Building from Source

AeroLiners Set uses CMake to organize the build: first the .pnml sources are expanded into a single .nml via the C preprocessor, then compiled into the final .grf with nmlc, and finally packaged into .tar release bundles.

Build dependencies

Tool	Purpose	Get it
C compiler (GCC/clang/MSVC)	Used only as a C preprocessor to expand #include/#define in .pnml	System / MinGW
nmlc	Compiles .nml into .grf (NML compiler)	https://github.com/OpenTTD/nml/releases/latest
grfid (grfcodec suite)	Computes the .grf MD5, processes doc templates	https://www.openttd.org/downloads/grfcodec-releases/latest
CMake ≥ 3.23	Build system	System package manager
Generator: Ninja / Make / VS	Actually runs the build	Pick one

Windows users: install MSYS2 + MinGW to get make, gcc, sed, awk, etc. all at once. Other Unix-like systems usually already have them.

Build steps

1. Configure

Use CMake Presets to choose a generator (generated files land in build/<generator>/):

# Ninja
cmake --preset ninja

# or Make
cmake --preset make

# or Visual Studio 2022
cmake --preset vs

2. Build

# Ninja (default, non-verbose)
cmake --build build/ninja --preset ninja-default

# Make
cmake --build build/make --preset make-default

# Visual Studio
cmake --build build/vs2022 --preset vs-default

The build runs these custom targets in order:

1. NML — expand WAS.pnml (summing src/header.pnml etc.) into bin/AeroLinersSet.nml via the C preprocessor.
2. GRF — compile the .nml into bin/AeroLinersSet.grf with nmlc.
3. Bundles (default ALL) — package the .grf and docs (readme.txt / license.txt / changelog.txt) into .tar / .tar.bz2 / .tar.gz / .tar.xz.

Build artifacts are in the bin/ directory.

3. Clean and rebuild

cmake --build build/ninja --target clean        # clean intermediates
# or target a single step
cmake --build build/ninja --target NML
cmake --build build/ninja --target GRF

Verbose output

To see the full command lines, use the build preset with the -verbose suffix (sets CMAKE_VERBOSE_MAKEFILE=on and VERBOSE=on):

cmake --build build/ninja --preset ninja-verbose

Build flow

WAS.pnml (include aggregation)
   │  C preprocessor (gcc -E)
   ▼
AeroLinersSet.nml
   │  nmlc -c
   ▼
AeroLinersSet.grf
   │  grfid -m + doc templates
   ▼
.tar / .tar.bz2 / .tar.gz / .tar.xz  (release bundles)

Notes

• Version / revision: CMakeLists.txt computes "days since 2000-01-01" as REPO_REVISION via string(TIMESTAMP), writing it into custom_tags.txt for the NewGRF version field.
• Multiplayer compatibility: if you modify the source, the compiled .grf will no longer be multiplayer-compatible with the official AeroLiners Set. Different grfcodec/nmlc versions also change the GRF checksum and break compatibility.
• Do not hand-edit Makefile / CMakeCache.txt: they are generated by CMake.

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