All-surface raycaster in C++ and SDL2

This is a simple raycasting engine written in C++, using the SDL2 libraries. Compared to Wolfenstein3D, there are features missing such as doors, enemies, etc. On the bright side, it has floor/ceiling texture mapping and depth-based lighting :)
The code is not optimized whatsoever, the FPS is a clear indicator here. For example, for each column of pixels a ray is cast, but the textures are in no way high-res so I could have drastically lowered the amount of casted rays (= lowering horizontal resolution) with negligible effect.
This build is running under Ubuntu 14.04, compiled with g++.
Source: github.com/T1m...