Compiling and running Doomsday 2.0–2.3 with CMake

Doomsday 2 is built with CMake 3.1 (or later).

Get the source

There are a couple of ways to get the source code:

Download a source package.
Check out the Doomsday-Engine repository from GitHub:
```
git clone --recursive https://github.com/skyjake/Doomsday-Engine
```
You can then switch to any release or a specific build via tags. Stable releases are tagged “release-x.y.z”.

The following libraries are required for compilation:

The following are optional:

SDL 2 (joystick support)
SDL_mixer 2 (audio plugin)
FMOD Studio Low-Level Programmer API for Doomsday 2.1+, or FMOD Ex for Doomsday 2.0 or earlier (audio plugin)
OpenAL (audio plugin)
libXrandr and libXxf86vm (X11 display mode support)

You must create a separate directory that is used for the build files. In-tree builds are not supported.

After the dependencies are available, run CMake and configure the appropriate build variables. The following variables are noteworthy:

Normally you will want to set the CMAKE_BUILD_TYPE to “Release”. Note that with gcc/clang, omitting this variable will result in an unoptimized build.
Set the DE_PREFIX variable to define the installation root path.
Set the QMAKE variable to the path of the qmake tool to use (unless autodetected). This determines which version of Qt will be used in the build.
DENG_ENABLE_* are used for enabling and disabling Doomsday features.
*_DIR (e.g., FMOD_DIR) are used for configuring locations of third-party libraries.

When CMake has configured the build successfully, run your chosen build tool.

After building, you must still deploy the binaries (e.g., using make install) because Doomsday expects a particular runtime directory layout.