Dither `<mv-dither>`

漂い、融合し、また分かれる液体のしずくを描く WebGL 背景です。小さなドームのように照らされ、規則的な Bayer 行列を通して 2 色のインクで印刷されます。ライトテーマではインクが版画のように影を描き、ダークテーマでは 1 ビットの画面のように光を描きます。

仕組み

漂い、融合し、また分かれる液体のしずくを描く WebGL 背景です。小さなドームのように照らされ、規則的な Bayer 行列を通して 2 色のインクで印刷されます。ライトテーマではインクが版画のように影を描き、ダークテーマでは 1 ビットの画面のように光を描きます。ポインターは自分のしずくを持ち、ほかのしずくを引き寄せ、光もそちらを向きます。きらめきにはアクセントカラーが使われます。

カテゴリー	背景
タイプ	WebGL 要素（`<mv-dither>`）
ステータス	安定版
同時にインストールされるもの	shader
Keywords	safe-rewrite, webgl, shader, dither, bayer, retro, pixel, 1-bit, metaballs, interactive, hero

When to use

A retro, 1-bit or print-inspired brand wants a calm, living backdrop that reads well in light and dark themes
A hero or launch page should answer the pointer in a playful way without leaving a two-color palette
Pixel art, zines or early computer graphics set the tone and a smooth gradient would feel off-brand

Avoid when

A still, CSS-only section background is enough and no WebGL context should be spent → use Backdrop instead
Small body text sits directly on top; the crisp dither edges hurt legibility without a solid panel

インストール

node scripts/add.mjs dither --out ./src/marvelous

Marvelous UI の MCP サーバーを使う AI エージェント：install_components({ slugs: ["dither"], target_dir: "<absolute path>/src/marvelous", framework: "react" })。

コピーされるファイル（依存関係を含む）：tokens/tokens.css, core/base.css, core/canvas.js, core/dom.js, core/element.js, core/i18n.js, core/motion.js, core/observe.js, core/webgl.js, components/shader/shader.js, components/shader/shader.css, components/dither/dither.js。

使い方

基本となるマークアップです。ここから属性、data-*、CSS 変数でカスタマイズしてください：

<mv-dither data-fill></mv-dither>
<div style="position:relative;display:grid;place-items:center;height:100%;min-height:320px;padding:1rem;color:var(--mv-fg);text-align:center;pointer-events:none">
  <div style="padding:.9rem 1.25rem;border-radius:var(--mv-radius-md);background:var(--mv-bg);box-shadow:0 0 0 1px var(--mv-border)">
    <p style="margin:0;font:700 clamp(1.5rem,4vw,2.4rem)/1.1 var(--mv-font-sans);letter-spacing:-.03em">Printed in two inks</p>
    <p style="margin:.4rem 0 0;color:var(--mv-fg-muted);font-size:.9rem">Drops merge as they drift. Hover to bring one along.</p>
  </div>
</div>

API

Attributes

Name	タイプ	Default	Description
`color`	CSS color	`var(--mv-fg-muted)`	Ink color (tokens accepted, read again on theme change). Darker than the background, it draws the shadows; lighter, it draws the light.
`background`	CSS color	`var(--mv-bg)`	Paper color: the lowest level and the empty floor.
`highlight`	CSS color	`var(--mv-accent)`	Color of the glints on the drops (set it to the ink color for a strict two-color look).
`pixel-size`	number	`2`	Size of a dither pixel in CSS pixels (multiplied by the pixel ratio).
`levels`	number	`2`	Number of tones between paper and ink (2 = 1-bit).
`matrix`	2 \| 4 \| 8	`8`	Side of the ordered threshold matrix: 2 and 4 give coarser, more graphic patterns.
`scale`	number	`1`	Drop size (0.25 to 4); larger drops are fewer.
`turbulence`	number	`1`	Strength of the pointer response, 0 to 3: size of the drop it carries and how hard it pulls the others (0 = none, the light still follows).
`speed`	number	`1`	Time multiplier.
`paused`	boolean		Freezes the drops on the current frame.
`interactive`	boolean		Follows the pointer only over the element (otherwise across the whole window).
`dpr`	number	`1.5`	Max pixel density (capped at 2).
`data-fill`	boolean		Fills the positioned parent (absolute, inset 0).

Events

Name	Description
`mv-error`	Inherited from `<mv-shader>`: the GLSL failed to compile. The element gets data-error and shows its fallback.

Content structure

Name	Description
`children`	Content placed inside the element sits above the canvas.

Accessibility

Decorative: the canvas is aria-hidden and never takes pointer events; content placed inside stays in the normal reading order. The loop stops off screen and in hidden tabs, and no WebGL context is created until the element comes near the viewport. Reduced motion (OS or <html data-motion="reduce">) and paused keep one still frame, with no pointer response. Forced colors and print hide the canvas; without WebGL2 a static sketch in the theme tokens is shown. Put text on a solid panel: the dither pattern is busy behind small type.