Snippet Zone

Gravity Dots

```
d = document
```
```
b = d.body
```
```
b.style.margin = 0
```
```
b.style.background = 'black'
```
```
r = (v = 1) => Math.random() * v
```
```
 
```
```
with(
```
```
  b.appendChild(
```
```
    d.createElement`canvas`
```
```
  ).getContext`2d`) {
```
```
 
```
```
  onresize = () => {
```
```
    canvas.width = innerWidth
```
```
    canvas.height = innerHeight
```
```
  }
```
```
  onresize()
```
```
 
```
```
  fillStyle = 'red'
```
```
 
```
```
  dot = (
```
```
    x = r(innerWidth),
```
```
    y = r(innerHeight),
```
```
    mass = 10, sr = r(8) + 4, 
```
```
    R = sr,
```
```
    dx, dy,
```
```
    dist, vx = .2, vy = 0) => { 
```
```
 
```
```
    return () => { 
```
```
      fillStyle = '#005eb0'
```
```
      R = sr
```
```
      if (r() < .005) {
```
```
        vx = r() * 4 - 2
```
```
        R = sr * 2
```
```
        fillStyle = 'white'
```
```
      }
```
```
 
```
```
      dx = innerWidth / 2 - x
```
```
      dy = innerHeight / 2 - y
```

      dist = Math.sqrt(dx * dx + dy * dy)

```
      dist *= dist
```
```
      vx += dx / dist * mass
```
```
      vy += dy / dist * mass
```
```
 
```
```
      x += vx
```
```
      y += vy
```
```
 
```
```
      beginPath()
```
```
      arc(x, y, R, 0, 6.29)
```
```
      fill()
```
```
    }
```
```
  }
```
```
 
```
```
  const dots = []
```

  for (let i = 0; i < 10; i++) dots.push(dot())

```
  loop = () => {
```
```
    fillStyle = 'rgba(0, 0, 0, 0.2)'
```

    fillRect(0, 0, canvas.width, canvas.height)

```
    dots.map(d => d())
```
```
  }
```
```
  setInterval(loop, 16)
```
```
}
```

Some speed coded dots that gravitate to the center of the screen and occasionally change direction.

November 16, 2021

// animation // canvas // graphics // javascript // math // random // speed-coded

Wiggly Line on Canvas 2

const canvas = document.body.appendChild(

```
  document.createElement('canvas')
```
```
);
```
```
const c = canvas.getContext('2d');
```
```
document.body.style.margin = 0;
```
```
 
```
```
function resize() {
```
```
  canvas.width = innerWidth * 2;
```
```
  canvas.height = innerHeight * 2;
```

  canvas.style.width = innerWidth + 'px';

  canvas.style.height = innerHeight + 'px';

```
}
```
```
addEventListener('resize', resize);
```
```
resize();
```
```
 
```
```
const PAD = 50;
```
```
const RAD = 2;
```
```
const SPEED = 200;
```
```
const TWO_PI = Math.PI * 2;
```
```
 
```
```
let mode = 'draw';
```
```
 
```
```
let t = Math.random() * TWO_PI, 
```
```
    x = canvas.width / 2, 
```
```
    y = canvas.height / 2,
```
```
    vx = 0, vy = 0, ta = 0;
```
```
 
```
```
let solid = false;
```
```
let dotMod = 3;
```
```
function loop() {
```

  if (Math.random() < .01) solid = !solid;

  if (Math.random() < .01) dotMod = [2, 3, 6][Math.floor(Math.random() * 3)]

```
 
```
```
  for (var i = 0; i < SPEED; i++) {
```
```
    t = Math.sin(ta) * TWO_PI;
```
```
    vx = RAD * Math.cos(t);
```
```
    vy = RAD * Math.sin(t);
```
```
    ta += Math.random() * 0.1 - 0.05;
```
```
    x += vx;
```
```
    y += vy;
```
```
 
```
```
    if (Math.random() < 0.005) {
```
```
      mode = 'no draw';
```
```
    } else if (Math.random() < 0.005) {
```
```
      mode = 'draw';
```
```
    }
```
```
 
```

    if (mode === 'draw' && (solid || i % dotMod === 0)) {

```
      c.fillStyle = 'black';
```
```
      c.fillRect(x, y, 2, 2);
```
```
    }
```
```
 
```
```
    if (x < -PAD) {
```
```
      x = canvas.width + PAD;
```

    } else if (x > canvas.width + PAD) {

```
      x = -PAD;
```
```
    }
```
```
    if (y < -PAD) {
```
```
      y = canvas.height + PAD;
```

    } else if (y > canvas.height + PAD) {

```
      y = -PAD;
```
```
    }
```
```
  }
```
```
 
```
```
  requestAnimationFrame(loop);
```
```
}
```
```
loop();
```

This is a variation on a post from awhile back. I was posting it over on dev.to and realized I wanted it to look a bit different.

