Multiple Asset Sources

Cargo.toml

@@ -242,7 +242,10 @@ shader_format_spirv = ["bevy_internal/shader_format_spirv"]
 webgl2 = ["bevy_internal/webgl"]
 
 # Enables watching the filesystem for Bevy Asset hot-reloading
-filesystem_watcher = ["bevy_internal/filesystem_watcher"]
+file_watcher = ["bevy_internal/file_watcher"]
+
+# Enables watching in memory asset providers for Bevy Asset hot-reloading
+embedded_watcher = ["bevy_internal/embedded_watcher"]
 
 [dependencies]
 bevy_dylib = { path = "crates/bevy_dylib", version = "0.12.0-dev", default-features = false, optional = true }
@@ -1053,6 +1056,7 @@ wasm = true
 name = "hot_asset_reloading"
 path = "examples/asset/hot_asset_reloading.rs"
 doc-scrape-examples = true
+required-features = ["file_watcher"]
 
 [package.metadata.example.hot_asset_reloading]
 name = "Hot Reloading of Assets"
@@ -1064,7 +1068,7 @@ wasm = true
 name = "asset_processing"
 path = "examples/asset/processing/processing.rs"
 doc-scrape-examples = true
-required-features = ["filesystem_watcher"]
+required-features = ["file_watcher"]
 
 [package.metadata.example.asset_processing]
 name = "Asset Processing"

crates/bevy_asset/Cargo.toml

@@ -11,8 +11,10 @@ keywords = ["bevy"]
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [features]
-filesystem_watcher = ["notify-debouncer-full"]
+file_watcher = ["notify-debouncer-full", "watch"]
+embedded_watcher = ["file_watcher"]
 multi-threaded = ["bevy_tasks/multi-threaded"]
+watch = []
 
 [dependencies]
 bevy_app = { path = "../bevy_app", version = "0.12.0-dev" }

crates/bevy_asset/src/io/android.rs

@@ -72,11 +72,4 @@ impl AssetReader for AndroidAssetReader {
         error!("Reading directories is not supported with the AndroidAssetReader");
         Box::pin(async move { Ok(false) })
     }
-
-    fn watch_for_changes(
-        &self,
-        _event_sender: crossbeam_channel::Sender<super::AssetSourceEvent>,
-    ) -> Option<Box<dyn AssetWatcher>> {
-        None
-    }
 }

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

@@ -0,0 +1,88 @@
+use crate::io::{
+    file::{get_asset_path, get_base_path, new_asset_event_debouncer, FilesystemEventHandler},
+    memory::Dir,
+    AssetSourceEvent, AssetWatcher,
+};
+use bevy_log::warn;
+use bevy_utils::{Duration, HashMap};
+use notify_debouncer_full::{notify::RecommendedWatcher, Debouncer, FileIdMap};
+use parking_lot::RwLock;
+use std::{
+    fs::File,
+    io::{BufReader, Read},
+    path::{Path, PathBuf},
+    sync::Arc,
+};
+
+/// A watcher for assets stored in the `embedded` asset source. Embedded assets are assets whose
+/// bytes have been embedded into the Rust binary using the [`embedded_asset`](crate::io::embedded::embedded_asset) macro.
+/// This watcher will watch for changes to the "source files", read the contents of changed files from the file system
+/// and overwrite the initial static bytes of the file embedded in the binary with the new dynamically loaded bytes.
+pub struct EmbeddedWatcher {
+    _watcher: Debouncer<RecommendedWatcher, FileIdMap>,
+}
+
+impl EmbeddedWatcher {
+    pub fn new(
+        dir: Dir,
+        root_paths: Arc<RwLock<HashMap<PathBuf, PathBuf>>>,
+        sender: crossbeam_channel::Sender<AssetSourceEvent>,
+        debounce_wait_time: Duration,
+    ) -> Self {
+        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();
+        Self { _watcher: watcher }
+    }
+}
+
+impl AssetWatcher for EmbeddedWatcher {}
+
+/// A [`FilesystemEventHandler`] that uses [`EmbeddedAssetRegistry`](crate::io::embedded::EmbeddedAssetRegistry) to hot-reload
+/// binary-embedded Rust source files. This will read the contents of changed files from the file system and overwrite
+/// the initial static bytes from the file embedded in the binary.
+pub(crate) struct EmbeddedEventHandler {
+    sender: crossbeam_channel::Sender<AssetSourceEvent>,
+    root_paths: Arc<RwLock<HashMap<PathBuf, PathBuf>>>,
+    root: PathBuf,
+    dir: Dir,
+    last_event: Option<AssetSourceEvent>,
+}
+impl FilesystemEventHandler for EmbeddedEventHandler {
+    fn begin(&mut self) {
+        self.last_event = None;
+    }
+
+    fn get_path(&self, absolute_path: &Path) -> Option<(PathBuf, bool)> {
+        let (local_path, is_meta) = get_asset_path(&self.root, absolute_path);
+        let final_path = self.root_paths.read().get(&local_path)?.clone();
+        if is_meta {
+            warn!("Meta file asset hot-reloading is not supported yet: {final_path:?}");
+        }
+        Some((final_path, false))
+    }
+
+    fn handle(&mut self, absolute_paths: &[PathBuf], event: AssetSourceEvent) {
+        if self.last_event.as_ref() != Some(&event) {
+            if let AssetSourceEvent::ModifiedAsset(path) = &event {
+                if let Ok(file) = File::open(&absolute_paths[0]) {
+                    let mut reader = BufReader::new(file);
+                    let mut buffer = Vec::new();
+
+                    // Read file into vector.
+                    if reader.read_to_end(&mut buffer).is_ok() {
+                        self.dir.insert_asset(path, buffer);
+                    }
+                }
+            }
+            self.last_event = Some(event.clone());
+            self.sender.send(event).unwrap();
+        }
+    }
+}

