Converting Gunslugs to Megadrive / Genesis
Overview This is all about porting Gunslugs, a PC game written in Java (by OrangePixel ) to SEGA Genesis / Megadrive, written in 68000 assembler. Original Game (PC) Genesis Conversion Code Objects / Entities There are quite a lot of active objects at once in the original game- something lke 100-200 plus bullets and effects. This would not be doable on the Genesis, so instead I generate a list of spawn points for level objects. These are sorted horizontally so that I only need to check one at a time as the screen scrolls. Once a spawnpoint is determined to be just off the right edge of the screen, it is promoted to being an active GameObject, and the spawer code continues looking for the next object in the spawner list. Early on I knew there would be a problem with this, due to objects disappearing off the left of the screen. In the original these continue to be active. But at the start I didn't know enough about the game to determine what to do about it. In other games I'd uns