October 18, 2021

// animation // canvas // graphics // javascript

Canvas Particle

const canvas = document.createElement('canvas'),

```
  c = canvas.getContext('2d');
```
```
 
```
```
canvas.width = 500;
```
```
canvas.height = 500;
```
```
 
```
```
document.body.appendChild(canvas);
```
```
 
```
```
c.fillStyle = 'black';
```

c.fillRect(0, 0, canvas.width, canvas.height);

```
 
```
```
let a = 0.29, b = 0.22;
```
```
 
```
```
function f(x, y) {
```

  if (Math.random() < 0.001) b = Math.random();

  return Math.cos((x + Math.sin(x) * 0.01 + Math.cos(x * a)) * b);

```
}
```
```
 
```
```
let x = 1, y = 0;
```
```
 
```
```
setInterval(() => {
```
```
  if (Math.random() < 0.03) {
```
```
    x = 1;
```
```
    y = 0;
```
```
  }
```

  if (Math.random() < 0.001) a = Math.random();

```
  for (let i = 0; i < 1e3; i++) {
```
```
    x = x + f(y);
```
```
    y = y + f(x);
```
```
    c.save();
```
```
    c.translate(150, 250);
```
```
    c.scale(0.5, 0.5);
```

    c.fillStyle = 'rgba(255, 255, 255, 0.01)';

```
    c.fillRect(x, y, 5, 5);
```
```
    c.restore();
```
```
  }
```
```
}, 20);
```

A single particle moves around and leaves a trail

October 17, 2021

// canvas // graphics // javascript // math // speed-coded

ASCII Circles (Bresenham Fun)

```
// some circles made of text
```
```
 
```
```
const cols = 50;
```
```
const rows = 50;
```
```
const sym = '.';
```
```
const body = document.body;
```
```
 
```
```
Object.assign(body.style, {
```
```
  userSelect: 'none',
```
```
  fontFamily: 'Courier, monospace',
```
```
  position: 'fixed', 
```
```
  width: '100%',
```
```
  height: '100%',
```
```
  margin: 0
```
```
});
```
```
 
```
```
const el = body.appendChild(
```
```
  document.createElement('span')
```
```
);
```
```
el.innerHTML = sym;
```
```
 
```
```
Object.assign(el.style, {
```
```
  position: 'absolute',
```
```
  left: '50%',
```
```
  top: '50%',
```
```
  wordWrap: 'break-word',
```
```
  cursor: 'pointer'
```
```
});
```
```
 
```

const charSize = el.getBoundingClientRect().width;

```
const elWidth = charSize * cols;
```
```
el.style.display = 'block'
```
```
el.style.width = `${elWidth}px`;
```
```
 
```
```
const info = body.appendChild(
```
```
  document.createElement('div')
```
```
);
```
```
 
```
```
Object.assign(info.style, {
```
```
  background: '#fff',
```
```
  padding: '4px',
```
```
  position: 'absolute'
```
```
})
```

info.innerHTML = 'click/tap and hold for different fx';

```
 
```
```
function resize() {
```
```
  const scl = Math.min(
```
```
    1.23, 
```

    Math.min(innerWidth, innerHeight) / elWidth * .93

```
  );
```

  el.style.transform = `translate(-50%, -50%) scale(${scl}, ${scl * .55})`

```
}
```
```
addEventListener('resize', resize);
```
```
resize();
```
```
 
```
```
const size = cols * rows;
```
```
const pix = sym.repeat(size);
```
```
el.innerHTML = pix;
```
```
 
```
```
let cells = pix.split('')
```
```
const blank = cells.concat();
```
```
 
```
```
function setSym(x, y, col) {
```
```
  const idx = x + y * cols;
```
```
  if (cells[idx] != null) {
```
```
    cells[idx] = col;
```
```
  }
```
```
  return setSym
```
```
}
```
```
 
```
```
const grad = '::;|0UU888NN';
```
```
function circ(shooter) {
```

  let x = Math.round(Math.random() * cols);

  let y = Math.round(Math.random() * rows);

```
  const rad = Math.round(
```
```
    shooter ? Math.random() * 2 :
```

