40 commits

Author	SHA1	Message	Date
Kanabenki	ec34fe01d1	Finish documenting bevy_scene (#9949) ... # Objective Finish documenting `bevy_scene`. ## Solution Document the remaining items and add a crate-level `warn(missing_doc)` attribute as for the other crates with completed documentation.	2023-10-01 17:54:19 +00:00
Carter Anderson	5eb292dc10	Bevy Asset V2 (#8624) ... # Bevy Asset V2 Proposal ## Why Does Bevy Need A New Asset System? Asset pipelines are a central part of the gamedev process. Bevy's current asset system is missing a number of features that make it non-viable for many classes of gamedev. After plenty of discussions and [a long community feedback period](https://github.com/bevyengine/bevy/discussions/3972), we've identified a number missing features: * **Asset Preprocessing**: it should be possible to "preprocess" / "compile" / "crunch" assets at "development time" rather than when the game starts up. This enables offloading expensive work from deployed apps, faster asset loading, less runtime memory usage, etc. * **Per-Asset Loader Settings**: Individual assets cannot define their own loaders that override the defaults. Additionally, they cannot provide per-asset settings to their loaders. This is a huge limitation, as many asset types don't provide all information necessary for Bevy _inside_ the asset. For example, a raw PNG image says nothing about how it should be sampled (ex: linear vs nearest). * **Asset `.meta` files**: assets should have configuration files stored adjacent to the asset in question, which allows the user to configure asset-type-specific settings. These settings should be accessible during the pre-processing phase. Modifying a `.meta` file should trigger a re-processing / re-load of the asset. It should be possible to configure asset loaders from the meta file. * **Processed Asset Hot Reloading**: Changes to processed assets (or their dependencies) should result in re-processing them and re-loading the results in live Bevy Apps. * **Asset Dependency Tracking**: The current bevy_asset has no good way to wait for asset dependencies to load. It punts this as an exercise for consumers of the loader apis, which is unreasonable and error prone. There should be easy, ergonomic ways to wait for assets to load and block some logic on an asset's entire dependency tree loading. * **Runtime Asset Loading**: it should be (optionally) possible to load arbitrary assets dynamically at runtime. This necessitates being able to deploy and run the asset server alongside Bevy Apps on _all platforms_. For example, we should be able to invoke the shader compiler at runtime, stream scenes from sources like the internet, etc. To keep deployed binaries (and startup times) small, the runtime asset server configuration should be configurable with different settings compared to the "pre processor asset server". * **Multiple Backends**: It should be possible to load assets from arbitrary sources (filesystems, the internet, remote asset serves, etc). * **Asset Packing**: It should be possible to deploy assets in compressed "packs", which makes it easier and more efficient to distribute assets with Bevy Apps. * **Asset Handoff**: It should be possible to hold a "live" asset handle, which correlates to runtime data, without actually holding the asset in memory. Ex: it must be possible to hold a reference to a GPU mesh generated from a "mesh asset" without keeping the mesh data in CPU memory * **Per-Platform Processed Assets**: Different platforms and app distributions have different capabilities and requirements. Some platforms need lower asset resolutions or different asset formats to operate within the hardware constraints of the platform. It should be possible to define per-platform asset processing profiles. And it should be possible to deploy only the assets required for a given platform. These features have architectural implications that are significant enough to require a full rewrite. The current Bevy Asset implementation got us this far, but it can take us no farther. This PR defines a brand new asset system that implements most of these features, while laying the foundations for the remaining features to be built. ## Bevy Asset V2 Here is a quick overview of the features introduced in this PR. * **Asset Preprocessing**: Preprocess assets at development time into more efficient (and configurable) representations * **Dependency Aware**: Dependencies required to process an asset are tracked. If an asset's processed dependency changes, it will be reprocessed * **Hot Reprocessing/Reloading**: detect changes to asset source files, reprocess them if they have changed, and then hot-reload them in Bevy Apps. * **Only Process Changes**: Assets are only re-processed when their