help me learn

[kindred sorrel]

alright so i know basics i just need to learn the advanced scripting dont recomend brawl dev because he bored me

[buoyant arch]

davnced scripting is literally just mastering the use of modules

and knowing everything about types

thats it

rrally

[kindred sorrel]

i take advanced as tweenservice and such

[buoyant arch]

they're defo not advanced

[fluid prism]

intermediate on Roblox is at best buffer bit-packing and compression

to be honest, nothing really qualifies as "advanced" on roblox

[trail escarp]

rollback netcode

and the full prediction pattern

[fluid prism]

I have never needed "rollback", nor do I want to do something on a client that would be misleading

If something changes in the server state, then that one thing is simply replicated exactly, if needed, or a part of it is

prediction is different for everything, so that really depends on which thing you trying to predict

[trail escarp]

predict knockback on an npc like a zombie.

can't be done with existing tools, you need to make the full prediction pattern to do it

predicting hp changes also has its fair share of problems

[fluid prism]

change in health is usually a very simple, linear pattern. desync can grow but it can be good enough to simply send a snapshot value to be offset by latency from the server whenever the value changes. as far as NPCs are concerned, there are many different strategies to handle those, so idk which one you're going for there

If the NPC is client-specific, then obviously there isn't really anything that you need to worry about. The client owns the NPC and the only thing the server can do is verify if, for example, the commands (basic move direction, for example) from the client's NPC are acceptable

serversided npcs are simple enough that the reverse is possible, except clients probably don't need to sanitize it and culling should be implemented

for strictly chaotic physics, though, you might honestly be better off with either replicating the exact forces while taking into consideration other collidable objects and the timing of it all (good luck lmfao) or relying on the server's simulation entirely and using the exact CFrame or position for individual objects

[trail escarp]

the prediction pattern leaves very little to ambiguity. if you don't know which one the prediction pattern goes for, that sounds like a skill issue ngl

[trail escarp]

the point of prediction is to sync client and server to the same gamestate. by definition for context of an npc, it is server owned for what other purpose would prediction serve?

[trail escarp]

serversided npcs are not simple, that is my point. you cannot predict hp changes without making a prediction pattern, and if you're doing just the hp my point is why stop at hp, why not just do the full pattern?

[trail escarp]

the prediction pattern is only chaotic during misprediction, that's both an upside and a downside, but that's the trade-off the prediction pattern makes.

[fluid prism]

"the prediction pattern" is unfortunately a very ambiguous name to give whatever it is you're trying to point out, so it's less of a skill issue and more of a language barrier

[trail escarp]

it is very clear to me you don't understand the problem that prediction is supposed to solve. but that's okay! you didn't know design patterns which qualify as "advanced" actually exist and apply to roblox. it's not about the destination, it's the journey, amirite?

[fluid prism]

it honestly sounds to me like you're making something more complicated than it has to be and crowning it "advanced"

[trail escarp]

naw see it's not ambiguous. again, that's okay! you're still learning! ⭐ see, the problem with prediction hp changes is if you change the hp on the client and then change hp again, it is possible for the server to register the first hp change and send it back to the client before or after (this is the problem) the second hp change event occurs. that's what i mean by even the simplest prediction problem is very, for lack of better words;

[trail escarp]

has its fair share of problems

[trail escarp]

i understand how it sounds. but you are mistaken. the prediction pattern is extremely useful and important, and understandably, as you seem to misunderstand it, a real pain in the arse: https://developer.valvesoftware.com/wiki/Prediction

[fluid prism]

1. event that changes health, sends from server to client health correction
2. client continues doing what it does every frame if need be, with the correction

there is no problem with ordering, since that can be guaranteed by remote events queuing

[trail escarp]

roblox introduces a problem with ordering if you try to perform the action on both client and server

[fluid prism]

i'm not really sure when you would need to perform something like that one both

[trail escarp]

gold star ⭐ the prediction problem is an issue with ordering of events, when the client predicts an event vs when it receives server authority notify of same event 💯

[trail escarp]

it needs to happen a lot, particularly with server owned entities. it applies between players too, but one client to the server is the simplest situation to work with

player to server is the easiest. player to player is the real problem this is trying to solve

as it stands, player to server in roblox has no prediction. there exists attempts by roblox, but there is nothing official or formally announced about it: AuroraService (Unannounced) https://robloxapi.github.io/ref/class/AuroraService.html this has all the api functionality I expect from a prediction service, issue is, it's either unrelease or deprecated or idk what's going on with it. in the meantime, whatever is going on with aurora service, you need to make your own in the meantime.

