Pen Settings



CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource


Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource


Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.


Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.


                h1 ⸨ POND ⸩


  | viewing angle:
  input[type='range' min='0.2' max='1' step='0.1' value='0.2']



  transform: translate(-50%, -50%)
  font: 8px monospace
  position: absolute
  text-align: center
  left: 50%
  top: 50%
  display: inline-block
  font-size: 3em
  color: #efefef
    &, & + pre, & + pre + label
      color: blue
  margin: 0
label, input
  margin-top: 1.5em
  display: block
  font-size: 16px
  margin-right: auto
  margin-left: auto


                window.addEventListener('load', _ => {
	const FONT_SIZE = '72px';
	const FONT_FAMILY = 'monospace';

	// ctx.measureText() only returns width for now, so we'll just place characters
	// into a dummy span element and measure their approximate size.
	const span = document.createElement('span');
	const canvas = document.createElement('canvas');
	const ctx = canvas.getContext('2d');

	const chars = Array.from({length: 95}, (_, i) => String.fromCharCode(i + 32)); = `${FONT_SIZE} "${FONT_FAMILY}"`; = 'hidden'; = 'absolute';
	const {w: maxWidth, h: maxHeight} = chars.reduce((max, char) => {
		span.textContent = char;
		const {width, height} = span.getBoundingClientRect();
		return {w: Math.max(max.w, width), h: Math.max(max.w, height)};
	}, {w: 0, h: 0});

	const horizontalPadding = maxWidth / 4;
	const verticalPadding = maxHeight / 4;
	const fullWidth = canvas.width = maxWidth + 2 * horizontalPadding;
	const fullHeight = canvas.height = maxHeight + 2 * verticalPadding;
	ctx.font = `${FONT_SIZE} "${FONT_FAMILY}"`;
	ctx.textBaseline = 'top';

	function getPixelWeight (char) {
		ctx.clearRect(0, 0, fullWidth, fullHeight);
		ctx.fillText(char, horizontalPadding, verticalPadding);
		// r, g, b channels will always be 0. Transparent pixels will have an alpha
		// channel of 0. So by summing `data`, we're summing the opacity of all filled-in
		// pixels. This is wildly inefficient but it gives us a dead simple, reliable
		// measure of relative size.
		return ctx.getImageData(0, 0, fullWidth, fullHeight).data.reduce((a, b) => a + b);

	const sortedChars = chars
		.map(char => ({char, weight: getPixelWeight(char)}))
		.sort(({weight: a}, {weight: b}) => a - b)
		.map(({char}) => char)
    const {sin, cos, pow} = Math;
    const [w, h] = [100, 40];

    // Get references to DOM nodes.
    const slider = document.querySelector('input');
    const pre = document.querySelector('pre');

    // Hook the slider up.
    let viewingAngle = slider.value;
    slider.addEventListener('input', () => viewingAngle = slider.value);

    // Main draw loop.
    !(function draw (t) {
      pre.textContent = Array.from({length: h}, (_, y) => Array.from({length: w}, (_, x) => sortedChars[

          (t - pow(
            (viewingAngle*pow(x-w/2, 2) + pow(y-h/2, 2)
          ), .7)) / 18

        )) * (sortedChars.length - 1))]
    ).join(' ')).join('\n');

      requestAnimationFrame(draw.bind(null, t + 1));