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Animated hexagon in polar coordinates with a superimposed naive sawtooth signal. (source: https://jsfiddle.net/tx1kfuae/42/)
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body { | |
background-color: #222; | |
} | |
#canvas { | |
border: 1px solid #eee; | |
} | |
} |
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<canvas id="canvas"></canvas> |
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const canvas = document.getElementById('canvas'); | |
const ctx = canvas.getContext('2d'); | |
function init() { | |
canvas.width = 400; | |
canvas.height = 300; | |
} | |
function deg2rad(deg) { | |
return deg * 2 * Math.PI / 360; | |
} | |
/** Converts polar coordinates to cartesian. */ | |
function poltocar(r, theta) { | |
return { | |
x: r * Math.cos(theta), | |
y: r * Math.sin(theta), | |
}; | |
} | |
/** Returns the radius of an n-sided polygon for a given theta. */ | |
function polygon(n, theta) { | |
let radPerSide = deg2rad(360 / n); | |
let denom = Math.sin(theta - radPerSide * (-1 + Math.floor(theta / radPerSide))); | |
let r = (Math.sqrt(3) / 2) * (1 / denom); | |
return r; | |
} | |
function naiveSawtooth(theta) { | |
return theta % (Math.PI * 2); | |
} | |
function step() { | |
let cx = canvas.width / 2; | |
let cy = canvas.height / 2; | |
ctx.fillStyle = 'rgba(22, 22, 22, 0.1)'; | |
ctx.fillRect(0, 0, canvas.width, canvas.height); | |
ctx.beginPath(); | |
for (let i = 0; i <= 360; i++) { | |
let theta = deg2rad(i); | |
let r = polygon(6, theta) + 0.01 * naiveSawtooth(theta * 40); | |
let p = poltocar(r, theta - deg2rad(Date.now() * 0.08)); | |
if (i === 0) { | |
ctx.moveTo(cx + p.x * 80, cy + p.y * 80); | |
} else { | |
ctx.lineTo(cx + p.x * 80, cy + p.y * 80); | |
} | |
} | |
ctx.strokeStyle = 'rgba(187, 255, 252, 0.1)'; | |
ctx.stroke(); | |
window.requestAnimationFrame(step); | |
} | |
init(); | |
window.requestAnimationFrame(step); |
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