   Managing graphics for a 3D game
  In 2D games you have tile sections that you manage and change graphics with that is fairly simple. Let me see if I have this correct.  A 3D multiplayer game like WoW has a background scene/image (domed), then nonmoving objects like trees and buildings, there are other avatars moving around, your avatar stays in the center (usually) and there are animated animals/NPCs and terrain/topography/elevations.For this type of 3D game what manages keeping track of and rendering the basic background image of clouds or whatever graphic you have for that and the different objects like trees, buildings, etc and where to position the animated images, buildings and objects relative to the terrain so they look like they're not floated or sunk into the ground? Your avatar's view can whirl around 360 degrees which is much more complex to render all that.  Does the basic coding keep track of this mapping or a game engine (if you decide to use one)?   
  I don't know about WoW, but looking around with your 'view' is probably done in the graphics API by perspective transformations and all that, with the actual 'game' functions controlling what parameters are passed to the API for the transformation.I don't know how their coordinate system works either, but in the programming that I've done, the player doesn't stay at 0,0, but is reset to 0,0 or the local area edge whenever the edge is crossed.  That way, if you have a large area, you don't suffer from lower accuracy floats at high numbers.  My player does however keep track of a global or 'absolute' x that is stored as an integer and incremented each time a boundary is crossed so far reaching areas of the map are reached.   ;  Also even though a game is 3d, the underlying map may still be essentially a 2d map with each section having it's own mesh or height value associated so you can determine where objects are placed.  You might place objects based relative to this underlying map or based on some global coordinate depending on the need.   