Programming on jverkamp.com

Rescuing Gentoos with a Rust Solver (Part 3)

Sat, 04 Apr 2026 00:00:00 +0000

Part 3! Wherein we learn about rockets, recursion, and ricocheting items (oh my). And make it to … the end?

Here are all of the commits from part 1 up through part 3.

And here are all of the parts in this series so far:

Posts in Solving Gentoo Rescue:

Rescuing Gentoos with a Rust Solver (Part 2)

Tue, 31 Mar 2026 00:00:00 +0000

And here we have Part 2! It’s not been that long for you, but since the first part took six months for me to actually get around to writing it… well, this is much better!

Things get a bit more complicated this time, with buttons that can open/close doors and even holes in the floor and BOMBS. But what’s really crazy is how we actually get around to solving how to get to new sublevels this time… and how to take penguins back out of them. Things are getting complicated!

Here are all of the commits from part 1 up through part 2.

And here are all of the parts in this series so far:

Posts in Solving Gentoo Rescue:

Rescuing Gentoos with a Rust Solver (Part 1)

Wed, 25 Mar 2026 00:00:00 +0000

Months ago now¹, I started playing Gentoo Rescue (after seeing the Aliensrock video). At the core, it’s a Sokoban style puzzle game where you have to guide cute little sliding penguins to their color coded nests… but oh man does it start getting more complicated quickly.

On top of that, it has a really interesting nesting level concept–the level select screens are levels themselves. You can go several ’levels’ deep into levels or eventually further back out. And that’s just with how far I’ve gotten so far…

Syncing Kobo Annotations... again!

Mon, 16 Mar 2026 00:00:00 +0000

A few months back, I gave a Kobo a try. I’m still really enjoying it. At the time, I was using a script on the Kobo + Dropbox to sync annotations. But it was a little heavy (to send the entire database) and tended to fail silently. Plus, I had to use a second script to take the exported database and actually turn it into Markdown I could easily read and share.

So I took a chance to make that a bit better!

The code for this is available on Github here: https://github.com/jpverkamp/kobo-highlights/

Genuary 2026: And so it ends

Sat, 31 Jan 2026 23:00:00 +0000

I just wanted to make a quick montage of all 31 sketches:

You can combine all of the preview images and then add some nice text with a pair of imagemagick commands:

montage content/programming/2026/genuary/*/gen26.??.png \
 -tile 6x6 \
 -geometry +2+2 \
 -background none \
 gen26-grid.png

mogrify \
 -gravity southeast \
 -pointsize 200 \
 -fill "white" \
 -stroke "black" -strokewidth 2 \
 -annotate +20+20 "Genuary 2026" \
 gen26-grid.png

Genuary 2026.31: Shader

Sat, 31 Jan 2026 00:00:00 +0000

I have very little experience with graphics shaders, but I’d like to learn. Perhaps I’ll take a month to redo all these prompts with shaders. That’d be neat.

But for now, one shader, messing around a bit.

Genuary 2026.30: Bug

Fri, 30 Jan 2026 00:00:00 +0000

A throwback to what’s probably one of my earliest programming projects (originally in qbasic…): bugs!

It’s very simple: each frame, each bug moves randomly and the draws a dot.

That’s really it.

I’ve updated it a bit with various parameters to tweak. Play with them. See what they do!

Genuary 2026.29: Evolution

Thu, 29 Jan 2026 00:00:00 +0000

That got quite a bit more than I expected. So now it’s basically an evolving programmatic image generator. 😄

Genuary 2026.28: No Libraries, No Canvas

Wed, 28 Jan 2026 00:00:00 +0000

Whelp. I’m not a fan of that, but it was interesting enough. I got to brush off my tabbed view code. And do some weird things with CSS. Whee?

Genuary 2026.27: Lifeform

Tue, 27 Jan 2026 00:00:00 +0000

So this one really fits better for Genuary 2026.25: Organic Geometry and that one is a lifeform like this one, so… we’ll consider them swapped or something.

Anyways, spawn branching nodes and draw a bunch of squares. Not only an organic looking lifeform but creepy to boot! I do love it without borders and with fade.

Be careful with high child count without either a high segment length or death rate to compensate, it will get slow.

Genuary 2026.26: Recursive Grids

Mon, 26 Jan 2026 00:00:00 +0000

A favorite technique of mine. I’ve already done it on day 5, day 7, and day 13. But now we can go one a-maze-ing step further…

See what I did there? 😄

Basically: generate a maze. For each cell in the maze… generate a smaller maze! Recursively.