crates/bevy_asset/src/io/embedded/mod.rs

@@ -0,0 +1,246 @@
+#[cfg(feature = "embedded_watcher")]
+mod embedded_watcher;
+
+#[cfg(feature = "embedded_watcher")]
+pub use embedded_watcher::*;
+
+use crate::io::{
+    memory::{Dir, MemoryAssetReader, Value},
+    AssetSource, AssetSourceBuilders,
+};
+use bevy_ecs::system::Resource;
+use std::path::{Path, PathBuf};
+
+pub const EMBEDDED: &str = "embedded";
+
+/// A [`Resource`] that manages "rust source files" in a virtual in memory [`Dir`], which is intended
+/// to be shared with a [`MemoryAssetReader`].
+/// Generally this should not be interacted with directly. The [`embedded_asset`] will populate this.
+#[derive(Resource, Default)]
+pub struct EmbeddedAssetRegistry {
+    dir: Dir,
+    #[cfg(feature = "embedded_watcher")]
+    root_paths: std::sync::Arc<
+        parking_lot::RwLock<bevy_utils::HashMap<std::path::PathBuf, std::path::PathBuf>>,
+    >,
+}
+
+impl EmbeddedAssetRegistry {
+    /// Inserts a new asset. `full_path` is the full path (as [`file`] would return for that file, if it was capable of
+    /// running in a non-rust file). `asset_path` is the path that will be used to identify the asset in the `embedded`
+    /// [`AssetSource`]. `value` is the bytes that will be returned for the asset. This can be _either_ a `&'static [u8]`
+    /// or a [`Vec<u8>`].
+    #[allow(unused)]
+    pub fn insert_asset(&self, full_path: PathBuf, asset_path: &Path, value: impl Into<Value>) {
+        #[cfg(feature = "embedded_watcher")]
+        self.root_paths
+            .write()
+            .insert(full_path.to_owned(), asset_path.to_owned());
+        self.dir.insert_asset(asset_path, value);
+    }
+
+    /// Inserts new asset metadata. `full_path` is the full path (as [`file`] would return for that file, if it was capable of
+    /// running in a non-rust file). `asset_path` is the path that will be used to identify the asset in the `embedded`
+    /// [`AssetSource`]. `value` is the bytes that will be returned for the asset. This can be _either_ a `&'static [u8]`
+    /// or a [`Vec<u8>`].
+    #[allow(unused)]
+    pub fn insert_meta(&self, full_path: &Path, asset_path: &Path, value: impl Into<Value>) {
+        #[cfg(feature = "embedded_watcher")]
+        self.root_paths
+            .write()
+            .insert(full_path.to_owned(), asset_path.to_owned());
+        self.dir.insert_meta(asset_path, value);
+    }
+
+    /// Registers a `embedded` [`AssetSource`] that uses this [`EmbeddedAssetRegistry`].
+    // NOTE: unused_mut because embedded_watcher feature is the only mutable consumer of `let mut source`
+    #[allow(unused_mut)]
+    pub fn register_source(&self, sources: &mut AssetSourceBuilders) {
+        let dir = self.dir.clone();
+        let processed_dir = self.dir.clone();
+        let mut source = AssetSource::build()
+            .with_reader(move || Box::new(MemoryAssetReader { root: dir.clone() }))
+            .with_processed_reader(move || {
+                Box::new(MemoryAssetReader {
+                    root: processed_dir.clone(),
+                })
+            });
+
+        #[cfg(feature = "embedded_watcher")]
+        {
+            let root_paths = self.root_paths.clone();
+            let dir = self.dir.clone();
+            let processed_root_paths = self.root_paths.clone();
+            let processd_dir = self.dir.clone();
+            source = source
+                .with_watcher(move |sender| {
+                    Some(Box::new(EmbeddedWatcher::new(
