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General Purpose Visualization Engine

This is a simple object based 2D visualization engine for visualizing objects on a single web page.

Philosophy

The engine watches on a message source for JSON based messages. A message contains a list of objects with status. When a message arrives, the engine memorizes all objects with status and forwards the changes to web pages which connects to the engine via web socket. The web page visualizes the objects using renders according to the object types.

The message source can be a pipe to a process, a subscription to MQTT topics, or anything else. It is extensible.

In additional to messages, the web page also listens for interactive events like mouse, keyboard, and forwards the events to message source regardless if it accepts.

Getting Started

Supported platforms:

  • Mac OS X
  • Linux AMD64/ARM64/ARMv7

Build using Go:

go build -o bin/see ./cmd/see

Build for specific target OS/Arch:

./scripts/build.sh linux-amd64
./scripts/build.sh darwin-arm64

It will generate executable bin/OS/ARCH/see. And now you can hook up your own simulation program:

bin/see -- my-sim-prog args...

Point your browser to http://localhost:3500 and you will see the objects emitted from your simulation program.

To watch an MQTT topic:

bin/see mqtt://server:port/topic-prefix

And it will watch messages from topic topic-prefix/msgs, and emits events to topic-prefix/events.

Renders in Plugins

To hook up your own rendering extensions:

bin/see -I ext-dir1 -I ext-dir2 ... -- my-sim-prog args...

In each of extension directory, file visualizer.plugin is expected. It's a YAML file, with simple information like:

---
name: my-ext
visualizer:
  stylesheets:
    - styles.css
  scripts:
    - objects.js

The following directories are always scanned for plugins before anything else:

  • $HOME/.robotalks
  • Current directory

Details

Messages to visualizer

Reset the world

{
  "action": "reset"
}

Update/Insert an object

{
  "action": "object",
  "object": {
    "id": "object-id",
    "type": "object-type",
    "style": "css-class",
    "styles": ["css-class"],
    "rect": { "x": 0, "y": 0, "w": 0, "h": 0 },
    "origin": { "x": 0, "y": 0 },
    "radius": 0
  }
}

Other properties are type specific.

Camera
{
  "type": "camera",
  "angle": 0,
}
Corner
{
  "type": "corner",
  "loc": "lt|rb|lb|rt"
}
Dot
{
  "type": "dot"
}
Image
{
  "type": "image",
  "src": "url"
}

Keyword TIMESTAMP in src will be replaced with current timestamp if present.

Label
{
  "type": "label",
  "content": "text to show"
}
Joystick
{
  "type": "joystick"
}

Remove an object

{
  "action": "remove",
  "id": "object-id"
}

Events from visualizer

[
  {
    "action": "click",
    "position": { "x": 0, "y": 0 },
  },
  {
    "action": "keyup/keydown/keypress",
    "key": {
      "repeat": false,
      "charCode": 0,
      "code": "ArrowDown/KeyI/...",
      "key": "ArrowDown/i/...",
      "keyCode": 40, /* 73 for i */
      "ctrl": false,
      "alt": false,
      "shift": false,
      "meta": false,
    }
  }
]

License

MIT

Example/Reference

Project ZuPi is an example using this visualizer.