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SAS_Storebror

Multiplayer: Hits vs. Net Code

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Posted (edited)

Hi guys,

 

I thought I'd share this with you, since every now and then complaints about the inefficiency of certain weapons arise and as a rule of thumbs, if "evidence" is provided from online/multiplayer incidents, devs won't accept them.

Reason is that odd results from bullet impacts online are credited to shortcomings in IL-2 GB's net code, instead of the alleged relation to general issues with the weapon itself.

 

I've been playing IL-2 GB quite a while now, and usually when I thought that a bullet hit would not show the expected results, it was because it was underperforming to a notable degree.

I always thought that the general denial of complaints from multiplayer events was a bit too drastic, but what I've witnessed today indeed makes me believe that net code has a massive (and not quite desirable) effect on bullet performance.

And I'm saying so as the one who had the "benefit" from such odd occurance.

 

This was me trying to scare @Myp3uk when I was chasing him down with Fw 190 A-8, with me flying in a Yak 9 ser.1 behind him.

From about 500 meters distance, I squeezed the trigger very briefly two times just to make him move and bleed some energy, but instead... well, see for yourself.

I've watched this scene from every possible angle, looked for muzzle flashes and tracers, and the only conclusion I could come to was that it's apparently been a single 12.7mm AP bullet from the UBS gun that impacted slightly behind the cockpit, on the right side of the fuselage, at an angle where you'd expect it to simply bounce off the plane's skin - which was not what happened.

 

Sorry to @Myp3uk for this incident, he surely didn't deserve to get blown out of the sky by net code glitches like this.

 

 

Edit: Yes I know there's a P-38 right behind me... didn't notice him while I was flying, it's one of those incidents where AI just starts chasing down the same plane like you just did for countless minutes, and of course AI completely ignores the player's presence. Few seconds later, AI would probably have blown me out of the skies or simply run into me.
For the sake of completeness, this multiplayer sortie took place on our own server, RTT was 40ms, the server was not overloaded at all, so no good excuse for such strange results.

 

:drinks:

Mike

Edited by SAS_Storebror
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Posted (edited)

Wow!  Fuel tank hit maybe?  I defer to your expertise.

Edited by JG51_Beazil

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Looks like a fuel tank explosion to me.  Note the flames before the aircraft is blown up.

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Its delay data for bullets, in that situations when enemy finaly recives data his airplane recives 100% of damage at once and blows away just like in video, there was many videos like that before when this problem was comon last year.

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25 minutes ago, CountZero said:

Its delay data for bullets, in that situations when enemy finaly recives data his airplane recives 100% of damage at once and blows away just like in video, there was many videos like that before when this problem was comon last year.

Yeah, for a while there you saw a lot of 'Delayed hit received' in the chat. It does seem less common with recent patches but it still happens.

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Posted (edited)

since they did that big fixes to MP at begining of last year i never had this happend to me again and it was offten online before it, but i played on servers that are ~40ping to me maybe it can still happend in cases of big ping differance betwen server and players, but for sure not as offten like it was before fix.

Edited by CountZero

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Looks like a fuel tank explosion, you can get this in SP as well. Just after the large damage update in April, I did some test runs against P-38s. One short burst of MG behind and left of the cockpit and the whole thing exploded.

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Naah it is your skills. I know looking at myself that its hard to be as unbelievable good as me. 
Unbelievable how many times I said to myself “thats ubelievable”

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Posted (edited)

Why i dont think its fuel tank explosion is because you see airplane just get separated at all parts that can detach, you dont see that even when you colide and not when you have fuel tank explode in SP, i see this type of instant separation only in videos where data delay for bullet was happening.

like on this video from 3007 before fix (0:40s), and there was few more like that:

 

 

 

Edited by CountZero
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Posted (edited)

I suspect what we see in OP video is a bullet hitting the magazine of the FW190. Its been confirmed that the game does use RNG in the damage model to determine what is hit and damaged on plane , and has limited numbers of hit boxes modelled. ( so in this case RNG (resulted in a Yes/TRUE) on a vital part something like the magazine , and resulted in a Ka boom!.

