Planetside 2 Hit detection

SKYeXile · 2012-01-09, 06:20 AM

TLDR: read the pink.

I have made threads in the past and read asmuch info as possible on Planetsides 2 netcode and all netcodes possible, playing from Australia one must know their enemy well. I have tried to find as many sources as possible, but some have eluded my searches, I believe now with 99% certainly that Planetside will use a serverside hit detection model featuring hit prediction.

Before I start though, I will use some terms, I don’t claim these are the correct terms, but to avoid confusion in these thread it would be nice if you used them.

Severside hit detection(SSHD): This is a standard code that was used by games like the original halo and the Unreal Series, everything happens on the server, you need to lead your target to compensate for your ping and predict where they will be on the server when your packet gets there.

Clinetside hit detection(CSHD): Your client sends a packet to the server saying, " I hit" server agrees with the hit, sometimes known as zero ping. Planetside 1uses this code.

Severside hit prediction.(SSHP) This ones tricky to explain some people will say this is CSHD or also zero ping. Anyway the process is that your computer sends a packet to the server with a timestamp, the server gets this packet rolls its data back based on this timestamp and see's if you hit. it has the same effect..most of the time as CSHD with more security. but it has 1 drawback, ill explain more on this later. Games that use this code are games on the source engine and I believe most modern games use this code along with BF3, though getting info on the codes developers use is always tricky.

Before I go on, I would like to state again that hit detection has nothing to do with warping, warping is a result of movement prediction, and that’s the word, it predicts and then re-corrects itself when it gets proper data. Planetside will unlikely feature this code.

On the good stuff, This is the info we have on PS2 netcode:

Is the hit detection client-side or server-side? We all know how frustrating it is to get killed after you've already taken cover on your screen. The developers want to minimize the effect of lag in PlanetSide 2. Hit detection will use a hybrid model of client and server-side tracking. Physics will be handled by the client, and some other details will be handled by the server. I was told the target latency is around 100-150 ms maximum. How this would be achieved or enforced is unknown. However, there will be multiple servers, so players can choose the server with the shortest latency.

http://comms.planetsidesyndicate.com...ead.php?t=4516

Quote:
PlanetSide Universe: Ping will effect gameplay less than it did before.
http://www.planetside-universe.com/p...overage-67.htm

Came up on the second live blog.

Smedly has stated in a fan fare Q&A that Planetside 1 used one hit detection model, and that Planetside 2 will use the other.
http://www.g4tv.com/videos/54137/Pla...c-Panel-Video/
hit detections talk starts at 43:30

this last one has eluded me:
But im 100% positive higby has stated somewhere that planetside 2 hit detection will be similar to BF3;s where I uses a client/server design and he says something like a hit will be a hit"
it wasn't a fully informative quote with 100% accuracy to say its SSHP, but to know its similar to BF3's is enough.

With that info, a "hybrid model" can defiantly been seen as SSHP or SSHP Smedly said that planetside uses one model(CSHD) and that planetside 2 will use the other, it can only be interpreted as SSHD. They said that ping will play less of an issue in PS2, this could be because of a change to movement prediction or it could be that they believe there is inconsistencies with CSHD.

While it does say it requires 100-150ms ping, that’s an American talking, I play with a lot of Americans and let me say that your interpretation of whats playable with a pad ping is meaningless. OH THE SCREAMS WHEN YOU GET ABOUVE 100PING, THE END OF THE WORLD! MY PING ITS SPIRALING OUT OF CONTROL, IT TERRIBLE!!!....I'm done.

This leads me to conclude that the game is going to use SSHP. What does this mean for you? it means that most of the time a hit on your screen will be a hit on the server, it caters to everybody equally, nobody has to lead their target. However the major downside is that same thing, this leads to people getting killed around corners and is a major contributor to rage in BF3 by people that don’t understand the code...even those that do.

the other downside is sync issues, this ones hard to explain, so ill let valve do it.

This screenshot was taken on a listen server with 200 milliseconds of lag (using net_fakelag), right after the server confirmed the hit. The red hitbox shows the target position on the client where it was 100ms + interp period ago. Since then, the target continued to move to the left while the user command was travelling to the server. After the user command arrived, the server restored the target position (blue hitbox) based on the estimated command execution time. The server traces the shot and confirms the hit (the client sees blood effects).
Client and server hitboxes don't exactly match because of small precision errors in time measurement. Even a small difference of a few milliseconds can cause an error of several inches for fast-moving objects. Multiplayer hit detection is not pixel perfect and has known precision limitations based on the tickrate and the speed of moving objects. Increasing the tickrate does improve the precision of hit detection, but also requires more CPU, memory, and bandwidth capacity for server and clients.
The question arises, why is hit detection so complicated on the server? Doing the back tracking of player positions and dealing with precision errors while hit detection could be done client-side way easier and with pixel precision. The client would just tell the server with a "hit" message what player has been hit and where. We can't allow that simply because a game server can't trust the clients on such important decisions. Even if the client is "clean" and protected by Valve Anti-Cheat, the packets could be still modified on a 3rd machine while routed to the game server. These "cheat proxies" could inject "hit" messages into the network packet without being detected by VAC (a "man-in-the-middle" attack).
Network latencies and lag compensation can create paradoxes that seem illogical compared to the real world. For example, you can be hit by an attacker you can't even see anymore because you already took cover. What happened is that the server moved your player hitboxes back in time, where you were still exposed to your attacker. This inconsistency problem can't be solved in general because of the relatively slow packet speeds. In the real world, you don't notice this problem because light (the packets) travels so fast and you and everybody around you sees the same world as it is right now.

there would offcourse be more issues with syncing the faster a player is moving.

While I read asmuch as possible about netcode I have to wonder, the source engine canlag with 32 players using this code while the server runs at 66 ticks per second. (for reference planetside runs at 5 ticks) is this even possible for forgelight to do? now obviously SSHP uses more server processing power than CSHD.

But the real question is does SSHP use more processing power than SSHD? planetside WILL feature bullets with arching projectiles, I wonder does the server need to calculate the arch of a projectile with SSHP? I guess it would since it needs to check if a hit is possible, so I would presume that SSHP does use more server resources than SSHD, since it has to rollback data? the answer to this could very well confirm the type of hit detection they plan to use...or Matt could stroll into this thread...

I made this thread because myself and elude sort of hijacked another thread.
http://www.planetside-universe.com/f...t=38481&page=9
our discussion started there, there is obviously confusion to what hit detection some games use, but I believe SSHP sync issues is the cause of hit detection issues he has had and other do have in some of these games that apparently use "CSHD." use this thread to continue any discussion about that though.