it varies from game to game. most often there is some kind of sparse 'navmesh' containing nodes in a 'grid' for doing the classical part of path finding. its po

it varies from game to game. most often there is some kind of sparse 'navmesh' containing nodes in a 'grid' for doing the classical part of path finding. its possible to do this sort of thing automatically if you split the world into volumes as well, but its more difficult to get very fast, good results (i.e. you can't hack the data by hand so easily). as well as that there will be some (usually quite off the cuff, hacky) logic to get a character from wherever they are to the nearest node (or its vicinity) and something to avoid them from hitting each other (too much) there is nothing special about the 3d part, you just make the mesh in 3d and respect the constraints of gravity, player movement etc. so that you can't connect nodes badly the floating point number thing is not important. any pathfinding can be made to have this 'extra complexity' if you simply go between the points over time smoothly...