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August 20, 2020 14:04
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Turn a page into matrix scrolling code.
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var canvas = document.createElement('canvas') | |
document.body.appendChild(canvas) | |
canvas.style.position = 'absolute'; | |
canvas.style.width = '100vw'; | |
canvas.style.height = '100vh'; | |
canvas.style.top = 0; | |
canvas.style.left = 0; | |
canvas.style.zindex = 100; | |
var ctx = canvas.getContext('2d'); | |
var columns = []; | |
var chars = []; | |
canvas.height = window.screen.height; | |
canvas.width = window.screen.width; | |
ctx.translate(canvas.width, 0); | |
ctx.scale(-1, 1); | |
for (i = 0; i < 256; columns[i] = 1, chars[i++] = '゠'); // aka 12448 | |
ctx.shadowBlur = 2; | |
function step() { | |
ctx.fillStyle = 'rgba(0,0,0,0.05)'; | |
ctx.shadowColor = '#000'; | |
ctx.fillRect(0, 0, canvas.width, canvas.height); | |
columns.map(function (value, index) { | |
// overwrites the previous light-green char with a green one | |
ctx.fillStyle = ctx.shadowColor = '#000'; | |
ctx.fillRect(index * 10, value - 10, 10, 10); | |
ctx.fillStyle = ctx.shadowColor = '#0F0'; | |
ctx.fillText(chars[index], index * 10, value - 10); | |
columns[index] = value > 758 + Math.random() * 1e4 ? 0 : value + 10; | |
chars[index] = String.fromCharCode(12448 + Math.random() * 96); | |
ctx.fillStyle = ctx.shadowColor = '#AFA'; | |
ctx.fillText(chars[index], index * 10, value); | |
}); | |
} | |
//1000/33 = ~30 times a second | |
setInterval(step, 33); |
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