Condensation shader preview: Misted glass over any image: draw on it to wipe it clear, and watch the mist creep back.
ittybitty

Condensation

Misted glass over any image: draw on it to wipe it clear, and watch the mist creep back.

Code

The usage always matches the preview, layers and performance settings included. No build step or package.

Copy embed gives one block to paste into any page or site builder, no setup. For your own code: add condensation.js, ittybitty-shader.js, runtime.js, container.js, pointer.js, shape.js, texture.js next to this page. Highlighted values follow the controls.

<!-- Quickest: one element. Size it with CSS; it fills its box. -->
<script type="module" src="./ittybitty-shader.js"></script>
<ittybitty-shader effect="condensation" style="width: 100%; aspect-ratio: 16 / 10;"></ittybitty-shader>

<!-- Or with JavaScript, for full control: -->
<canvas id="condensation" aria-hidden="true" style="width: 100%; aspect-ratio: 16 / 10; display: block"></canvas>

<script type="module">
  import { condensation } from './condensation.js';

  const canvas = document.getElementById('condensation');
  const effect = condensation(canvas, {
    showImage: true,
    showFog: true,
    showDrops: true,
    image: '/examples/still-life.webp',
    fog: 0.75,
    droplets: 0.6,
    brush: 1,
    refog: 6,
    tint: '#e9eef2',
    interactive: true,
    responsiveness: 0.9,
    container: 'off',
    outline: 'itty',
    edgeLight: 0.6,
    rim: 0.6,
    gloss: 0.5,
    innerShadow: 0.5,
    // Performance
    dpr: 2,
    adaptive: true,
  });

  // Later: effect.set(…), effect.pause(), effect.resume(), effect.destroy()
</script>

Details

Fine droplets speckle the mist and a few beads cling to it. Draw with the pointer and the glass wipes clear with a ragged edge, beads gathering along the rim of each stroke; then the mist slowly returns. It only draws while something changes.

Payload
9.3 KB brotli for condensation.js and ittybitty-shader.js and runtime.js and container.js and pointer.js and shape.js and texture.js, measured at build time. See the method.
Resolution
Device pixel ratio capped at 2.
Frame rate
None. One frame per change.
When unseen
Stops rendering when the canvas leaves the viewport or the tab is hidden, and resumes where it left off.
Reduced motion
Nothing to change: it never moves.
Layers
Up to five effects fuse into one shader and one draw call. Filters such as dithering and halftone process the layers beneath them.
Browsers
Any browser with WebGL2: Chrome and Edge 56+, Firefox 51+, Safari 15+.
Licence
MIT. Copy it, change it, ship it.