Only turn off, not re-run

[rbdr/r.bdr.sh] / js / animation.js

(function () {

  if (window.matchMedia('(prefers-reduced-motion: reduce)').matches) return

  var K = document.querySelector('canvas'),
    { random: R, PI, cos: C, sin: S, atan2: A } = Math,
    id = p => p,
    spn = rad => p => ({
        x: p.x + rad * C(l),
        y: p.y + rad * S(l)
    }),
    X = K.getContext('2d'), F = X.fill.bind(X), B = X.beginPath.bind(X),
    f = 24, l = 0, s = 1, z = 5 + r(10),
    k = R() > 0.5, c = R() > 0.5,
    I = Array(r(10) + 6).fill().map(() => ({
      x: r(64), y: r(64),
      a: R() * 2 * PI, c: r(100)
    })),
    H = [sqr, crc, hrt, chs, lch], P = [id, spn(5), spn(15)],
    draw = H[r(H.length)], pos = P[r(P.length)],
    Z = 1

  function r(x) {
    return ~~(R() * x)
  }

  function sqr(i) {
    var p = pos(i)
    X.fillRect(p.x, p.y, z, z)
  }

  function crc(i) {
    var p = pos(i)
    B()
    X.arc(p.x, p.y, z / 2, 0, 2 * PI)
    F()
  }

  function chs(i) {
    var {x, y} = pos(i)
    B()
    X.moveTo(x, y)
    X.lineTo(x * 10 * C(i.a), y * 10 * S(i.a))
    X.lineTo(r(64), r(64))
    F()
  }

  function lch(i) {
    var {x, y} = pos(i)
    B()
    X.lineWidth = 5
    X.strokeStyle = `hsl(0,0%,${i.c}%)`
    X.moveTo(x, y)
    X.lineTo(x * 10 * C(i.a), y * 10 * S(i.a))
    X.stroke()
  }

  function hrt(i) {
    var {x, y} = pos(i)
    X.fillRect(x, y, z, z)

    B()
    X.arc(x + z / 2, y, z / 2, 0, 2 * PI, false)
    F()
    X.closePath()

    B()
    X.arc(x + z, y + z / 2, z / 2, 0, 2 * PI, false)
    F()
    X.closePath()
  }

  function mov(i) {
    i.x = i.x + s * C(i.a)
    i.y = i.y + s * S(i.a)

    if (i.x < 0 || i.x > 64) {
      i.a = A(S(i.a), -C(i.a))
    }
    if (i.y < 0 || i.y > 64) {
      i.a = A(-S(i.a), C(i.a))
    }
  }

  function ucl(i) {
    i.c = (i.c + 2) % 101
  }

  function frm(t) {
    if (Z) requestAnimationFrame(frm)

    var dt = t - l

    if (dt > 1000 / f) {
      k && X.clearRect(0, 0, 64, 64)
      for (var i of I) {
        X.fillStyle = `hsl(0,0%,${i.c}%)`
        draw(i)
        c && ucl(i)
        mov(i)
      }

      l = t
    }
  }

  K.addEventListener('click', () => (Z=0))
  frm()
}
)()