asset: WasmAssetIo (#703)

asset: WasmAssetIo

Author: cart

crates/bevy_asset/Cargo.toml

@@ -37,3 +37,10 @@ log = { version = "0.4", features = ["release_max_level_info"] }
 notify = { version = "5.0.0-pre.2", optional = true }
 parking_lot = "0.11.0"
 rand = "0.7.3"
+async-trait = "0.1.40"
+
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+wasm-bindgen = { version = "0.2" }
+web-sys = { version = "0.3", features = ["Request", "Window", "Response"]}
+wasm-bindgen-futures = "0.4"
+js-sys = "0.3"

crates/bevy_asset/src/asset_server.rs

@@ -1,8 +1,8 @@
 use crate::{
     path::{AssetPath, AssetPathId, SourcePathId},
     Asset, AssetIo, AssetIoError, AssetLifecycle, AssetLifecycleChannel, AssetLifecycleEvent,
-    AssetLoader, Assets, FileAssetIo, Handle, HandleId, HandleUntyped, LabelId, LoadContext,
-    LoadState, RefChange, RefChangeChannel, SourceInfo, SourceMeta,
+    AssetLoader, Assets, Handle, HandleId, HandleUntyped, LabelId, LoadContext, LoadState,
+    RefChange, RefChangeChannel, SourceInfo, SourceMeta,
 };
 use anyhow::Result;
 use bevy_ecs::Res;
@@ -35,8 +35,8 @@ pub(crate) struct AssetRefCounter {
     pub(crate) ref_counts: Arc<RwLock<HashMap<HandleId, usize>>>,
 }
 
-pub struct AssetServerInternal<TAssetIo: AssetIo = FileAssetIo> {
-    pub(crate) asset_io: TAssetIo,
+pub struct AssetServerInternal {
+    pub(crate) asset_io: Box<dyn AssetIo>,
     pub(crate) asset_ref_counter: AssetRefCounter,
     pub(crate) asset_sources: Arc<RwLock<HashMap<SourcePathId, SourceInfo>>>,
     pub(crate) asset_lifecycles: Arc<RwLock<HashMap<Uuid, Box<dyn AssetLifecycle>>>>,
@@ -47,20 +47,20 @@ pub struct AssetServerInternal<TAssetIo: AssetIo = FileAssetIo> {
 }
 
 /// Loads assets from the filesystem on background threads
-pub struct AssetServer<TAssetIo: AssetIo = FileAssetIo> {
-    pub(crate) server: Arc<AssetServerInternal<TAssetIo>>,
+pub struct AssetServer {
+    pub(crate) server: Arc<AssetServerInternal>,
 }
 
-impl<TAssetIo: AssetIo> Clone for AssetServer<TAssetIo> {
+impl Clone for AssetServer {
     fn clone(&self) -> Self {
         Self {
             server: self.server.clone(),
         }
     }
 }
 
-impl<TAssetIo: AssetIo> AssetServer<TAssetIo> {
-    pub fn new(source_io: TAssetIo, task_pool: TaskPool) -> Self {
+impl AssetServer {
+    pub fn new<T: AssetIo>(source_io: T, task_pool: TaskPool) -> Self {
         AssetServer {
             server: Arc::new(AssetServerInternal {
                 loaders: Default::default(),
@@ -70,7 +70,7 @@ impl<TAssetIo: AssetIo> AssetServer<TAssetIo> {
                 handle_to_path: Default::default(),
                 asset_lifecycles: Default::default(),
                 task_pool,
-                asset_io: source_io,
+                asset_io: Box::new(source_io),
             }),
         }
     }
@@ -180,7 +180,7 @@ impl<TAssetIo: AssetIo> AssetServer<TAssetIo> {
     }
 
     // TODO: properly set failed LoadState in all failure cases
-    fn load_sync<'a, P: Into<AssetPath<'a>>>(
+    async fn load_async<'a, P: Into<AssetPath<'a>>>(
         &self,
         path: P,
         force: bool,
@@ -221,17 +221,18 @@ impl<TAssetIo: AssetIo> AssetServer<TAssetIo> {
         };
 
