rubenwardy's blog

I’m a huge fan of RimWorld, a base building game where you manage a group of colonists. Rather than directly controlling the colonists, you place blueprints for buildings, mark trees for cutting, and animals for hunting. NPCs will then decide what to do automatically, based on their skills and priorities.

I’ve made two games recently with similar mechanics. The first was Ruben’s Virtual World Project (RVWP), a hybrid basebuilder/topdown shooter. The second was Tin Mining, a mining sim created as an entry to Ludum Dare 48. Both of these games allowed placing building plans that NPC workers would then build out.

In this article, I will explain how I implemented the NPC AIs, and the problems I faced.

This article was written at a time when LLM AIs were brand new. As such, this post is very outdated and does not represent my current opinions.

OpenAI’s GPT-3 is a powerful new Artificial Intelligence model that uses deep learning to produce human-like text. It was trained on a large body of text, with sources including websites, Wikipedia, and books. It doesn’t just understand natural language, it can also work with programming languages.

This topic is especially relevant with the recent introduction of GitHub Copilot. Copilot is an “AI pair programmer” for your IDE that suggests code and entire new functions. It’s based on same technology as GPT-3, but with a model derived from GPT-3 and optimised for code called Codex. This article will use GPT-3 and Codex, as I wasn’t able to get GitHub Copilot, but the results will be identical.

In this article, I will ask GPT-3 to write Minetest code and explore how much it knows about modding, creating simple and advanced Minetest mods. I will finish by using it to convert Minecraft mods to Minetest.

In 2018, I had the opportunity to create a web app for University coursework, as a solo project. I chose to create a package repository for Luanti, an open-source project I help maintain.

Luanti (formerly Minetest) is an open-source game engine with millions of downloads and thousands of weekly players. The project has a very active modding community, and many available games to run. There was one big issue - you had to manually install mods and games by unzipping their files into a directory. This was a very poor user experience.

In April 2021, I participated in my first game jam, Ludum Dare 48. Ludum Dare is a popular online game jam; this event received over 3800 submissions. The theme was “Deeper and Deeper,” and I created a game where you manage a tin mine.

The year is 1790, and the Cornish tin industry is booming. You are a businessperson who has just secured investment to build a mine. The area is known to be rich in tin, which is in high demand.

Rather than controlling your workers directly, you drag out plans for tiles to be mined and built. The workers will mine tunnels and build where ordered. They will carry mined resources to the surface to be sold.

I have a lot of houseplants, but I often forget to water them. I’ve been getting into electronics and thought this would be a great opportunity to make something.

I made a plant monitor, which measures soil moisture, temperature, and humidity, and reports these things to a cloud IoT service called Thinger.io.

Markdown is a common choice for rich text formatting due to its readability and ease-of-use. Unlike a lot of markup, it aims to match natural text. It’s even easy for beginner users, and there are WYSIWYG editors available.

We will be using the Python Markdown library to convert Markdown to HTML. Markdown doesn’t have a well-defined standard. The library aims to comply with what little is defined by the Markdown syntax specification, meaning that it is also often stricter than other parsers.

I worked as an Android developer just over two years ago, creating native apps for clients using Java and Kotlin. During that time, Kotlin was gaining prominence and had just been made official by Google. Google also introduced Architecture Components that year, later renamed to JetPack. Since then, the Android ecosystem has changed significantly, with Kotlin and JetPack gaining significant maturity and development. Out with Realm, Activities, and Model-View-Presenter (MVP), in with Room, fragment-based architecture, and MVVM. Data-binding and MVVM are pretty awesome and breathe a whole new life into Android app development.

Sandboxing can protect the user’s computer from malicious or buggy scripts. But sandboxes are difficult to get right; you need to be very careful with what you expose, and make sure you test for vulnerabilities. The Sandboxes on the Lua wiki is required reading, as it contains very helpful advice.

Many APIs in my game push Vector3s to and from Lua. It’s such a common operation, that most of my functions used to look like this:

sol::table add(sol::table tPos) {
    Vector3f pos = TableToPos(tPos);

    // do something
    return PosToTable(pos);
}

One of the benefits of sol is that it is able to bind Lua arguments to C++ function arguments, converting types implicitly. Having to convert from a table to a vector ourselves is quite annoying. It would be much nicer to have sol do it for us. Luckily, sol allows you to customise how types are retrieved and pushed to Lua using Customisation Points.

When trying to convert a type from Lua to C++, sol will call certain templated functions. We will be customisating sol’s behaviour using a technique called template specialization, which allows us to specialise a specific instance of the templated functions and structs. By the end of this article, we’ll be able to use Vector3 directly when using sol, allowing the above code to be turned into this:

Vector3f add(Vector3f pos) {
    // do something

    return pos;
}

Drop shadows are created using a Gaussian blur drawn underneath the original element. You can do this using either a fixed texture or a post-processing fragment shader.

Data binding greatly reduces the amount of code you need to connect user-interfaces with ViewModels. It keeps Activity and Fragment code small, and makes it easier to manage lifecycles.

<EditText
    android:id="@+id/username"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:text="@={viewModel.username}"/>

I discovered that there was no attribute to bind the elements in a RecyclerView, due to the fact that a RecyclerView needs an adapter to be able to create element views. It would also be nice to automatically use data binding to create the viewholders. There are a number of guides to do both of these halves, but I now present the code to do the whole.

Since switching to GitLab, a few people have asked me why. There are several draws towards GitLab, and several pushes from GitHub.

SFML is an excellent library that can be used to create 2D games and similar applications in C++. It’s an abstraction over OpenGL and various system APIs, presenting a consistent and easy-to-use interface.

Providing a Graphical User Interface (GUI / UI) API is out of scope for SFML. GUIs are complicated, and there’s no single good way to implement them. The S in SFML stands for Simple but GUI code rarely is.

There are many different options to choose from when making GUIs. This article is an in-depth comparison of the options for making GUIs in SFML, discussing their pros and cons.

Ruben’s Virtual World Project is a game I’ve been working on for almost 4 years now. Recently I rewrote the rendering code to support voxel lighting and multiple z-level - heights of the map.

YouTube Music is a great way to listen for music for free, and with no adverts if you use an adblocker. There is one annoying problem however: after listening for a while, Youtube will keep pausing the music to show a dialog which says “Are you still listening?”. This article will show how to automatically confirm the dialog.

Google’s C++ testing library has a nice syntax for registering tests, without needing to remember to add the tests to some central index. This article will show how to use macros to allow the creation of tests using only the following code:

Test(IntegerComparisonTest) {
    int a = 3;
    assert(a == 3);
}

Recently I had to reinstall Windows to debug a hardware issue. I decided to try to make the most of this by trying to build my game on Windows.

Progress Renderer (Steam | GitHub) is a brilliant mod that takes a screenshot once a day, and dumps it into a folder.

The following bash script can be used to generate an mp4 timelapse of the screenshots. Simply specify a region to cut out of the screenshots, and some other parameters, and run the script in the working directory.

I wrote a raytracer and a rasteriser as part of my university course. The raytracer supported features such as indirect lighting, reflection, refraction, and a photon mapper capable of simulating the final positions of 60,000,000 photons in a few minutes (and quite a few GBs of RAM).

I wrote a Bash script to sort git commits into buckets, to be used as the first step of making a change log. It supports rewording commit messages, can be stopped and resumed, and supports automatic filtering based on keywords.