Genuary 2026.25: Organic Geometry

Sun, 25 Jan 2026 00:00:00 +0000

So basically we have a simulation where each of n different species has a weight of attraction/repulsion for each other species. This is, by itself, enough to generate some pretty organic behavior!

Edit: This one probably fits better for Genuary 2026.27: Lifeform and that one here.

Genuary 2026.24: Perfectionist's Nightmare

Sat, 24 Jan 2026 00:00:00 +0000

It started off with a neat grow of blocks and just sort of grew from there–as these things seem wont to do.

This is another one that really benefits from the animation, but it’s neat enough to see each simulation done.

Try playing with the settings. This one looks like a game of Pick Up Sticks. And this one is just tiny brick chaos!

Genuary 2026.23: Transparency

Fri, 23 Jan 2026 00:00:00 +0000

Genuary 2026.10: Polar coordinates did the transparency thing, but … let’s do it again!

This is one that really stands out when it’s animated.

Genuary 2026.22: Pen plotter ready

Thu, 22 Jan 2026 00:00:00 +0000

Split a polygon into triangles and then recursively split those triangles over and over again!

Genuary 2026.21: Bauhaus poster

Wed, 21 Jan 2026 00:00:00 +0000

A Bauhaus style poster.

Genuary 2026.20: One line

Tue, 20 Jan 2026 00:00:00 +0000

One line… that repeatedly splits, albeit without (mostly) crossing itself.

Fractal trees GO!

splitChance controls how quickly the line branches
minChildren / maxChildren controls branching
angleRange is how many radians the new branches can change by
randomizeAngles controls if child angles are random/evenly spaced
spacing is roughly how spread out the tree is
pauseOnResetFor / stopOnReset controls what happens when a tree is done
colorMode changes drawing colors
anchor changes where the tree starts

It does get a bit sluggish, especially if you have a high number of children.

Genuary 2026.19: 16x16

Mon, 19 Jan 2026 00:00:00 +0000

I’m… not really sure where I was going with this one. 😄

Basically, 16x16 tiny sketches that slide around like a sliding block puzzle. Although with how chaotic some of the simulations are, it’s not always easy to see.

Genuary 2026.18: Unexpected paths

Sun, 18 Jan 2026 00:00:00 +0000

I feel like the most unexpected of paths is Langton’s Ant!.

Okay, it’s fairly expected. And I’ve even done it before. Been a while though.

Anyways, here we go!

In a nutshell, you have a grid with N possible values (the length of the rule string). For each pattern, when the ‘ant’ walks on that cell, the value in incremented by one and you will turn according to these rules:

R turn right (90° or 60° in hex)
L turn left (same)
S turn right 120° in hex mode (nothing in square)
M turn left 120° in hex mode
U turn 180° in hex mode
anything else (N above), do nothing/go straight

This ends up with some really interesting behavior for such a short ruleset. Langton’s Ant (LR, the default) is definitely an interesting one. For 10,000 ticks, you get chaotic behavior… and then suddenly it stabilizes!

Genuary 2026.17: Wallpaper Groups

Sat, 17 Jan 2026 00:00:00 +0000

Wallpaper group. There are only 17 ways to cover a plane with a repeating pattern, choose your favourite on this page: Wallpaper group

This is a great article about Classifying Symmetries that says there are actually 35 tiling patterns!

List of planar symmetry groups is another Wikipedia page with a good summary of the wallpaper group.

I spent waaaaay too long on this one.

group is the 17 groups mentioned
subGroup is horizontal or vertical for some of the above
cellType is the shape of each cell
cellStyle is what to fill them with
debugDrawOne shows what one tile looks like
debugDisplay prints what random values were selected
pauseBuffer is useful for pausing the generation (although if any of the others are random they will keep changing)

Not all of the groups and cell types are perfectly compatible. In fact, probably half or more aren’t. But they still produce something, and I think that’s pretty cool!

Genuary 2026.16: Order vs Disorder

Fri, 16 Jan 2026 00:00:00 +0000

Order vs Disorder

So I have two kinds of agents: Order, which always moves in straight lines and Chaos which… doesn’t!

Settings:

updateRate is how fast it runs
minAgentCount will spawn agents until you reach this number
maxAgentCount will kill off agents until you’re under this number
dieOfOldAge will kill off old agents
maxAge is the longest an agent can last
agentRatio of 0 is all order and 1 is all chaos
spawnRate is how often an agent will spawn a new agent (of the same kind)
resetPercent is how much of the screen can be full before resetting
pauseOnReset will pause on a reset to allow downloading! (change any setting include this one to unpause)

Genuary 2026.15: Invisible Object

Thu, 15 Jan 2026 00:00:00 +0000

Create an invisible object where only the shadows can be seen.

