I'm currently working with a large(ish) map for a game, using tonypa's tutorials as a foundation.

When I make a map that's larger than a certain amount, it stops displaying all the tiles on the screen and it looks like the screenshot:



Is there any reason why it does this? The only thing I have changed from the default code is the size of the tiles, the tile width/height, and then the size of the map array.

I need something like a 71x40 map with 12x12 tiles and I don't see how that would be unreasonable.