The trick is to move the sprites and not the playfield.
This iteration I found a way to clip the sprites so there is no pop-in or pop-out at the edges. Basically, I made the playfield the FOREGROUND and made it black. Sprites are drawn underneath the black playfield pixels so when they pass through the edges they appear to smoothly scroll off the screen. The tradeoff is that the ground and sky both share the same color.
Edited by theloon, Fri Jul 13, 2012 2:19 PM.