* Raycaster Engine

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This is a graphics engine which uses the raycasting method to draw the
world.

The world is defined in a 2D matrix. Then, rays are cast from the
player's point of view, and the DDA (Digital Differential Analyzer)
algorithm is used to intercept the cells and check for wall
collissions, which then lets me draw the world line by line.

A similar method is used for rendering the floor and the ceiling.

The engine has no hardware acceleration at all. Everything is
processed by the CPU. As such, your fans will spin very rapidly when
this thing is running. It also will use all of your CPUs cores to
speed up rendering, as it would be unbearably slow without it. So have
fun with your new heater.

** Features

- A fake 3D world drawn from a 2D matrix.
- Walls, ceiling and floors can have different textures, per tile.
- Use arbitrary textures, of any size. They'll get squashed to a
  square shape.
- A tacked on dynamic lighting system with shadows and everything (one
  of the main reasons for the poor performance).
- Oh, did I mention poor performance?
- A somewhat working level editor (works in real time!) which even
  lets you save your levels!
- A crappy widget system which only has buttons, spinners, and labels.
- Two hand drawn textures, rest were stolen from various places,
  mostly Wolf3D.
- Look up/down and crouch/stretch your neck? In short, player has
  variable height.
- Angled walls, can be at any angle... ANY. That's a lot of angles.
- A wonky skybox.
- Billboard style sprites.

** Building

Simply run make. Do note that this engine makes use of =pthread.h=,
which is Linux only. And as such, the engine is Linux only. Windows
support would be trivial... but meh.

#+begin_src sh
  make
#+end_src

The executable will be in the build folder:

#+begin_src sh
  ./build/main
#+end_src

Open it from the root of the project, as it depends on that path to
find the levels and the textures. Speaking of... you won't have any,
since they are stored in Git LFS. So, install git lfs, then run:

#+begin_src sh
  git lfs install
  git lfs pull
#+end_src

** Controls

When you launch the engine you'll be in the level editor.

*** Level Editor

- =T=: Toggle between editor and game.
- =Left click=: Place tile.
- =Middle click=: Pan the view.
- =Right click=: Delete tile.
- =1-9=: Switch textures. Not all of them are accesible. Oh well.
- GUI controls on the bottom left. You can change the size of the map
  and change the layer you're currently editing.
- When you click on save level the level will be saved on
  =./assets/maps/test.map=. There's no confirmation.

*** Game

- =WASD=: Move.
- =T=: Go into level editor.
- =Ctrl=: Crouch.
- =Left Alt=: Stetch neck.
- =Left Shift=: Run.
- Use mouse to look around.