      Math.random() * Math.random() * 13 + 1

```
  );
```
```
 
```

  const sym = shooter ? '#' : grad.charAt(rad % grad.length);

```
  let speed = rad / 10 + .1;
```
```
  let dir = Math.random() * 2 - 1;
```
```
  return () => {
```

    drawCircle(x, y, rad, sym, shooter);

```
    y += speed;
```
```
    if (shooter) x += speed * 3 * dir;
```
```
    if (y > rows + 10) y = -14;
```
```
  }
```
```
}
```
```
 
```
```
const circs = [];
```
```
const NUM = 40;
```
```
for (let i = 0; i < NUM; i++) {
```
```
  circs.push(circ(Math.random() > 0.5))
```
```
}
```
```
 
```
```
let down;
```

document.addEventListener('mousedown', () => {

```
  down = true;
```
```
});
```

document.addEventListener('mouseup', () => {

```
  down = false;
```
```
});
```

document.addEventListener('touchstart', () => {

```
  down = true;
```
```
});
```

document.addEventListener('touchend', () => {

```
  down = false;
```
```
});
```
```
 
```
```
let tweak;
```
```
let tweakChoice;
```
```
let tweakChance = 0.4;
```

const clear = () => cells = blank.concat();

```
 
```
```
function draw() {
```
```
  if (!down) {
```
```
    tweak = false;
```
```
    tweakChoice = Math.random();
```
```
    clear();
```
```
  } else {
```
```
    if (tweakChoice < tweakChance) {
```
```
      tweak = true;
```
```
      clear();
```
```
    }
```
```
  }
```
```
 
```
```
  circs.forEach(circ => circ());
```
```
  el.innerHTML = cells.join('');
```
```
}
```
```
 
```

// 60fps is too fast, so use 30ms interval

```
setInterval(draw, 30);
```
```
 
```
```
function hLine(xp, yp, w, col) {
```
```
  for (let i = 0; i < w; i++) {
```
```
    setSym(xp + i, yp, col);
```
```
  }
```
```
  return hLine;
```
```
}
```
```
 
```
```
// bresenham circle
```

function drawCircle(xp, yp, radius, sym = '@', isFilled) {

```
  if (isFilled && tweak) sym = '';
```
```
 
```
```
  xp = parseInt(xp, 10);
```
```
  yp = parseInt(yp, 10);
```
```
  radius = parseInt(radius, 10);
```
```
  let balance = -radius,
```
```
    xoff = 0,
```
```
    yoff = radius;
```
```
 
```
```
  while (xoff <= yoff) {
```
```
    const p0 = xp - xoff;
```
```
    const p1 = xp + xoff;
```
```
 
```
```
    const p2 = yp + yoff;
```
```
    const p3 = yp - yoff;
```
```
    const p4 = yp + xoff;
```
```
    const p5 = xp + yoff;
```
```
    const p6 = xp - yoff;
```
```
    const p7 = yp - xoff;
```
```
 
```
```
    if (isFilled) {
```
```
      const w0 = xoff + xoff;
```
```
      const w1 = yoff + yoff;
```
```
 
```
```
      hLine
```
```
        (p0, yp + yoff, w0, sym)
```
```
        (p0, yp - yoff, w0, sym)
```
```
        (p6, yp + xoff, w1, sym)
```
```
        (p6, yp - xoff, w1, sym);
```
```
 
```
```
    } else {
```
```
      setSym
```
```
        (p1, p2, sym)
```
```
        (p0, p2, sym)
```
```
        (p0, p3, sym)
```
```
        (p1, p3, sym)
```
```
        (p5, p4, sym)
```
```
        (p6, p4, sym)
```
```
        (p6, p7, sym)
```
```
        (p5, p7, sym);
```
```
    }
```
```
 
```

    // never been able to find the original

```
    // source for the below condition 
```

    // more info here: https://actionsnippet.com/?p=492

    if ((balance += xoff++ + xoff) >= 0) {

```
      balance -= --yoff + yoff;
```
```
    }
```
```
  }
```
```
}
```

This is a bit of a longer snippet that uses the Bresenham circle drawing algorithm to draw some circles with text. I recommend looking at it with the fullscreen button.

