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John Carmack on QuakeWorld latency and business model (1996)

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Re: John Carmack on QuakeWorld latency and business model (1996)

#21

Post by ethbro »

Nition wrote: post #15
pvg wrote: post #12

Earlier quoted context omitted.

The Wikipedia page has a link to a thingie that says Duke Nukem 3D had clientside prediction. https://en.wikipedia.org/wiki/Client-side_prediction

I clicked your link and at first kind of brushed it off as dubious since the only linked source is a press article, but the article is an interview with Ken Silverman himself! So that's pretty credible. The source of the released game is available, so it should be possible to check, except that it's a huge mess (check out BUILD.C).[1] Seems weird that no-one has actually verified this when it could be the first game…

I have no idea how I remember this, but there's a write-up about the Age of Empires netcode (written ~96, released end-of-97): https://www.gamasutra.com/view/feature/131503/1500_archers_o...

Because of the unique challenges, they did a lot of synchronized client-side simulation (based on minimal state transfer over the net).

... and apparently encountered a lot of the issues with doing that (no random anything!!!).

Re: John Carmack on QuakeWorld latency and business model (1996)

#22

Post by ethbro »

keyle wrote: post #2

Pretty impressive when you consider this was in 1996! I really like his ability to take out code and 'shoot it'. Back to the drawing board. It's a quality of a great engineer, to be able to reflect on what's been done and admit it's not good enough.

> "While I can remember and justify all of my decisions about networking from DOOM through Quake, the bottom line is that I was working with the wrong basic assumptions for doing a good internet game."

I'm not one for hero worship, but I think that's as close to engineering zen as one can get.

Aka 'I'm brilliant. I thought I was doing the smart thing. Turns out reality was otherwise. I'm changing my approach.'

Re: John Carmack on QuakeWorld latency and business model (1996)

#23

Post by SmirkingRevenge »

kzahel wrote: post #17

The only thing QW really added over vanilla "netquake" was client side movement prediction. Hitscan weapons (infinite velocity bullets) only let you know if you had hit or missed based on the response from the server. You had to lead your shots a certain amount based on your current latency in order to hit your target. It was great though. It meant you could bunny hop around corners at extremely high speeds without r…

You say "only", but for those of us who's ping on a good day was between 250-300ms, it was miraculous. It is interesting though, how lag compensation on one particular aspect of the game can make such a big difference, even though the lag is still there in full force in other (just as critical) aspects of the game.

Re: John Carmack on QuakeWorld latency and business model (1996)

#27

Post by tkiley »

timeimp wrote: post #10
Nition wrote: post #3

Someone correct me if I'm wrong, but I believe this was the genesis of client-side prediction for games. If you don't know what that is, Valve has some good documentation on it (relating to Source engine, but it's the same concept).[1] Latency was still a problem even with CSP because we didn't yet have lag compensation on the server. So although you got an authoritative server (no cheating) and instant inputs (no ro…

Any idea why the would not implement lag compo for projectile-based weapons? Too much processing power required?

lag compensating projectiles on the client decreases usability more often than you'd think.

Projectiles like rockets apply a lot of forces to the player which are not easily predictable. If you fire a rocket and client-side prediction has it leaving your vicinity without collision but the server has someone stepping into the path of the rocket so it explodes close enough that the explosion exerts force that changes your position, you're going to have a really bad misprediction on the player's position, which of course can get waaaay worse if the player launches another rocket while the first rocket's effect on player position has not been sorted out properly.

Re: John Carmack on QuakeWorld latency and business model (1996)

#28

Post by speedplane »

Why is this article hosted on github? Obviously it wasn't created there as it was written in 1996. Are all the message boards and forums where this type of material was likely posted really defunct or unusable now? Do we now need to rely on enterprising internet historians to find gems on older platforms just to copy them to the newer platforms? Will Github be around in 20 years? Will the next historian have to unearth it from github just to copy it to the next platform?

Re: John Carmack on QuakeWorld latency and business model (1996)

#29

Post by reifiedgent »

timeimp wrote: post #10
Nition wrote: post #3

Someone correct me if I'm wrong, but I believe this was the genesis of client-side prediction for games. If you don't know what that is, Valve has some good documentation on it (relating to Source engine, but it's the same concept).[1] Latency was still a problem even with CSP because we didn't yet have lag compensation on the server. So although you got an authoritative server (no cheating) and instant inputs (no ro…

Any idea why the would not implement lag compo for projectile-based weapons? Too much processing power required?

I think the effect on other players would be pretty jarring, especially if said projectiles / explosions jolted players in the air at high velocity.

IIRC QW's client side movement prediction didn't attempt to predict the effects of, for instance, shooting a rocket at your feet/rocket jumping, which meant on high latency connections there'd often be a bit of a delay before your view caught up with where the server thought you actually were. This also applies to rockets fired by other players. Lower latency had the effect of not only making it easier to fire rockets at enemy players, it also made everything seem smoother when people fired rockets at you.

Later versions of QW created from the GPL source release have introduced lag compensation for hitscan weapons, but I'm not aware of any attempts to do so for projectiles.

Re: John Carmack on QuakeWorld latency and business model (1996)

#30

Post by jib »

usefulcat wrote: post #26
ttul wrote: post #24

“I have a T1 to my house...”

In 1996, one would have been lucky to be able to have ISDN, so having a T1 was more like 'money is no object' territory.

Or you were in university/connected to a university.

The Swedish qwctf scene at least was very clearly divided in 20ms people who went to or worked at, a university, and 150ms people who played from home.

There were some 50-60ms ISDN people too but I can only remember a few.

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