 

Net code lag occurs on all mplayer games regardless of ping. It just get more intense with higher pings/jitter

Jitter is the more likely network issue here , not ping. Most networks have some jitter(the internet certainly does as its not a guaranteed network, its a best effort delivery network). It helps if you understand how data is sent on a network. Certainly appears to occur in that video also.

 

I can certainly see the problems for the developers when they have no way to check what's occurring within this aspect of any multiplayer error report, when troubleshooting and fixing problems related to different users connections. 

 

Its pure luck or badluck in this case. This kind of thing may have happened in real life if very unlucky (if it did it was a likely a very low probability, dependant on number of hits to that specific part of the plane). I also know you can not rely on in game visuals to give very accurate information on how many shots hit or what damage is done to specific parts of the plane (and also remember for every tracer there is 4 or 5 other bullets potentially also hitting.

 

 

YAK1 guns
Forward-firing armament: 
20mm gun "SsVAK", 120 rounds, **800 rounds per minute**, nose-mounted 
2 x 7.62mm machine gun "ShKAS", **750 rounds, 1800 rounds per minute**, synchronized 

 

Edited by =RS=Stix_09
clarity of meaning, and links
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I always figured the smallest round in game in the right place could do magic.  Even a single 303 can make a bad day.

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Posted (edited)

I had a similar experience using a P39 against a 109-G4 and not using the 37mm but that was offline so I guess I just hit something vital.

 

 

Edited by 56RAF_Roblex

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Posted (edited)
2 hours ago, CountZero said:

Its delay data for bullets, in that situations when enemy finaly recives data his airplane recives 100% of damage at once and blows away just like in video, there was many videos like that before when this problem was comon last year.

 

Yeah I have been experiencing this repeatedly online. Instant explosion, wing off, plane falling apart or fire after only one or two hits. Netcode for multiplayer really needs an overhaul. Thanks for making this very concerning topic @SAS_Storebror as I have been noticing this issue more and more.

Edited by Geronimo553

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6 minutes ago, JG51_Beazil said:

I always figured the smallest round in game in the right place could do magic.  Even a single 303 can make a bad day.

Which, generally speaking, is kind of how it works in real life. All it takes is one rifle calibre bullet through the canopy to kill the pilot. or hit the wrong distribution line in the engine and kill it dead or start a fire. 

Fire enough bullets and the million to one shot becomes a certainty. 

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Posted (edited)

It looks a lot like a hit to a magazine, which happens in single player too.

Edited by 71st_AH_Barnacles

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Posted (edited)

Not multiplayer specific. Just an hour ago I (190A-8) lost my left wing to a single hit (to the right-side fuselage) from an Il-2's rear UBT in a quick mission.

 

No doubt single machine gun rounds can bring down planes (by killing the pilot, or starting fires, or damaging critical parts). But I'm pretty skeptical of the idea that these warplanes would explode into fragments from single hits like they do now.

 

 

magic1.jpg

magic2.jpg

magic3.jpg

Edited by Charon
Screenshots

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Posted (edited)

FYI : Network optimisation:

Combat box has a nice network setup guide to help optimise you network settings, def worth a look especially if you are connecting to game servers that are not local in il-2/dcs etc

https://combatbox.net/en/info/

 

Quote

Network issues

Our server is located in New York, in a commercial datacentre. We have thousands of pilots each month playing, including pilots from Australia, Brazil and Europe. If you are getting ping kicked, the problem is most likely your internet connection, not the server. Try using a wired connection instead of home wifi. You can ping combatbox.net to see your current ping. Our maximum average ping over one minute is 350ms round-trip. We will not increase our ping limit; we already have some players warping around with jittery ping, and increasing ping limit makes the experience worse for all the other players.

If your ping is good but you sometimes lose connection, you might need to optimize your MTU to reduce packet fragmentation. Yes, that probably sounds like gibberish. Here's a guide to doing it.

