Polar lights

Soft bands of northern lights drift across the frame in slowly cycling colors, with rays that flicker upward.

element
shader
ambient
aurora
since 0.2

Background Studio: tune it below, then copy the code

Your system asks for reduced motion: the demo shows its final state and nothing moves.

Live demo

Polar lights example

Code

It follows the controls above: change an option and the code changes with it.

<link rel="stylesheet" href="/axi0/motion/motion.css?v=6">
<script src="/axi0/motion/motion.js?v=10" defer></script>

<axi0-polar-lights cover></axi0-polar-lights>

import { PolarLights } from "./motion/react/PolarLights";

<PolarLights />

<script setup lang="ts">
import PolarLights from "./motion/vue/PolarLights.vue";
</script>

<template>
  <PolarLights />
</template>

const fx = document.createElement("axi0-polar-lights");
document.querySelector("#hero").append(fx);

The wrappers: PolarLights.tsx (React, TypeScript) and PolarLights.vue (Vue). Both render the same attributes as the HTML; the loader does the rest.

Options

Attribute	Default	What it does
`height`	`0.5`	Where the bands sit, from the bottom
`width`	`1`	How thick the bands are
`colors`	auto	Colors, comma separated (empty: the palette for the page's theme)
`background`	auto	Background color (empty: the theme's)
`speed`	`1`	How fast it moves
`theme`	`auto`	Light or dark palette (auto: from the page behind it)
`cover`	`false`	Fill the nearest positioned parent, behind its content

Decorative: the canvas is aria-hidden and takes no focus; with cover it ignores the pointer, so the content above it stays clickable and readable. The pointer only adds to the motion; touch and keyboard users see the same scene. Drawn by the shared WebGL runner below device resolution (never more than one pixel per CSS pixel, device pixel ratio capped at 2); it starts when it comes within 300 px of the screen, the frame loop stops off screen and in hidden tabs, and reduced motion draws one still frame with no movement. Without WebGL it shows a still gradient in its own colors.

Size

polar-lights.js is 0.8 KB gzip, with gl.js 2.1 KB and backgrounds-kit.js 3.4 KB it needs. A page loads the loader (2.7 KB) and core.js (1.4 KB) once, whatever it uses.