# saxi
##### make plot good

saxi is a tool for interacting with the [AxiDraw
drawing machine](https://axidraw.com/) by Evil Mad Scientist. It comes with an
easy-to-use interface, and is exactingly precise.

- automatically scales & centers your drawing to fit on the paper
- minimizes pen-up travel time by reordering & reversing paths
- uses a custom motion planning algorithm (inspired by [axi](https://github.com/fogleman/axi)) that's smooth & fast
- automatically splits apart layers based on SVG stroke colors or group IDs
- has a web-based UI, so there's no need to muck around with installing X11 and Inkscape
- can run on a Raspberry Pi or similar, so you don't need to be tethered to your plotter while it plots

![a screenshot of the saxi user interface](docs/saxi.png)

### Installation

#### For Raspberry Pi 2 / 3 / 4 / 5

1. **Install Node.js (if not already installed):**

```bash
$ curl -sL https://deb.nodesource.com/setup_20.x | sudo -E bash -
$ sudo apt-get install -y nodejs
```

2. **Install `saxi` globally:**

```bash
$ sudo npm install -g saxi
```

If you encounter an `EACCES` error when installing the package globally, see [Resolving EACCES permissions errors when installing packages globally](https://docs.npmjs.com/resolving-eacces-permissions-errors-when-installing-packages-globally).

---

#### For Raspberry Pi Zero / 1 (armv6l)

The official Node.js builds don’t support armv6l. Use an unofficial build:

1. **Download and extract Node.js v20 for armv6l:**

```bash
$ wget https://unofficial-builds.nodejs.org/download/release/v20.5.1/node-v20.5.1-linux-armv6l.tar.xz
$ tar xf node-v*-armv6l.tar.xz
$ export PATH=$PATH:$PWD/node-v*-linux-armv6l/
```

2. **Install `saxi`:**

```bash
$ npm install -g saxi
```

If you encounter an `EACCES` error when installing the package globally, see [Resolving EACCES permissions errors when installing packages globally](https://docs.npmjs.com/resolving-eacces-permissions-errors-when-installing-packages-globally).

---

### Usage

Start the `saxi` server from the terminal:

```bash
$ saxi
Server listening on http://0.0.0.0:9080
Connecting to EBB on /dev/tty.usbmodem1461
```

Then open a web browser:

Go to `http://localhost:9080` if you're using the same computer where saxi is running.

Go to `http://<computer-ip>:9080` if you're on a different device.
(You can find the IP address by running `hostname -I` on the computer running saxi.)

---

### Running `saxi` over SSH

If you're connecting to your Raspberry Pi via SSH, it’s a good idea to keep the `saxi` server running inside a `tmux` session so it stays active even if your SSH session disconnects.

#### Install `tmux` (if not installed)

```bash
$ sudo apt-get install -y tmux
```

#### Start a `tmux` session and run `saxi`

```bash
$ tmux new -s saxi
$ saxi
```

To detach from the session (leaving it running), press:

```
Ctrl + b, then d
```

To reattach later:

```bash
$ tmux attach -t saxi
```

To list sessions:

```bash
$ tmux ls
```

To terminate session:

```bash
$ tmux kill-session -t saxi
```

---

If you want `saxi` to run at boot on the Pi you can use a systemd unit file and enable the service:

```bash
sudo tee /lib/systemd/system/saxi.service <<EOF
[Unit]
Description=Saxi
After=network.target

[Service]
ExecStart=saxi
Restart=always
User=pi

[Install]
WantedBy=multi-user.target
EOF
sudo systemctl enable saxi.service
```

To watch the logs while it is running, use:
```bash
journalctl -f -u saxi
```

#### Raspberry Pi Zero OTG

![Pi Zero on an AxiDraw with a Y-shaped USB cable](docs/pi-zero.jpg)

For the Pi Zero you can make a USB "OTG" cable out of two Micro-B cables and two 0.1" headers
to tap into the AxiDraw's 5V servo supply to power the Pi.  This makes for a more compact
installation without the need for an additional wall-wart.


```
           +------ Center pin on servo rail
           | +---- Ground pin on servo rail
           | |
           | |
Red   -----+-|---- Red
Black -------+---- Black
White ------------ White
Green ------------ Green (sometimes Blue)
```

The Pi will also need to have the `dr_mode=host` parameter set in
`config.txt` to force host mode, since normal USB Micro cables do not
include the `ID` pin that would be used to signal that it is an OTG
connection.

```
echo dtoverly=dwc2,dr_mode=host | sudo tee -a /boot/config.txt
```


#### CORS

If you want to connect to saxi from a web page that isn't served by saxi
itself, you'll need to enable
[CORS](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS), otherwise
GET/POST requests will be denied by the browser. CORS is disabled by default as
a security precaution, but if you need it it's available. Just launch saxi with
the `--enable-cors` flag.