source file (or meta file) has changed. This uses hashing and timestamps to avoid processing assets that haven't changed. * **Transactional and Reliable**: Uses write-ahead logging (a technique commonly used by databases) to recover from crashes / forced-exits. Whenever possible it avoids full-reprocessing / only uncompleted transactions will be reprocessed. When the processor is running in parallel with a Bevy App, processor asset writes block Bevy App asset reads. Reading metadata + asset bytes is guaranteed to be transactional / correctly paired. * **Portable / Run anywhere / Database-free**: The processor does not rely on an in-memory database (although it uses some database techniques for reliability). This is important because pretty much all in-memory databases have unsupported platforms or build complications. * **Configure Processor Defaults Per File Type**: You can say "use this processor for all files of this type". * **Custom Processors**: The `Processor` trait is flexible and unopinionated. It can be implemented by downstream plugins. * **LoadAndSave Processors**: Most asset processing scenarios can be expressed as "run AssetLoader A, save the results using AssetSaver X, and then load the result using AssetLoader B". For example, load this png image using `PngImageLoader`, which produces an `Image` asset and then save it using `CompressedImageSaver` (which also produces an `Image` asset, but in a compressed format), which takes an `Image` asset as input. This means if you have an `AssetLoader` for an asset, you are already half way there! It also means that you can share AssetSavers across multiple loaders. Because `CompressedImageSaver` accepts Bevy's generic Image asset as input, it means you can also use it with some future `JpegImageLoader`. * **Loader and Saver Settings**: Asset Loaders and Savers can now define their own settings types, which are passed in as input when an asset is loaded / saved. Each asset can define its own settings. * **Asset `.meta` files**: configure asset loaders, their settings, enable/disable processing, and configure processor settings * **Runtime Asset Dependency Tracking** Runtime asset dependencies (ex: if an asset contains a `Handle<Image>`) are tracked by the asset server. An event is emitted when an asset and all of its dependencies have been loaded * **Unprocessed Asset Loading**: Assets do not require preprocessing. They can be loaded directly. A processed asset is just a "normal" asset with some extra metadata. Asset Loaders don't need to know or care about whether or not an asset was processed. * **Async Asset IO**: Asset readers/writers use async non-blocking interfaces. Note that because Rust doesn't yet support async traits, there is a bit of manual Boxing / Future boilerplate. This will hopefully be removed in the near future when Rust gets async traits. * **Pluggable Asset Readers and Writers**: Arbitrary asset source readers/writers are supported, both by the processor and the asset server. * **Better Asset Handles** * **Single Arc Tree**: Asset Handles now use a single arc tree that represents the lifetime of the asset. This makes their implementation simpler, more efficient, and allows us to cheaply attach metadata to handles. Ex: the AssetPath of a handle is now directly accessible on the handle itself! * **Const Typed Handles**: typed handles can be constructed in a const context. No more weird "const untyped converted to typed at runtime" patterns! * **Handles and Ids are Smaller / Faster To Hash / Compare**: Typed `Handle<T>` is now much smaller in memory and `AssetId<T>` is even smaller. * **Weak Handle Usage Reduction**: In general Handles are now considered to be "strong". Bevy features that previously used "weak `Handle<T>`" have been ported to `AssetId<T>`, which makes it statically clear that the features do not hold strong handles (while retaining strong type information). Currently Handle::Weak still exists, but it is very possible that we can remove that entirely. * **Efficient / Dense Asset Ids**: Assets now have efficient dense runtime asset ids, which means we can avoid expensive hash lookups. Assets are stored in Vecs instead of HashMaps. There are now typed and untyped ids, which means we no longer need to store dynamic type information in the ID for typed handles. "AssetPathId" (which was a nightmare from a performance and correctness standpoint) has been entirely removed in favor of dense ids (which are retrieved for a path on load) * **Direct Asset Loading, with Dependency Tracking**: Assets that are defined at runtime can still have their dependencies tracked by the Asset Server (ex: if you create a material at runtime, you can still wait for its textures to load). This is accomplished via the (currently optional) "asset dependency visitor" trait. This system can also be used to define a set of assets to load, then wait for those assets to load. * **Async folder loading**: Folder loading also uses this system and immediately returns a handle to the LoadedFolder asset, which means folder loading no longer blocks on directory traversals. * **Improved Loader Interface**: Loaders now have a specific "top level asset type", which makes returning the top-level asset simpler and statically typed. * **Basic Image Settings and Processing**: Image assets can now be processed into the gpu-friendly Basic Universal format. The ImageLoader now has a setting to define what format the image should be loaded as. Note that this is just a minimal MVP ... plenty of additional work to do here. To demo this, enable the `basis-universal` feature and turn on asset processing. * **Simpler Audio Play / AudioSink API**: Asset handle providers are cloneable, which means the Audio resource can mint its own handles. This means you can now do `let sink_handle = audio.play(music)` instead of `let sink_handle = audio_sinks.get_handle(audio.play(music))`. Note that this might still be replaced by https://github.com/bevyengine/bevy/pull/8424. **Removed Handle Casting From Engine Features**: Ex: FontAtlases no longer use casting between handle types ## Using The New Asset System ### Normal Unprocessed Asset Loading By default the `AssetPlugin` does not use processing. It behaves pretty much the same way as the old system. If you are defining a custom asset, first derive `Asset`: ```rust #[derive(Asset)] struct Thing { value: String, } ``` Initialize the asset: ```rust app.init_asset:<Thing>() ``` Implement a new `AssetLoader` for it: ```rust #[derive(Default)] struct ThingLoader; #[derive(Serialize, Deserialize, Default)] pub struct ThingSettings { some_setting: bool, } impl AssetLoader for ThingLoader { type Asset = Thing; type Settings = ThingSettings; fn load<'a>( &'a self, reader: &'a mut Reader, settings: &'a ThingSettings, load_context: &'a mut LoadContext, ) -> BoxedFuture<'a, Result<Thing, anyhow::Error>> { Box::pin(async move { let mut bytes = Vec::new(); reader.read_to_end(&mut bytes).await?; // convert bytes to value somehow Ok(Thing { value }) }) } fn extensions(&self) -> &[&str] { &["thing"] } } ``` Note that this interface will get much cleaner once Rust gets support for async traits. `Reader` is an async futures_io::AsyncRead. You can stream bytes as they come in or read them all into a `Vec<u8>`, depending on the context. You can use `let handle = load_context.load(path)` to kick off a dependency load, retrieve a handle, and register the dependency for the asset. Then just register the loader in your Bevy app: ```rust app.init_asset_loader::<ThingLoader>() ``` Now just add your `Thing` asset files into the `assets` folder and load them like this: ```rust fn system(asset_server: Res<AssetServer>) { let handle = Handle<Thing> = asset_server.load("cool.thing"); } ``` You can check load states directly via the asset server: ```rust if asset_server.load_state(&handle) == LoadState::Loaded { } ``` You can also listen for events: ```rust fn system(mut events: EventReader<AssetEvent<Thing>>, handle: Res<SomeThingHandle>) { for event in events.iter() { if event.is_loaded_with_dependencies(&handle) { } } } ``` Note the new `AssetEvent::LoadedWithDependencies`, which only fires when the asset is loaded _and_ all dependencies (and their dependencies) have loaded. Unlike the old asset system, for a given asset path all `Handle<T>` values point to the same underlying Arc. This means Handles can cheaply hold more asset information, such as the AssetPath: ```rust // prints the AssetPath of the handle info!("{:?}", handle.path()) ``` ### Processed Assets Asset processing can be enabled via the `AssetPlugin`. When developing Bevy Apps with processed assets, do this: ```rust app.add_plugins(DefaultPlugins.set(AssetPlugin::processed_dev())) ``` This runs the `AssetProcessor` in the background with hot-reloading. It reads assets from the `assets` folder, processes them, and writes them to the `.imported_assets` folder. Asset loads in the Bevy App will wait for a processed version of the asset to become available. If an asset in the `assets` folder changes, it will be reprocessed and hot-reloaded in the Bevy App. When deploying processed Bevy apps, do this: ```rust app.add_plugins(DefaultPlugins.set(AssetPlugin::processed())) ``` This does not run the `AssetProcessor` in the background. It behaves like `AssetPlugin::unprocessed()`, but reads assets from `.imported_assets`. When the `AssetProcessor` is running, it will populate sibling `.meta` files for assets in the `assets` folder. Meta files for assets that do