In a remarkable fusion of creativity and engineering, an inventive mind has taken the beloved world of Minecraft and distilled it down to a microcontroller the size of a penny. This ambitious endeavor, known as bareiron, is a custom Minecraft server built on the ESP32 processor, a feat that feels akin to fitting an ocean into a teacup.
PortalRunner, the visionary behind this project, embarked on a mission to create a Minecraft server that could comfortably fit in a pocket. The ESP32, with its modest 400KB of memory and a 160MHz processor, is typically designed for simpler applications like smart lightbulbs rather than the demands of a gaming server. In stark contrast, a conventional Minecraft server usually requires gigabytes of RAM and processors operating in the gigahertz range. To achieve this ambitious goal, PortalRunner had to rewrite the rules of server architecture, crafting a bespoke solution in C while working intimately with the hardware. The outcome, bareiron, sacrifices certain features for performance yet still delivers a commendable Minecraft experience, all while consuming a mere half a watt of power.
Innovative Terrain Generation
One of the most formidable challenges faced was the generation of terrain. In standard Minecraft gameplay, the environment is created using Perlin noise, a method that layers random patterns to yield natural-looking landscapes. However, this approach is both memory and CPU intensive, making it impractical for the ESP32’s limited memory. PortalRunner’s ingenious solution involved employing bilinear interpolation, a technique familiar to anyone who has enlarged pixelated images. By generating pseudo-random integers based on a chunk’s coordinates, the server can produce a smooth landscape gradient without the need for extensive noise maps. This method provides height values for each corner of a chunk, with interpolation filling in the gaps to create rolling hills and valleys. Adjacent chunks exchange coordinates, ensuring a seamless transition as players navigate the world.
The introduction of biomes—distinct environments such as deserts and snowy plains—added another layer of complexity to the project. While traditional Minecraft utilizes intricate features like temperature and humidity to define biomes, bareiron opts for a more straightforward approach. Each biome is represented as a circular island on a grid, its type determined by a repeating pattern linked to the world’s seed. This grid-like structure offers predictability and uniformity in size, albeit at the cost of performance. Forests feature scattered trees, deserts are dotted with cacti, and snowy plains host small bushes, all randomly placed from chunk corners. The terrain shape varies with each biome; plains are generally flat with occasional rises, while snowy slopes exhibit dramatic elevation changes, achieved by adjusting the number of random elements in height calculations.
Imaginative Cave Systems and Simplified Crafting
Creating caves and subsurface elements required a touch of imagination. Rather than developing a separate algorithm for cave generation, PortalRunner mirrored the surface landscape to craft deep, expansive tunnels reminiscent of Minecraft’s deepslate caves. Ores, such as diamonds, are intentionally sparse and typically located at the depths of these caves, simplifying the process and avoiding the complexities of the original game’s vein generation. Player-induced changes, such as mined or placed blocks, are stored in a compact array, with each entry occupying just 6 bytes. This allows for approximately 25,000 changes—equivalent to about one and a half chunks—while limiting the build height to 256 blocks and the horizontal spread to 32,000 blocks, a reasonable compromise for fitting everything onto the hardware.
Crafting and inventory management also received a streamlined redesign. Instead of items dropping when blocks are mined, they are directly added to the player’s inventory, accompanied by a visual effect that simulates items flying toward the player. Crafting recipes have been simplified; the server counts items in the crafting grid, checks for recipe compliance, and verifies their positions. For instance, a furnace requires eight cobblestone blocks surrounding an empty center, while shears necessitate two iron ingots in specific arrangements. Furnaces and chests operate without timers or long-term storage requirements, with furnaces producing items rapidly and chests storing items as “invisible blocks” within the same array as block changes—a clever adaptation that maximizes the existing data structure.
Performance is where bareiron truly excels; on the ESP32-C3, a chunk loads in approximately 200 milliseconds, facilitating smooth gameplay, although performance may lag with more than three players. In contrast, modern PCs can generate chunks in just 0.5 milliseconds, but the absence of network compression can hinder the experience in areas with poor internet connectivity. The server operates on a trust-based model, allowing clients to make inventory changes or mine blocks without verification, which opens the door to potential cheating in untrusted environments. These trade-offs reflect the project’s ethos: it’s about exploring possibilities rather than achieving perfection.
