Minecraft4k (2023)
View source on GitHub
Summary
In 2010, Notch remade Minecraft for a jam in a very limited form, using the now-defunct Java
Applets framework.
Additionally, performance was limited by the single-threaded sequential CPU raymarcher which
Notch implemented.
I fully reverse engineered the game, and multi-threaded the raymarcher. However, this was not
fast enough to run at a reasonable resolution.
I decided to remake it fully in a fully custom GPU-accelerated ray-marched C++ engine.
My cross-platform engine uses a suite of methods to finagle a lower storage footprint, as was the objective of the original Java game.
- Rather than storing them as space-costly PNG files, the textures are generated through unique procedural algorithms at runtime;
- In place of using a large library, the raymarcher is specifically implemented in compact and efficient GLSL;
- Rather than dynamically linking entire DLL files, the build selectively strips unused functions and statically links libraries;
- The accurate fixed-step physics engine is contrived in a single short function;
- Shadows are inexpensively yet precisely calculated through reflecting rays towards the light source and shading accordingly;
However, this was not yet as small as the original. I made it my goal over several years to fit
a playable, hardware-accelerated version of Minecraft into a QR code.
That gives me 2953 bytes to work with, which is smaller than the original Java app.
I have fully docummented the journey in a blog post, this was one of the projects I found the most fun.
Tech Used
- C
- Voxel raymarching
- Manual dynamic linking
- OpenGL compute shaders
- Inline x86 assembly
- GNU Makefiles
- Custom linker scripts
- Executable self-decompression
Things Learned
- Data compressibility optimization
- OpenGL performance profiling
- 3D texture handling and generation
- Procedural texture algorithms
- Complex build environments
- Code size profiling