Noise that pushes a bunch of particles around on the screen. There is 1 (or more) ‘shadows’ on the screen that push the dust away.

If the shadow runs off the screen it will come back in a bit from the opposite edge.

Settings:

dustCount is how much dust
dustSpeed is a multiplier for how fast the dust goes per frame
dustDieOff is how much dust disappears each frame
onlyEdgeDust sets dust to only spawn on the edges, rather than anywhere (has some weird visual artifacts when the dust is a nearly horizontal / vertical)
rainbowDust makes the dust far more colorful
windScale is the scale of the noise, 1 will wiggle a lot more, 5 is closer to straight lines and slow changes
fade will leave trails by fading the screen; turning this off is interesting since the shadow will be much more subtle
shadowCount is how many shadows there are
shadowForce is how strongly they repel dust
shadowWindIndependent means the shadow doesn’t always move with the particles
shadowEdge will show where the shadow shape actually is
shadowsMove will allow the shadows to move / stop them

Genuary 2026.14: Fits Perfectly

Wed, 14 Jan 2026 00:00:00 +0000

14) Fits Perfectly

Basically, we’ll pack as many circles in as we can!

retriesPerFrame is how many circles it will try to place before giving up and drawing the frame
minDiameter is the smallest a circle can be (this should be 1 for a ‘perfect fit’)
maxDiameter is the largest one can be
spacing is how much space to leave between circles (this should be 0 a ‘perfect fit’)
borders will draw a black border on each circle
fillInside will place circles inside of each other as well as outside, so long as there is still enough spacing
blackPercent is how many of the circles will be black rather than bright colors

Genuary 2026.13: Self Portrait

Tue, 13 Jan 2026 00:00:00 +0000

13) Self Portrait

That was surprisingly fun.

Basically, it will take recursively divide the picture over time. Each time, it will find the node with the largest error (real image color compared to the current random color) and split it in 4, assigning each to the nearest random color from our palette.

colors controls how many maximum (random) colors will be chosen
edges will draw the boxes of the tree
minimumBlock is the size at which it won’t split any more
resetAfter will generate new colors even this many frames
evenSplit will split each box into exactly 4; if this is off, each axis will randomly be 25-75%
weightErrorBySize will split small boxes earlier; with this off, larger boxes have more error because they are larger

If you don’t want to look at me any more, turning off selfPortraitMode will load an image from picsum.dev.

Genuary 2026.12: Boxes

Mon, 12 Jan 2026 00:00:00 +0000

12) Boxes

It’s like draw a box. But somehow even more. And automatic.

If you let it run for a while, you get some crazy abstract art!

Genuary 2026.11: Quine

Sun, 11 Jan 2026 00:00:00 +0000

11) Quine

Making a genart quine? That’s… certainly a thing!

So basically I made a very simple stack based virtual machine. You can check the source code below for what commands it can actually run. It will then run until it outputs enough code to match the input length (or times out). If it happens to output a quine? Woot!

If not, it will randomly mutate and try again.

cellSize - Change how big the program is (default is 10, theoretically with semi quines size shouldn’t matter)
ticksPerFrame - How fast the simulation will run
asFastAsPossible - Ignore the above and run an entire simulation per frame (it could technically go even faster 😄)
pauseAfter - Pause to see what happened after output is done or a break
stopAfter - When a single program has run, stop the main loop (mostly useful for debugging)
randomizePercent - How much of the input to randomly change for the next iteration
runOutput - Run the output as the next program (otherwise, randomize the input)
highlightActive - Highlight the parts of the program that actually ran (brighter colors)
allowSemiQuine - Ignore non-active parts of the program when considering a quine (if you copied the output to the program in these parts, they’d be a quine, so I think it counts)
allowReadingCode - Allow (new) commands that allow reading our own source code
allowWritingCode - Allow (new) commands that can modify the code you were originally running
debugPrint - Print each command run/output to console.log for debugging
debugSlow - Drops the framerate to 1 fps for debugging
debugStepButton - Add a ‘step’ button that runs one step at a time (noLoop) for debugging (reload the page)

In addition, you can put in code in the box and ’load’ it to run. This will be helpful to verify quines! I have some interesting code below (including a hand written quine! That uses the self reading instructions).

