# GDevelop.js

This is the port of GDevelop core classes to WebAssembly+JavaScript. This allows [GDevelop Core libraries](https://github.com/4ian/GDevelop) to run in a browser or on Node.js.

> 🎮 GDevelop is a full-featured, cross-platform, open-source game development software requiring no programming skills. Download it on [the official website](https://gdevelop.io).

## How to build

> 👋 Usually, if you're working on the GDevelop editor or extensions in JavaScript, you don't need to rebuild GDevelop.js. If you want to make changes in C++ extensions or classes, read this section.

- Prerequisite tools installed:

  - [CMake 3.17+](http://www.cmake.org/) (3.5+ should work on Linux/macOS). On macOS, you can install it via Homebrew (recommended for Apple M1 Architectures).
  - [Node.js](https://nodejs.org/). (We recommend using [nvm](https://github.com/nvm-sh/nvm) to be able to switch between Node versions easily).
  - Python (via [pyenv](https://github.com/pyenv/pyenv) for versions management).

- Install [Emscripten](https://github.com/kripken/emscripten) version `3.1.21`, as explained below or on the [Emscripten installation instructions](http://kripken.github.io/emscripten-site/docs/getting_started/downloads.html):

```bash
git clone https://github.com/emscripten-core/emsdk/
cd emsdk
git pull
./emsdk install 3.1.21
./emsdk activate 3.1.21
```

> ⚠️ If you are on Apple M1, this version of emsdk may not be available for this architecture and you will get an error when installing it, indicating a missing binary. If this is the case, a workaround is to modify the `emsdk.py` line 132 with `machine = 'x86_64'` to ensure a correct binary is downloaded.

- Whenever you try to build GDevelop.js in the future, you will have to load the emsdk environement into your terminal window again by running:

| Linux/macOS             | Windows (Powershell) | Windows (cmd.exe) |
| ----------------------- | -------------------- | ----------------- |
| `source ./emsdk_env.sh` | `./emsdk_env.ps1`    | `./emsdk_env.bat` |

- With the emscripten environement loaded into your terminal, launch the build from GDevelop.js folder:

```bash
cd GDevelop.js
npm install
npm run build
```

> ⚠️ If the npm install fails, relaunch it in a different terminal using a recent Node.js and npm version (to avoid using the old npm version from Emscripten).

> ℹ️ Output is created in _/path/to/GD/Binaries/embuild/GDevelop.js/_ and also copied to GDevelop 5 IDE (`newIDE` folder).

> ℹ️ You only need to run `npm install` the first time you make a build.

-> ⏱ The linking (last step) of the build can be made a few seconds faster by specifying `-- --dev`. Be sure to remove it before building a release version, as this disable "link-time optimizations" of the generated WebAssembly module.

- You can then launch GDevelop 5 that will use your build of GDevelop.js:

```bash
cd ..
cd newIDE/app
npm install
npm start
```

More information in [GDevelop 5 README](https://github.com/4ian/GDevelop/blob/master/newIDE/README.md).

### Tests

```bash
npm test
```

### About the internal steps of compilation

The npm _build_ task:

- Creates `Binaries/embuild` directory,
- Launches CMake inside to compile GDevelop with _emconfigure_ to use Emscripten toolchain,
- Updates the glue.cpp and glue.js from Bindings.idl using _Emscripten WebIDL Binder_,
- Launches the compilation with `make` (or `ninja` on Windows with CMake 3.17+) (you can also compile using MinGW-32 using `npm run build-with-MinGW`).

See the [CMakeLists.txt](./CMakeLists.txt) for the arguments passed to the Emscripten linker. For instance, if you want to see the function names in stacks or for profiling, the compilation flags can be changed.

## Documentation

- The file [Bindings.idl](https://github.com/4ian/GDevelop/blob/master/GDevelop.js/Bindings/Bindings.idl) describes all the classes available in GDevelop.js.
- Refer to [GDevelop documentation](https://docs.gdevelop.io/GDCore%20Documentation/) for detailed documentation of the original C++ classes.