Backrooms Project

Generator V1 wasn't the biggest breakthrough for the progress of the game, but it layed a foundation which I could work from to create a more optimized system. To show the work I had done to that point, below is a preview video from 2024 which shows the functionality of Generator V1 (completely coded in Blueprints)

Code

As seen below, the first Generator was fully made in Blueprints. I had some small experience with Procedural generation in Killer in Purple 2 and I experimented with coding Minecraft in Blueprints in the past, but never at this scale.

The system was very experimental, mostly to see if the game I had in mind was even possible, basically a sketch.

At first the idea was to code everything in Blueprints, but as talked about above, the performance was horrible on larger render distances.

To show off the concept I had in mind, I made a preview video to show my followers the rough idea of the Generation System.

Generator V2

Moving on from Blueprints, as it was shown that it was extremely slow, I decided to learn C++ for this project. This is where Generator V2 comes in. Generator V2 is litterately just V1, but copied to C++, with some small changes here and there

A very early prototype with no noise generation is shown below here. To optimize the code, I decided to store the largest and smallest X and Y coordinates, and just generate only 1 line when the player moved in a certain direction by adding or removing from those largest / smallest coordinates. This worked extremely fast, but also brought desyncing issues when the player would go faster than the game could generate, or when a player would teleport over large distances.

With this new Gen V2 in place, I also wanted to implement some more detail like more completed models and better lighting, to already show some promo material to the Discord server.

In order to make the game slightly creepy, I made some areas in the Backrooms which would not generate lighting, to have a lot of bright areas, but also have large darker sections where you had to use your flashlight to traverse.

The generator however was sadly only 2 Dimensional (X, Y), which limited my options a lot. I would need a seperate generator for each level, which later on would cost losts of performance, so after some initial tests to see how well C++ performed.

Generator V3

While on Vacation, I really wanted to recode the Generator to work 3 Dimensional, and as I had more experience in C++, I decided to start from scratch completely.

With this I re-implemented most systems, a lot more optimized, including Structures this time to add variety to the world generation, below here is a screenshot if the very first Backrooms Structure generated with Gen V3.

Generator V3 is also 1 of the longer lasting Generators, as it took a long time to make, as much as how great it was, it still ran quite slow due to the lack of optimization knowledge I had in C++.

To account for that, I decided to transfer Gen V3 to be multithreaded.

Generator V4

Generator V4 is the biggest generator made, with over 800 lines of code in the generator alone, and 300 lines of code in the multithread task. Generator V4 was extremely complex due to the multithreading, but it ran quite good!

I only had small spikes, which was a limiting factor of Unreal Engine 5. The Generator spawned in Blueprints that cost a lot more data then needed, but it worked at the time.

Lighting however was a major factor that caused the game to slow down by at least 20fps. 

During the creation of Gen V4, I also implemented a Rule System which could remove chunks, overwrite chunks, add structures and some other smaller things. This gave me lots of control over certain specific placements like the entrance hall.

To show the progress I made since Generator V1, I decided to make a preview trailer for the game.

Generator V5

For Optimizations I made Gen V5, this generator completely removes the multithreading from the game, as it was too uncontrollable to work with when working with large scale procedural generation, and is better used for complex math equations.

Instead, I adress the biggest bottleneck: the spawning of actors. Spawning Actors does give a lot of control, but a lot of data within it is not needed, and the CPU overhead of them spawning in, and rendering chunks seperately on the GPU, is just a giant bottleneck which adds on top of the lighting lag.

Instead of this, I went with Instances, which only cost 1 drawcall per chunk type, going from around 400 drawcalls in a 20x20x1 radius, to only 8 drawcalls, extremely reducing overhead.

The game could now handle over 10.000 chunks at a time, while the old one couldn't even come close to that.

Also this is the first Generator which steps away from generating only around players, which was hard coded in, but instead uses Chunk Loaders which can be expanded infinitely to also load chunks around certain areas, this is useful for stuff like generating around Portals.

This system is currently still in progress of being completed.

Code

For V5 I decided to go with a simpler system, although it is still in the works, the system works by simply filling a Queue and processing it in Batches. It also uses Instances instead of Actors now to optimize the render time.