Day 1 + Day 2
I've been learning a lot, but I don't feel like I have a lot to show for it, except for an appreciation for better planning. Things went swift at first, making some odd sprites I knew I'd need and working on preparing the stage. This involves drawing a big blue rectangle over the screen (THE OCEAN!?) then drawing Ace, our protagonist, on top. A basic pong-like tutorial featured in Pico-8 Zine #1 had already prepared me to set the controls, and I'm smart enough to set rules to keep Ace on the screen (don't let his X or Y positions increment up or down at their respective borders). That's where I left off last night.
Today, things got more interesting. I drew some really rough functions for firing bullets and tracking those bullets across the scren. Then, I drew an enemy sprite. He's uh... an alien ship. A demon head?
okay, he's programmer art
I realized I'd need to control when and where these jerks would spawn, which took some thinking on my part until I came up with a solution I'm not really satisfied with. I'm keeping a count of frames that increments on each frame. Then, when the count reaches a certain number, in this case 30 (aka 1 second in 30fps), the enemy appears on a position I designate. In theory I can time and release enemies at specific positions this way. Seems kind of cumbersome, but I'm not really sure how else I'll do it.
The next horrible realization I had is that I would need to be able to track the positions and states of multiple enemies throughout the game. In truth, I had realized I'd need to do the same thing for bullets beforehand, but I had cheated by just setting the life of each bullet to roughly the amount of time it would take the bullet to cross the speed and then preventing the user from firing another one until that time had passed. Kinda gross to be honest.
I really really really didn't want to have to write code to declare, track, and draw every single enemy in the game, so I took a break with PAT Shooter before diving into its code. As a side note, other PICO-8 games are definitely my main excuse for procrastination during this jam. I couldn't stop playing more lives of PAT Shooter for "inspiration."
Anyway, it took me quite a while to figure out what I was looking at, but when I got it, it was like a lightbulb going off in my head. Actors with consistent behavior in the game are all declared in tables. As far as I can tell, Lua tables are basically just arrays. The way this handles is pretty smooth. At any point I choose, I can (for example) declare enemy E, sent E.X and E.Y to the appropriate X and Y coordinates I want to set it at, then add E to a table called Enemies. At any other time I want, including while iterating through that table, I can change these properties of the enemy, or even delete the enemy outright. From there, it was child's play to write code to iterate through the enemies to alter their positions (movement) and draw them.
I opted to refactor my bullet code to take advantage of tables and it has already payed off. I ended my day by setting up a bullet and enemy collision check where I iterate through each bullet in my Bullets table and, in each loop, iterate through each enemy in my Enemies table. If their positions overlap (or more accurately, exist within ranges that appear like an overlap on the screen), I delete the given bullet and the given enemy from the table. They stopped being tracked or drawn and PICO-8 doesn't choke on the mid-iteration adjustment to the tables at all! Beautiful!
When I started on all this bullet and enemy stuff this morning, I thought I had hit the hard part. Oh boy was I wrong. Now I have to consider enemy movement and firing behavior. I guess I could just have each enemy move at a static speed and fire a bullet that moves at a faster static speed? Kind of boring, but I think I'll stick with that plan for now. If I end up with more time later, I may try to fit in more complex enemy behavior, but at this point I'm already choking on the idea of just trying to declare and position enemies over the course of the game.
I gotta be careful going forward. I made my first bullet system in a rush and ended up having to refactor the whole thing when taking shortcuts failed me. That was already painful and it was a relatively small chunk of code. I could definitely see this blowing up in my face.