Game of Life

Try it

The app runs here in your browser. Nothing you type leaves it. Open it on its own.

Download life.wardian Import it in Wardian: Settings → Import.

A Wardian page app: Conway's Game of Life, with the whole simulation in WebAssembly. Press Play, or Step one generation at a time. Click or drag on the board to draw cells. Load a classic pattern, fill the board at random, or switch the rule to HighLife or Seeds.

Why a page: the world is a grid of thousands of cells, and the app needs a canvas and live controls. A module app passes only numbers. It is a page and not a suite because it has one job, and every panel works on the same world.

File	What it is
`index.html`	The page: the run, world and help panels, and the board.
`app.js`	Plays the generations, draws the board, reads clicks, and holds the patterns.
`src/lib.rs`	The world: `init`, `set_rule`, `set_cell`, `get_cell`, `clear`, `randomize`, `step`, `population`, `render`.
`app.wasm`	Built from `src/lib.rs` by `./build.sh`.
`ui/`	The Wardian component library: theme, button, field, card, switch and Arrange.

How the data moves:

The world lives inside the module's memory. It is two grids of one byte per cell, plus a "heat" grid that remembers how recently each cell died.
step(n) reads one grid and writes the next generation into the other, then swaps them. It does this n times in one call and returns the population. At high speed the page asks for many generations per frame, so JavaScript never touches a cell in the loop.
render(ptr, live, dead, glow, trail) writes one RGBA pixel per cell into a buffer the page reserved once with alloc. The page reads memory.buffer again after the call, puts the pixels on a small canvas, and scales it up onto the board without smoothing.
A click or drag calls set_cell for each cell on the line, so a fast drag leaves no gaps.

The edges wrap around: a glider that leaves on the right comes back on the left.

Patterns: glider, lightweight spaceship, Gosper glider gun, pulsar, R-pentomino, acorn, and the HighLife replicator. They are written in RLE, the text format Life programs share, so adding one to PATTERNS in app.js takes one line.

Motion: the board starts playing when it opens. If your system asks for less motion (prefers-reduced-motion), it starts paused and says why.

Limits:

The largest grid is 640 × 400 cells. A bigger grid is possible (init allows 2000 × 2000), but the cells become too small to draw with the mouse.
The page cannot keep anything between visits. Your drawing ends when you close the page.

The panels are Arrange panels (data-panel): each viewer may reorder them, move them between the two columns, or hide them.

This page is apps/life/README.md in the repository. Something wrong or missing? Change that file.