 

25 minutes ago, Charon said:

Not multiplayer specific. Just an hour ago I (190A-8) lost my left wing to a single hit (to the right-side fuselage) from an Il-2's rear UBT in a quick mission.

 

No doubt single machine gun rounds can bring down planes (by killing the pilot, or starting fires, or damaging critical parts). But I'm pretty skeptical of the idea that these warplanes would explode into fragments from single hits like they do now.

 

Pretty sure if a magazine exploded that was full of cannon shells , it would not be a good day, but would it be like in game , no idea🤔 

(or what likelihood they exploded at all ) The more likely scenario is a fire as the cause of this happening , which does also occur in game.

Edited by =RS=Stix_09

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3 minutes ago, =RS=Stix_09 said:

Pretty sure if a magazine exploded that was full of cannon shells , it would not be a good day, but would it be like in game , no idea🤔 

 

I've never heard of a magazine explosion in an airplane. I'm not saying for sure that it couldn't happen, but I've never heard any report of such a thing in the real world. I'm skeptical that a 20mm HE round has enough payload to breach the neighboring shell and cause a chain detonation.

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6 minutes ago, Charon said:

 

I've never heard of a magazine explosion in an airplane. I'm not saying for sure that it couldn't happen, but I've never heard any report of such a thing in the real world. I'm skeptical that a 20mm HE round has enough payload to breach the neighboring shell and cause a chain detonation.

 

Maybe not a chain reaction in the magazine, but shells and fuel tanks might explode together. Its prob a little overdone in game though and more generalised (cost $ to model/develop all the scenarios possible )  to not overcomplicate all the various combinations of fuel/cannon shell types etc possible in game. 

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Posted (edited)
19 minutes ago, Charon said:

 

I've never heard of a magazine explosion in an airplane. I'm not saying for sure that it couldn't happen, but I've never heard any report of such a thing in the real world. I'm skeptical that a 20mm HE round has enough payload to breach the neighboring shell and cause a chain detonation.

 

Check gun cams (at your own peril) where FW190s get hit, you can see wings being torn off by ammo explosions. 109 pilots said in their memoirs that the Mustang escorts over Europe would try to shoot at their left side to hit the cannon ammo box in the left wing.

 

Other than ammo boxes in the wings, there are 109 models which stored oxygen bottles in their right wing.

Edited by Raven109
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2 hours ago, =RS=Stix_09 said:

I suspect what we see in OP video is a bullet hitting the magazine of the FW190. Its been confirmed that the game does use RNG in the damage model to determine what is hit and damaged on plane , and has limited numbers of hit boxes modelled. ( so in this case RNG (resulted in a Yes/TRUE) on a vital part something like the magazine , and resulted in a Ka boom!.

 

It uses probability, not RNG. Not really the same thing.

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Posted (edited)
11 minutes ago, JG51_Beazil said:

@SAS_Storebror, @Geronimo553, What makes you suspect the net code itself?  I acknowledge as a fan of SAS for a long time that they may know or see things we don't.  Thanks in advance.

 

It is difficult to explain in a technical sense. But in layman's terms, you see the enemy hit you once and a few seconds later your wing falls off or your plane turns into multiple pieces without any real indication. It is like the plane falls apart in mid air. I would guess that damage is not being calculated correctly above 100-200 ping. Which is a ping easily achievable for a US player like myself were to play on a server like wings of liberty in Russia.

 

Another iL-2 netcode issue is fps. Somehow being around other players online will considerably tank fps. Offline I can run 90 fps all day and online soon ping heavy users are around I am down to 20-30 fps. This turns any plane into a flying brick with limited controls. Both of these points play a factor when people refer to netcode issues. 

Edited by Geronimo553

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But it that hit is registered, and it makes an ammo cartdrige go off like a hand grenade next to a fuel cell in the wing root....?  I'm not trying to be augmentative.  :)

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Posted (edited)
3 minutes ago, JG51_Beazil said:

But it that hit is registered, and it makes an ammo cartdrige go off like a hand grenade next to a fuel cell in the wing root....?  I'm not trying to be augmentative.  :)

 

There is no explosion, the plane just falls apart with zero audio. Yes internal explosions do occur as well now. Which is a feature I like, but when I see a single bullet hit the tip of my left wing and seconds later that whole wing flies away. Well that is netcode not calculating damage correctly. 

