2023 Lisp Game Jam Entry

“Apple”

Apple is a reverse snake — you’re an apple trying to avoid the snake.

Dependencies

• chicken scheme (csi) with eggs:
  • matchable
  • r7rs
  • stty
• my ansi library, yolk

Running

Run ./apple.scm in this directory. Alternatively, run make to build a static binary and run that instead.

License

This software is licensed under the God Willing License, version 1.0. See COPYING for details.

Also, here is a picture of a cool rock I found:

Development log

2023-06-01

• Changed name to apple

• Added a makefile for compilation

• I made the snake smart!
  • now it follows the appple around the screen trying to eat it
  • figuring out collision logic and making sure the snake didn’t eat itself and all was .. whoo boy, it was wild
  • but in the end it works well enough!
• Added game win/lose conditions
• Added fruit
  • will make that work tomorrow
  • hacky AS HECK! here be dragons yall
  • collision detection is full of special cases, and I don’t like how it works

2023-05-31

• Added color using the (yolk attrs) library
• Parameterize (me) and (snake) in main to make definition order unimportant
• Change game loop and event handling to allow for independent snake movement
  • This didn’t require using threads!
  • Also enabled hjkl for movement.
  • The snake is very dumb right now — it just goes in a circle.
  • Also includes timing!
  • And changing direction!
• Randomly place snake and apple
• Refactor functions to pass around the world less
  • This means that things now hold a reference to the world they’re in .. I think this makes sense
• Add checking if things are around a given thing

2023-05-30

• Changed license to LATCRIFPL
• Added beginning of snake and came up with basic idea for game

I’m going to have to add threads >_< Curse you non-turn-based games!

The snake is interesting … it’s its own structure with a head thing and a list of tail things trailing behind. Each time it moves it just cuts off its tail at the length it needs to be, giving the illusion of movement. I had some complicated stuff with each segment storing its own age … but that was a bad idea lol.

2023-05-29

• I’ve changed the basic logic from just throwing characters on the screen wherever to a vector-based approach. I thought there was a multiple-dimensional vector egg or something, but I apparently was mistaken. So I’m doing the ol’ multiply-by-one-thing-and-add-another approach.
• Implementing collision detection was slightly easier than I thought it might be.
• Figuring out the vector bounds math was tricky… lots of “off-by-one” errors. I suppose I’ve hit both of the main errors of computer science with this game, then.
• I encapsulated things in their own records (so far, world, thing, and me … and world and me are parameterized) to keep stuff together. I think this’ll work… I hope!

.. before

I started out by writing yolk, which has a bunch of procedures returning strings for terminal escapes. NIH and all :)

Originally I had a big loop to just draw all the border stuff at once, then the character where I wanted it. The character would erase itself and redraw as it moved, which worked fine … for one object.

I was walking around when I realized I’d need to redo things.