# Gradient

A linear, radial, conic or wave gradient drawn as a dither.

## 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="gradient" palette={["#000000", "#00b2ff", "#d6efff"]} />
```

Four modes under one prop: linear sweeps along an angle, radial grows from a point, conic spins around it, and wave strips the screen horizontally. The ramp itself is two stops, `from` and `to`, blended through the palette.

The props group like this:

Shape: `mode`, `angle`, `cx`, `cy`, `radius`. Ramp: `from` and `to`, blended through `palette`. Motion: `speed` rotates linear and conic modes.

## Examples

### Conic spin

`mode` 2 turns the ramp around its centre, and `speed` keeps it turning.

```astro
<DitherEffect effect="gradient" params={{"mode":2,"cx":0.5,"cy":0.5}} speed={0.4} />
```

### Horizontal wave

`mode` 3 drops the ramp for soft horizontal bands that drift.

```astro
<DitherEffect effect="gradient" params={{"mode":3}} speed={0.6} />
```

## Props

| Prop | Type | Default | Description |
| --- | --- | --- | --- |
| `mode` | `number` | 1 | 0 linear, 1 radial, 2 conic, 3 wave. 0 to 3. |
| `angle` | `number` | 180 | Ramp direction in degrees (linear and conic). 0 to 360. |
| `cx` | `number` | 0.5 | Centre x, 0 to 1. 0 to 1. |
| `cy` | `number` | 0 | Centre y, 0 to 1. 0 to 1. |
| `radius` | `number` | 1.05 | Radial reach. 0.1 to 2. |
| `from` | `number` | 1 | Ramp start stop. 0 to 1. |
| `to` | `number` | 0 | Ramp end stop. 0 to 1. |
| `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. Rounded to whole device pixels so cells stay even. |
| `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. |
| `stillTime` | `number` | the effect's | The moment drawn when motion is off or reduced, in seconds. |
| `levels` | `number` | 0 (all) | Tones the field snaps to before dithering. Low values give hard, posterised steps. |
| `bloom` | `number` | 0 | Bloom around lit cells, 0 to 1. Set a positive prop to create the overlay before overriding it with CSS `--dither-bloom`. |
| `bloomRadius` | `number` | 10 | Bloom blur in CSS pixels. CSS `--dither-bloom-radius` overrides it. |
| `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 0s) 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.