If you manage to find a quine organically (or write one), I’d love to hear what it was!

Genuary 2026.10: Polar coordinates

Sat, 10 Jan 2026 00:00:00 +0000

10) Polar coordinates

CIrcles within circles within circles.

Genuary 2026.09: Cellular automata

Fri, 09 Jan 2026 00:00:00 +0000

9) Cellular automata

Just a bunch of random rules, with the ability (if you put this in p5js at least) to add them pretty easily.

This one can do some wacky things if you randomize it. But also, it might crash your browser tab on some of these settings. Sorry. 😄

Try:

Perlin, Max, fuzz, diffuse

Genuary 2026.08: A city

Thu, 08 Jan 2026 00:00:00 +0000

8) A city

Simple parallax graphics and (slowly) blinking windows. I enjoyed this one.

Genuary 2026.07: Boolean algebra

Wed, 07 Jan 2026 00:00:00 +0000

5) Boolean algebra

So the basic idea here is to recursively divide the space. The black squares are the randomly chosen values. Then, for each level of the tree, combine the children using one of the selected functions (and/or/xor/etc), drawing a border if the result of that combination is true.

Try various combinations of settings!

Genuary 2026.06: Lights on/off

Tue, 06 Jan 2026 00:00:00 +0000

5) Lights on/off

😄

(Turn on flickering.)

(If you dare.)

Genuary 2026.05: Write 'genuary'

Mon, 05 Jan 2026 00:00:00 +0000

5) Write ‘genuary’

Yeah, this one got weird and recursive. But it’s only sort of font data, so I think it works.

Genuary 2026.04: lowres

Sun, 04 Jan 2026 00:00:10 +0000

4) lowres

Perlin noise, but … really lowres? You can play with how low res or how many colors you want.

Genuary 2026.03: Fibonacci forever

Sat, 03 Jan 2026 00:00:00 +0000

3) Fibonacci forever

Fibonacci

This is entirely based around this Fibonacci generator function:

function makeFibber(maxValue = 1000) {
 let a = 1;
 let b = 1;
 return () => {
 let n = a + b;
 a = b;
 b = n;
 if (b > maxValue) {
 a = 1;
 b = 1;
 }
 return a;
 };
}

Make a fibber and then just keep calling it for next values.

All sorts of exciting options here!

Genuary 2026.02: Twelve principles of animation

Fri, 02 Jan 2026 00:00:00 +0000

2) Twelve principles of animation

Twelve principles of animation

Stretch and shrink
Anticipation
Staging
Direct animation
Complementary
Accelerate and decelerate
Arcs
Secondary action
Synchronization
Exaggeration
Solid drawing
Attractive

That … is a lot. And I’m not really an animator. But let’s see what we can do!

Genuary 2026.01: One color, one shape

Thu, 01 Jan 2026 00:00:00 +0000

It’s been a couple years since I last did Genuary. Let’s do it again. I don’t expect to make any masterpieces, but I enjoy making tiny pretty pictures. It’s something I’ve been doing honestly as long as I’ve been programming (I remember making brownian motion ‘bugs’ in QBasic in the 90s…).

1) One color, one shape

Syncing Kobo Annotations

Mon, 29 Dec 2025 00:00:00 +0000

I’ve recently been trying out a Kobo. Amazon has some issues and Kindles are hard to do any amount of customization to, let’s just leave it at that.

So what fun tricks can one do with a Kobo?

Well, for one, it’s a Linux system. And if you attach it to your computer, you get access to a lot of the local filesystem. This includes the SQLite database holding all of teh system metadata, along with places to install all sorts of interesting scripts.

One that I’ve been wanting in particular is the ability to extract my annotations. It’s a great way to review books. Highlight, write a note, and then export right at the end.

So how do you do that on a Kobo?

Locking BGA tabs with UserScripts

Sat, 20 Dec 2025 00:00:00 +0000

I play a lot of games on Board Game Arena (BGA!). A lot of those are turn based games with random people, but I have two subsets of games that I consider ‘more important’:

Turn based games with people I know
Alpha games I’m testing

Unfortunately, the first tends to have longer ‘per turn’ times and the latter doesn’t have a timer at all, so both end up right at the very end of the sorted table list. But both, I’d rather play first and in-between other games.

Super niche problems, I know.

Generally, my solution has been to keep a tab open for each of those games in a Firefox Tab Group, but in those cases, I keep navigating off those pages accidentally (thank you next table button).

Super super niche problems, now.