         // load the asset bytes
-        let bytes = self.server.asset_io.load_path(asset_path.path())?;
+        let bytes = self.server.asset_io.load_path(asset_path.path()).await?;
 
         // load the asset source using the corresponding AssetLoader
         let mut load_context = LoadContext::new(
             asset_path.path(),
             &self.server.asset_ref_counter.channel,
-            &self.server.asset_io,
+            &*self.server.asset_io,
             version,
         );
         asset_loader
             .load(&bytes, &mut load_context)
+            .await
             .map_err(AssetServerError::AssetLoaderError)?;
 
         // if version has changed since we loaded and grabbed a lock, return. theres is a newer version being loaded
@@ -291,7 +292,7 @@ impl<TAssetIo: AssetIo> AssetServer<TAssetIo> {
         self.server
             .task_pool
             .spawn(async move {
-                server.load_sync(owned_path, force).unwrap();
+                server.load_async(owned_path, force).await.unwrap();
             })
             .detach();
         asset_path.into()

crates/bevy_asset/src/io.rs renamed to crates/bevy_asset/src/io/file_asset_io.rs

@@ -1,4 +1,6 @@
+use crate::{filesystem_watcher::FilesystemWatcher, AssetIo, AssetIoError, AssetServer};
 use anyhow::Result;
+use async_trait::async_trait;
 use bevy_ecs::Res;
 use bevy_utils::HashSet;
 use crossbeam_channel::TryRecvError;
@@ -10,33 +12,6 @@ use std::{
     path::{Path, PathBuf},
     sync::Arc,
 };
-use thiserror::Error;
-
-use crate::{filesystem_watcher::FilesystemWatcher, AssetServer};
-
-/// Errors that occur while loading assets
-#[derive(Error, Debug)]
-pub enum AssetIoError {
-    #[error("Path not found")]
-    NotFound(PathBuf),
-    #[error("Encountered an io error while loading asset.")]
-    Io(#[from] io::Error),
-    #[error("Failed to watch path")]
-    PathWatchError(PathBuf),
-}
-
-/// Handles load requests from an AssetServer
-pub trait AssetIo: Send + Sync + 'static {
-    fn load_path(&self, path: &Path) -> Result<Vec<u8>, AssetIoError>;
-    fn save_path(&self, path: &Path, bytes: &[u8]) -> Result<(), AssetIoError>;
-    fn read_directory(
-        &self,
-        path: &Path,
-    ) -> Result<Box<dyn Iterator<Item = PathBuf>>, AssetIoError>;
-    fn is_directory(&self, path: &Path) -> bool;
-    fn watch_path_for_changes(&self, path: &Path) -> Result<(), AssetIoError>;
-    fn watch_for_changes(&self) -> Result<(), AssetIoError>;
-}
 
 pub struct FileAssetIo {
     root_path: PathBuf,
@@ -67,8 +42,9 @@ impl FileAssetIo {
     }
 }
 
+#[async_trait]
 impl AssetIo for FileAssetIo {
-    fn load_path(&self, path: &Path) -> Result<Vec<u8>, AssetIoError> {
+    async fn load_path(&self, path: &Path) -> Result<Vec<u8>, AssetIoError> {
         let mut bytes = Vec::new();
         match File::open(self.root_path.join(path)) {
             Ok(mut file) => {
@@ -98,15 +74,6 @@ impl AssetIo for FileAssetIo {
         )))
     }
 
-    fn save_path(&self, path: &Path, bytes: &[u8]) -> Result<(), AssetIoError> {
-        let path = self.root_path.join(path);
-        if let Some(parent_path) = path.parent() {
-            fs::create_dir_all(parent_path)?;
-        }
-
-        Ok(fs::write(self.root_path.join(path), bytes)?)
-    }
-
     fn watch_path_for_changes(&self, path: &Path) -> Result<(), AssetIoError> {
         #[cfg(feature = "filesystem_watcher")]
         {
@@ -139,7 +106,13 @@ impl AssetIo for FileAssetIo {
 #[cfg(feature = "filesystem_watcher")]
 pub fn filesystem_watcher_system(asset_server: Res<AssetServer>) {
     let mut changed = HashSet::default();
-    let watcher = asset_server.server.asset_io.filesystem_watcher.read();
+    let asset_io =
+        if let Some(asset_io) = asset_server.server.asset_io.downcast_ref::<FileAssetIo>() {
+            asset_io
+        } else {
+            return;
+        };
+    let watcher = asset_io.filesystem_watcher.read();
     if let Some(ref watcher) = *watcher {
         loop {
             let event = match watcher.receiver.try_recv() {
@@ -155,9 +128,7 @@ pub fn filesystem_watcher_system(asset_server: Res<AssetServer>) {
             {
                 for path in paths.iter() {
                     if !changed.contains(path) {
-                        let relative_path = path
-                            .strip_prefix(&asset_server.server.asset_io.root_path)
-                            .unwrap();
+                        let relative_path = path.strip_prefix(&asset_io.root_path).unwrap();
                         let _ = asset_server.load_untracked(relative_path, true);
                     }
                 }

