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const canvas = document.getElementById("sierpinski-triangle")
const context = canvas.getContext("2d")
function triangle(width, height, n) {
if (n === 0)
return
context.beginPath()
context.moveTo(width / 2, 0)
context.lineTo(width, height)
context.lineTo(0, height)
context.closePath()
context.stroke()
// top
context.save()
context.translate(width / 4, 0)
triangle(width / 2, height / 2, n - 1)
context.restore()
// bottom left
context.save()
context.translate(0, height / 2)
triangle(width / 2, height / 2, n - 1)
context.restore()
// bottom right
context.save()
context.translate(width / 2, height / 2)
triangle(width / 2, height / 2, n - 1)
context.restore()
}
const depth_input = document.getElementById("depth")
function draw() {
context.clearRect(0, 0, canvas.width, canvas.height)
triangle(canvas.width - 1, canvas.height - 1, parseInt(depth_input.value))
}
depth_input.addEventListener("input", draw)
function updateCanvas() {
const canvas_size = Math.min(window.innerWidth, window.innerHeight - 255)
canvas.width = canvas_size
canvas.height = canvas_size
context.strokeStyle = "#DDDDDD"
context.lineWidth = 0.7
draw()
}
window.addEventListener("resize", updateCanvas)
updateCanvas()
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