# Smoke

Soft smoke that billows upward and thins out.

## 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="smoke" />
```

Rising fractal noise masked to the lower half, so the surface clears for text on top. `scale` sets the blob size, `rise` the speed of the drift, `gain` the density.

The props group like this:

Texture: `scale`, `rise`. Density: `gain`.

## Examples

### Embers

An ember palette turns the smoke into heat under a dark sky.

```astro
<DitherEffect effect="smoke" palette={["#000000","#2a0a02","#7a2808","#e86a20","#ffd9a0"]} />
```

### Dense fog

Low `scale` and high `gain` fill the bottom with a solid bank.

```astro
<DitherEffect effect="smoke" params={{"scale":1.5,"gain":2.2}} />
```

## Props

| Prop | Type | Default | Description |
| --- | --- | --- | --- |
| `scale` | `number` | 3 | Blob size. 1 to 8. |
| `rise` | `number` | 0.15 | Upward drift speed. 0 to 0.6. |
| `gain` | `number` | 1.2 | Density. 0.2 to 3. |
| `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 5s) 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.