Assuming your level is at least 4 times as big as your viewing distance, you can use the following technique.
- Split your level in at least 4 pieces*
- Loop the position of your player / camera at the level' dimensions.
- When a level piece is more then half the level size away, move it a "level size" closer ( per axis ).
So for example .. the red player starts moving towards a edge of the level.
![](http://img819.imageshack.us/img819/6352/89827744.jpg)
Now that he's gotten closer to the edge of the level then the center, the level pieces jump to the other side.
![](http://img820.imageshack.us/img820/271/37782644.jpg)
After passing through the level boundary ( green rectangle ) the player ends up on the other side, which makes the level pieces move back into place.
![](http://img188.imageshack.us/img188/4271/36684990.jpg)
*It is recommended to make each piece slightly bigger then your viewing distance, this will allow you to do some very cheap & efficient clipping.