Inline Static Assets in Builds

[ggetz]

The current CesiumJS distribution consists of a single, bundled JS entry point, Cesium.js, which inlines all library JS code. It also ships with several other static files, including standalone Worker JS files, third party wasm files, JSON data, images/textures, and CSS files. Depending on what features of the library is being used, some or all of these static files are required to be loaded at runtime.

While we've operated with these static files as part of the distribution since the beginning, it can require extra infrastructure on the part of developers depending on CesiumJS. We'd like to re-evaluate our strategy and look into providing a single-file CesiumJS distribution

As a first step, we could allow an optional inline flag as part of the build script. esbuild has a loader option which allows other file types besides JS to be inlined most likely as data urls.

After ensuring everything works, we should put some thought into potentially shipping by default as part of the release zip.

[ggetz]

Tangential to this discussion, for those that are using CesiumJS from Source, we'll also want to ensure the proper files are exported via package.json.

[ggetz]

@TJKoury You have some experience with doing this, via rollup I believe, in https://github.com/DigitalArsenal/c137.js. Are there any gotchas that you may have experienced in the process?

[TJKoury]

Plenty gotchas! I'll start with the big one (for me): WebWorkers.

My approach was to import all the webworkers into a single file. The packager can walk the dependency tree and pull everything into a single worker that can be called whenever you need a worker.

That is then injected as a string into TaskProcessor.js. Since this will now be part of the official build you can probably come up with a more elegant solution (import it using the esbuild loader option per the above).

[TJKoury]

@ggetz I’m considering applying for a grant through the new program so I can dedicate some time towards adapting my old approach to the current build system. If this will be duplicating effort, let me know.

[ggetz]

@TJKoury Awesome! Please go ahead!