not have a processor configured look like this: ```rust ( meta_format_version: "1.0", asset: Load( loader: "bevy_render::texture::image_loader::ImageLoader", settings: ( format: FromExtension, ), ), ) ``` This is metadata for an image asset. For example, if you have `assets/my_sprite.png`, this could be the metadata stored at `assets/my_sprite.png.meta`. Meta files are totally optional. If no metadata exists, the default settings will be used. In short, this file says "load this asset with the ImageLoader and use the file extension to determine the image type". This type of meta file is supported in all AssetPlugin modes. If in `Unprocessed` mode, the asset (with the meta settings) will be loaded directly. If in `ProcessedDev` mode, the asset file will be copied directly to the `.imported_assets` folder. The meta will also be copied directly to the `.imported_assets` folder, but with one addition: ```rust ( meta_format_version: "1.0", processed_info: Some(( hash: 12415480888597742505, full_hash: 14344495437905856884, process_dependencies: [], )), asset: Load( loader: "bevy_render::texture::image_loader::ImageLoader", settings: ( format: FromExtension, ), ), ) ``` `processed_info` contains `hash` (a direct hash of the asset and meta bytes), `full_hash` (a hash of `hash` and the hashes of all `process_dependencies`), and `process_dependencies` (the `path` and `full_hash` of every process_dependency). A "process dependency" is an asset dependency that is _directly_ used when processing the asset. Images do not have process dependencies, so this is empty. When the processor is enabled, you can use the `Process` metadata config: ```rust ( meta_format_version: "1.0", asset: Process( processor: "bevy_asset::processor::process::LoadAndSave<bevy_render::texture::image_loader::ImageLoader, bevy_render::texture::compressed_image_saver::CompressedImageSaver>", settings: ( loader_settings: ( format: FromExtension, ), saver_settings: ( generate_mipmaps: true, ), ), ), ) ``` This configures the asset to use the `LoadAndSave` processor, which runs an AssetLoader and feeds the result into an AssetSaver (which saves the given Asset and defines a loader to load it with). (for terseness LoadAndSave will likely get a shorter/friendlier type name when [Stable Type Paths](#7184) lands). `LoadAndSave` is likely to be the most common processor type, but arbitrary processors are supported. `CompressedImageSaver` saves an `Image` in the Basis Universal format and configures the ImageLoader to load it as basis universal. The `AssetProcessor` will read this meta, run it through the LoadAndSave processor, and write the basis-universal version of the image to `.imported_assets`. The final metadata will look like this: ```rust ( meta_format_version: "1.0", processed_info: Some(( hash: 905599590923828066, full_hash: 9948823010183819117, process_dependencies: [], )), asset: Load( loader: "bevy_render::texture::image_loader::ImageLoader", settings: ( format: Format(Basis), ), ), ) ``` To try basis-universal processing out in Bevy examples, (for example `sprite.rs`), change `add_plugins(DefaultPlugins)` to `add_plugins(DefaultPlugins.set(AssetPlugin::processed_dev()))` and run with the `basis-universal` feature enabled: `cargo run --features=basis-universal --example sprite`. To create a custom processor, there are two main paths: 1. Use the `LoadAndSave` processor with an existing `AssetLoader`. Implement the `AssetSaver` trait, register the processor using `asset_processor.register_processor::<LoadAndSave<ImageLoader, CompressedImageSaver>>(image_saver.into())`. 2. Implement the `Process` trait directly and register it using: `asset_processor.register_processor(thing_processor)`. You can configure default processors for file extensions like this: ```rust asset_processor.set_default_processor::<ThingProcessor>("thing") ``` There is one more metadata type to be aware of: ```rust ( meta_format_version: "1.0", asset: Ignore, ) ``` This will ignore the asset during processing / prevent it from being written to `.imported_assets`. The AssetProcessor stores a transaction log at `.imported_assets/log` and uses it to gracefully recover from unexpected stops. This means you can force-quit the processor (and Bevy Apps running the processor in parallel) at arbitrary times! `.imported_assets` is "local state". It should _not_ be checked into source control. It should also be considered "read only". In practice, you _can_ modify processed assets and processed metadata if you really need to test something. But those modifications will not be represented in the hashes of the assets, so the processed state will be "out of sync" with the source assets. The processor _will not_ fix this for you. Either revert the change after you