crates/bevy_asset/src/io/mod.rs

@@ -0,0 +1,45 @@
+#[cfg(not(target_arch = "wasm32"))]
+mod file_asset_io;
+#[cfg(target_arch = "wasm32")]
+mod wasm_asset_io;
+
+#[cfg(not(target_arch = "wasm32"))]
+pub use file_asset_io::*;
+#[cfg(target_arch = "wasm32")]
+pub use wasm_asset_io::*;
+
+use anyhow::Result;
+use async_trait::async_trait;
+use downcast_rs::{impl_downcast, Downcast};
+use std::{
+    io,
+    path::{Path, PathBuf},
+};
+use thiserror::Error;
+
+/// Errors that occur while loading assets
+#[derive(Error, Debug)]
+pub enum AssetIoError {
+    #[error("Path not found")]
+    NotFound(PathBuf),
+    #[error("Encountered an io error while loading asset.")]
+    Io(#[from] io::Error),
+    #[error("Failed to watch path")]
+    PathWatchError(PathBuf),
+}
+
+/// Handles load requests from an AssetServer
+#[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
+#[cfg_attr(not(target_arch = "wasm32"), async_trait)]
+pub trait AssetIo: Downcast + Send + Sync + 'static {
+    async fn load_path(&self, path: &Path) -> Result<Vec<u8>, AssetIoError>;
+    fn read_directory(
+        &self,
+        path: &Path,
+    ) -> Result<Box<dyn Iterator<Item = PathBuf>>, AssetIoError>;
+    fn is_directory(&self, path: &Path) -> bool;
+    fn watch_path_for_changes(&self, path: &Path) -> Result<(), AssetIoError>;
+    fn watch_for_changes(&self) -> Result<(), AssetIoError>;
+}
+
+impl_downcast!(AssetIo);

crates/bevy_asset/src/io/wasm_asset_io.rs

@@ -0,0 +1,54 @@
+use crate::{AssetIo, AssetIoError};
+use anyhow::Result;
+use async_trait::async_trait;
+use js_sys::Uint8Array;
+use std::path::{Path, PathBuf};
+use wasm_bindgen::JsCast;
+use wasm_bindgen_futures::JsFuture;
+use web_sys::Response;
+
+pub struct WasmAssetIo {
+    root_path: PathBuf,
+}
+
+impl WasmAssetIo {
+    pub fn new<P: AsRef<Path>>(path: P) -> Self {
+        WasmAssetIo {
+            root_path: path.as_ref().to_owned(),
+        }
+    }
+}
+
+#[async_trait(?Send)]
+impl AssetIo for WasmAssetIo {
+    async fn load_path(&self, path: &Path) -> Result<Vec<u8>, AssetIoError> {
+        let path = self.root_path.join(path);
+        let window = web_sys::window().unwrap();
+        let resp_value = JsFuture::from(window.fetch_with_str(path.to_str().unwrap()))
+            .await
+            .unwrap();
+        let resp: Response = resp_value.dyn_into().unwrap();
+        let data = JsFuture::from(resp.array_buffer().unwrap()).await.unwrap();
+        let bytes = Uint8Array::new(&data).to_vec();
+        Ok(bytes)
+    }
+
+    fn read_directory(
+        &self,
+        _path: &Path,
+    ) -> Result<Box<dyn Iterator<Item = PathBuf>>, AssetIoError> {
+        Ok(Box::new(std::iter::empty::<PathBuf>()))
+    }
+
+    fn watch_path_for_changes(&self, _path: &Path) -> Result<(), AssetIoError> {
+        Ok(())
+    }
+
+    fn watch_for_changes(&self) -> Result<(), AssetIoError> {
+        Ok(())
+    }
+
+    fn is_directory(&self, path: &Path) -> bool {
+        self.root_path.join(path).is_dir()
+    }
+}

