A beautiful, interactive, zoomable Game of Life (and friends) written in Odin using raylib.

This project was created as a delightful way to learn Odin by doing something genuinely fun.

Most language tutorials stop at "print hello". This one gives you:

• A complete, real-time simulation with proper fixed-tick game loop
• Clean data-oriented design (just slices of bytes + procedures)
• Odin's fantastic bit_set used for elegant, fast CA rules
• Excellent use of vendor:raylib (one of the best parts of the Odin ecosystem)
• Camera, mouse painting, keyboard patterns — the kind of interactivity that makes you want to experiment
• Heavy, friendly comments explaining both the algorithm and the language features

• Four rulesets hot-swappable with 1–4 keys:
  • Conway's Life (the classic)
  • HighLife (has replicators!)
  • Seeds (chaotic, everything dies)
  • Day & Night (gorgeous organic patterns)
• Infinite zoom & pan with mouse wheel + middle mouse / WASD / arrows
• Live painting with left/right mouse (different brush sizes with [ ])
• Famous patterns at your cursor: G (glider), P (pulsar), X (R-pentomino), U (Gosper glider gun)
• Randomize, clear, pause, single-step
• Population sparkline in the corner so you can see stability at a glance
• Resizable window, VSync, 60 fps smooth

Odin + raylib (both come together via Homebrew on macOS):

mise use odin

This installs raylib as well and wires everything up.

cd odin-life
odin build . -out:life -o:minimal
./life

For development (better debug info, slower binary):

odin build . -out:life -debug

Read the file in roughly this order:

1. The Rules struct + RULESETS — see how bit_set[0..=8] makes cellular automata rules almost declarative.
2. World struct — notice there are no classes, no vtables, just plain data. This is data-oriented design.
3. step() — the double-buffer swap and neighbor counting. Dead simple, very fast.
4. Input handling — see how raylib makes mouse + camera interaction trivial.
5. The main loop — fixed timestep accumulator + free_all(context.temp_allocator) every frame. This pattern is pure Odin joy.
6. Camera math — zooming toward the mouse cursor is only a few lines.

Beginner

• Add a fifth ruleset (search "Life-like cellular automata" on Wikipedia)
• Change the starting density or initial patterns
• Make the brush leave "embers" (cells that stay alive for a few frames)

Intermediate

• Add a "heatmap" mode that colors cells by how long they've been alive
• Implement copy/paste of rectangular regions
• Make the simulation wrap in only one axis (cylinder world)

Advanced (you will learn a ton)

• Implement Hashlife (Gosper's insanely fast algorithm for huge sparse patterns)
• Add a second simulation layer (e.g. simple "predator" particles that eat live cells)
• Add recording: dump frames to disk as images or a .gif
• Make the camera smoothly follow large moving patterns (like the glider gun)

odin-life/
├── main.odin     # Everything lives here (deliberately)
├── README.md
└── .gitignore

One file. No hidden magic. Read it, change it, break it, understand it.

• Odin documentation
• vendor:raylib source — the bindings are tiny and readable
• ConwayLife.com — the greatest collection of patterns and knowledge
• The demo/ folder that ships with Odin (odin build $ODIN_ROOT/examples/demo)

Enjoy playing with little pixels that make other pixels. That's the whole game.