Category Archives: Programming

Counting digit occurrences in a range

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I was asked if I knew an easy way to count how many times digits occur within a range of numbers. For example in the range 10–15, how many times does each digit occur? The numbers 0, 2, 3, 4 & 5 each occur once, and 1 occurs 6 times, that is twice in the number 11, and one in every other number in the range, because the tens all start with a 1. It seemed like an odd request, but it’s for number tags on utility poles, like this one:

There might be several rows of yellow tag numbers on a given utility pole

By Onore Baka Sama – Own work, Public Domain, source

Electricians use these tags to identify the poles and, at least in Hungary, they’re made up of individual plates for each digit, that are screwed on to a larger plate on the pole. If you estimate too few when ordering the digits you’ll run out obviously, and if you order too many you’ll be stuck with a pile of unused digits.

It seemed like a problem that should have a simple mathematical solution to it. Unfortunately, the answers I found on Continue reading →

Custom thumbnail generators for audio waveforms and GIMP XCF files

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I recently packaged these 3D thumbnailers for Arch Linux and this act inspired me to dig into this topic a bit and make some of my own. First off, what’s a “thumbnailer”? It related to this Free Desktop specification and I’d summarise it as:

A thumbnailer is a program that can generate a small preview image (called “thumbnail”) of a specific file type. File browsers know about thumbnailers by reading configuration from .thumbnailer files which specify which program to call for a specific MIME type, and which arguments to use to get the desired output.

For more details and practical examples of what these files look like and what you can do with them, see this blog post by Radu Zaharia. For most of the 3D thumbnailers I packaged, the thumbnailer programs are small purpose-built scripts, written in Python or Bash, that understand the specified format and how to get a PNG image out of it. The thumbnailer config just specified which order it wants its file input and output arguments in. However, as Radu’s blog post points out these can also be more advanced one-liners using programs you already have installed, so I decided to try that out and this post I’ll cover 2 such examples: Audio & GIMP.

tl;dr: Copy-pastable version at the end of the post Continue reading →

It’s better to use floats for maths and leave ints for indices

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Someone showed me a bug in my recent game, Freefall, whereby you can get as far as you like, by just changing speeds continuously, you don’t even need to look at the screen, just tap with a consistent tempo to keep changing speeds. This works because the projectile speeds are set with integers which means they have:

  1. A base speed at which they will hit you with the parachute
  2. Fast (double base) speed they will you with if in free fall
  3. Anything faster than this will miss you because it will get off the screen before it reaches you and is therefore only in there for decoration / to confuse the player

I used integers for practically everything in the game because the low resolution meant that even moving one pixel at a time is a pretty big step (there are only 48px in the vertical axis) and you can’t draw smaller than that.

During testing I focussed on checking that 1 & 2 would hit you at their respective speeds and that you could dodge them if you changed at the last moment. If you change speeds so infrequently the problem is less apparent. Continue reading →

Launched a new game: Freefall

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On 27 February I released a new Nokia 3310-style game: Freefall. In this game you control a parachute for humanitarian airdops in hostile territory. It’s my entry to Nokia 3310 Jam 5 and the theme was Fast & Slow so the main game action revolves around controlling the speed of the airdop between parachuting and freefall to dodge bullets coming from both sides.

The aim of the Nokia 3310 Jam is to have fun making a game using the restrictions of a Nokia 3310, so green, low-res, 1-bit screen, monophonic and only 12 keypad buttons. My entry placed 28th out of a 147 submissions and I’m especially proud of this because I did the music, animations, programming and game design all by myself. The game is open source and you can read it in the GitHub repository.

Ebiten vs PyGame

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The following is a copy of a response I wrote to a university student asking in the Ebiten Discord server whether they should use Ebiten or PyGame for their first time making a game:

Having used both I can say that PyGame provides much more out of the box but that this is not just a pro but also a con. For example in pygame there is a concept of “sprite” that has movement and you can tell it move left, move right etc. In Ebiten it surprised me to find that there is no such thing but it’s nice for two reasons: Continue reading →