have tested it, or delete the processed files so they can be re-populated. ## Open Questions There are a number of open questions to be discussed. We should decide if they need to be addressed in this PR and if so, how we will address them: ### Implied Dependencies vs Dependency Enumeration There are currently two ways to populate asset dependencies: * **Implied via AssetLoaders**: if an AssetLoader loads an asset (and retrieves a handle), a dependency is added to the list. * **Explicit via the optional Asset::visit_dependencies**: if `server.load_asset(my_asset)` is called, it will call `my_asset.visit_dependencies`, which will grab dependencies that have been manually defined for the asset via the Asset trait impl (which can be derived). This means that defining explicit dependencies is optional for "loaded assets". And the list of dependencies is always accurate because loaders can only produce Handles if they register dependencies. If an asset was loaded with an AssetLoader, it only uses the implied dependencies. If an asset was created at runtime and added with `asset_server.load_asset(MyAsset)`, it will use `Asset::visit_dependencies`. However this can create a behavior mismatch between loaded assets and equivalent "created at runtime" assets if `Assets::visit_dependencies` doesn't exactly match the dependencies produced by the AssetLoader. This behavior mismatch can be resolved by completely removing "implied loader dependencies" and requiring `Asset::visit_dependencies` to supply dependency data. But this creates two problems: * It makes defining loaded assets harder and more error prone: Devs must remember to manually annotate asset dependencies with `#[dependency]` when deriving `Asset`. For more complicated assets (such as scenes), the derive likely wouldn't be sufficient and a manual `visit_dependencies` impl would be required. * Removes the ability to immediately kick off dependency loads: When AssetLoaders retrieve a Handle, they also immediately kick off an asset load for the handle, which means it can start loading in parallel _before_ the asset finishes loading. For large assets, this could be significant. (although this could be mitigated for processed assets if we store dependencies in the processed meta file and load them ahead of time) ### Eager ProcessorDev Asset Loading I made a controversial call in the interest of fast startup times ("time to first pixel") for the "processor dev mode configuration". When initializing the AssetProcessor, current processed versions of unchanged assets are yielded immediately, even if their dependencies haven't been checked yet for reprocessing. This means that non-current-state-of-filesystem-but-previously-valid assets might be returned to the App first, then hot-reloaded if/when their dependencies change and the asset is reprocessed. Is this behavior desirable? There is largely one alternative: do not yield an asset from the processor to the app until all of its dependencies have been checked for changes. In some common cases (load dependency has not changed since last run) this will increase startup time. The main question is "by how much" and is that slower startup time worth it in the interest of only yielding assets that are true to the current state of the filesystem. Should this be configurable? I'm starting to think we should only yield an asset after its (historical) dependencies have been checked for changes + processed as necessary, but I'm curious what you all think. ### Paths Are Currently The Only Canonical ID / Do We Want Asset UUIDs? In this implementation AssetPaths are the only canonical asset identifier (just like the previous Bevy Asset system and Godot). Moving assets will result in re-scans (and currently reprocessing, although reprocessing can easily be avoided with some changes). Asset renames/moves will break code and assets that rely on specific paths, unless those paths are fixed up. Do we want / need "stable asset uuids"? Introducing them is very possible: 1. Generate a UUID and include it in .meta files 2. Support UUID in AssetPath 3. Generate "asset indices" which are loaded on startup and map UUIDs to paths. 