Alt-F4 #6 - Purple Goop  25-09-2020

Napsal arrow in my gluteus maximus, stringweasel, psihius, upravil Therenas, nicgarner


Hello and welcome to the sixth issue of the community-driven weekly blog by the name Alt-F4! This week, you can read about the insanity that is arrow in my gluteus maximus’s raycasting engine constructed with vanilla Factorio, while stringweasel gives us a history lesson on how biters used to take part in the production of science, and psihius recommends a Factorio review that’s worth watching for newcomers and veterans alike.

Facto-RayO v2.0 arrow in my gluteus maximus

Almost a year and a half ago, I released a raycasting engine to the Factorio community. But it didn’t live up to my expectations from when I started the project and it didn’t take long before I started working on an improved version.

Soon after starting work I had to pause development for multiple months as personal things got in the way, like finishing up my master’s degree, for example. After a few months of hiatus though, I started uploading my progress to my second YouTube channel.

The first thing I worked on was a new and improved screen. Using the built-in lamps was too limiting, so out they went and in came a belt-based display. Next, I implemented a way to scale textures. A parallel lookup table did the trick. The scale of the texture is then dependent on how fast you iterate over all the pixels in the table. Every three ticks 256 parallel lookups occur to find the next row of pixels to display. After that, all other components got an upgrade too.

All this resulted in a design that is significantly more compact, has improved fidelity, and, most importantly, is easier to expand upon in the future. I go over the new version in more detail in my YouTube video:

Fun bonus fact: This video, and many of my previous videos, were recorded entirely via in-game screenshots. That’s more than 12,000 screenshots of about 20 MiB each. (The largest screenshot was 77 MiB.)

This recording technique has a few advantages:

  • It allows me to record at higher resolution than my own screen, and in-game screenshots even have anti-aliasing.
  • The recording remains smooth no matter the UPS Factorio is running at, as the recording ‘automatically’ slows down/speeds up to match.
  • I can do other things on my computer while recording, including fixing small raycasting engine bugs while it’s running. If you noticed that while demonstrating all the colours that the screen can display not all colours are on screen for the same amount of time, that was me changing the timings while it was running.
  • It allows me to seamlessly stop and start recording.

For those who wish to download the map and take a look in game, you can do so here.

Nauvis Archives: How Far We’ve Come stringweasel

Players know and love Factorio for its simple, but deep, gameplay mechanics, and relentless overtones of lifelong addiction. However, Factorio was not always this well-oiled machine. It took years of hard work, dedication, and communication by the developers to deliver this gem to the world.

My hope is to document some of the journey that this game has taken over the years in order to show newer players the dedication that is required to create a game like this, and to tickle the nostalgia-bone of some of the veterans among us.

There are various things that I would love to revisit, like ancient priority splitters, short underneathies, belt corner compression loss, and many other topics. I could talk about it for hours. But for this first post, there is one thing that has always stood out for me during my six years of playing Factorio.

Alien Artifacts: A Primitive Technology

I believe one thing that people remember with fondness, but would never want back, is the Alien Artifacts. The veterans-of-old called it purple orbs or purple goop. Remembering these artifacts makes you smile with nostalgia, but then you close your eyes — happy that you don’t have to experience it ever again.

Back before the Research Revolution™ of 0.15 there were only four science packs. The first three, Red, Green and Blue Science, were close to what we know them as today, but Purple Science was called Alien Science. These infamous science packs were made from Alien Artifacts, which were obtained by destroying biter nests.

The steps for producing alien science: Killing biters, assembling science

Interestingly, in older versions of the game, this artifact looked slightly different — you might recognise it as the developers’ tags on /r/factorio. Some said this artifact looked familiar. Some said it was taken from a different universe. Some said it looked sort of … alive.

Editor’s note: After publishing, the wiki admin Bilka brought to our attention that the sprite was changed with the second to last version of Factorio 0.14. At the time, it wasn’t clear why it got updated, just to be removed completely shortly after, with version 0.15. You can read people’s confused reactions on the forums and on /r/factorio. What this means though is that the ‘old’ artifact sprite is the one almost everyone will be familiar with.

Further note: The note above originally said that no one knows why the sprite got changed. Klonan, who works at Wube as the community manager, made me aware that there is someone who knows the reason, and that that certain someone is him. So, if you want to know the real reason for the change, and not keep an air of mystery about it, read on. Spoiler alert! They changed the sprite because it was not created by Wube, but borrowed from somewhere else originally, much like the original car sprite. So, they replaced it with one that they created themselves. Fascinating, I know.

The old alien artifact sprite

Anyway, this meant that everyone had big production lines for the three science packs, and then this (usually lonely) assembler slowly turning alien remains into science. Most people enjoyed killing the natives of Nauvis to build yet another iron outpost, which means typically there was enough goop lying around. However, when you urgently needed to unlock the next technology, and were enjoying struggling with oil refineries, then you ran out of purple science. At this point you quickly realized that there was no way to automate it! This meant that every time you wanted to advance the research tree, you had to go outside and create mayhem.

Day-in, day-out, you hunted down biters, destroying their homes and taking their remains, all for the sake of progress. Throwing poison and destroyer capsules wildly with each wave of enemies charging at you (while smartly leaving the laser defence at home). It became an endless and unforgiving battle, but you had to push on because the factory must grow. You began to feel sorry for the biters, but co-existance was not an option. The only way to progress was to actively destroy everything they love and cherish.

Then /u/theLV2 graced us with this piece of art that spoke to all our hearts. A thought so harsh and sweet that it still keeps me awake at night.

A Tribute to the Purple Orb

The best Factorio review I’ve seen so far! psihius

While browsing the depths of YouTube I stumbled upon a fresh review of Factorio, by MandaloreGaming. Being the curious person I am, I like to see what people have to say about the game. From time to time you run into something special, and this is the case here for sure. All I will say is that this is a Factorio addict’s confession; the meta jokes are strong and there are many quotable lines. Enjoy!

P.S. The comment section on the video is a lot of fun.


As always, we’re looking for people that want to contribute to Alt-F4, be it by submitting an article or by helping with translation. If you have something interesting in mind that you want to share with the community in a polished way, this is the place to do it. If you’re not too sure about it we’ll gladly help by discussing content ideas and structure questions. We’ll have a bit of a special issue soon, so if you want to get involved with that join the Discord so you don’t miss it!