# Circle Packing — Randomly

> Grow until collision, keep what fits. 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.circles` — Circle Packing

Grow until collision, keep what fits.

| | |
|---|---|
| **Key** | `images.circles` |
| **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/circles |
| **API** | `GET https://randomly.cluxnei.dev/api/v1/g/images.circles` |

`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 | `1100` | `256` – `2048` | Width |
| `height` | int | `760` | `256` – `2048` | Height |
| `attempts` | int | `26000` | `500` – `90000` | Darts thrown — Candidate points tried. Most of the late ones land inside a circle that already exists and are thrown away; the ones that survive are what fills the gaps. |
| `min_radius` | float | `3` | `1` – `40` | Smallest circle — Candidates that cannot grow this large are discarded. Raise it and the gaps between the big circles stay open. |
| `max_radius` | float | `95` | `8` – `320` | Largest circle |
| `gap` | float | `2.5` | `0` – `24` | Gap — Clear space kept between circles. At zero they touch exactly, which is the true packing and reads as denser than it is. |
| `style` | enum | `mixed` | `filled`, `rings`, `nested`, `mixed` | Draw as |
| `weight` | float | `0.14` | `0.03` – `0.5` | Stroke weight — As a fraction of each circle's own radius, so a large circle is drawn more boldly than a small one rather than the same. |
| `colouring` | enum | `field` | `radius`, `field`, `order` | Colour by |
| `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 | `0.014` | `0` – `0.08` | Grain |

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.circles?width=1100&height=760&attempts=26000' -H 'Accept: text/plain'
curl -o out.png 'https://randomly.cluxnei.dev/api/v1/g/images.circles?width=1100&height=760&attempts=26000&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/circles)