# Dobble / Spot It Card Generator

Generate printable Dobble card sets from your own images.

## Usage

```bash
nix run . -- ./my-images/ -o cards.pdf
```

### Options

| Flag | Description | Default |
|------|-------------|---------|
| `-o`, `--output` | Output PDF path | `dobble.pdf` |
| `-n`, `--order` | Prime order (auto-detected if omitted) | auto |
| `--card-diameter` | Card diameter in mm | `80` |
| `--cards-per-page` | Max cards per page | `6` |
| `--page-size` | `a4` or `letter` | `a4` |

## Deck sizes

The order must be a prime number. If not specified, the largest valid order is auto-detected from the number of images provided.

| Order | Symbols/card | Total cards | Images needed |
|-------|-------------|-------------|---------------|
| 2     | 3           | 7           | 7             |
| 3     | 4           | 13          | 13            |
| 5     | 6           | 31          | 31            |
| 7     | 8           | 57          | 57            |
| 11    | 12          | 133         | 133           |
| 13    | 14          | 183         | 183           |

Formula: for prime order `n`, you need `n² + n + 1` images and get exactly `n² + n + 1` cards, each with `n + 1` symbols. Every pair of cards shares exactly one symbol.

Order 7 (8 symbols/card, 57 cards) is what the real Dobble game uses.