OpenTTD-patches/os/emscripten/README.md
Jonathan G Rennison cf4cf5c08f Codechange: vendor the nlohmann-json library (#11290)
(cherry picked from commit ba67f39db6)

# Conflicts:
#	.github/workflows/ci-build.yml
#	CMakeLists.txt
#	COMPILING.md
#	src/os/macosx/survey_osx.cpp
#	src/os/windows/survey_win.cpp
#	src/script/api/script_admin.cpp
#	src/script/api/script_event_types.cpp
#	src/tests/test_script_admin.cpp
2023-11-17 19:20:35 +00:00

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## How to build with Emscripten
Please use docker with the supplied `Dockerfile` to build for emscripten.
It takes care of a few things:
- Use a version of emscripten we know works
- Patch in LibLZMA support (as this is not supported by upstream)
First, build the docker image by navigating in the folder this `README.md` is in, and executing:
```
docker build -t emsdk-openttd .
```
Next, navigate back to the root folder of this project.
Now we build the host tools first:
```
mkdir build-host
docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build-host emsdk-openttd cmake .. -DOPTION_TOOLS_ONLY=ON
docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build-host emsdk-openttd make -j$(nproc) tools
```
Finally, we build the actual game:
```
mkdir build
docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build emsdk-openttd emcmake cmake .. -DHOST_BINARY_DIR=../build-host -DCMAKE_BUILD_TYPE=Release -DOPTION_USE_ASSERTS=OFF
docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build emsdk-openttd emmake make -j$(nproc)
```
In the `build` folder you will now see `openttd.html`.
To run it locally, you would have to start a local webserver; something like:
```
cd build
python3 -m http.server
````
You can now play the game via http://127.0.0.1:8000/openttd.html .