[trail escarp]

so uh... yeah i hope you learned something today

[trail escarp]

things that are "advanced" do in fact qualify and exist in roblox... but tl;dr, skill issue bruh

[fluid prism]

you say it needs to happen, but i genuinely can't think of a situation where ordering is an issue

i'm gonna leave this one up to eternity

[trail escarp]

hp change prediction

[fluid prism]

yeah, not really

[trail escarp]

issue:

[trail escarp]

issue #2:

you can't even faux apply physics to server owned objects on a client, therefore you need to do the full prediction pattern. auroraserver has the api functions you would need to make this possible, but as i said idk what's going on with it. news about it is appreciate if you have any.

in the mean time... advanced-qualified code in roblox is the only way

[fluid prism]

let's see if we're talking about the same thing, and let's say we have a projectile

server tells client to make a projectile with a velocity, both server and client simulate projectile

when projectile hits something, it is supposed to bounce, but the client's happens first and that somehow irreversibly changes something such that when the server's notification of this event, things break

if this isn't what you're trying to say, such that there is a race condition, i am completely lost

[trail escarp]

you're 90% there. the race condition happens when the projectile is being aimed at the local player 💯 the server will have registered the projectile hitting a wall, but in between that time and when the projectile would have actually hit, the player moved into the path of the projectile. does the projectile stay on the wall, or deal damage to the player? - prediction is assuming the player receives damage, because that is what occurred on that player's screen. there are lots of ways to phrase this problem and put into context, and this is one of many ways.

the way i was phrasing earlier with the hp problem is I shoot an arrow (and then a second one) that on my screen, both hits a server-owned NPC, but the server is several frames ahead for that npc and several frames behind for my character+input, and the npc was moving so it didn't actually get hit by the time the server knows about the input, so some time warping is needed plus not sending the hp change twice such that it does not interfere with a second hp change that happened in between the first hit. it gets a bit tricky to describe but i think you're getting the idea

https://developer.valvesoftware.com/wiki/Prediction

Prediction is the notion of the client predicting the effects of the local player's actions without waiting for the server to confirm them.

In the vast majority of cases the client's prediction is confirmed by the server and it continues happily as if there was no latency. If there is a mis-match, which is rare if the prediction code is written correctly, then the client goes back and re-simulates all of the commands it ran with bad data. Depending on the severity of the error this can cause a noticeable hitch in the player's position and state, and possibly the state of the world too.

without prediction you have input delay. you press W and you have to wait for the server to both receive that input, and send back an acknowledgement of input.

50ms is almost unnoticeable, but at 300ms ... bruh if you've played games on 300ms latency you would understand why i care so much about having good prediction 💀

and often roblox will put you on 300ms servers... 💀 your users may be mobile further increasing latency... it's worth it

[fluid prism]

So, this is actually a problem that I have had before and I do have a way to fix it, but I generally don't because I prioritize synchronicity across all players, which means that what one player sees at a particular timestamp is as close as it can be to what other players see, at the cost of some individual issues when latency is introduced

but I understand why you would want it

[trail escarp]

you are most certainly familuar with this problem, just perhaps not the language of it. sounds like you prioritize the server authority, which is completely understandable, in fact TSB has no prediction at all and relies on having low latency. if it had full prediction, and did it well, it would be quite possibly 2 to 3x bigger than it is now, if not more

[trail escarp]

but also that's a tricky thing to predict right, because you're correct on that it does depend on what is being predicted

[fluid prism]

i generally don't care as much for individual player movement, so i'll usually allow some desync between players

[trail escarp]

player vs player in close quarters fast paced combat subject to latency and prediction is one helluva prediction problem

[trail escarp]

yea at low latencies it doesn't matter tooooo much, almost unnoticeable under 50ms, 100 tops. above 100 it becomes unbearably infuriating

the technique to solve for the +100ms, that is the full prediction pattern i'm talking about, is rather advanced compared to most things you would typically find on roblox

[fluid prism]

a perfect example is rampant reborn pvp on roblox, cool game but the moment you hit like 150+ ping, you're GOING to be hit from 90 meters away

[trail escarp]

point is, advanced things exist, yes even in roblox. learn something every day

[trail escarp]

yes that is very fun at 300ms ping

prediction where you can, y'know? 🙏 so i'm starting with clients to server npcs, it's the easiest as it gets. maybe a player can hit you at 90 meters away, but a server owned npc can be more accurate than that 🙏

...prediction is how you make it more accurate

[fluid prism]

understandable, anyways i personally would categorize it as less of an advanced thing and more of a tedious thing that requires care

"advanced" to me is more of a separation of the algorithms and data structures that you might get from traditional problems from the heavy-lifting hardware and system level development

like, making an audio engine is advanced

in any case, language

good talk

[trail escarp]

i have made a few audio engines in my time... not even remotely as advanced as what the prediction pattern demands

extreme separation of algorithms and data structures. in essence, you're partially interpolating the gamestate, most of it is positions and forces, but can include properties like health and animation frames (e.g it would need to interpolate animation frames to decide if your arm was in the way of a bullet raycast on a particular rolled-back frame).

rollback netcode is an early/lower-complexity version of the full prediction pattern :p

absolutely agree that prediction is indeed extremely tedious 💀

anyway, hope you learned something ⭐

[kindred sorrel]

erm

sure

[buoyant arch]

holy argument

oh also vulner gg on getting GUI 1

[kindred sorrel]

Try

Ty