I hope this thread can be used to just discuss the merits of the server side antilag feature.

There is an another thread to comment on it being enabled secretly on many servers.

A quote from an old thread:

Quick facts about the server side antilag:

When server receives a command by client to shoot an instant-hit weapon (SG, SSG or LG) it doesn't use it's current view of enemy positions to figure out whether the shot hits them, instead it remembers the enemy positions from a past time based on the attacker's latency.

Other weapons are not affected in any way.*

After you run through a teleporter, you can NOT be hit by an enemy even if he still sees you on the other side of the teleport.

The attacker's position that is used is always the server's view on it. So if you get hit by a rocket and fire shaft before you know you got hit, you will miss even if you are pointing straight at the enemy.

* Currently there is a projectile antilag that has loads of issues. Renzo has said that it will be removed.

How does the server know where objects were in the past? Does it record the positions on every 'tick' and keep a record, or is it just some guess?

My opinions after a lot of testing and later reading the code:

I think the positives overwhelmingly outweigh the negatives when it comes to this feature.

The most important thing is that it's still always better to have a smaller ping, even if you are just fighting with LG (mainly because of knockback). The difference is of course smaller, but that is a good thing.

One possible problem is getting hit around the corners. Luckily it turns out that this is really hard to notice in practice. Anyone with reasonable ping won't be shooting so much behind you that it creates bad situations for you. Random statistic to put things in a perspective: A fast bunny-hopping speed is 500 ups (most fights happen in much slower speeds), the player is 32 units wide. Thus it takes 64 ms to move one player width. So you need to be either going really really fast or play versus a really high pinging opponent for this to be noticeable.

Another possible problem is the surprise attack, opponent getting free shots because your reaction to him will be "lagged". The fastest shooting weapon is the LG that fires every 100 ms, so you will need to have over 113 ms ping to get one extra free cell of in the surprise attack situation. Again the disadvantages of the high ping clearly outweigh any slight advantage there.

A note worth making is that there is surely weird things that can happen if one player has a huge ping like 250 ms. But that really isn't relevant since no-one actually plays with such a ping and because playing with 250 ms without antilag is impossible anyway.

It turns out that "moving" the hitbox slightly makes a big difference from the attacker's point of view, but not very noticable difference from the victim's pov. And that's why antilag works.

Yes, it records the old positions. You can only be hit in positions where you have (very very recently) been.

So if someone has 5000ms delay, I can basically get hit at ra, because I was earlier at ya?

I agree that if most of the issues get fixed, antilag is a good feature. Nice summary btw, medar. One more thing though.. Does antilag make your lg hit exactly inside your crosshair, or where the beam is?

Short answer: Exactly inside your crosshair

Nitpick: You always hit exactly on your crosshair antilag or not, it's just "when" you hit that changes. With antilag you hit enemies where you see them now. Without antilag you hit enemies where you see them a little bit afterwards.

So this is why I have recently pulled insane 50-60% sg constantly? Hitting is just easier?

There are three views on your own position:
1) Your own view that has predicted where you will move based on your input.
2) The server's view that is based on the input that has actually reached the server.
3) The opponent's view that is what he has received from the server.

Without antilag you will get hit based on server's viewpoint and with antilag you will get hit based on the opponent's viewpoint.

This means that it has always been possible to run behind a corner (from your own POV) and still die to a LG shot. The difference with antilag is that the timeframe for that to happen becomes higher and is not solely based on your own ping, but also your opponent's ping.

Yes but of course prediction should remain just prediction and things should really happen only on the server. That is the real reality of the game, and before it was not possible to get hit in positions where you are not in server reality.

There are some issues with the current antilag implementation. I have fixed most of them in a patch that is not (yet?) in use.

1) There is antilag for projectiles.

This is extremely bad and there is no excuse for it. Projectiles direct hit earlier when you have higher ping. Splash damage is not affected which makes the whole thing very inconsistent.

This is fixed in my patch.

2) Antilagged position is based on the position that was sent to the client, not the predicted position that client shows.

QuakeWorld predicts/extrapolates the enemy positions by small amounts, but the antilag code doesn't take this into account. This means that you actually need to hit a little bit behind what you see currently.

My patch takes prediction into account which in practice makes antilag on 26ms and bigger pings be 13.5ms "less effective". And 6.5ms "less effective" with 13ms ping.

3) Teleporters are not handled well

In the current implementation once your opponent goes through a teleporter you can't hit him anywhere with an instant hit weapon for a short period of time. The time is based on your own ping and is a detriment for the higher pinging player.

