4 ms·

Maybe if you just have a flat world where you move in any direction with a max speed, but this sort of anti-cheat becomes incredibly difficult once you add feat

by judge2020 5y ago

Maybe if you just have a flat world where you move in any direction with a max speed, but this sort of anti-cheat becomes incredibly difficult once you add features like terrain, physics, vehicles, things like gliders (in BR games), speed boosts, etc. It's possible, but takes a lot more effort. For example, in Fortnite, if you toggle a lagswitch (as in, block Fortnite UDP for some time), then reconnecting to the server will return you to the same position you were at when you disconnected, assuming you were just trying to run on the ground. However, if you toggle a lagswitch in a vehicle, the servers don't want to do expensive, complicated physics server-sided, so your client becomes authoritative to your position and the sanity checks are simply making sure you're not teleporting around large chunks of the map in seconds. If you were to hack your client and give your vehicle moon gravity, the server generally wouldn't care about that.

jbluepolarbear 5y ago
I’m pretty sure the car uses dead reckoning. So you position in the car is static (the last place you where), but the car is moving at speed and will continue even if you disconnect.
- judge2020 5y ago
  Sure, but I’m talking about the control you have over the car when in the car. During the start of this battle pass season there was immense server issues, which I guessed was the tick rate dropping to super low values due to some bad code. During a few games where the servers degraded in this way, moving would be extremely slow on the ground as it kept pushing you back (since the server isn’t processing your ‘move forward’ commands as often) but getting in a car gave back free movement since I assume it’s a direct broadcast that doesn’t hit the game loop and doesn’t have any position-correcting sanity checks running.
  - jbluepolarbear 5y ago
    I’m saying a car is easier to predict because of dead reckoning. With less frequent updates your actions still feel fluid because the cars momentum can’t change a whole lot between updates. Say you’re driving a car in a straight line, there’s very good odds that in .25 seconds you’ll still be going straight so your predicted line will be very close to the real line. With players you can’t guarantee that, they could zig zag, turn around, jump, etc much more likely to change and require prediction reconciliation.
    - meheleventyone 5y ago
      Cars and vehicles in general are actually much harder because player simulation is much simpler, usually not happening in some middleware physics engine and is much more bounded in terms of the accelerations and speeds involved. Straightforward extrapolation as with dead reckoning does poorly with both cases. Then once you’ve mastered the art of getting cars not looking wonky you have to deal with collisions between them when they’re moving at speeds where typical gameplay latencies make it easy for discrepancies between clients to cause mispredictions which result in complete misses or large interpenetrations that physics engines have a bad time with.
      - jbluepolarbear 5y ago
        Collision between 2 vehicles is a nightmare to make look good. But I haven’t had issues with extrapolating vehicles, it’s generally much easier to predict and reconcile than players.
        meheleventyone 5y ago
        The problem with extrapolation is that you’re always predicting into the future so any state change you don’t predict causes a reconciliation which ends up looking bad. So even if you send the full physics state regularly any non-determinism in the physics engine (hello PhysX), any change in the control state and so on results in misprediction and reconciliation. This always ends up looking wrong, particularly for rigidbody driven things and in particular when mispredictions errors are large like fast moving vehicles.
        jbluepolarbear 5y ago
        Disagree on this, if you’re getting constant updates and you smooth to the real position from the predicted position while continuing to predict you’ll have a very smooth non jittery movement. Determinism isn’t even required because you’re getting authoritative states from the server. This overview of Call of Duty explains why what you say isn’t the case. https://youtu.be/tCpYV4k_izE https://youtu.be/tCpYV4k_izE
mox1 5y ago
So that is fair, but I'm certain that there is a (large?) group of players who would pay $$ / month to have this expensive computation done server-side, IF it means cheating drops to nothing. Stadia (and similar) can render entire games server-side and then deliver them to you for a nominal fee. I'm certain that in 2021, we can hook up a nvidia gpu to the server and allow some basics physics calculations run for ~128 players. If we can't, there 100% is a market for a chip, card, server, etc. that can do this. There is an entire group of gamers (30's+ with kids and demanding job, not a lot of time) who are sick and tired of FPS cheats and just want to relax and play a game for an hour a night. They would happily pay for a non-cheating version of a game.

jbluepolarbear 5y ago

I’m pretty sure the car uses dead reckoning. So you position in the car is static (the last place you where), but the car is moving at speed and will continue even if you disconnect.

judge2020 5y ago
Sure, but I’m talking about the control you have over the car when in the car. During the start of this battle pass season there was immense server issues, which I guessed was the tick rate dropping to super low values due to some bad code. During a few games where the servers degraded in this way, moving would be extremely slow on the ground as it kept pushing you back (since the server isn’t processing your ‘move forward’ commands as often) but getting in a car gave back free movement since I assume it’s a direct broadcast that doesn’t hit the game loop and doesn’t have any position-correcting sanity checks running.
- jbluepolarbear 5y ago
  I’m saying a car is easier to predict because of dead reckoning. With less frequent updates your actions still feel fluid because the cars momentum can’t change a whole lot between updates. Say you’re driving a car in a straight line, there’s very good odds that in .25 seconds you’ll still be going straight so your predicted line will be very close to the real line. With players you can’t guarantee that, they could zig zag, turn around, jump, etc much more likely to change and require prediction reconciliation.
  - meheleventyone 5y ago
    Cars and vehicles in general are actually much harder because player simulation is much simpler, usually not happening in some middleware physics engine and is much more bounded in terms of the accelerations and speeds involved. Straightforward extrapolation as with dead reckoning does poorly with both cases. Then once you’ve mastered the art of getting cars not looking wonky you have to deal with collisions between them when they’re moving at speeds where typical gameplay latencies make it easy for discrepancies between clients to cause mispredictions which result in complete misses or large interpenetrations that physics engines have a bad time with.
    - jbluepolarbear 5y ago
      Collision between 2 vehicles is a nightmare to make look good. But I haven’t had issues with extrapolating vehicles, it’s generally much easier to predict and reconcile than players.
      - meheleventyone 5y ago
        The problem with extrapolation is that you’re always predicting into the future so any state change you don’t predict causes a reconciliation which ends up looking bad. So even if you send the full physics state regularly any non-determinism in the physics engine (hello PhysX), any change in the control state and so on results in misprediction and reconciliation. This always ends up looking wrong, particularly for rigidbody driven things and in particular when mispredictions errors are large like fast moving vehicles.
        jbluepolarbear 5y ago
        Disagree on this, if you’re getting constant updates and you smooth to the real position from the predicted position while continuing to predict you’ll have a very smooth non jittery movement. Determinism isn’t even required because you’re getting authoritative states from the server. This overview of Call of Duty explains why what you say isn’t the case. https://youtu.be/tCpYV4k_izE https://youtu.be/tCpYV4k_izE

mox1 5y ago

So that is fair, but I'm certain that there is a (large?) group of players who would pay $$ / month to have this expensive computation done server-side, IF it means cheating drops to nothing. Stadia (and similar) can render entire games server-side and then deliver them to you for a nominal fee. I'm certain that in 2021, we can hook up a nvidia gpu to the server and allow some basics physics calculations run for ~128 players. If we can't, there 100% is a market for a chip, card, server, etc. that can do this. There is an entire group of gamers (30's+ with kids and demanding job, not a lot of time) who are sick and tired of FPS cheats and just want to relax and play a game for an hour a night. They would happily pay for a non-cheating version of a game.