noticed that raging FPs don't seem to have the issue - only unraged walking fps.
Don't know if it only affects walking zeds or just happens to be unraged moving attacks that have the issue.

Though, hasn't it been the same for both games, since forever?

KF1 didn't have the same variety in animation. It had more instant transitions between animations but I don't remember any of them teleporting at the start of attacks.

For KF2, the animations play properly in singleplayer. It's just multiplayer where they always move far faster than they should at the start of certain moving attacks.
The endpoint of the attack is correct - it's just the movement towards that point that's accelerated.

At 60 fps, the zed closes the distance within a couple of frames. Given them moving 2 metres, that'd equate to them moving at 134 miles per hour an instant after being stationary, then coming to a full stop within the next second or so. Needless to say, it makes getting headshots in online play pretty much impossible during these animations. A particularly common annoyance when dealing with bloats that you are trying to decapitate with a close range shotgun.


Tested some more and noticed the issue is reduced to the point of not being noticeable during zed-time.
With slomo 0.5 on a default 30 tickrate server, the attacks are pretty normal. Slomo 1 and they skip the start of the movement.

With my client and server set to 60 tick rate, it also happened during slomo, but doesn't happen during slomo at the default 30 tickrate.

Made a very slowed down video (with in-game slowmo at 0.5 on 60 tick server/client just to get more frames for a smoother playback):
https://youtu.be/kwRT5gOQZJg?t=25
Even at this really low speed, it closes the distance in under a second of video. The healthbar is a good reference point - it moves so fast it even goes offscreen before I can turn to face the FP again.

 

[Foster Parent]

As I said, we are taking a look.