Build from source

OpenGTA is C11 with CMake. The product is opengta.wasm, the gasm module; a native build exists for the tools and the headless tests.

git clone https://github.com/emdzej/opengta && cd opengta

opengta.wasm

tools/fetch-gasm-sdk.sh downloads wasi-sdk (clang and the C library for wasm32) and gasm's C SDK (gasm.h and a CMake toolchain) into .deps/. The gasm version is pinned there (GASM_VERSION, currently 0.6.0, the minimum).

tools/fetch-gasm-sdk.sh
cmake -S . -B build-gasm -DOPENGTA_PLATFORM=gasm -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_TOOLCHAIN_FILE=.deps/gasm-c-sdk/cmake/gasm-toolchain.cmake -DWASI_SDK_PREFIX="$PWD/.deps/wasi-sdk"
cmake --build build-gasm -j                    # -> build-gasm/opengta.wasm

Run it with the released runner, fetched into .deps/ at the pinned version:

RUN="$(tools/fetch-gasm-runner.sh macos-universal)/gasm-run"   # or linux-x86_64, linux-arm64, windows-x86_64
$RUN build-gasm/opengta.wasm --asset-dir game

Native build (tools and tests)

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release && cmake --build build -j

This builds the portable core and one test program per tests/*_test.c. See Run the tests.

Game data in the checkout

The tests and scripts look for the data in the repository: ./game (the installed folder) and ./installer (the unzipped GTAINSTALLER.zip). Both are git-ignored, as are out/ (decoded assets and renders) and re/ (decompiler dumps). Never commit them, and never copy data from the executable into the source: tables are read from it at run time.

The site

This site is VitePress in docs/ (Node 22, pnpm):

cd docs && pnpm install
scripts/vendor-web.sh        # the play page's gasm and csfs runtime, from the pinned npm packages
scripts/copy-wasm.sh         # build-gasm/opengta.wasm -> public/play/
pnpm dev                     # http://localhost:5173 (the player: /play/index.html)
pnpm build                   # -> docs/.vitepress/dist

tools/screenshots.sh regenerates the screenshots from opengta.wasm (Headless runs).