+                        dir.clone(),
+                        root_paths.clone(),
+                        sender,
+                        std::time::Duration::from_millis(300),
+                    )))
+                })
+                .with_processed_watcher(move |sender| {
+                    Some(Box::new(EmbeddedWatcher::new(
+                        processd_dir.clone(),
+                        processed_root_paths.clone(),
+                        sender,
+                        std::time::Duration::from_millis(300),
+                    )))
+                });
+        }
+        sources.insert(EMBEDDED, source);
+    }
+}
+
+/// Returns the [`Path`] for a given `embedded` asset.
+/// This is used internally by [`embedded_asset`] and can be used to get a [`Path`]
+/// that matches the [`AssetPath`](crate::AssetPath) used by that asset.
+#[macro_export]
+macro_rules! embedded_path {
+    ($path_str: expr) => {{
+        embedded_path!("/src/", $path_str)
+    }};
+
+    ($source_path: expr, $path_str: expr) => {{
+        let crate_name = module_path!().split(':').next().unwrap();
+        let after_src = file!().split($source_path).nth(1).unwrap();
+        let file_path = std::path::Path::new(after_src)
+            .parent()
+            .unwrap()
+            .join($path_str);
+        std::path::Path::new(crate_name).join(file_path)
+    }};
+}
+
+/// Creates a new `embedded` asset by embedding the bytes of the given path into the current binary
+/// and registering those bytes with the `embedded` [`AssetSource`].
+///
+/// This accepts the current [`App`](bevy_app::App) as the first parameter and a path `&str` (relative to the current file) as the second.
+///
+/// By default this will generate an [`AssetPath`] using the following rules:
+///
+/// 1. Search for the first `$crate_name/src/` in the path and trim to the path past that point.
+/// 2. Re-add the current `$crate_name` to the front of the path
+///
+/// For example, consider the following file structure in the theoretical `bevy_rock` crate, which provides a Bevy [`Plugin`](bevy_app::Plugin)
+/// that renders fancy rocks for scenes.
+///
+/// * `bevy_rock`
+///     * `src`
+///         * `render`
+///             * `rock.wgsl`
+///             * `mod.rs`
+///         * `lib.rs`
+///     * `Cargo.toml`
+///
+/// `rock.wgsl` is a WGSL shader asset that the `bevy_rock` plugin author wants to bundle with their crate. They invoke the following
+/// in `bevy_rock/src/render/mod.rs`:
+///
+/// `embedded_asset!(app, "rock.wgsl")`
+///
+/// `rock.wgsl` can now be loaded by the [`AssetServer`](crate::AssetServer) with the following path:
+///
+/// ```no_run
+/// # use bevy_asset::{Asset, AssetServer};
+/// # use bevy_reflect::TypePath;
+/// # let asset_server: AssetServer = panic!();
+/// #[derive(Asset, TypePath)]
+/// # struct Shader;
+/// let shader = asset_server.load::<Shader>("embedded://bevy_rock/render/rock.wgsl");
+/// ```
+///
+/// Some things to note in the path:
+/// 1. The non-default `embedded:://` [`AssetSource`]
+/// 2. `src` is trimmed from the path
+///
+/// The default behavior also works for cargo workspaces. Pretend the `bevy_rock` crate now exists in a larger workspace in
+/// `$SOME_WORKSPACE/crates/bevy_rock`. The asset path would remain the same, because [`embedded_asset`] searches for the
+/// _first instance_ of `bevy_rock/src` in the path.
+///
+/// For most "standard crate structures" the default works just fine. But for some niche cases (such as cargo examples),
