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add ability to provide custom a AssetIo implementation (#1037)
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make it easier to override the default asset IO instance
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blunted2night authored Dec 18, 2020
1 parent 841755a commit 596bed8
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Showing 4 changed files with 146 additions and 22 deletions.
4 changes: 4 additions & 0 deletions Cargo.toml
Original file line number Diff line number Diff line change
Expand Up @@ -177,6 +177,10 @@ path = "examples/asset/asset_loading.rs"
name = "custom_asset"
path = "examples/asset/custom_asset.rs"

[[example]]
name = "custom_asset_io"
path = "examples/asset/custom_asset_io.rs"

[[example]]
name = "audio"
path = "examples/audio/audio.rs"
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6 changes: 5 additions & 1 deletion crates/bevy_asset/src/asset_server.rs
Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,10 @@ impl Clone for AssetServer {

impl AssetServer {
pub fn new<T: AssetIo>(source_io: T, task_pool: TaskPool) -> Self {
Self::with_boxed_io(Box::new(source_io), task_pool)
}

pub fn with_boxed_io(asset_io: Box<dyn AssetIo>, task_pool: TaskPool) -> Self {
AssetServer {
server: Arc::new(AssetServerInternal {
loaders: Default::default(),
Expand All @@ -69,7 +73,7 @@ impl AssetServer {
handle_to_path: Default::default(),
asset_lifecycles: Default::default(),
task_pool,
asset_io: Box::new(source_io),
asset_io,
}),
}
}
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54 changes: 33 additions & 21 deletions crates/bevy_asset/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -51,28 +51,41 @@ impl Default for AssetServerSettings {
}
}

/// Create an instance of the platform default `AssetIo`
///
/// This is useful when providing a custom `AssetIo` instance that needs to
/// delegate to the default `AssetIo` for the platform.
pub fn create_platform_default_asset_io(app: &mut AppBuilder) -> Box<dyn AssetIo> {
let settings = app
.resources_mut()
.get_or_insert_with(AssetServerSettings::default);

#[cfg(all(not(target_arch = "wasm32"), not(target_os = "android")))]
let source = FileAssetIo::new(&settings.asset_folder);
#[cfg(target_arch = "wasm32")]
let source = WasmAssetIo::new(&settings.asset_folder);
#[cfg(target_os = "android")]
let source = AndroidAssetIo::new(&settings.asset_folder);

Box::new(source)
}

impl Plugin for AssetPlugin {
fn build(&self, app: &mut AppBuilder) {
let task_pool = app
.resources()
.get::<IoTaskPool>()
.expect("`IoTaskPool` resource not found.")
.0
.clone();

let asset_server = {
let settings = app
.resources_mut()
.get_or_insert_with(AssetServerSettings::default);

#[cfg(all(not(target_arch = "wasm32"), not(target_os = "android")))]
let source = FileAssetIo::new(&settings.asset_folder);
#[cfg(target_arch = "wasm32")]
let source = WasmAssetIo::new(&settings.asset_folder);
#[cfg(target_os = "android")]
let source = AndroidAssetIo::new(&settings.asset_folder);
AssetServer::new(source, task_pool)
};
if app.resources().get::<AssetServer>().is_none() {
let task_pool = app
.resources()
.get::<IoTaskPool>()
.expect("`IoTaskPool` resource not found.")
.0
.clone();

let source = create_platform_default_asset_io(app);

let asset_server = AssetServer::with_boxed_io(source, task_pool);

app.add_resource(asset_server);
}

app.add_stage_before(
bevy_app::stage::PRE_UPDATE,
Expand All @@ -84,7 +97,6 @@ impl Plugin for AssetPlugin {
stage::ASSET_EVENTS,
SystemStage::parallel(),
)
.add_resource(asset_server)
.register_type::<HandleId>()
.add_system_to_stage(
bevy_app::stage::PRE_UPDATE,
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104 changes: 104 additions & 0 deletions examples/asset/custom_asset_io.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,104 @@
use bevy::{
asset::{AssetIo, AssetIoError},
prelude::*,
utils::BoxedFuture,
};
use std::path::{Path, PathBuf};

/// A custom asset io implementation that simply defers to the platform default
/// implementation.
///
/// This can be used as a starting point for developing a useful implementation
/// that can defer to the default when needed.
struct CustomAssetIo(Box<dyn AssetIo>);

impl AssetIo for CustomAssetIo {
fn load_path<'a>(&'a self, path: &'a Path) -> BoxedFuture<'a, Result<Vec<u8>, AssetIoError>> {
println!("load_path({:?})", path);
self.0.load_path(path)
}

fn read_directory(
&self,
path: &Path,
) -> Result<Box<dyn Iterator<Item = PathBuf>>, AssetIoError> {
println!("read_directory({:?})", path);
self.0.read_directory(path)
}

fn is_directory(&self, path: &Path) -> bool {
println!("is_directory({:?})", path);
self.0.is_directory(path)
}

fn watch_path_for_changes(&self, path: &Path) -> Result<(), AssetIoError> {
println!("watch_path_for_changes({:?})", path);
self.0.watch_path_for_changes(path)
}

fn watch_for_changes(&self) -> Result<(), AssetIoError> {
println!("watch_for_changes()");
self.0.watch_for_changes()
}
}

/// A plugin used to execute the override of the asset io
struct CustomAssetIoPlugin;

impl Plugin for CustomAssetIoPlugin {
fn build(&self, app: &mut AppBuilder) {
// must get a hold of the task pool in order to create the asset server

let task_pool = app
.resources()
.get::<bevy::tasks::IoTaskPool>()
.expect("`IoTaskPool` resource not found.")
.0
.clone();

let asset_io = {
// the platform default asset io requires a reference to the app
// builder to find its configuration

let default_io = bevy::asset::create_platform_default_asset_io(app);

// create the custom asset io instance

CustomAssetIo(default_io)
};

// the asset server is constructed and added the resource manager

app.add_resource(AssetServer::new(asset_io, task_pool));
}
}

fn main() {
App::build()
.add_plugins_with(DefaultPlugins, |group| {
// the custom asset io plugin must be inserted in-between the
// `CorePlugin' and `AssetPlugin`. It needs to be after the
// CorePlugin, so that the IO task pool has already been constructed.
// And it must be before the `AssetPlugin` so that the asset plugin
// doesn't create another instance of an assert server. In general,
// the AssetPlugin should still run so that other aspects of the
// asset system are initialized correctly.
group.add_before::<bevy::asset::AssetPlugin, _>(CustomAssetIoPlugin)
})
.add_startup_system(setup)
.run();
}

fn setup(
commands: &mut Commands,
asset_server: Res<AssetServer>,
mut materials: ResMut<Assets<ColorMaterial>>,
) {
let texture_handle = asset_server.load("branding/icon.png");
commands
.spawn(Camera2dBundle::default())
.spawn(SpriteBundle {
material: materials.add(texture_handle.into()),
..Default::default()
});
}

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