Edited by Geronimo553

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Tip?  Not I that example, but again, your example is a different one.  Maybe Mike has seen this before as well.

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Posted (edited)
1 hour ago, 56RAF_Roblex said:

I had a similar experience using a P39 against a 109-G4 and not using the 37mm but that was offline so I guess I just hit something vital.

 

 

I encounter this exactly in SP but like in your case you can see multiple hits and then big explosion of ammo or fuel tank, in case on first post you just see airplane fell apart and no big explosion before it like you would se in SP when ammo or tank is couse of it, to me it looks more like cases i see when bullet data is lost and then recived. 

Edited by CountZero

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57 minutes ago, Charon said:

 

I've never heard of a magazine explosion in an airplane. I'm not saying for sure that it couldn't happen, but I've never heard any report of such a thing in the real world. I'm skeptical that a 20mm HE round has enough payload to breach the neighboring shell and cause a chain detonation.


it's not the payload per se but the cartdridge propellant that get's blown off when this sort of event happens, for planes, tanks and ships.

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Posted (edited)
4 hours ago, Jade_Monkey said:

 

It uses probability, not RNG. Not really the same thing.

 

Yes its probability , but In context of Il-2 we have limited hitboxes. My point was some X statistical calculation is done, and that uses some  RNG component in the DM.  I have no idea the specifics, only the devs know particulars.

 

So yes calling it RNG is an oversimplification. 

 

Edited by =RS=Stix_09

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Posted (edited)
5 hours ago, Geronimo553 said:

 

It is difficult to explain in a technical sense. But in layman's terms, you see the enemy hit you once and a few seconds later your wing falls off or your plane turns into multiple pieces without any real indication. It is like the plane falls apart in mid air. I would guess that damage is not being calculated correctly above 100-200 ping. Which is a ping easily achievable for a US player like myself were to play on a server like wings of liberty in Russia.

 

Another iL-2 netcode issue is fps. Somehow being around other players online will considerably tank fps. Offline I can run 90 fps all day and online soon ping heavy users are around I am down to 20-30 fps. This turns any plane into a flying brick with limited controls. Both of these points play a factor when people refer to netcode issues. 

 

The problem will be more noticeable when you have players in very different regions of the world. Netcode is  quite difficult to resolve keeping players and the server in sync. Any network packet loss/fragmentation/jitter  etc is going to be a big problem for the game to resolve, especially for something like a flight simulator, with small time windows available to get data and use it before it starts to impacts gameplay in a noticeable way.

Slowing the user updates down to get them in sync is occurring here I believe. (Either speed data link up or slow the players down, or loose sync)

 

This will always be a problem, no game can fully resolve this. I guess that why many call it "wings of latency"

 

Edited by =RS=Stix_09

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Thanks for all your feedback guys :salute:

 

6 hours ago, JG51_Beazil said:

@SAS_Storebror, @Geronimo553, What makes you suspect the net code itself?  I acknowledge as a fan of SAS for a long time that they may know or see things we don't.  Thanks in

advance.

 

It's just the first excuse for what happened that came to my mind.

Plus a little bit of investigation from updating a couple of old mods lately, which for instance revealed this in the AP bullet's code (this is from the russian 12.7x108mm AP bullet as example, but all AP bullets ingame seem to have the same):

DestroyOnExplosion=false	//используется только для бронебойных пуль (default =true) с целью обеспечить применение Hit..Effect вместо Hit.., при сохранении пробоя препятствия на вылет
							//что в свою очередь требуется для "прицепления" эффектов попадания по движущейся технике, а так же гарантированной передаче попаданий в сетевой игре

The russian text translated says "is used only for armor-piercing bullets (default = true) in order to ensure the use of Hit..Effect instead of Hit .., while maintaining the breakdown of the obstacle on the fly which in turn is required to "hook" the effects of hitting a moving vehicle , as well as guaranteed transfer of hits in the multiplayer game".

