[Merged by Bors] - bevy_asset: Add AssetServerSettings watch_for_changes member

crates/bevy_asset/src/asset_server.rs

@@ -115,6 +115,8 @@ impl AssetServer {
  loaders.push(Arc::new(loader));
  }
 
+ /// Enable watching of the filesystem for changes, if support is available, starting from after
+ /// the point of calling this function.
  pub fn watch_for_changes(&self) -> Result<(), AssetServerError> {
  self.server.asset_io.watch_for_changes()?;
  Ok(())
@@ -622,7 +624,7 @@ mod test {
  handle_to_path: Default::default(),
  asset_lifecycles: Default::default(),
  task_pool: Default::default(),
- asset_io: Box::new(FileAssetIo::new(asset_path)),
+ asset_io: Box::new(FileAssetIo::new(asset_path, false)),
  }),
  }
  }

crates/bevy_asset/src/io/file_asset_io.rs

@@ -27,12 +27,26 @@ pub struct FileAssetIo {
 }
 
 impl FileAssetIo {
- pub fn new<P: AsRef<Path>>(path: P) -> Self {
- FileAssetIo {
+ pub fn new<P: AsRef<Path>>(path: P, watch_for_changes: bool) -> Self {
+ let file_asset_io = FileAssetIo {
  #[cfg(feature = "filesystem_watcher")]
  filesystem_watcher: Default::default(),
  root_path: Self::get_root_path().join(path.as_ref()),
+ };
+ if watch_for_changes {
+ #[cfg(any(
+ not(feature = "filesystem_watcher"),
+ target_arch = "wasm32",
+ target_os = "android"
+ ))]
+ panic!(
+ "Watch for changes requires the filesystem_watcher feature and cannot be used on \
+ wasm32 / android targets"
+ );
+ #[cfg(feature = "filesystem_watcher")]
+ file_asset_io.watch_for_changes().unwrap();
  }
+ file_asset_io
  }
 
  pub fn get_root_path() -> PathBuf {

crates/bevy_asset/src/lib.rs

@@ -44,12 +44,16 @@ pub struct AssetPlugin;
 
 pub struct AssetServerSettings {
  pub asset_folder: String,
+ /// Whether to watch for changes in asset files. Requires the `filesystem_watcher` feature,
+ /// and cannot be supported on the wasm32 arch nor android os.
+ pub watch_for_changes: bool,
 }
 
 impl Default for AssetServerSettings {
  fn default() -> Self {
  Self {
  asset_folder: "assets".to_string(),
+ watch_for_changes: false,
  }
  }
 }
@@ -64,7 +68,7 @@ pub fn create_platform_default_asset_io(app: &mut App) -> Box<dyn AssetIo> {
  .get_resource_or_insert_with(AssetServerSettings::default);
 
  #[cfg(all(not(target_arch = "wasm32"), not(target_os = "android")))]
- let source = FileAssetIo::new(&settings.asset_folder);
+ let source = FileAssetIo::new(&settings.asset_folder, settings.watch_for_changes);
  #[cfg(target_arch = "wasm32")]
  let source = WasmAssetIo::new(&settings.asset_folder);
  #[cfg(target_os = "android")]

examples/asset/hot_asset_reloading.rs

@@ -1,10 +1,15 @@
-use bevy::prelude::*;
+use bevy::{asset::AssetServerSettings, prelude::*};
 
 /// Hot reloading allows you to modify assets on disk and they will be "live reloaded" while your
 /// game is running. This lets you immediately see the results of your changes without restarting
 /// the game. This example illustrates hot reloading mesh changes.
 fn main() {
  App::new()
+ // Tell the asset server to watch for asset changes on disk:
+ .insert_resource(AssetServerSettings {
+ watch_for_changes: true,
+ ..Default::default()
+ })
  .add_plugins(DefaultPlugins)
  .add_startup_system(setup)
  .run();
@@ -14,9 +19,6 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
  // Load our mesh:
  let scene_handle = asset_server.load("models/monkey/Monkey.gltf#Scene0");
 
- // Tell the asset server to watch for asset changes on disk:
- asset_server.watch_for_changes().unwrap();
-
  // Any changes to the mesh will be reloaded automatically! Try making a change to Monkey.gltf.
  // You should see the changes immediately show up in your app.