nostalgia

You need to install Emscripten from https://emscripten.org/docs/getting_started/downloads.html, and have the environment variables set, as described in https://emscripten.org/docs/getting_started/downloads.html#installation-instructions
Depending on your configuration, in Windows you may need to run emsdk/emsdk_env.bat in your console to access the Emscripten command-line tools.
You may also refer to our Continuous Integration setup for Emscripten setup.
Then build using make while in the example_emscripten_opengl3/ directory.

How to Run

To run on a local machine:

make serve will use Python3 to spawn a local webserver, you can then browse http://localhost:8000 to access your build.
Otherwise, generally you will need a local webserver:
- Quoting https://emscripten.org/docs/getting_started:
  "Unfortunately several browsers (including Chrome, Safari, and Internet Explorer) do not support file:// XHR requests, and can’t load extra files needed by the HTML (like a .wasm file, or packaged file data as mentioned lower down). For these browsers you’ll need to serve the files using a local webserver and then open http://localhost:8000/hello.html."
- Emscripten SDK has a handy emrun command: emrun web/example_emscripten_opengl3.html --browser firefox which will spawn a temporary local webserver (in Firefox). See https://emscripten.org/docs/compiling/Running-html-files-with-emrun.html for details.
- You may use Python 3 builtin webserver: python -m http.server -d web (this is what make serve uses).
- You may use Python 2 builtin webserver: cd web && python -m SimpleHTTPServer.
- If you are accessing the files over a network, certain browsers, such as Firefox, will restrict Gamepad API access to secure contexts only (e.g. https only).

Emscripten 2.0 (August 2020) obsoleted the fastcomp backend, only llvm is supported.
Emscripten 1.39.0 (October 2019) obsoleted the BINARYEN_TRAP_MODE=clamp compilation flag which was required with version older than 1.39.0 to avoid rendering artefacts. See #2877 for details. If you use an older version, uncomment this line in the Makefile: #EMS += -s BINARYEN_TRAP_MODE=clamp