 

Makes me wonder whether it's a good idea to have that set to "false" on all AP bullets, or whether the explanation doesn't match the real state of the game anymore.

 

For those who mentioned common networking or server issues:

Our Server is a dedicated Server hosted in a Datacenter in Germany.

OS is Windows Server 2016.

CPU is Intel Core i7-4770 @3.8GHz

It has 32 GB RAM, 2x2TB HDD (Raid 1), 1GBit/s network connection non-clocked.

This thing is a real beast, not the "Layman's solution". It takes real money to operate it and the only other thing running on that server is IL-2 1946, where we have no network issues at all.

My ping to the server is 40ms. Can't say what @Myp3uk's ping was.

 

Talking about network hit issues, lag, IL-2 1946 and the technical impossibility to solve such issues or the presence of the same in other games:

As a long-time modder of IL-2 1946 who went down to the inner core and particularly to the network code of that game, I can definitely say that such things will not and cannot happen there, because 1946 uses a pretty simple yet effective approach to transferring network hits:

The hit itself - meaning whether you hit something and if so, where you hit it - is solely being calculated on client side at the "shooters" client.

The damage caused by the hit - be it simpy an AP bullet punch or an explosion from HE rounds - is solely being calculated on client side at the "targets" client.

This is completely independent of ping times, lag, jitter or any such thing. And it's inherently safe from packet loss as the game uses "guaranteed" packets for this, which means the receiver has to acknowledge the packet or it will be resent almost immediately, and if the receiver fails to ack such packet multiple times, he'll get kicked off the server.

That being said, shooting in 1946 is like "if the shooter sees a hit, then it is a hit, and the hit is precisely where the shooter sees it", and "the damage is calculated by the client of the one who got shot", simple as that.

I'm not saying this scheme was perfect. It does have it's shortcomings, e.g. the victim might think he's safe from getting hit but the shooter still scores hits, especially in case of large ping times, and not to forget the efforts you have to put into this to make it safe from cheats to a certain extent...

 

IL-2 Great Battles seems (can't say for sure, can't look into game's network code) to use some approximation like "shooter sends to server a bullet launch from gun index n" and the rest is being calculated by the server - but the server could use a different location/direction/speed of the participating clients than any of the clients does, thus lag/jitter comes into play big times. And since every packet in GB seems to be UDP, any packet loss would be just that, unless there's some other layer of acknowledgements on top.

 

:drinks:

Mike

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I remember a comparable discussion on the ATAG forums long ago about wing offs after hits and how likely they were. Some mad lad combed through all the historical gun cam footage and after action reports he could scrape together(and there really isn't a lot to begin with) and noticed the following: 

1. Wing offs/wing folding mostly seemed to happen on 190s.

2. Wing offs/wing folding often seemed to coincide with explosions at the wing roots, probably ammo explosions.

3. This is corroborated by some after action reports that mention these wing root explosions /collapses on 190s (famous example being the 190 with the upfolded wings during the Y-29 Bodenplatte event).

 

To the topic at hand, this event could very well be such an ammo cookoff combined with a nasty lag spike but the overall behaviour could be historical.

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Posted (edited)

I see this sort of thing a lot as I host the BlitzPigs on my own computer while I am flying.   Mostly it's positioning error type of things.   We will be in formation on the way to a target, I am flying lead.  I will indicate say, 330kph in an IL2, and the rest of the formation will blow by me and they are having trouble to not suffer from stalls as they are indicating 270 or below, yet on screen they streak by me.  Then when we do attack things on the ground I will often get warnings that one or the other of them has 4 or 5 second delays in registering hit data.

 

I am in Ohio, the other guys are in Maine, Washington state, Los Angeles area, Vancouver, London in the UK, Germany, and Tel Aviv Israel.  Just something we have to live with.

Edited by BlitzPig_EL

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