Aurora shader hero background (fullscreen-quad fbm noise with domain warping)
AleBrito124356/threejs-hero-collection@08e9325ce258 · 1 code file(s)

Licence notice — required by the licence; keep it with this code:

MIT License

Copyright (c) 2026 Alejandro Brito

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

--- aurora.html ---
<!DOCTYPE html>
<!--
MIT License

Copyright (c) 2026 Alejandro Brito

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
-->
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Aurora shader hero — threejs-hero-collection</title>
<style>
  :root {
    --bg: #0A0D14;
    --border: #1E293B;
    --accent: #2563EB;
    --accent-2: #38BDF8;
    --text: #F1F5F9;
    --body: #94A3B8;
    --muted: #64748B;
    --mono: 'Cascadia Code', Consolas, Menlo, monospace;
  }
  * { box-sizing: border-box; margin: 0; padding: 0; }
  html, body { height: 100%; }
  body {
    background: var(--bg);
    color: var(--body);
    font-family: -apple-system, 'Segoe UI', Inter, Roboto, sans-serif;
    line-height: 1.6;
    overflow-x: hidden;
  }
  #scene { position: fixed; inset: 0; width: 100%; height: 100%; display: block; }

  .site-header {
    position: fixed; top: 0; left: 0; right: 0; z-index: 2;
    display: flex; align-items: baseline; gap: 16px;
    padding: 14px 24px;
    background: rgba(10, 13, 20, 0.72);
    border-bottom: 1px solid var(--border);
  }
  .site-header .repo { font-family: var(--mono); color: var(--accent-2); text-decoration: none; font-weight: 600; }
  .site-header .tag { color: var(--muted); font-size: 0.85rem; flex: 1; min-width: 0;
                      white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
  .site-header nav { display: flex; gap: 14px; }
  .site-header nav a { color: var(--body); text-decoration: none; font-size: 0.85rem; }
  .site-header nav a:hover { color: var(--accent-2); }

  .hero {
    position: relative; z-index: 1;
    min-height: 100vh;
    display: flex; flex-direction: column; justify-content: center; align-items: center;
    text-align: center; padding: 96px 24px 64px;
  }
  .hero h1 {
    color: var(--text);
    font-size: clamp(2rem, 6vw, 3.6rem);
    font-weight: 700; letter-spacing: -0.02em; line-height: 1.1;
    max-width: 720px;
    text-shadow: 0 2px 24px rgba(10, 13, 20, 0.8);
  }
  .hero p {
    margin-top: 18px; max-width: 560px; font-size: 1.05rem;
    text-shadow: 0 1px 12px rgba(10, 13, 20, 0.8);
  }
  .cta {
    margin-top: 32px; display: inline-block;
    padding: 12px 28px; border-radius: 8px;
    background: linear-gradient(135deg, var(--accent), var(--accent-2));
    color: #fff; text-decoration: none; font-weight: 600; font-size: 0.95rem;
    transition: filter 0.2s ease, transform 0.2s ease;
  }
  .cta:hover { filter: brightness(1.12); transform: translateY(-1px); }
  a:focus-visible { outline: 2px solid var(--accent-2); outline-offset: 3px; }

  @media (prefers-reduced-motion: reduce) {
    .cta { transition: none; }
    .cta:hover { transform: none; }
  }
  @media (max-width: 480px) {
    .site-header .tag { display: none; }
  }
</style>

<!-- The ONLY external dependency of this repo: three.js, pinned to 0.170.0.
     To self-host, download three.module.js and point this import map at it. -->
<script type="importmap">
{
  "imports": {
    "three": "https://unpkg.com/three@0.170.0/build/three.module.js"
  }
}
</script>
</head>
<body>
<header class="site-header">
  <a class="repo" href="index.html">threejs-hero-collection</a>
  <span class="tag">Drop-in animated hero backgrounds built with Three.js</span>
  <nav aria-label="Repository links">
    <a href="index.html">All heroes</a>
    <a href="https://github.com/AleBrito124356/threejs-hero-collection">GitHub</a>
  </nav>
</header>

<canvas id="scene" aria-hidden="true"></canvas>

<main class="hero">
  <h1>Northern lights, on demand</h1>
  <p>An aurora painted entirely in a fragment shader — layered fbm noise, no textures, no assets, just GLSL and two brand blues.</p>
  <a class="cta" href="https://github.com/AleBrito124356/threejs-hero-collection">Read the shader</a>
</main>

<script type="module">
import * as THREE from 'three';

/* =============================== customize ===============================
   The palette is passed to the shader as uniforms, so tweaking these three
   values restyles the whole aurora without touching any GLSL.             */
const COLORS = {
  deep: '#0A0D14',   // night sky base (matches the page background)
  blue: '#2563EB',   // main curtain color
  cyan: '#38BDF8',   // hot core of the brightest curtains
};
const SPEED = 1.0;   // global time multiplier (0.5 = half speed)
/* ========================================================================= */

const canvas = document.getElementById('scene');
const renderer = new THREE.WebGLRenderer({ canvas, antialias: false });
// DPR cap matters MOST here: this is a full-screen fragment shader, so cost
// scales with pixel count. DPR 3 would mean 2.25x the work of DPR 2.
renderer.setPixelRatio(Math.min(window.devicePixelRatio, 2));
renderer.setSize(window.innerWidth, window.innerHeight);

