embedded_watcher does not work in multi-crate workspaces

[SludgePhD]

Bevy version

0.12

What you did

Enable the embedded_watcher feature and use embedded_asset! in a subcrate.

What went wrong

The embedded watcher does not react to changes to the embedded file.

Additional information

This is caused by the file watcher watching only the "base path" for changes (by default, this is the runtime value of CARGO_MANIFEST_DIR, which is the path containing the Cargo.toml of the final binary):

bevy/crates/bevy_asset/src/io/embedded/embedded_watcher.rs

Lines 32 to 40 in 675aac9

	let root = get_base_path();
	let handler = EmbeddedEventHandler {
	dir,
	root: root.clone(),
	sender,
	root_paths,
	last_event: None,
	};
	let watcher = new_asset_event_debouncer(root, debounce_wait_time, handler).unwrap();

It should either be watching every single embedded file path separately, or merge them together by crate (though watching many separate paths may be bad for performance).

[garyttierney]

As a temporary workaround I've been able to do:

BEVY_ASSET_ROOT=`pwd` cargo run --package sub_crate

From the workspace root.

[nicopap]

Testing this today, embedded_assets! at least works with bevy itself, meaning that it should work with arbitrary multi-crate workspaces now. I'm closing this. But do not hesitate re-opening the issue if I'm mistaken.

[SludgePhD]

What fixed it? I'll retest when I find the time.

[nicopap]

Dunno, looking the blame, I don't see anything specifically addressing this issue, the relevant ones are:

• Fix embedded watcher to work with external crates #11370
• Fix embedded asset path manipulation #10383
• AssetPath source parse fix #11543

[SludgePhD]

Nope, still doesn't seem to work for me on bevy 0.13.

Or to be precise, embedded_asset! does work, but the embedded_watcher does not react to any changes to the embedded file.

[nicopap]

Ooops, I'm re-opening then.

[SludgePhD]

It's possible that this only reproduces with virtual workspaces, where the outermost Cargo.toml lacks a [package] section. Bevy doesn't do that, so it might work fine there.

[SK83RJOSH]

I ran into this today as I started moving some of my rendering plugins to their own crates and realized shader reloading stopped working. I can confirm that it only affects virtual workspaces, and I fixed it on my end by moving my app to be the root crate.

Would be nice to not need to do this though, as down the line I would like to be able to do shader dev while working on examples and so on as well...

[SK83RJOSH]

Just to follow up on this, I can confirm this happens under the following circumstances:

• Your project is a virtual workspace
• Your embedded assets are in a directory outside of the CARGO_MANIFEST_DIR for your app

The only workaround is to set BEVY_ASSETS_ROOT to be the root of your cargo workspace. This of course, means your assets need to live outside of your app crate. Not ideal, but I can work with this for my project, and embed most of my assets into the app and it's crates.

It is unfortunately very unlikely that we will ever have CARGO_WORKSPACE_DIR, so I'm not really sure how you could fix this. Just about the only solution I can see working, would be patching up the embedded_watcher to use a new environment variable, such as BEVY_EMBEDDED_ASSET_ROOT.

Which would require patches here, here and here.