setVehicleHandling client-side function to work on vehicles created server-side

[Grafu]

Is your feature request related to a problem? Please describe.

Please allow using client-side setVehicleHandling on remote vehicles. Server developers like me could then experiment with synchronization improvements like temporary removing mass (between collision moment and collision sync) from remote vehicles. Now the hit vehicle controller stays like a wall until collision synchronizes. And that can take a while if the remote player has high ping or packet loss.

Describe the solution you'd like

Remove this check

if (!pVehicle->IsLocalEntity())
    return false;

from

bool CStaticFunctionDefinitions::SetVehicleHandling(CClientVehicle* pVehicle, eHandlingProperty eProperty, unsigned int uiValue)
{
    assert(pVehicle);

    if (!pVehicle->IsLocalEntity())
        return false;

    CHandlingEntry* pEntry = pVehicle->GetHandlingData();

    if (pEntry)
    {
        if (SetEntryHandling(pEntry, eProperty, uiValue))
        {
            pVehicle->ApplyHandling();
            return true;
        }
    }
    return false;
}

and overloads

Describe alternatives you've considered

Using setElementCollidableWith would make the collisions lose visual effects like car changing velocity and position on collision.
Using setVehicleHandling serverside changes the physics for remote vehicle controlling player and that is something I am trying to avoid.

Additional context

What does it look like hitting a vehicle with lower mass? Can you push it around more easily?

If you set remote vehicle mass to 1 using server-side setVehicleHandling and that vehicle is controlled by a high ping player, then pushing his vehicle is easy. Otherwise, if mass of the remote vehicle isn't lowered, your car crashes into that remote vehicle like into a wall.

if you push it away it's gonna warp around the place when sync packets correct it

synced packets will warp the vehicle back, but remote vehicle after sync packet won't push the local vehicle since it has no mass (very low mass = 1)
so it will get pushed out once again
and this way local vehicle doesn't lose velocity when hitting the lagging remote vehicle

I think it is worth leaving freedom for server developers to do some experimenting and maybe implementing things based on using setVehicleHandling client-side to set remote vehicle handling.
If it is something weird, server admins will just remove the script
If you set remote vehicle masses serverside to 1 and laggy player drives that vehicle, you will be able to push it easily even if push packets and sync packets lag due to player high ping

[LosFaul]

biggest problems are values like engineAcceleration
if a client A has vor a vehicle a value of 50 and client B only a value of 5 for the vehicle
you get a desync immediatly as soon client A accelerates

a client side variant for server side created vehicle would require that the values would get synced over the server after a value has been changed

the update packet would have to become part of the main sync packet for position, rotation, velocity, ...
since mta uses some kind of recorder technique for sync from what i have seen

[Grafu]

You just would not implement scripts modifying those values if you do not want that behavior. Maybe someone would find that useful after doing some research, we should not decide for everybody if we do not find the benefit ourselves. I personally see benefit in modifying mass and turnMass, someone may see benefit in modifying some other properties.

[LosFaul]

almost every value can cause desync to some degree

[Grafu]

Desync to some degree is the goal of this suggestion. Let's take an example use case:
I want to stop remote high ping player vehicle from causing my local vehicle to get lagged out of the way when the collision happens. To do that I am going to change remote vehicle mass to 1 from the collision moment until the remote player is actually affected by the collision (and that is some hundred milliseconds depending on ping). And when the remote vehicle is affected by the collision on local screen, I am going to restore mass to normal value. This way the remote lagging vehicle would not lag out local vehicle out of trajectory this much because its mass would have micro effect. And the desync would look like vehicles ramming each other due to frequent position resync - that wouldn't be a long or far desync.

[LosFaul]

mhhhhh

my idea would be if this should become a thing (which i hope so)

setVehicleHandling(vehicle, property, value[, sync = true])

so you could disable automatic value syncing

[Grafu]

Client-side function with sync would require more implementation effort and, anyways, it does not make sense to me. If you want sync, you could call setVehicleHandling server-side.

[LosFaul]

Client-side function with sync would require more implementation effort and, anyways, it does not make sense to me. If you want sync, you could call setVehicleHandling server-side.

what about ping times
not everyone has same ping times
and when you change handling on localPlayer vehicle you don't want to have ping

[Grafu]

what about ping times
not everyone has same ping times
and when you change handling on localPlayer vehicle you don't want to have ping

Yes, ping times are different when everyone is connecting from different place.
I would be changing remote player's vehicle handling, not local player's, and just for a specific period of time.
I don't want anybody to have ping in general but reality works like that and we have to adapt.

[LosFaul]

what about ping times
not everyone has same ping times
and when you change handling on localPlayer vehicle you don't want to have ping

Yes, ping times are different when everyone is connecting from different place.
I would be changing remote player's vehicle handling, not local player's, and just for a specific period of time.
I don't want anybody to have ping in general but reality works like that and we have to adapt.

a sync option is simply a requirement

[Grafu]

a sync option is simply a requirement

Server-side setVehicleHandling is that option.

[LosFaul]

a sync option is simply a requirement

It's already implemented as a server-side setVehicleHandling.

but if you add it client side you need to add sync option

otherwise it's only beneficial to you
and not for the whole community

[Grafu]

otherwise it's only beneficial to you
and not for the whole community

I am just an example user who came up with the idea to improve collision synchronization by temporary changing vehicle mass only for the colliding client. It could be any other user, not just me. I was just the one who decided to go further with this and offer this idea to the community. Other users might have come up with other brilliant ideas how to harness unsynchronized setVehicleHandling but were stopped by that 'false' return value from setVehicleHandling and simply gave up at that step.

How is it only beneficial to me? I do not agree with you. If it was only beneficial to me, it meant I was the only one who could use this function. But what I am doing is completely opposite action - offering this functionality for every MTA:SA user.

[LosFaul]

you would completly confuse people by not having a default sync option on client side variant too
most people would get confused by desynced vehicles -> which would happen by not having default sync = true

[Grafu]

I agree with you but this is too much effort for me. So I give up at this point. Good luck.

[Dutchman101]

I agree with you but this is too much effort for me. So I give up at this point. Good luck.

Then i guess we should close PR #1935.. will do so if there's no other feedback (or more opinions regarding the 'desync' discussion) soon

[Dutchman101]

Related issue: #1898
It's closed, but a good read to see the bigger picture.

[xLive]

You can already make such desync with setElementModel

[Fernando-A-Rocha]

this was indeed implemented

[lynconsix]

You yourself have already solved the problem, it can be said that you can close the discussion #1935