readme.md

2020-06-06.enthusiasticon

EnthusiastiCon is a remote conference for the programming community scheduled for 2020-06-06. This Repo is the designated location for my talk proposal and subsequent materials.

The CfP was extended to 2020-05-03, and I've handed in a proposal to it.

Usage

Below are some things I like to do with the code in this repo:

Dependencies

• Some of the code is typescript and to be used with node.
  • I like using yarn, but npm should work just as well.
  • Run yarn install; yarn build to install dependencies and compile
    • You could also run this with ts-node, but it's a bit more resource hungry.
• To render animations blender and python are used.

Slides

Use yarn slides to view the slides of the talk.

Converting and resizing

The node portion of code deals with .png images exclusively and works on the assumption that images are already of the desired size. I like to use the convert tool that comes with ImageMagick to convert and resize images: convert $input --resize 48x48 output.png

The scripts truncate images to the highest multiple of 3 in each dimension. Images don't have to be square or of a specific size. It's just that larger sizes imply bigger computational work and file sizes.

Image Quantization

The scripts make use of the image-q library to reduce the color palette so that it fits the 6 colors of our cubes.

Execution of yarn quantify test.png will result in the creation of several quantified images in the same place as test.png, but with the specific quantization in the file name, such as test.floyd-steinberg.png.

Animation JSON

Call of yarn animate test.floyd-steinberg.png will result in a test.floyd-steinberg.json that contains animations for the cubes. The animate script works on the assumption that the image was quantized before.

Creating a blend file

Call of yarn mkBlend test.floyd-steinberg.json blender/test.blend will result in execution of the blender/rotations.py script in blender using the template.blend as the template for our cube.

The resulting blender/test.blend file can be rendered and used with blender regularly. For example I like rendering headless with blender --background test.blend -a. The template.blend is set to render a .mp4 and save it in /tmp/, which is copied over to the test.blend, but can of course be adjusted at will.

Sources

I'm trying to keep track of sources I've used to at least some extend:

• Wikipedia:
  • Rubiks Cube
  • Kociemba's algorithm
  • Cayley graph
  • Symmetric group
• Rubik's for cryptographers
• Cayley graphs
• Ruwix: Twisty Puzzles
• YouTube
  • Cycle notation of permutations
  • Matt Parker on impossible Rubiks Cubes
• Ruwix:
  • Rubik's cube notation
  • Advanced Rubik's cube notation
  • Rubik's cube algorithms
  • Mathematics of the Rubik's cube
• Metamagical Themas:
  • Chapter 14: Magic Cubology
• Blender stackexchange for a question regarding rotations of cubelets:
  • How to sort objects from a collection using python

Tweets

I've tweeted about related topics in the past and use this list to find my old tweets again:

• Happy about holding my current cube in hands the first time
• Permuting some bs on a 7x7x7 cube
• 1/3 of a receiving a bunch of cubes
• A dino mosaic
• Several mosaics
• A bw scene
• The mosaic table
• Special-spork recordings with OBS
• Special-spork restickering
• Special-spork broken
• A rotated corner
• One more logo
• Python+Blender cube factory
• Getting rotations to work
• BBB more logo
• Superflip

Screenshots

Out of amusement I took some screenshots where things went in unexpected directions.

Some rotations used unexpected axis:

I was happy once the cloning of cubes from my template worked, and so made a whole field:

To practise selecting a side of the cube I used these cubes and tried to delete their inner sides:

Somehow two rotations were working in sequence:

Shortly after that the superflip worked:

Side selection was not always working:

In between people liked to draw on some shared sceenshots:

A bunch of cubes was broken by incorrectly rotating stuff into each other. This was often due to trouble correctly selecting the cubelets that needed rotation or due to wrongly performing the rotations:

It finally worked out to rotate a bunch of cubes automagically to build the Chaotikum Logo - except it was mirrored and some of the cubes were just wrong :)