crates/bevy_asset/src/lib.rs

@@ -1,6 +1,6 @@
 mod asset_server;
 mod assets;
-#[cfg(feature = "filesystem_watcher")]
+#[cfg(all(feature = "filesystem_watcher", not(target_arch = "wasm32")))]
 mod filesystem_watcher;
 mod handle;
 mod info;
@@ -37,7 +37,7 @@ use bevy_type_registry::RegisterType;
 pub struct AssetPlugin;
 
 pub struct AssetServerSettings {
-    asset_folder: String,
+    pub asset_folder: String,
 }
 
 impl Default for AssetServerSettings {
@@ -61,7 +61,11 @@ impl Plugin for AssetPlugin {
             let settings = app
                 .resources_mut()
                 .get_or_insert_with(AssetServerSettings::default);
+
+            #[cfg(not(target_arch = "wasm32"))]
             let source = FileAssetIo::new(&settings.asset_folder);
+            #[cfg(target_arch = "wasm32")]
+            let source = WasmAssetIo::new(&settings.asset_folder);
             AssetServer::new(source, task_pool)
         };
 
@@ -74,7 +78,7 @@ impl Plugin for AssetPlugin {
                 asset_server::free_unused_assets_system.system(),
             );
 
-        #[cfg(feature = "filesystem_watcher")]
+        #[cfg(all(feature = "filesystem_watcher", not(target_arch = "wasm32")))]
         app.add_system_to_stage(stage::LOAD_ASSETS, io::filesystem_watcher_system.system());
     }
 }

crates/bevy_asset/src/loader.rs

@@ -5,14 +5,18 @@ use crate::{
 use anyhow::Result;
 use bevy_ecs::{Res, ResMut, Resource};
 use bevy_type_registry::{TypeUuid, TypeUuidDynamic};
-use bevy_utils::HashMap;
+use bevy_utils::{BoxedFuture, HashMap};
 use crossbeam_channel::{Receiver, Sender};
 use downcast_rs::{impl_downcast, Downcast};
 use std::path::Path;
 
 /// A loader for an asset source
 pub trait AssetLoader: Send + Sync + 'static {
-    fn load(&self, bytes: &[u8], load_context: &mut LoadContext) -> Result<(), anyhow::Error>;
+    fn load<'a>(
+        &'a self,
+        bytes: &'a [u8],
+        load_context: &'a mut LoadContext,
+    ) -> BoxedFuture<'a, Result<(), anyhow::Error>>;
     fn extensions(&self) -> &[&str];
 }
 
@@ -94,8 +98,8 @@ impl<'a> LoadContext<'a> {
         Handle::strong(id.into(), self.ref_change_channel.sender.clone())
     }
 
-    pub fn read_asset_bytes<P: AsRef<Path>>(&self, path: P) -> Result<Vec<u8>, AssetIoError> {
-        self.asset_io.load_path(path.as_ref())
+    pub async fn read_asset_bytes<P: AsRef<Path>>(&self, path: P) -> Result<Vec<u8>, AssetIoError> {
+        self.asset_io.load_path(path.as_ref()).await
     }
 
     pub fn get_asset_metas(&self) -> Vec<AssetMeta> {

crates/bevy_audio/Cargo.toml

@@ -18,6 +18,7 @@ bevy_app = { path = "../bevy_app", version = "0.2.1" }
 bevy_asset = { path = "../bevy_asset", version = "0.2.1" }
 bevy_ecs = { path = "../bevy_ecs", version = "0.2.1" }
 bevy_type_registry = { path = "../bevy_type_registry", version = "0.2.1" }
+bevy_utils = { path = "../bevy_utils", version = "0.2.1" }
 
 # other
 anyhow = "1.0"