4 (maybe). Consider only supporting UUIDs for processed assets so we can generate quick-to-load indices instead of scanning meta files. The main "pro" is that assets referencing UUIDs don't need to be migrated when a path changes. The main "con" is that UUIDs cannot be "lazily resolved" like paths. They need a full view of all assets to answer the question "does this UUID exist". Which means UUIDs require the AssetProcessor to fully finish startup scans before saying an asset doesnt exist. And they essentially require asset pre-processing to use in apps, because scanning all asset metadata files at runtime to resolve a UUID is not viable for medium-to-large apps. It really requires a pre-generated UUID index, which must be loaded before querying for assets. I personally think this should be investigated in a separate PR. Paths aren't going anywhere ... _everyone_ uses filesystems (and filesystem-like apis) to manage their asset source files. I consider them permanent canonical asset information. Additionally, they behave well for both processed and unprocessed asset modes. Given that Bevy is supporting both, this feels like the right canonical ID to start with. UUIDS (and maybe even other indexed-identifier types) can be added later as necessary. ### Folder / File Naming Conventions All asset processing config currently lives in the `.imported_assets` folder. The processor transaction log is in `.imported_assets/log`. Processed assets are added to `.imported_assets/Default`, which will make migrating to processed asset profiles (ex: a `.imported_assets/Mobile` profile) a non-breaking change. It also allows us to create top-level files like `.imported_assets/log` without it being interpreted as an asset. Meta files currently have a `.meta` suffix. Do we like these names and conventions? ### Should the `AssetPlugin::processed_dev` configuration enable `watch_for_changes` automatically? Currently it does (which I think makes sense), but it does make it the only configuration that enables watch_for_changes by default. ### Discuss on_loaded High Level Interface: This PR includes a very rough "proof of concept" `on_loaded` system adapter that uses the `LoadedWithDependencies` event in combination with `asset_server.load_asset` dependency tracking to support this pattern ```rust fn main() { App::new() .init_asset::<MyAssets>() .add_systems(Update, on_loaded(create_array_texture)) .run(); } #[derive(Asset, Clone)] struct MyAssets { #[dependency] picture_of_my_cat: Handle<Image>, #[dependency] picture_of_my_other_cat: Handle<Image>, } impl FromWorld for ArrayTexture { fn from_world(world: &mut World) -> Self { picture_of_my_cat: server.load("meow.png"), picture_of_my_other_cat: server.load("meeeeeeeow.png"), } } fn spawn_cat(In(my_assets): In<MyAssets>, mut commands: Commands) { commands.spawn(SpriteBundle { texture: my_assets.picture_of_my_cat.clone(), ..default() }); commands.spawn(SpriteBundle { texture: my_assets.picture_of_my_other_cat.clone(), ..default() }); } ``` The implementation is _very_ rough. And it is currently unsafe because `bevy_ecs` doesn't expose some internals to do this safely from inside `bevy_asset`. There are plenty of unanswered questions like: * "do we add a Loadable" derive? (effectively automate the FromWorld implementation above) * Should `MyAssets` even be an Asset? (largely implemented this way because it elegantly builds on `server.load_asset(MyAsset { .. })` dependency tracking). We should think hard about what our ideal API looks like (and if this is a pattern we want to support). Not necessarily something we need to solve in this PR. The current `on_loaded` impl should probably be removed from this PR before merging. ## Clarifying Questions ### What about Assets as Entities? This Bevy Asset V2 proposal implementation initially stored Assets as ECS Entities. Instead of `AssetId<T>` + the `Assets<T>` resource it used `Entity` as the asset id and Asset values were just ECS components. There are plenty of compelling reasons to do this: 1. Easier to inline assets in Bevy Scenes (as they are "just" normal entities + components) 2. More flexible queries: use the power of the ECS to filter assets (ex: `Query<Mesh, With<Tree>>`). 3. Extensible. Users can add arbitrary component data to assets. 4. Things like "component visualization tools" work out of the box to visualize asset data. However Assets as Entities has a ton of caveats right now: * We need to be able to allocate entity ids without a direct World reference (aka rework id allocator in Entities ... i worked around this in my prototypes by just pre allocating big chunks of entities) * We want asset change events in addition to ECS change tracking ... how do we populate them when mutations can come from anywhere? Do we use Changed queries? This would require iterating over the change data for all assets every frame. Is this acceptable or should we implement a new "event based" component change detection option? * Reconciling manually created assets with asset-system managed assets has some nuance (ex: are they "loaded" / do they also have that component metadata?) * "how do we handle "static" / default entity handles" (ties in to the Entity Indices discussion: https://github.com/bevyengine/bevy/discussions/8319). This is necessary for things like "built in" assets and default handles in things