Deploying to HTML5¶

Configure HTML5 deployer¶

Install emscripten¶

Install emscripten:

https://emscripten.org/docs/getting_started/downloads.html

Set environment variables¶

export EMSCRIPTEN=<emsdk>/upstream/emscripten

Running the generated output¶

Use emrun to run the generated index.html:

cd <output_dir>
<emsdk>/upstream/emscripten/emrun index.html

Streaming data¶

HTML5 deployments normally download all game data up front. This makes deployment simple, but players have to wait for the download to finish before the game can start.

Streaming downloads resources as the game needs them, reducing the amount of data needed at startup. Music and other streamed resources are read in small chunks as they are used, so the whole file does not have to be downloaded first or kept entirely in memory.

Streaming requires configuration in both Crown and the web server. Set Bundle URL in the HTML5 deploy dialog to the URL where you will host the game data. The deployer exports a data/ directory alongside the runtime instead of data.bin and data.js. For example, with Bundle URL set to https://example.com/game/, upload data/ to https://example.com/game/data/.

On the server hosting data/, enable byte-range requests and disable HTTP compression. Range requests must return 206 Partial Content with a matching Content-Range. For cross-origin hosting, set Access-Control-Allow-Origin to the game’s origin and include Content-Range and Content-Encoding in Access-Control-Expose-Headers.

If the server cannot serve uncompressed ranges, Crown downloads each resource in full to temporary OPFS storage before opening it. This fallback requires OPFS and HTTPS or localhost.

Runtime arguments¶

Set runtime arguments in the Module object in index.html:

arguments: ['--bundle-url', 'https://example.com/game/'],

The URL ?bundle-url=https://example.com/game/ passes the same arguments. URL options take precedence over HTML options.