I'm making excellent progress on Invaders From Beyond! So far, most of the code is culled from Zap Pod!, but it'll get more of a personality of its own as it goes on. The invaders look quite good, so I decided to post an early screen shot here. I like the way the aliens turned out, and they wiggle quite cutely. I'm not too happy with the ship on the bottom or the background, and I'll probably replace 'em. I'll need to make the missiles bigger, as they're pretty hard to see.
Just for fun, I thought I'd have the aliens drop stuff other than little squiggly missiles on the ship. Round black bombs with sputtering fuses would be cute. They could also drop chairs, cinderblocks, kitchen sinks, etc. I also thought of importing some cameo appearances over from Olive Wars. Nothing quite as scary as a giant evil broccoli descending from the sky!
As for the objects themselves, I've currently just got the Marcher class working. I had to put a lot of thought into how they were to turn around. Originally, I had a static boolean "Reverse" member that I'd switch as soon as an alien hit the edge of the workspace. While it sounds good, I eventually changed it in favor of everyone changing their direction manually. I did this because I want some Marchers to do other stuff when they hit the edge.
I still need to figure out how a marcher can quickly determine if he can fire. A Marcher can only fire if there's nobody below him. This would be easy if I was storing the aliens in an array. I've currently got 'em in a linked list because it's easier to traverse. I was thinking of doing both, giving each Marcher it's position in a two-dimensional array. The Marchers could simply check the array items below 'em to see if they can fire. In the Marcher's destructor, they could null out their own element in the array.