AssetServer.watch_for_changes() must be called before creating window

[jakobhellermann]

For some reason, calling watch_for_changes in a setup function will not register file events in the future, while doing it before starting the app will.

The exact point at which it breaks is winit::WindowBuilder::build, call watch_for_changes before and it will work, call it after and it won't.

Tested on linux with x11 and wayland, will try windows later.

[mockersf]

Example hot_asset_reloading which does that is working for me on macOS.

Were you able to reproduce on windows?

[johanhelsing]

The hot_asset_reloading example works for me on windows 10. Shaders don't reload, though, but I'm guessing that's unrelated?

[johanhelsing]

Works on linux for me as well (tested v0.6.0 tag and main)

[gajop]

I can confirm multiple issues with shader hotreload:

• Bevy's official post_processing.rs example doesn't reload shaders for me.
• adding it in one of my code's startup system has no effect (shaders don't reload)

asset_server.watch_for_changes().unwrap();

• inserting it as a resouce after I've added my other plugins didn't work

    App::new()
        .add_plugins(DefaultPlugins)
        .insert_resource(AssetServerSettings { // does NOT work
            watch_for_changes: true,
            ..default()
        })
        // other stuff
        .add_startup_system(setup)
        .add_system(some_system)
        .run();

Thankfully due to insight from this issue I figured I should put this at the top of my program, something like:

    App::new()
        .insert_resource(AssetServerSettings { // Works
            watch_for_changes: true,
            ..default()
        })
        .add_plugins(DefaultPlugins)
        // other stuff
        .add_startup_system(setup)
        .add_system(some_system)
        .run();

[mwbryant]

Someone on the discord also noted using asset_server.watch_for_changes().unwrap() anywhere in the app will break this workaround.

[jakobhellermann]

Fixed by removing the watch_for_changes method: #5968