My patch allows you to instantly hit the enemy once he comes out of the teleporter.

4) Moving platforms are not antilagged

This bug is relatively hard to come by in practice, but it's possible to make impossible shots with high pings when there a moving platform involved. This is because the platform is always considered to be in it's current location while the enemy is in the lagged position.

My patch does NOT fix this.

This _might_ be because of the bug #2 that my patch fixes. There is no reason that SG aim should get better with <26ms pings if the antilag is properly implemented.

Your patch? Are you somehow involved in this? Ah sorry didn't notice the post above.

this is a very interesting thread to read. thanks for coming out with this one. keep on explaining.

In my opinion what matters is trying to provide the best possible gaming experience given the circumstances. None of the players actually sees what you call "the real reality of the game" and it's really not what's important.

When pings get high the gaming experience will suffer one way or the other, in my opinion antilag makes the suffering a lot smaller and brings the game much closer what you get with LAN pings.

Medar, does your patch remove the client side antilag, and make /antilag command and the indicator active for the server side antilag?

No it doesn't. That would be quite easy of course though.

Personally I'm not a fan of making everything toggle-able. Especially for features that require you to play differently.

It would be much better to have a standard setting for this kind of thing. You get very used to the way you aim with your LG, and if you have change that depending on what server you are on, or who your opponent is... it's not good.

I just don't believe in silver bullets. Aimbot would also make hitting with a high ping easy, but it's not what I want to happen.

blAze, even if this feature ends up not being perfect enough to be used, I still think Medar and whoever should keep working on it. There is no point in dismissing something we haven't tried yet.

The problem with aimbot is that it makes hitting with high ping easier than hitting without aimbot on low ping is. It also reduces the amount of skill required.

Antilag on the other hand doesn't have these problems. Hitting with high ping with antilag is not easier than hitting with low ping without antilag and it still requires all the same skills.

Apparently we have tried it and it has made hitting very easy and hpw opponents feel like playing vs aimbots. Can we get our old QW back now, thanks!

We didn't try the Medar patch yet

As I said the bug #2 might have something to do with that. With properly implemented antilag hitting with 13ms won't be any easier than hitting with 13ms is without antilag.

Other than that are you claiming that it's easier to hit with higher ping? I find that very hard to believe.

Sure 52 ms player hits better with antilag than without antilag, but he would still hit better if he had 13 ms ping.

Maybe the hpw opponents can just hit so well? ;>

Anyway imo the nice side on this is, that it makes competitive qw scene bigger (people with 51-65ms have a chance now too).

But of course it's not acceptable if there's something which makes it an advantage for a lagged player.

How depressing. I guess I'm going to get even worse when antilag is turned off!

You'll have to excuse my uneducated question, but I just don't have the knowledge of how FPS-games (Quakeworld in particular) works completely:

Q: Does the server record positions, for sv_antilag purpose, while the player is in the air as well?

I haven't done much research or given much thought to it, but I've often found it to be much easier to avoid getting hit in the while I'm in the air by opponents LG when the opponent has a high ping compared to avoid getting hit in a ground battle.
I've played povdmm4 with some very good opponents with high ping (i.e. BuLaT) and I had a great deal of problems avoiding getting hit by the high ping opponents LG in ground fights, but escaped pretty easy while in the air.
As I stated above, I haven't done much research and I also don't have the necessary skill set/experience to be sure if this is just due to flaws in my own movements/aim in LG ground fights vs LG air fights (or flaws in the opponents skill set/experience for that matter) or if there is actually any difference in the way sv_antilag functions. Hence the above question

Yes, it doesn't matter where the enemy is. Only exception is when using teleporters which cuts of the antilag "trail" so no-one can be hit on the wrong side of the teleporter.

You are holding on to this notion that the most important thing out there is this "reality" of what the server side sees. But that's a very arbitrary thing, it's an implementation detail. The goal QW server and client is to be able to play as good a game of QW as the conditions allow. The server-client model is just one way to try to achieve this goal.

It turns out though that when latencies get high this technical implementation of QW begins to have some issues. Now antilag a technique that tries to lessen the effect of latencies and allow people play a better QW game.

Server "reality" shouldn't be an intrinsic value, it's just an implementation detail that players don't even need to know about.

It's the reality that we have been used to expect and play by for 13 or so years. 95% of players have good enough connection to enjoy QW without magic tricks with lag, changing everything for the 5% doesn't make sense. Playing with antilag on is not as enjoyable, it's too easy. For instance aiming with lg has always been about where the beam hits, now you can just put fakeshaft 1 and aim with crosshair. Completely different.