Caustics
Underwater light: interfering bright lines drifting over a dark pool floor, the way sun looks through a wave. A Charcoal original. WebGL, written in the file.
- Category: Backgrounds
- Licence: Charcoal UI Pro
- Built with: React 19, Tailwind CSS 4, Motion
- Dependencies: motion, clsx, tailwind-merge
Examples
Caustics
API reference
| Prop | Type | Default | Description |
|---|---|---|---|
speed | number | 1 | |
scale | number | 1 | |
intensity | number | 1 | |
color | string | "var(--ember)" | |
className | string | — |
About Caustics
Caustics draws underwater light: interfering bright lines drifting over a dark pool floor, the way sun looks through a wave. A Charcoal original.
Caustics is an animated background for React 19, styled with Tailwind CSS 4 and animated with Motion. It drops into Next.js, Vite, Remix or Astro through the shadcn CLI as a single file you own.
When to use Caustics
- Water, pool and travel brands.
- Wellness and spa.
- Calm product heroes.
- Summer campaigns.
How it works
It is a WebGL fragment shader written in the file, with no three.js. Props are read each frame so tuning never rebuilds the context, it pauses off screen, and it falls back to a gradient without WebGL.
The whole layer is decorative and aria-hidden, sits behind your content without taking pointer events it does not need, and pauses when scrolled off screen. With prefers-reduced-motion on, it holds still or settles instantly instead of animating.
Customizing Caustics
Every prop is documented in the API reference above with its type and default. The ones you will reach for first are listed here.
The Customize panel next to the preview lets you change speed, scale, intensity, color live, and the Code tab updates to match, so the snippet you copy already carries your values.
- speed (number, default 1).
- scale (number, default 1).
- intensity (number, default 1).
- color (string, default "var(--ember)").
Goes well with Caustics
These backgrounds pieces share its tokens and motion language, so they sit together on one page without clashing.
- Ember Field: An animated React ember background: glowing embers drift up and flicker as they cool
- Smoke: A slow React smoke background: blurred plumes drifting over dark sections, CSS only
- Aurora: An animated React aurora background: soft light bands drifting across a section
- Grid Beams: A React grid background with beams of light running along its lines
- Meteors: A React meteor shower background: streaks falling diagonally, CSS only
Install Caustics
npx shadcn@latest add @charcoal/causticsCaustics is part of Charcoal UI Pro. One seat unlocks all 300 Pro components, 107 landing-page sections and 100 full templates, for every personal and client project, with updates included. Add the @charcoal registry once with your access token, then the command above copies caustics.tsx into components/ui and installs clsx, tailwind-merge.
You own the file you install: no runtime package, no lock-in, nothing to keep in sync. Change it however your product needs.
See Charcoal UI Pro pricing · Pro setup
Frequently asked questions
- How do I install Caustics?
- Caustics is part of Charcoal UI Pro. Add the @charcoal registry to components.json with your access token, then run npx shadcn@latest add @charcoal/caustics. It copies caustics.tsx into components/ui and installs motion, clsx, tailwind-merge.
- Is Caustics free for commercial use?
- Caustics needs a Charcoal UI Pro seat, monthly or a one-time lifetime price. A seat covers unlimited personal and commercial projects, including client work, and every future Pro component.
- Does Caustics work with Next.js?
- Yes. It is a client component for React 19 styled with Tailwind CSS 4, so it works in the Next.js App Router and Pages Router, Vite, Remix and Astro.
- Can an AI coding agent install Caustics?
- Yes. Connect the Charcoal UI MCP server (https://charcoalui.com/mcp) to Claude Code, Cursor or any MCP client; get_component returns Caustics's props and get_install_command returns the exact command.