Brotli-Wasm Decompression for Godot Game Files

This guide demonstrates how to modify .html and .js files after exporting a Godot game to enable Brotli-Wasm decompression for game files.

UPDATE:

These instructions are only for the non-auto Brotli decompression example.

If you want to try browser-based auto-decompression (where the browser handles decompression automatically), simply upload the .br files to your platform, and the user's browser will handle the rest. For this exmaple, check the auto_browser_decompress_example folder.

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Quick Start

To jump right in, follow these steps:

1. Go to brotli_export folder.

2. Start a local server to test:

   python -m http.server 8000

   Visit http://localhost:8000 in your browser.

3. Game engine must start with *.br files.

For detailed instructions, see below. Example images are provided in the changes_in_* folders, and a complete demo is available in the brotli_export folder.

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Changes in HTML

1. Add type="module to the <script> tag:

   <script type="module" src="{project_name}.js"></script>

2. Add type="module to the inline <script> tag:

   <script type="module"></script>

3. Insert await load_b(); before the engine creation line:

   <script>
       await load_b();
       // Your engine initialization code
   </script>

For reference, see the images in the changes_in_html folder.

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Changes in {project_name}.js

1. Add the Brotli loader function: At the top of your .js file, include:

   var brotli = null;
   
   window.load_b = async function () {
       brotli = await import("./brotli.js").then(m => m.default);
   };

2. Modify the loadFetch function: Add this at the beginning of the function:

   if (file === "index.pck") {
       file += ".br";
   }

3. Update WebAssembly instantiation: Replace this block:

   if (typeof (WebAssembly.instantiateStreaming) !== 'undefined') {
       // Replace this
   }

   With:

   var decompressed = await brotli.decompress(new Uint8Array(await r.arrayBuffer()));
   WebAssembly.instantiateStreaming(Promise.resolve(new Response(decompressed, { 'headers': [['content-type', 'application/wasm']] })), imports).then(done);

4. Update preloader path: Find this line:

   loadPromise = preloader.loadPromise(`${loadPath}.wasm`, size, true);

   Add .br:

   loadPromise = preloader.loadPromise(`${loadPath}.wasm.br`, size, true);

5. Replace the block in Promise function: Locate this block:

   return new Promise(async function (resolve, reject) {
       for (const file of preloader.preloadedFiles) {
        me.rtenv['copyToFS'](file.path, file.buffer);
        }
   });

   Replace it with:

   for (const file of preloader.preloadedFiles) {
       var b = await file.buffer.arrayBuffer();
       me.rtenv['copyToFS'](file.path, b);
   }

For more clarity, refer to the changes_in_js folder.

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Compression Script

After applying the changes:

1. Run the Python compression script:

   python compress.py

2. Remove the original .wasm and .pck files.

3. Start the local server:

   python -m http.server 8000

   Test the changes at http://localhost:8000.

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Troubleshooting

If you encounter any issues, inspect the demo files and refer to the images provided in the changes_in_* folders.

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Have Fun!

Enjoy a more efficient, Brotli-compressed game loading experience!