/* --- Fullscreen quad technique -------------------------------------------
   A 2x2 plane whose vertex shader writes clip-space coordinates DIRECTLY
   (gl_Position = vec4(position.xy, ...)), bypassing all camera math. The
   camera below is a formality — three.js requires one to call render().  */
const scene = new THREE.Scene();
const camera = new THREE.OrthographicCamera(-1, 1, 1, -1, 0, 1);

const uniforms = {
  uTime:       { value: 0 },
  uResolution: { value: new THREE.Vector2(window.innerWidth, window.innerHeight) },
  uDeep:       { value: new THREE.Color(COLORS.deep) },
  uBlue:       { value: new THREE.Color(COLORS.blue) },
  uCyan:       { value: new THREE.Color(COLORS.cyan) },
};

const material = new THREE.ShaderMaterial({
  uniforms,
  vertexShader: /* glsl */`
    void main() {
      // Pass the quad straight through to clip space: no projection,
      // no model-view. The quad IS the screen.
      gl_Position = vec4(position.xy, 0.0, 1.0);
    }
  `,
  fragmentShader: /* glsl */`
    precision highp float;

    uniform float uTime;
    uniform vec2  uResolution;
    uniform vec3  uDeep;
    uniform vec3  uBlue;
    uniform vec3  uCyan;

    // --- Classic value-noise stack, inlined so the file stays standalone ---
    // hash: deterministic pseudo-random from a 2D coordinate.
    float hash(vec2 p) {
      return fract(sin(dot(p, vec2(127.1, 311.7))) * 43758.5453123);
    }

    // Value noise: random values at integer lattice points, smoothly
    // interpolated between them (smoothstep weights kill grid artifacts).
    float noise(vec2 p) {
      vec2 i = floor(p);
      vec2 f = fract(p);
      vec2 u = f * f * (3.0 - 2.0 * f);
      return mix(
        mix(hash(i),                 hash(i + vec2(1.0, 0.0)), u.x),
        mix(hash(i + vec2(0.0, 1.0)), hash(i + vec2(1.0, 1.0)), u.x),
        u.y
      );
    }

    // fbm (fractal Brownian motion): octaves of noise, each twice the
    // frequency and half the amplitude — small detail on large structure.
    float fbm(vec2 p) {
      float value = 0.0;
      float amplitude = 0.5;
      for (int i = 0; i < 5; i++) {
        value += amplitude * noise(p);
        p = p * 2.03 + 17.13;  // offset decorrelates the octaves
        amplitude *= 0.5;
      }
      return value;
    }

    void main() {
      vec2 uv = gl_FragCoord.xy / uResolution.xy;      // 0..1 screen coords
      vec2 p = uv;
      p.x *= uResolution.x / uResolution.y;            // aspect correction

      float t = uTime * 0.05;

      // Domain warping: one fbm field distorts the coordinates fed into the
      // next. This is what turns flat noise into flowing aurora curtains.
      float warp = fbm(vec2(p.x * 1.6 + t, p.y * 0.7 - t * 0.6));
      float curtain = fbm(vec2(p.x * 3.0 - t * 1.4, warp * 2.2 + t * 0.4));

      // Vertical rays: high-frequency noise in x only, stretched along y.
      float rays = fbm(vec2(p.x * 6.0 + warp, t * 0.8));

      // Shape the light: curtains gated to the upper half of the screen,
      // rays multiplied in for that streaked aurora texture.
      float glow = smoothstep(0.35, 0.95, curtain * (0.7 + 0.5 * rays));
      glow *= smoothstep(1.05, 0.15, uv.y);            // fade toward bottom

      // Palette: deep night -> brand blue -> cyan core. The pow() keeps
      // cyan reserved for only the brightest spots (no neon soup).
      vec3 color = uDeep;
      color = mix(color, uBlue, glow * 0.85);
      color = mix(color, uCyan, pow(glow, 3.0) * 0.9);

      // Gentle vignette grounds the corners and keeps overlay text legible.
      float vignette = smoothstep(1.3, 0.4, length(uv - vec2(0.5, 0.45)));
      color *= mix(0.72, 1.0, vignette);

      gl_FragColor = vec4(color, 1.0);
    }
  `
});

scene.add(new THREE.Mesh(new THREE.PlaneGeometry(2, 2), material));

function update(delta, elapsed) {
  uniforms.uTime.value = elapsed * SPEED;
}

/* --- Render loop: DPR-capped, pauses when hidden, static under
       prefers-reduced-motion. This block is identical in every hero. ------ */
const reducedMotion = window.matchMedia('(prefers-reduced-motion: reduce)');
let rafId = null;
let last = null;
let elapsed = 0;

function frame(now) {
  if (last === null) last = now;
  const delta = Math.min((now - last) / 1000, 0.1);
  last = now;
  elapsed += delta;

  update(delta, elapsed);
  renderer.render(scene, camera);
  rafId = requestAnimationFrame(frame);
}

function start() {
  if (rafId === null && !reducedMotion.matches && !document.hidden) {
    last = null;
    rafId = requestAnimationFrame(frame);
  }
}
function stop() {
  if (rafId !== null) { cancelAnimationFrame(rafId); rafId = null; }
}

// Reduced motion: freeze the aurora at a photogenic moment.
function renderStatic() {
  update(0, 40);
  renderer.render(scene, camera);
}

document.addEventListener('visibilitychange', () => {
  if (document.hidden) stop(); else start();
});
reducedMotion.addEventListener('change', () => {
  if (reducedMotion.matches) { stop(); renderStatic(); } else { start(); }
});
window.addEventListener('resize', () => {
  renderer.setSize(window.innerWidth, window.innerHeight);
  uniforms.uResolution.value.set(window.innerWidth, window.innerHeight);
  // The orthographic camera needs no aspect update: the vertex shader
  // ignores it entirely and the fragment shader corrects aspect itself.
  if (reducedMotion.matches) renderStatic();
});

/* SPA embedding? Dispose on unmount:
   material.dispose(); renderer.dispose(); and the plane geometry.        */

if (reducedMotion.matches) renderStatic(); else start();
</script>
</body>
</html>