2D PostScript output as well:
(planar graphs are 4colorable, there is a linear time 5coloring algorithm, and even simpler linear time six_coloring(G))
Planar graph embedding onto sphere is not that easy. Just mapping plane embedding onto sphere and then using spring embedder might unravel (left) all vertices into same place (right):
Work in progress algorithm node.tetra.js OpenSCAD output:
JSCAD output:
The repo provides spherical edge, half vertex and vertex text, and spherical polygon modules/functions to generate sphere embedding OpenSCAD/JSCAD output.
Provides "vertex()" and "edge()" OpenSCAD modules for drawing graph onto cube[oid] as well, here visualization of "cube[oid] shortest surface path problem" solution, details: https://forums.raspberrypi.com/viewtopic.php?p=2038730#p2038730 (orange/blue/yellow shortest paths pass through 3/4/5 faces, from single bottom face start point to top face target point)
C/C++ scripts / (tcc) "-run" option for gcc and g++ (for Linux ELF, verified for x86_64 and armv7l)
ELF executable gets compiled into RAM, and executed from there — no auxiliary filesystem files!
<peg-solitaire/> (1-player board game [browser XSLT])
It knows all solutions for 33/37/39 pegs English/French/3-3-2-2 boards.
You may choose "Cheat" link (based on 1+16+64=81GB data files on this website).
There are 2,990,375,067 good positions for French board that allow to end with single peg on target field (forum link).
Instructions on how to revert a move can be found just above that posting (animation):
new binomial formula "C(a+b,c) = sum(k=0..a, …" and animation in A007318
Blue links in .svg work; "10-edge CCs" at bottom right uses GraphvizFiddle mentioned above for display.
Before that, submitted 4 interlaced bisections found manually.
Raspberry camera / gstreamer / raspivid / raspiraw
Teaser video of a closing mouse trap; the whole closing is completed in 0.01s(!).
This is an animation from Raspberry v2 camera 640x75 video captured at 1007fps(!), played at 1fps.
When the mouse trap bar touches down, it hits the black piezo igniter, showing a spark in front:
Multiple exposures of 84.3m/s (303km/h) inflight airgun bullet (1012x760 frame scaled to 25%, github repo)
Nearly ultrasonic speed (340m/s) 3Dprinted pellet shot with airgun.
Captured 5 times inflight by five 10000lm flashes of 2µs(!) duration each: https://forums.raspberrypi.com/viewtopic.php?p=1952629#p1956584
The front 10000lm led on side does not look too bright (each of its 100 led spots does light for 10µs in total).
Slowmo of raspcatbot passing, 100× slower than real, only 1.14m/s here:
Bring your own light and monochrome global shutter camera / free running 1774rpm(!), 6.04m/s with 65mm wheel ⌀
On left 2.2" display, Raspberry Pi3A+ and L298N motor driver / with 330rpm motors steep uphill
front view video from 22.5km/h toy train …
… slightly faster than 5m/s (18km/h) raspcatbot target speed.
Just to get an idea of what autonomous line following at maximal speed will have to deal with.
1kg raspcatbot running (with steel wire rope) on 1.25m radius around screw in garage floor.
Speed 3.24m/s or 11.65km/h, kinetic energy 0.5*m*v² = 5.25 Joule, centripetal force m*v²/r = 8.4 kg*m/s²
youtube video of unplanned backward roll high in the air
full stop back wheelies
• U-turn w/o speed (>2m/s) reduction
• just swap one motor's direction for some time
• slowed down by factor 90/25=3.6
• 90fps slowmo youtube video
• positions at start of (overshooted) U-turn, at 90°, 180° and finally before going straight again
• Arduebot can do similar U-turn
For fun I registered as participant of South-German (Bavaria, Baden-Württemberg, Hesse and Saxony) 100km road race championship 1998 in Leipzig. There were 59 starters, 52 finishers, and I was 50th finisher (at age of 33). There were only 6 starters in male 30-34 age group, and only 3 of them were from South-Germany. One South-German starter did not finish -- therefore I got official silver medal from German Athletics Association(!), was "2nd best South-German 100km road race runner in age group 30-34 in 1998" … ;-)
[winner finished in 7:07h, I finished in 12:26h -- better than 8km/h on average]
, after 1800ms braking delay only 1 (power) LED left on, details in 
single move mode 
animation
