I'm going to start working on a new game and one of the things I'd like to accomplish is a dynamic array sort of system that would hold map data. The game will be top-down 2d and made with XNA 4.0 and C#. You will begin in a randomized area which will essentially be tile based. As such a 2 dimensional array would be one way to accomplish this by holding numerical values which would correspond to a list of textures and that would be how it would draw this randomly created map. The problem is I would kind of only like to create the area around where you start and they could venture in which ever direction they wanted to. This would mean I'd have to populate the map array with more randomized data in the direction they go. I could make a really large array and use the center of it and the rest would be in anticipation of new content to be made, but that just seems very inefficient.
I suppose when they start a new game I could have a one time map creation process that would go through and create a large randomly generated map array, but holding all of in memory at all times seems also inefficient. Perhaps if there was a way that I'd only hold parts of that map data in memory at one time and somehow not hold the rest in memory. In the end I only need to have a chunk of the map somewhat close to them in memory so perhaps some of you might have suggestions on good ways to approach this kind of randomized map and dynamic array problem. It wouldn't need to be a dynamic array type of thing if I made it so that it pulled in map data nearby that is needed and then once off the screen and not needed it could somehow get rid of that memory that way I wouldn't have a huge array taking up a bunch of memory.