Wrapping a pygame surface around a viewport

Question

I'm coding a game where the viewport follows the player's ship in a finite game world, and I am trying to make it so that the background "wraps" around in all directions (you could think of it as a 2D surface wrapped around a sphere - no matter what direction you travel in, you will end up back where you started).

I have no trouble getting the ship and objects to wrap, but the background doesn't show up until the viewport itself passes an edge of the gameworld. Is it possible to make the background surface "wrap" around?

I'm sorry if I'm not being very articulate. It seems like a simple problem and tons of games do it, but I haven't had any luck finding an answer. I have some idea about how to do it by tiling the background, but it would be nice if I could just tell the surface to wrap.

Answer 1

Thanks everyone for the suggestions. I ended up doing something a little different from the answers provided. Essentially, I made subsurfaces of the main surface and used them as buffers, displaying them as appropriate whenever the viewport included coordinates outside the world. Because the scrolling is omnidirectional, I needed to use 8 buffers, one for each side and all four corners. My solution may not be the most elegant, but it seems to work well, with no noticeable performance drop.

Answer 2

I don't think so, I have an idea though. I'm guessing your background wraps horizontally and always to the right, then you could attach part of the beginning to the end of the background.

Example, if you have a 10,000px background and your viewport is 1000px, attach the first 1000px to the end of the background, so you'll have a 11,000px background. Then when the vieport reaches the end of the background, you just move it to the 0px position and continue moving right.

Answer 3

I was monkeying around with something similar to what you described that may be of use. I decided to try using a single map class which contained all of my Tiles, and I wanted only part of it loaded into memory at once so I broke it up into Sectors (32x32 tiles). I limited it to only having 3x3 Sectors loaded at once. As my map scrolled to an edge, it would unload the Sectors on the other side and load in new ones.

My Map class would have a Rect of all loaded Sectors, and my camera would have a Rect of where it was located. Each tick I would use those two Rects to find what part of the Map I should blit, and if I should load in new Sectors. Once you start to change what Sectors are loaded, you have to shift

Each sector had the following attributes: 1. Its Coordinate, with (0, 0) being the topleft most possible Sector in the world. 2. Its Relative Sector Coordinate, with (0, 0) being the topleft most loaded sector, and (2,2) the bottom right most if 3x3 were loaded. 3. A Rect that held the area of the Sector 4. A bool to indicate of the Sector was fully loaded

Each game tick would check if the bool to see if Sector was fully loaded, and if not, call next on a generator that would blit X tiles onto the Map surface. I

1. The entire Surface
2. Each update would unload, load, or update and existing Sector
3. When an existing Sector was updated, it would shift

It would unload Sectors on update, and then create the new ones required. After being created, each Sector would start a generator that would blit X amount of tiles per update