Hi.
Suppose one has a 2D grid map for a game, and one wants to define special "areas" on the map, which could be bounded by a rectangle, ball, or polygon, and to which could be associated an effect or a name or something. I suppose one could store a list of these along with the level map, but what's the most efficient way then to find, given the player's position, which area(s) the player is in? How is this usually handled in games? Is the check performed every time the player moves?