Matrix digital rain · grok-build-0.1
Create the Matrix digital rain effect on a full-screen black canvas: columns of falling green katakana glyphs with a trailing fade and a brighter leading character.
transcript · 10 messages
Create the Matrix digital rain effect on a full-screen black canvas: columns of falling green katakana glyphs with a trailing fade and a brighter leading character.
thinking
The task is: "Create the Matrix digital rain effect on a full-screen black canvas: columns of falling green katakana glyphs with a trailing fade and a brighter leading character. Build a single-page w...
{"command":"ls -la /tmp/ws"}total 0 drwxr-sr-x. 2 node node 6 Aug 1 20:17 . drwxrwsrwx. 3 root node 16 Aug 1 20:17 ..
thinking
The task is to build a single-page web app with the Matrix digital rain effect, all in one self-contained file named index.html in the current directory. CSS in <style>, JS in <script>, no external re...The task is to create a single-page web app with the Matrix digital rain effect in one index.html file. It needs to be self-contained, no external resources, fully sandboxed. Current directory is /tmp/ws, so I need to write index.html there.
Key requirements:
- Full-screen black canvas
- Columns of falling green katakana glyphs
- Trailing fade
- Brighter leading character
I need to use HTML5 Canvas.
First, structure the HTML:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale 1.0">
<title>Matrix Digital Rain</title>
<style>
body, html {
margin: 0;
padding: 0;
overflow: hidden;
background: black;
}
canvas {
display: block;
width: 100vw;
height: 100vh;
}
</style>
</head>
<body>
<canvas id="matrix"></canvas>
<script>
// JS code here
</script>
</body>
</html>
For the JS part.
I need to implement the effect.
Get the canvas: const canvas = document.getElementById('matrix');
const ctx = canvas.getContext('2d');
Resize to 100%:
function resize() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
}
window.addEventListener('resize', resize);
resize();
Then, define katakana string.
const katakana = "アイウエオカキクケコサシスセソタチツ テトナニヌネノハヒフヘホマミムメモヤユヨラリルレロワヲン0123456789";
Better full list, but this is common.
const chars = 'アァイゥエオカガキギクグケゴコゴサザ シジスズセゼソゾタダチヂツヅテデトドナニ ヌネノハバパヒビピフビプヘベペホボポヴッン';
Use a standard one.
const chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789@#$%^& *()_+~`|}{[]\\:;'/?.>,< -~!";
No, for Matrix katakana.
Standard is:
const chars = "アイウエオカキクケコサシスセソタチツテトナニヌネノハヒフヘホマミム メモヤユヨラリルレロワヲン0123456789";
Yes.
const fontSize = 16; // adjust for performance, 14-20
const columnCount = Math.floor(canvas.width / fontSize);
const drops = new Array(columnCount).fill(1); // start from 1
Then the draw function:
function draw() {
// Fade
ctx.fillStyle = 'rgba(0, 0, 0, 0.05)';
ctx.fillRect(0, 0, canvas.width, canvas.height);
// Rain
ctx.font = `${fontSize }px monospace`;
for (let i = 0; i < columnCount; i++) {
const y = drops[i] * fontSize;
const char = chars[Math.floor(Math.random() * chars.length)];
// Brighter leading: draw current head in brighter green
ctx.fillStyle = '#00ff41'; // typical Matrix green
ctx.fillText(char, i * fontSize, y);
// Increment drop
drops[i]++;
if (y > canvas.height && Math.random() > 0.975) {
drops[i] = 0;
}
}
requestAnimationFrame(draw);
}
Then call draw();
For resize, need to update columnCount and drops.
So, better make a function initRain() {
const w = canvas.width;
const h = canvas.height;
const cols = Math.floor(w / fontSize);
columnCount = cols;
drops = new Array(cols).fill(0).map(() => Math.random() * (h / fontSize)); // stagger init
// better random start
}
Call initRain() after resize.
In resize:
function resize() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
initRain();
}
Yes.
For init: drops = Array.from({length: columnCount}, () => Math.random() * columnCount or wait, to start at random height: Math.random() * (canvas.height / fontSize)
Yes.
To have them falling from top-ish.
Also, in the if: if (drops[i] > columnCount) wait no, since drops is row index, when drops[i] > (canvas.height / fontSize) then reset with prob.
Yes, adjust the if:
if (drops[i] * fontSize > canvas.height && Math.random() > 0.975) {
drops [i] = 0;
}
Yes.
For brighter leading: by using '#00ff41' for the current drawn char, and since trail fades, the head is always bright, trail dimmer. Perfect.
Yes.
To make it even better, perhaps use a slightly varying green for head, but ok.
Also, to avoid jitter, use integer drops.
Yes.
I think this is good.
Now, to write the full file, I need to use the tool to write to /tmp/ws/index.html
Since it's create, use write_file tool? The available tools are list_dir, read_file, write_file, etc yes, write_file.
So, I'll call write_file with path /tmp/ws/index.html , content the full html string.
But to make sure, perhaps first write it.
Since confidence high, but need to get exact.
Let's compose the content./tmp/ws/index.html (2850 bytes)Successfully wrote 2850 bytes to /tmp/ws/index.html
thinking
The file has been written. I should verify it exists and perhaps do a quick sanity check.
{"command":"ls -la /tmp/ws/index.html && wc -c /tmp/ws/index.html"}-rw-r--r--. 1 node node 2994 Aug 1 20:18 /tmp/ws/index.html 2994 /tmp/ws/index.html
thinking
The file is created and self-contained. Let me verify it works by checking for any issues, though since it's HTML/JS, I can just confirm its presence. The instruction is: "End with index.html present....
{"path":"/tmp/ws/index.html","offset":1,"limit":50}<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Matrix</title> <style> * { margin: 0; padding: 0; box-sizing: border-box; } html, body { width: 100%; height: 100%; overflow: hidden; background: #000; font-family: monospace; } canvas { display: block; position: absolute; top: 0; left: 0; } </style> </head> <body> <canvas id="canvas"></canvas> <script> const canvas = document.getElementById('canvas'); const ctx = canvas.getContext('2d', { alpha: true }); let width = 0; let height = 0; let fontSize = 16; let columns = 0; let drops = []; let chars = 'アァィゥェォカガキギクグケゲコゴサザシジスズセゼソゾタダチヂツヅテデトドナニヌネノハバパヒビピフブプヘベペホボポマミムメモャュョラリルレロワヲン0123456789'; function resize() { width = canvas.width = window.innerWidth; height = canvas.height = window.innerHeight; columns = Math.floor(width / fontSize); drops = new Array(columns); for (let i = 0; i < columns; i++) { // Start drops at random positions (some above screen for staggered entry) drops[i] = Math.random() * (height / fontSize) - 20; } [61 more lines in file. Use offset=51 to continue.]
thinking
The file is complete and self-contained. No external resources. It has:
Done. `index.html` is created and fully self-contained with the Matrix digital rain effect.
TAKE IT TO CODE
A single self-contained HTML file — copy it and open in any browser, or reuse the prompt with your own pi-agent run.
RUN
EVALUATION
Classic Matrix digital rain with green katakana columns, fading trails, and continuous animation; inputs don't alter it, as expected.
Vision grade · anthropic/claude-sonnet-5
MEASUREMENTS
Raw readings from the capture, not a verdict — the grade above is the only judgement. Percentages are how much of the screen changed; the measure under-reports sparse motion on a dark background.