|Picky, picky, picky...|
1. I am reading a book called "Designing Virtual Worlds" right now, and technically, if its a multi-user environment, its almost certainly on some level very similar to a MUD, MUCK, etc. There are a *lot* a variations on just *how* muds and MMORPGs work, and most parallel each other heavilly, even if the MMO people are often too unaware or arrogant to admit it and learn from MUD developers mistakes. Instead people constantly reinvent the wheel. In fact, its one of the authors complaints in the book (He is one of the handful of people that developed the **first** MUD driver and library). Its one thing to invent new ideas, another to be completely ignorant of everything that came before, so that you ignore all of it. Acheron's call, for example, uses/used a load balancing system. Very few MUDs use that *ever*, but a few really big ones do. It was vastly superior to EQs method of "zoning", since there was no apparent delay when moving from area to area. However, Acheron's ignored damn near everything else ever done previously, thinking they where some sort of geniuses, and several *critical* flaws in the game design and management of the game world effectively killed it. What do we have now? Not Acheron's Call: We Finally Got it Right!, we have EQ2: Better Graphics And Now With More Zoning!
Techinically, EQ never "extended" anything. They built the entire framework for the system they use from scratch, then got sandbagged by people in the MUD community that tend to be sue happy and noticed the major similarities between the systems. That this is a bit like Ford sueing a new car company on the grounds that they accidentally, and entirely on their own, developed a nearly identical under carriage and suspension system...
2. Yeah, couldn't remember the precise name, BSP tree. In any case, its a fairly well known method. Point I was making is that 3D environments need to sort out "where" something is in relation to you. You can't click on something that is, in game terms, 10 miles away. You probably can't even see something like that in most of them. The better your GPU and cooler your system can run, the more likely that you can at least "see" some stuff, but there is still a limit to how far away user interactive objects will appear, since they are very small compared to the rest of the scenery. Probably 80% of it is pre-loaded, but even then, locations of NPCs, other players, and movable objects "all" have to be determined as you approach them, which means the server is "still" determining what you "should" be able to see, even if your local client setting can't see that far with your hardware. On the server end, there is still some class of sorting going on which says, "Given the direction and viewing angle of this player, what objects are in that field of view and which ones are close enough to bother showing. The only thing the client does is, "Given the info I got from the server, how many of these things it says is in front of the character are close enough to interact with?"
It might not be BSP trees. Other methods exist, but that wasn't the point I was making.