Lag causing collision

L

Laurent Keersmaekers

Member
Dear,

Yesterday I started my first ever rFactor2 online race in the WCSLeague. After having a very good qualifying (4th), I was looking forward to the race. However, a bug took me out on lap 1 of the race.

Bug: The driver in front of me had some kind of lag (I guess due to his connection?), which caused his car to perform a sudden stop (from +- 200km/h to 0 km/h in let's say 0.001s). Since I was right behind him there was no way to escape.

Possible fix: I guess the connection issue is rather difficult to fix. However, it could maybe be an idea to make a car non-touchable (or turn of collision detection) if d(Velocity)/dt exceeds a certain limit. Let's say > 1000m/s².

Do you think it would be possible to fix this bug?

Thanks in advance,
Laurent Keersmaekers
 
The "Collision Fade Thresh" parameter in the multiplayer.json does something similar.
"Collision Fade Thresh":0.7,
"Collision Fade Thresh#":"Collision impacts are reduced to zero at this latency",
 
Perhaps servers should be able to be set to prevent connections with a ping at a certain level to enter the server??
 
Mark Fuller said:
Perhaps servers should be able to be set to prevent connections with a ping at a certain level to enter the server??
Click to expand...

What ping would that be? My ping is around 190-210 for European servers, yet nobody has ever mentioned lag issues racing with me. I've even raced with @osiris32 on his American servers, where my ping is closer to 300.

People with <50ms ping but bad jitter have caused numerous issues, though, so you'd be better off looking at jitter than actual ping.
 
I think the OP has better ideas, where sudden and severe unexpected accelerations could trigger at least a delay in collision detection until the server can work out what's going on. The ping collision threshold doesn't work that well because the collision tends to happen before the high ping is detected.

The game already starts to simulate a collision between remote cars and walls when they look like they're going to happen (with that apparent collision sometimes cancelled when the remote car miraculously avoids the collision on their end), so there's not many occasions where a car will suddenly and immediately come to a stop on the track that the client isn't already anticipating anyway.

As much as we can try to avoid connection issues, I think the scope for endurance races etc should at least make erring on the safe side an option. Unfortunately there's probably no neat option when it comes to client lags, as the remote car will lag and then resume where it was, and is telling the server it's going along fine. Then you probably need to have some ghosting to alleviate the "two cars are now in one place" issue, and find a way to let them separate before resuming collisions.
 
Laurent Keersmaekers said:
Bug: The driver in front of me had some kind of lag (I guess due to his connection?), which caused his car to perform a sudden stop (from +- 200km/h to 0 km/h in let's say 0.001s). Since I was right behind him there was no way to escape.
Click to expand...

I think that it is not a connection issues. Looks like your opponent has CPU lag, stuttering issue. When ping is high the car not stopping suddenly but it does when purple CPU bar max out. It's different things.
 
lagg said:
The "Collision Fade Thresh" parameter in the multiplayer.json does something similar.
"Collision Fade Thresh":0.7,
"Collision Fade Thresh#":"Collision impacts are reduced to zero at this latency",
Click to expand...

Regarding the "Collision Fade Thresh": How should I use this value, and what are the units? Is there more information available on this setting?

As far as I understand, it should also help when an opponent has CPU lag?
 
Laurent Keersmaekers said:
Regarding the "Collision Fade Thresh": How should I use this value, and what are the units? Is there more information available on this setting?

As far as I understand, it should also help when an opponent has CPU lag?
Click to expand...
The units are seconds.
If a player has a ping bigger than this number the car turns to no collidable, avoiding accidents with him.
 
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