# Flow Field — Randomly

> Thousands of particles advected through fractal noise. One of 63 generators at [Randomly](https://randomly.cluxnei.dev), a library of random generators seeded from verifiable real-world entropy. Free HTTP API, no key, no signup.

## `images.flowfield` — Flow Field

Thousands of particles advected through fractal noise.

| | |
|---|---|
| **Key** | `images.flowfield` |
| **Module** | `images` |
| **Version** | `1` — a permalink carries this, and a replay against a different version returns `409` rather than something else |
| **Formats** | `application/json`, `text/plain`, `image/png` |
| **Studio** | https://randomly.cluxnei.dev/g/images/flowfield |
| **API** | `GET https://randomly.cluxnei.dev/api/v1/g/images.flowfield` |

`value` is a **render spec** — algorithm, parameters, palette and a render key — not pixels. Ask for `format=png` to get the image.

| Parameter | Type | Default | Accepts | What it does |
|---|---|---|---|---|
| `width` | int | `1200` | `256` – `2048` | Width |
| `height` | int | `750` | `256` – `2048` | Height |
| `particles` | int | `1500` | `100` – `2500` | Particles — Each one traces a single trail and is never reused. |
| `trail` | int | `190` | `10` – `420` | Trail length — Steps before a particle runs out. Long trails cross the whole canvas; short ones read as brushwork. |
| `step` | float | `1.6` | `0.4` – `6` | Step length — Pixels advanced per step. Small steps hug the field, large ones cut across it. |
| `scale` | float | `2.2` | `0.4` – `9` | Field zoom — How many noise cells fit across the canvas. |
| `octaves` | int | `4` | `1` – `7` | Detail (octaves) |
| `turns` | float | `1` | `0.2` – `3` | Angular range — How many full turns the noise maps onto. Below 1 the flow stays combed in one direction; above 2 it knots. |
| `alpha` | float | `0.2` | `0.01` – `0.8` | Line alpha — Per-segment opacity. The picture is the overlap, so this wants to stay low. |
| `line` | float | `1.1` | `0.4` – `4` | Line width |
| `glow` | bool | `true` | `true`, `false` | Additive blending — Trails add their light together instead of painting over each other. On a dark ground this is the whole look. |
| `background` | enum | `ink` | `ink`, `ground`, `paper`, `palette` | Ground |
| `palette` | enum | `golden` | `golden`, `analogous`, `complementary`, `triadic`, `split`, `viridis`, `magma`, `mono` | Colour |
| `colours` | int | `6` | `2` – `12` | Palette size |
| `grain` | float | `0.018` | `0` – `0.08` | Grain — Per-pixel noise over the finished render. A little of it is the difference between generative and computer-made. |

Out-of-range numbers are **clamped, not rejected**, so a request never fails for being
ambitious — but it may not do what you meant. Unknown keys are dropped and missing ones
fall back to the defaults above.

```bash
curl -s 'https://randomly.cluxnei.dev/api/v1/g/images.flowfield?width=1200&height=750&particles=1500' -H 'Accept: text/plain'
curl -o out.png 'https://randomly.cluxnei.dev/api/v1/g/images.flowfield?width=1200&height=750&particles=1500&format=png'
```

## The receipt

Every result carries one, naming the physical source of the randomness and linking to the
third party's own record of it:

```json
"receipt": {
  "source": "seismic",
  "source_label": "USGS Seismic Feed",
  "class": "C",
  "caveat": "Carries only tens of bits of genuine surprise. Always mixed with the OS CSPRNG.",
  "narrative": "A magnitude 3.6 earthquake, 67 km N of Culebra, Puerto Rico, 39.6 km down — 52 minutes ago.",
  "proof_url": "https://earthquake.usgs.gov/earthquakes/eventpage/us7000th33",
  "mixed_with_csprng": true,
  "degraded": false
}
```

Pick the source with `?source=`, or leave it at the default `auto`:

- **Class A** (Cryptographic) — `csprng`, `anu-qrng`, `random-org`
- **Class B** (Public beacon) — `nist-beacon`, `drand`, `bitcoin`. Published openly — anyone can look this value up after the fact.
- **Class C** (Observational) — `seismic`, `space-weather`, `atmosphere`, `iss`. Carries only tens of bits of genuine surprise. Always mixed with the OS CSPRNG.

## More

- [The full API contract](https://randomly.cluxnei.dev/api.md)
- [Everything in one file](https://randomly.cluxnei.dev/llms-full.txt)
- [The catalogue as JSON](https://randomly.cluxnei.dev/api/v1/generators)
- [This generator in the browser](https://randomly.cluxnei.dev/g/images/flowfield)