Remote vehicle collision bug

[suma 8]

We recently discovered a bug that can happen when some vehicle that is simulated on other computer collides as a result of predicion or lag. If this happens, a lot of messages notifing about the collision can be sent across network (sometimes even more than 1 MB) and very significant lag can be introduced.

It often happens in mission where cars move in convoy, especially when some user has ping over 100ms. An example of mission that exibits this problem is Malden:Desert ambush (1-8_C_DESERTAMBUSH.ABEL.PBO).

To reduce this problem, you can try to keep separation between vehicles in your missions.

This bug seems to be present since 1.00 and is also present  in 1.46/1.49.

[Lt_Damage 0]

As soon as we upgraded to 1.49 1-8_C_DESERTAMBUSH.ABEL.PBO no longer works. It crashes to desktop. :/

Crash files have been sent. But I am curious if you have tested this particular map with a dedicated 1.49 server and 1.46 client and managed to get it to work..

Regards,

[Espectro (DayZ) 0]

I cant wait till the new netcode is coming

[Placebo 29]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Suma @ April 03 2002,06:21)</td></tr><tr><td id="QUOTE">To reduce this problem, you can try to keep separation between vehicles in your missions.<span id='postcolor'>

Easier said than done when Hilandor is driving hehehehe

[BigQEd 0]

Hey Suma... I wonder... is this one of the major factors that cause lag on Missions with many vehicles? I am sure that collisions occur quite often on these types of missions.

[kegetys 2]

Suma, have you checked what happens when theres lag on the game an a tank drives over a tree? I have now many, many times gotten a horrible FPS loss for a few seconds when that happens, with the tree fallover sound playing about 10 times and the tree also going down and then bouncing back up again and then falling over again. I have heard some other people complaining about this too so I dont think its my comp only.

[BigQEd 0]

Keg... yes that happens to everyone. I also have noticed a bit of latency increase when this occurs too.

[suma 8]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Kegetys @ April 04 2002,07:05)</td></tr><tr><td id="QUOTE">Suma, have you checked what happens when theres lag on the game an a tank drives over a tree? I have now many, many times gotten a horrible FPS loss for a few seconds when that happens, with the tree fallover sound playing about 10 times and the tree also going down and then bouncing back up again and then falling over again. I have heard some other people complaining about this too so I dont think its my comp only.<span id='postcolor'>

I did not know about this issue. I will check it.

[suma 8]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (BigQEd @ April 04 2002,01:23)</td></tr><tr><td id="QUOTE">Hey Suma... I wonder... is this one of the major factors that cause lag on Missions with many vehicles? I am sure that collisions occur quite often on these types of missions.<span id='postcolor'>

It is possible.

[Espectro (DayZ) 0]

Well, i guess its not only vehicle collisions but all object collisions.

It also happends, for instance, when 2 bodys is laying on each other. (they jump on each other).

It also happends, as said, when tank collide with trees or houses.

U have probably seen tanks starting to teleport if they hit a house.

So Suma... for my question, would it be possible to include jip with the new netcode?

[Espectro (DayZ) 0]

JIP discussion removed from this thread. If you really want do discuss it, do it in separate thread, please.

[suma 8]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Espectro @ April 04 2002,11:06)</td></tr><tr><td id="QUOTE">Well, i guess its not only vehicle collisions but all object collisions.

It also happends, for instance, when 2 bodys is laying on each other. (they jump on each other).

It also happends, as said, when tank collide with trees or houses.<span id='postcolor'>

I checked the code now and I have to say the bug was specific to collission of two vehicles or vehicle and person.

If there are some problems with person-person collision, it is probably separate issue.

As for vehicle-object collision, there was one quite small problem present, that caused object to be destroyed even by remote (predicted) vehicles. This could cause destroying one object on each client, resulting in multiple sound effects, but should not cause any significant network lag.

[Espectro (DayZ) 0]

Does this have something to do with being run over even though the vehicle miss?

If u understand.... the vehicle doesnt hit a person on any of the computers (driver or victim), but the "victim" dies anyway?

[KaRRiLLioN 0]

Sometimes in a game on my server I see strange things with vehicles. Normally my ping is 69-89 on my server. If I'm driving a tank and hit a car, sometimes the car will go through the tank and then a few milliseconds later will go flying in front of the tank. Once I saw a car fly faster than a SU25 and it rocketed over the mountains and disappeared. It was amazing, but I think it was due to lag compensation or something.

Also, I have had times where I will be driving carefully and suddenly my character will say "1 Injured". I am sure this is because on another client machine it looked like I hit something when I really didn't on my machine. Sometimes this kills me as well.

I have also seen helicopters crash into the ground only to reappear in the air unharmed. I am assuming this is because of client prediction.

What is the order that this happens in? Client does action, sends information to server, server sends information to other clients?

I will say that 1.49 dedicated server performs very well for now and I think it is amazing what you all have done with netcode for this game. With everything that happens in this game I am sometimes surprised it works so well. Games like Quake3 have only running and few projectiles to track, but Opflash has about 30 different vehicles, many different ammo types and other things all moving at different speeds with hundreds of different calculations occuring about object collision. I must commend you all on an excellent job to date. If DirectPlay is a cause of trouble, then I cannot wait to see how it improves with better netcode.

Good luck!

[Psycho1 0]

I have also noticed lag occuring when a chopper crashes and doesn't stop bouncing up and down. It could be a coincidence but whenever I have noticed crashed choppers bouncing up and down, it seems their is lag present too. Usually people with 56k start getting desync, possibly because their is too much data being sent to them due to the chopper bouncing.

[HellToupee 0]

once we were playin a game and 2 trucks got stuck in each other the game game almost to a standstill the ai were invincable and did nothing there were deleys of 3mins before after using bombs on the two truks did they blow up and seperate and game went back to normal.