# Tunnel

A slow flight down a tunnel of glowing rings.

## Installation

```sh
pnpm add astro-dither
```

Or copy the source into your project:

```sh
npx astro-dither add effect
```

## Usage

```astro
---
import { DitherEffect } from "astro-dither";
---

<DitherEffect effect="tunnel" />
```

Polar rings rushing inward with a spiral twist. `twist` sets the depth of the spiral and `spokes` how many wall segments wrap around.

The props group like this:

Pattern: `twist`, `spokes`.

## Examples

### Straight well

`twist` 0 and no `spokes` leave plain concentric rings.

```astro
<DitherEffect effect="tunnel" params={{"twist":0,"spokes":0}} />
```

### Fan

More `spokes` cut the walls into a spinning turbine.

```astro
<DitherEffect effect="tunnel" params={{"twist":6,"spokes":9}} />
```

## Props

| Prop | Type | Default | Description |
| --- | --- | --- | --- |
| `twist` | `number` | 3 | Spiral depth. 0 to 12. |
| `spokes` | `number` | 4 | Wall segments around the ring. 0 to 12. |
| `palette` | `string[]` | the effect's | 2 to 8 colours, paper first, brightest last. `transparent` works. |
| `cell` | `number` | 2 | Size of one dither cell in CSS pixels, 1 to 8. |
| `matrix` | `2 | 4 | 8 | "noise"` | 8 | The Bayer threshold size, or noise for a random look. |
| `speed` | `number` | 1 | Playback speed. 0 draws one still frame. |
| `class` | `string` | undefined | Classes on the surface element, for size and position. |

## Notes

* Decorative and `aria-hidden`. Put real text on top, not inside it.
* With reduced motion it draws one still frame (at 4s) and stops.
* It pauses when scrolled out of view or when the tab is hidden.
* Shares one WebGL context with every other ordered effect on the page.