A very basic implementation of Lode's Computer Graphics ray-caster (https://lodev.org/cgtutor/raycasting.html) for the Game Boy Advance.
Uses gba-toolchain to build.
I recommend using a CMake compatible IDE such as CLion or Visual Studio Code.
Debug build is VERY slow. Use RelWithDebInfo for development. Clang also gives a bit of a performance boost.
This isn't fully optimised, for example no look-up-tables are used (which could help a fair bit). This is more of a proof-of-concept demonstrating how ray-casting engines are not the most optimal way to render 3D graphics.
The other directory has various alternative implementations at various stages of optimisation.
Do what you want. No support provided. If you do make a game out of this, then send screenshots.
If you find a cool optimisation then make a pull request and I'll review it.