Hey guys,

Why almost all mmos are not using physics like ragdoll, cloth, water, snow, smashing particles etc..?

I know all games use physics, but not high level physics like those.

Thanks

From Yaniv

I suspect the reason mostly lies in the "massive" part of MMO. Massive anything can be technically difficult to achieve; massive high-level physics simulation, I suspect, would be even more difficult.

I suspect the reason mostly lies in the "massive" part of MMO. Massive anything can be technically difficult to achieve; massive high-level physics simulation, I suspect, would be even more difficult.

It's super clear that developing mmo games is a hard challenge, but still the result of high level physics is just better.

I think its more related to the multiplayer part then the massive part..

still I hope to get a detailed answer

I think its more related to the multiplayer part then the massive part..

Well, it's the "massive multiplayer" that causes the problem (if you want to call it a problem).
When I'm fighting world bosses in Guild Wars 2 my FPS often drop down to 15-20, sometimes even less, because there are so many players on the screen. Now if each of these player would have a realistic cloth simulation, I can start measuring performance in frames per minute.
Other stuff like ragdolls would most likely need to be simulated on the server in order to let every player see the same result. That would put more stress on the server (it's not like there would be only 10 ragdolls active) and the internet traffic (also not that good if you have slow internet).

Cloth physics has started to show up on very modern MMOs (GW2 and FFXIV for example) because they are purely cosmetic and do not affect gameplay or pathing. As other posters have pointed out, however, it's expensive and MMOs frequently want to show lots of players on screen, so when they do use cloth physics, it can sometimes be restricted to only your character, or only to the closest X characters to prevent your framerate from tanking.

Physics that can affect collision/pathing is a whole other story, however, as physics simulations are notoriously non-deterministic so most people would see the physics objects "pop" and "jump" around as the server corrects the physics simulations to make sure everyone sees the same thing. Even in non-MMO multiplayer games like Battlefield physics is extremely limited for this same reason.

MMO's usually have some form of client side non-synched physics. A great example is all points bulletin's boxes.

Basically, the game has piles of boxes/trash laying around, that are client side only. You can knock into them + push them around, however, they aren't synchronized, and have no effect outside of showing debris in areas (They don't stop bullets, or impact movement).

Of course, when I first noticed they had physics objects ingame, I immidiately became fascinated as a programmer and tried to play trashcan soccer with a friend, until it got too desynched (2 kicks)

Synchronized physics...The issue is scalability (or the complexity of adding a "Only have X physics objects" option), and reliability. Maybe you click on a body of a fallen enemy to open a loot bag. Now, with ragdoll, it's position needs to actually be simulated by the server (God knows what happens when 3-4 players start making a pile of bodies). Add to that the huge task of actually doing deterministic physics for things like that over a network, and it's just not worth it.

Even if you have great servers, and every client is running top-notch hardware, most people don't have fast enough internet to communicate the information for tons of particles and objects. Perhaps if fiber internet becomes more common in the next decade we will start to see more "synchronized" physics in MMOs.

Even if you have great servers, and every client is running top-notch hardware, most people don't have fast enough internet to communicate the information for tons of particles and objects. Perhaps if fiber internet becomes more common in the next decade we will start to see more "synchronized" physics in MMOs.

You don't synchronise particles by sending them, you just synchronise their start time and seeds . . .

Even if you have great servers, and every client is running top-notch hardware, most people don't have fast enough internet to communicate the information for tons of particles and objects. Perhaps if fiber internet becomes more common in the next decade we will start to see more "synchronized" physics in MMOs.

So lets say I want to make a mmo game for only clients who has:

1) High-end gaming computer system.

2) Internet speed that's over 30mb.

I know its about only 30% of the gamers out there..

but still can it work???

Even if you have great servers, and every client is running top-notch hardware, most people don't have fast enough internet to communicate the information for tons of particles and objects. Perhaps if fiber internet becomes more common in the next decade we will start to see more "synchronized" physics in MMOs.

So lets say I want to make a mmo game for only clients who has:
1) High-end gaming computer system.
2) Internet speed that's over 30mb.
I know its about only 30% of the gamers out there..
but still can it work???

Well it's not going to be very "massive", for one. You simply won't have enough people.

Even so, multiplayer games need to minimize the amount of data they send over the network. The more things that are moving, the more data that needs to be sent (if things have to match up on everyone's PC) and the more chance that latency will cause the objects to pop or jump around as your local simulation is "corrected" by the server. Even if you had a perfectly deterministic physics system (and keep in mind that just having deterministic floating point numbers is a giant task on its own, especially if you're cross-platform), you still have to deal with players, who are far from deterministic...