+/// the `src` path will not be present. You can override this behavior by adding it as the second argument to [`embedded_asset`]:
+///
+/// `embedded_asset!(app, "/examples/rock_stuff/", "rock.wgsl")`
+///
+/// When there are three arguments, the second argument will replace the default `/src/` value. Note that these two are
+/// equivalent:
+///
+/// `embedded_asset!(app, "rock.wgsl")`
+/// `embedded_asset!(app, "/src/", "rock.wgsl")`
+///
+/// This macro uses the [`include_bytes`] macro internally and _will not_ reallocate the bytes.
+/// Generally the [`AssetPath`] generated will be predictable, but if your asset isn't
+/// available for some reason, you can use the [`embedded_path`] macro to debug.
+///
+/// Hot-reloading `embedded` assets is supported. Just enable the `embedded_watcher` cargo feature.
+///
+/// [`AssetPath`]: crate::AssetPath
+#[macro_export]
+macro_rules! embedded_asset {
+    ($app: ident, $path: expr) => {{
+        embedded_asset!($app, "/src/", $path)
+    }};
+
+    ($app: ident, $source_path: expr, $path: expr) => {{
+        let mut embedded = $app
+            .world
+            .resource_mut::<$crate::io::embedded::EmbeddedAssetRegistry>();
+        let path = $crate::embedded_path!($source_path, $path);
+        #[cfg(feature = "embedded_watcher")]
+        let full_path = std::path::Path::new(file!()).parent().unwrap().join($path);
+        #[cfg(not(feature = "embedded_watcher"))]
+        let full_path = std::path::PathBuf::new();
+        embedded.insert_asset(full_path, &path, include_bytes!($path));
+    }};
+}
+
+/// Loads an "internal" asset by embedding the string stored in the given `path_str` and associates it with the given handle.
+#[macro_export]
+macro_rules! load_internal_asset {
+    ($app: ident, $handle: expr, $path_str: expr, $loader: expr) => {{
+        let mut assets = $app.world.resource_mut::<$crate::Assets<_>>();
+        assets.insert($handle, ($loader)(
+            include_str!($path_str),
+            std::path::Path::new(file!())
+                .parent()
+                .unwrap()
+                .join($path_str)
+                .to_string_lossy()
+        ));
+    }};
+    // we can't support params without variadic arguments, so internal assets with additional params can't be hot-reloaded
+    ($app: ident, $handle: ident, $path_str: expr, $loader: expr $(, $param:expr)+) => {{
+        let mut assets = $app.world.resource_mut::<$crate::Assets<_>>();
+        assets.insert($handle, ($loader)(
+            include_str!($path_str),
+            std::path::Path::new(file!())
+                .parent()
+                .unwrap()
+                .join($path_str)
+                .to_string_lossy(),
+            $($param),+
+        ));
+    }};
+}
+
+/// Loads an "internal" binary asset by embedding the bytes stored in the given `path_str` and associates it with the given handle.
+#[macro_export]
+macro_rules! load_internal_binary_asset {
+    ($app: ident, $handle: expr, $path_str: expr, $loader: expr) => {{
+        let mut assets = $app.world.resource_mut::<$crate::Assets<_>>();
+        assets.insert(
+            $handle,
+            ($loader)(
+                include_bytes!($path_str).as_ref(),
+                std::path::Path::new(file!())
+                    .parent()
+                    .unwrap()
+                    .join($path_str)
+                    .to_string_lossy()
+                    .into(),
+            ),
+        );
+    }};
+}