The Wanderer - 2D Open world (Brainstorming)

This week I put together a little game called "The Wanderer". It loads a map created with my map editor and you're given control over a beetle that can walk around on the map. At the moment he's confined to his little map, but what I want to do is expand this to be an open world wanderer. This is my article about my solution to this open world problem.

The open world idea presents new challenges for me, but I have a plan about how I can do it. I generated a rather giant map (65536 tiles). It's really only feasible to have about 4096 tiles loaded at one time, which equates to an image of 2048x2048 with a size 32 tile. Anything more and loading times begin to become longer, and an image size of 2048x2048 is larger than what can fit on an average monitor - providing ample space.

My challenge is that of the 65536 tiles in this giant map, I can only ever have 4096 tiles loaded at a time. As the player moves, tiles need to be dynamically loaded and unloaded to maintain this small drawn window of the large world. I'm going to refer to these 4096 tiles as a chunk.

To figure out which tiles need to load/unload, I have to first take the tile that the player is standing on, and then calculate all the tiles around the player that fall within perimeter, determined by this chunksize.

Solution

My solution is simple, but untested. I will implement it and then report whether it works or not, but in theory, it should work.

The solution is that we know the tile that the player is standing on, and we know the size of the chunk. Therefore, the top left and bottom right tiles in the chunk can be predicted like this:

The amount of tiles behind and before the player's tile: Difference = (chunksize - 1) / 2
Therefore:
Top left tile in chunk = PlayerTile - Difference
Bottom right tile in chunk = PlayerTile + Difference

With these values I can determine which tiles to load into the new chunk whenever a player moves to a new tile. I have a visual representation of this below (sorry about the MSPaint.exe style quality). In this example, the chunk size is 25. X represents the player's tile and the big red box represents the chunk.

In this next image, the player walks one tile to the right. You can see drawn the tiles that need to be unloaded, and the tiles that need to be loaded.

Finally, based upon the player's tile and the chunksize, I learn can predict the indexes of the tiles to be loaded.

This is my open world strategy. It should work. If you have a better idea, please let me know in the comments.