In any case, I whipped up a quick userscript (I use ViolentMonkey) that will:

Detect if a tab I’m on is one of the games I want to ’lock’
Remove the next table button (buttons; there are two different ones)
Disable navigation (at least make it pop up a warning)
Periodically refresh the tab (BGA tends to go to sleep in the background)

AoC 2025 Day 12: Knapsackinator

Fri, 12 Dec 2025 00:00:03 +0000

Source: Day 12: Christmas Tree Farm

Full solution for today (spoilers!).

Part 1

Solve the knapsack problem.

…

…

But really, you are given a set of tiles (which all happen to be some subset of a 3x3) and a set of constraints–a MxN grid and how many of each tile to place. Count how many constraints are possible.

Tiles may be rotated and/or flipped.

AoC 2025 Day 11: Graphinator

Thu, 11 Dec 2025 00:00:03 +0000

Source: Day 11: Reactor

Full solution for today (spoilers!).

Part 1

Given a directed graph defined where aaa: you hhh means aaa is connected to you and hhh, how many paths are there from you to out.

AoC 2025 Day 10: Linear Algebranator

Wed, 10 Dec 2025 00:00:03 +0000

Source: Day 10: Factory

Full solution for today (spoilers!).

Part 1

Given a target light pattern [.##.] and a series of buttons ((3) (1, 3) etc) where the first button toggles light ‘3’ (the 4th light) and the second toggles the first and 4th etc, what is the minimum number of buttons you need to press to match the light pattern.

AoC 2025 Day 9: Polygoninator

Tue, 09 Dec 2025 00:00:03 +0000

Source: Day 9: Movie Theater

Full solution for today (spoilers!).

Part 1

Given a list of points (2D), find the pair of points which form the largest rectangle.

AoC 2025 Day 8: Point Cloudinator

Mon, 08 Dec 2025 00:00:03 +0000

Source: Day 8: Playground

Full solution for today (spoilers!).

Part 1

Given a list of points in 3D space, connect the 1000 closest nodes to each other. Calculate the product of the size of the 3 largest resulting regions?

AoC 2025 Day 7: Laser Splittinator

Sun, 07 Dec 2025 00:00:03 +0000

Source: Day 7: Laboratories

Full solution for today (spoilers!).

Part 1

You are given a map like this:
.......S.......
...............
.......^.......
...............
......^.^......
...............
A laser shines from the top S and splits each time it hits a ^, making this:
.......S.......
.......|.......
......|^|......
......|.|......
.....|^|^|.....
.....|.|.|.....
The two lasers in the center of this example merge to count as one laser.

Count how many times lasers hit splitters.

AoC 2025 Day 6: Column Operatinator

Sat, 06 Dec 2025 00:00:03 +0000

Source: Day 6: Trash Compactor

Full solution for today (spoilers!).

Part 1

Given input like this:
123 328 51 64 
 45 64 387 23 
 6 98 215 314
* + * + 
Apply the operation in each column then sum the results.

AoC 2025 Day 5: Range Merginator

Fri, 05 Dec 2025 00:00:03 +0000

Source: Day 5: Cafeteria

Full solution for today (spoilers!).

Part 1

Given a list of ranges (inclusive) and a list of IDs, how many of the IDs are in any range?

AoC 2025 Day 4: Fade Awayinator

Thu, 04 Dec 2025 00:00:03 +0000

Source: Day 4: Printing Department

Full solution for today (spoilers!).

Part 1

Given a grid of solid @ and empty cells ., count how many solid cells have less than 4 neighbors.

AoC 2025 Day 3: Loopinator

Wed, 03 Dec 2025 00:00:03 +0000

Source: Day 3: Lobby

Full solution for today (spoilers!).

Part 1

Given a list of numbers, for each find the two digits in the number which if concatenated make the largest. Sum these values.

For example: 811111111111119 should be 89.

AoC 2025 Day 2: Repeat Repeat Repeatinator

Tue, 02 Dec 2025 00:00:03 +0000

Source: Day 2: Gift Shop

Full solution for today (spoilers!).

Part 1

Given a list of ranges a-b (ie 11-22), sum all values that are made of two repeated chunks of digits (ie 123123)

AoC 2025 Day 1: Turn Turn Turninator

Mon, 01 Dec 2025 00:00:03 +0000

Source: Day 1: Secret Entrance

Full solution for today (spoilers!).

Part 1

Implement a padlock with 100 values (0-99). Run each command (L23 to turn left by 23 places) and then output the number of times you landed on zero.