I like to do this:

```
hLine
```
```
  (p0, yp + yoff, w0, sym)
```
```
  (p0, yp - yoff, w0, sym)
```
```
  (p6, yp + xoff, w1, sym)
```
```
  (p6, yp - xoff, w1, sym);
```

Make a function return itself, so that if you need to call it many times without having to repeat the function name. Because this isn’t a common style it is generally frowned upon, I’m always tempted to use it at work for some reason… maybe next April fools.

September 26, 2021

// animation // arrays // graphics // hacks // humor // javascript // math // random // strings // tricks

Cistercian Numerals (semi-golfed)

```
N = -1
```
```
S = 30
```
```
H = 90
```
```
h = 45
```
```
d = document
```
```
b = d.body
```
```
m = _ => d.createElement(_)
```
```
a = _ => b.appendChild(_)
```
```
 
```
```
with(a(
```
```
    Object.assign(
```
```
      m`canvas`,
```
```
      { width: 80, height: 120 }
```
```
    )
```
```
  ).getContext`2d`
```
```
) { 
```
```
  a(m`br`)
```
```
 
```
```
  L = (a, b, C, d) => {
```
```
    moveTo(a, b)
```
```
    lineTo(C, d)
```
```
  }
```
```
 
```
```
  M = _ => L(0, 0, 0, H)
```
```
  O = _ => L(0, 0, S, 0)
```
```
  W = _ => L(0, S, S, S)
```
```
  T = _ => L(0, 0, S, S)
```
```
  F = _ => L(0, S, S, 0)
```
```
  X = _ => L(S, 0, S, S)
```
```
 
```
```
  D = [
```
```
    _ => {},
```
```
    O, W, T, F, 
```
```
    [O,F],
```
```
    X,
```
```
    [O,X],
```
```
    [W,X],
```
```
    [O,W,X]
```
```
  ]
```
```
 
```
```
  n = s => {
```
```
    [...s].reverse().map((l, i) => {
```
```
      save()
```
```
      translate(S+9, h+9)
```
```
      scale(N**i, N**~~(i/2))
```
```
      translate(0, -h)
```

      M() ;[D[l]].flat().map(x => x && x())

```
      restore()
```
```
    })
```
```
  }
```
```
 
```
```
  a(m`input`).oninput = e => {
```
```
    clearRect(0, 0, 80, 120)
```
```
    beginPath()
```
```
    n(~~e.target.value+'')
```
```
    stroke()
```
```
  }
```
```
}
```

Type any number from 0-9999 into the input field and see the corresponding Cistercian Numeral. This snippet is partially golfed, I left the canvas commands intact to make things a bit easier to understand.

Simpler SVG Version

This one hardcodes all numbers 0-9 as paths, unlike the canvas version which only defines 1,2,3,4 and 6 as paths and then combines them to create 5,7,8 and 9.

```
h='innerHTML'
```
```
C='children'
```
```
 
```
```
document.body[h]=`
```

<svg id=G width=99 viewBox="0 0 80 120"

  style="stroke:black;fill:none;overflow:visible">

```
  <g transform="translate(30,2)">
```
```
    <path d="M0 0L 30 0"/>
```
```
    <path d="M0 30L 30 30"/>
```
```
    <path d="M0 0L 30 30"/>
```
```
    <path d="M0 30L30 0"/>
```
```
    <path d="M0 30L30 0 0 0"/>
```
```
    <path d="M30 0L30 30"/>
```
```
    <path d="M30 30L30 0 0 0"/>
```
```
    <path d="M0 30L30 30 30 0"/>
```
```
    <path d="M0 30L30 30 30 0 0 0"/>
```
```
  </g>
```

  <g transform=translate(30,2)scale(-1,1)></g>

  <g transform=translate(30,92)scale(1,-1)></g>

  <g transform=translate(30,92)scale(-1,-1)></g>

```
  <path id=m d="M 30 2 L 30 92"/>
```
```
</svg>
```

<style>path:not(#m){opacity:0}</style><br>

```
<input id=I>`
```
```
 
```
```
c=G[C]
```
```
p=c[0][h] 
```
```
 
```
```
n = s => 
```
```
  [...s].reverse().map((l, i) => 
```

   l-1>-1 && (c[i][C][l-1].style.opacity=1))

```
 
```
```
I.oninput = e => {
```
```
  for(i=0;i<4;i++)c[i][h]=p
```
```
  n(~~e.target.value+'')
```
```
}
```

September 24, 2021

// arrays // canvas // codegolf // graphics // hacks // javascript // math

Older Posts

Newer Posts