Sunday 27 April 2014

Working on the Minecraft-Scratch Interface for the Rube Goldberg Machine

For the Rube Goldberg project at the CoderDojo I need a way to interact with Scratch from Python.  Here's my steps of how I went about it:

  1. After reading around I realised that I'd have to run Scratch 1.4 and the Python interaction would come from scratchpy -
  2. Installed scratch 1.4 on Windows
  3. pip install scratchpy
  4. Enabled Scratch remote sensing -
  5. Played with the interaction -
  6. Create new branch for scratch plugin git checkout -b scratch-plug
  7. Check all tests pas
  8. python test
  9. Tests failed as wasn't on Rasp PI.  After some poking around I discovered that I'd installed the GPIO package on to my development virtual box environment, and so now the package was loading okay and the case that I had set up in the test file to spot the lack of GPIO wasn't working.  I deleted out the GPIO package and it all worked again...phew!
  10. Making the scratch target -- use a broadcast of either "BLOCK-PRESENT" or "BLOCK-ABSENT"
  11. Create a module
  12. Implemented the target code
  13. Tested that it worked using a file source
  14. Not quite sure how to make the unit tests work.  Will park that problem for now and come back to it later
  15. Now to make the source method
  16. The problem is that the scratch.receive() method blocks until it receives a broadcast, but the Rube Goldberg architecture needs to poll
  17. The solution will be to use the multiprocessing module as shown in this answer on Stack Overflow -
  18. Got a bit stuck coordinating the output with Queues since I didn't realise that multiprocessing had its own implementation of Queue -- you live and learn
  19. Committed that on to the scratch-plug and pushed to GitHub
  20. Made a quick demo of the Minecraft light going into scratch and scratch button turning on a light in Minecraft -

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