kenny2github / scratch-dexter

A Scratch extension to interact with Dexter.

scratch-dexter

A Scratch extension to interact with Dexter.

Loading

1. Install Node.JS: https://nodejs.org/en/download/
2. Make a folder, change into it, run npm init and npm install ws, and download the proxy file.

   mkdir DexProxy
   cd DexProxy
   npm init
   npm install ws
   wget https://raw.githubusercontent.com/Kenny2github/scratch-dexter/master/httpd.js

3. Run the proxy server: node httpd.js <Dexter IP> where <Dexter IP> is the IP of the robot.
4. Navigate to https://scratchx.org?url=https://kenny2github.github.io/scratch-dexter/ext.js#scratch
   • On Chrome, click to enable Flash
5. Accept the warning about experimental extensions.

Using

As an example:

This will make the robot wave back and forth.

scratch-dexter's Issues

Command oplets to implement for release

Command oplets to implement:

• P

  "pid_move_all_joints"

  PID_FINEMOVE

  Chases a goal position on each joint using the PID control system which must be enabled. Requires calibration. The goal can change in the middle of the move. Movement is not coordinated so each joint may arrive at the goal at a different time. The standard trapezoidal speed ramping is not used. See "a".

  
  Note: Encoder calibration is not yet a thing, and is likely to be too complicated for majority Scratch users. This block is therefore implemented but useless ._.

• g

  "get_robot_status"

  SEND_HEARTBEAT

  Returns the current status of the robot.

  
  Note: Scratch has nowhere near sophisticated enough data structures to understand the data returned by this. Probably forgo this altogether or only add it as an "update status" command; actual data parts will be returned by reporter(s):
  • ([joint 1 v] [sin v]) where "joint 1" can be 1-5 and "sin" can be "position at", "position delta" etc.
  • (last [instruction number v]) where "instruction number" can be "job number", "start time", "end time", "command" etc.

Create Scratch 3 version

It appears the newest version of Scratch doesn't support extensions via the mit web site. However, looking at the source for the Scratch 3 GUI at:
https://github.com/LLK/scratch-gui

I see there is an examples / extension folder. I think it would be worth hosting Scratch on Dexter, with the extensions pre-installed to work with it. Is that a project that interests you?

Documentation for setup of node.js proxy

I've documented the setup for this at:
https://github.com/HaddingtonDynamics/Dexter/wiki/Scratch-extension

Please feel free to copy that documentation to this repo to help people make use of it.

It's too bad that scratch can't directly communicate to the websocket proxy script that is already on the current robot. Perhaps we can add the proxy function to the DDE software.

Loading scratch extensions from github repo

It would be nice to go to
http://scratchx.org
click "more blocks" then "Load experimental extension" and be able to load the extension from this URL:
https://raw.githubusercontent.com/Kenny2github/scratch-dexter/master/ext.js
or to do that in one step with
http://scratchx.org?url=https://raw.githubusercontent.com/Kenny2github/scratch-dexter/master/ext.js
but when you try that, nothing happens. If you start the Chrome debug tools (menu, more tools, developer tools) you see an error message:
Refused to execute script from 'https://raw.githubusercontent.com/Kenny2github/scratch-dexter/master/ext.js' because its MIME type ('text/plain') is not executable, and strict MIME type checking is enabled.

See also:

• https://stackoverflow.com/questions/17341122/link-and-execute-external-javascript-file-hosted-on-github/18049842 For development, we may be able to turn off the script mime type checking by starting Chrome with:
  chrome.exe --user-data-dir="C://Chrome dev session" --disable-web-security

• RawGit.com is no longer an option

• https://pages.github.com/ is a hosting service, but the repo name must be your github user name followed by ".github.io" which is the url where the site can be accessed. e.g.
  https://github.com/JamesNewton/JamesNewton.github.io
  is accessable at
  https://jamesnewton.github.io/
  .js files loaded into that repo can be loaded in scratchx as desired, but then you can't have the extension in it's own repo. This appears to be the workaround used by the extensions which work on scratchx. The current version of the extension was copied to my github page and the following link appears to work
  https://scratchx.org/?url=https://jamesnewton.github.io/scratch/ext.js

• https://github.com/LLK/scratchx/wiki#load-a-javascript-file-hosted-on-github It is apparently possible to make a special branch on any of your repos and set it to be served via github pages. This is complex, but would make life simple for users.

Suggestion: Follow the directions in the link above to make it very easy for users to load scratchx with the url to the extension and talk to their dexter.