How to Build

• 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).

Obsolete features:

• 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