### Info

saxi makes use of the low-level `LM` command introduced in EBB firmware version
2.5.3 to carry out highly accurate constant-acceleration motion plans. If your
AxiDraw is running an older version of the firmware, saxi will fall back to the
less-accurate (but still pretty accurate) `XM` command.

To check what version of the EBB firmware your AxiDraw is running, run `saxi --firmware-version`:

```bash
$ saxi --firmware-version
EBBv13_and_above EB Firmware Version 2.5.3
```

To upgrade your AxiDraw's firmware, see [here](https://github.com/evil-mad/EggBot/tree/master/EBB_firmware).

### Developing

To work on saxi, you can clone this repo and then run `npm start`:

```sh
$ git clone https://github.com/alexrudd2/saxi
$ cd saxi
$ npm run start
```

This will not watch local files for changes. If you change the server code, you'll need to restart manually.

### Credits

saxi's motion planning algorithm is heavily inspired by Michael Fogleman's
[axi](https://github.com/fogleman/axi) project.

saxi's UI would be an ugly mess if it weren't for [@kylestetz](https://github.com/kylestetz)'s discerning eye.

Thanks to [Evil Mad Scientist](http://www.evilmadscientist.com/) for designing
and building such a lovely machine!

---

## Made with saxi

These images were plotted by folks using saxi. If you'd like to add something you've made here, [shoot me an email](mailto:nornagon@nornagon.net)!

<table>
  <tbody>
    <tr>
      <td width=300>
        <a href="https://www.instagram.com/p/B9hFx9KFOwG/"><img width="272" src="https://user-images.githubusercontent.com/172800/80814353-9760ce00-8b80-11ea-8a94-64e13c33a7bc.jpg" alt="Plotted image by @targz" /></a>
        <p>by <strong>Julien Terraz (<a href="https://www.instagram.com/targz/">@targz</a>)</strong></p>
      </td>
      <td width=300>
        <a href="https://github.com/abey79/vpype-explorations"><img width="272" src="https://user-images.githubusercontent.com/172800/80814313-81530d80-8b80-11ea-963a-9ea337f2c6a2.jpg" alt="Plotted image by @abey79" /></a>
        <p>by <strong>Antoine Beyeler (<a href="https://twitter.com/abey79">@abey79</a>)</strong></p>
      </td>
      <td width=300>
        <a href="https://twitter.com/MAKIO135/status/1253334618243125256"><img width="272" src="https://user-images.githubusercontent.com/172800/80814775-4ef5e000-8b81-11ea-896c-e7522d4c38d1.jpg" alt="Plotted image by @MAKIO135" /></a>
        <p>by <strong>Lionel Radisson (<a href="https://twitter.com/MAKIO135">@MAKIO135</a>)</strong></p>
      </td>
    </tr>
    <tr>
      <td width=300>
        <a href="https://www.instagram.com/p/B4iixy7gDB9/"><img width="272" src="https://user-images.githubusercontent.com/172800/80815693-faebfb00-8b82-11ea-81a3-24f825b405ce.jpg" alt="Plotted image by @daniel_feles" /></a>
        <p>by <strong>Daniel Feles (<a href="https://www.instagram.com/daniel_feles/">@daniel_feles</a>)</strong></p>
      </td>
      <td width=300>
      </td>
      <td width=300>
      </td>
    </tr>
  </tbody>
</table>

## SVG-IO For AI-Generated Images

Use the [SVG IO](https://svg.io/) integration to generate images with AI using a text prompt. Enable it by passing the `--svgio-api-key`
paremeter when running on the server:

```sh
npm run build
node cli.mjs --svgio-api-key <THE API KEY>
```