like SpriteBundle. * Storing asset information as a component makes it easy to "invalidate" asset state by removing the component (or forcing modifications). Ideally we have ways to lock this down (some combination of Rust type privacy and ECS validation) In practice, how we store and identify assets is a reasonably superficial change (porting off of Assets as Entities and implementing dedicated storage + ids took less than a day). So once we sort out the remaining challenges the flip should be straightforward. Additionally, I do still have "Assets as Entities" in my commit history, so we can reuse that work. I personally think "assets as entities" is a good endgame, but it also doesn't provide _significant_ value at the moment and it certainly isn't ready yet with the current state of things. ### Why not Distill? [Distill](https://github.com/amethyst/distill) is a high quality fully featured asset system built in Rust. It is very natural to ask "why not just use Distill?". It is also worth calling out that for awhile, [we planned on adopting Distill / I signed off on it](https://github.com/bevyengine/bevy/issues/708). However I think Bevy has a number of constraints that make Distill adoption suboptimal: * **Architectural Simplicity:** * Distill's processor requires an in-memory database (lmdb) and RPC networked API (using Cap'n Proto). Each of these introduces API complexity that increases maintenance burden and "code grokability". Ignoring tests, documentation, and examples, Distill has 24,237 lines of Rust code (including generated code for RPC + database interactions). If you ignore generated code, it has 11,499 lines. * Bevy builds the AssetProcessor and AssetServer using pluggable AssetReader/AssetWriter Rust traits with simple io interfaces. They do not necessitate databases or RPC interfaces (although Readers/Writers could use them if that is desired). Bevy Asset V2 (at the time of writing this PR) is 5,384 lines of Rust code (ignoring tests, documentation, and examples). Grain of salt: Distill does have more features currently (ex: Asset Packing, GUIDS, remote-out-of-process asset processor). I do plan to implement these features in Bevy Asset V2 and I personally highly doubt they will meaningfully close the 6115 lines-of-code gap. * This complexity gap (which while illustrated by lines of code, is much bigger than just that) is noteworthy to me. Bevy should be hackable and there are pillars of Distill that are very hard to understand and extend. This is a matter of opinion (and Bevy Asset V2 also has complicated areas), but I think Bevy Asset V2 is much more approachable for the average developer. * Necessary disclaimer: counting lines of code is an extremely rough complexity metric. Read the code and form your own opinions. * **Optional Asset Processing:** Not all Bevy Apps (or Bevy App developers) need / want asset preprocessing. Processing increases the complexity of the development environment by introducing things like meta files, imported asset storage, running processors in the background, waiting for processing to finish, etc. Distill _requires_ preprocessing to work. With Bevy Asset V2 processing is fully opt-in. The AssetServer isn't directly aware of asset processors at all. AssetLoaders only care about converting bytes to runtime Assets ... they don't know or care if the bytes were pre-processed or not. Processing is "elegantly" (forgive my self-congratulatory phrasing) layered on top and builds on the existing Asset system primitives. * **Direct Filesystem Access to Processed Asset State:** Distill stores processed assets in a database. This makes debugging / inspecting the processed outputs harder (either requires special tooling to query the database or they need to be "deployed" to be inspected). Bevy Asset V2, on the other hand, stores processed assets in the filesystem (by default ... this is configurable). This makes interacting with the processed state more natural. Note that both Godot and Unity's new asset system store processed assets in the filesystem. * **Portability**: Because Distill's processor uses lmdb and RPC networking, it cannot be run on certain platforms (ex: lmdb is a non-rust dependency that cannot run on the web, some platforms don't support running network servers). Bevy should be able to process assets everywhere (ex: run the Bevy Editor on the web, compile + process shaders on mobile, etc). Distill does partially mitigate this problem by supporting "streaming" assets via the RPC protocol, but this is not a full solve from my perspective. And Bevy Asset V2 can (in theory) also stream assets (without requiring RPC, although this isn't implemented yet) Note that I _do_ still think Distill would be a solid asset system for Bevy. But I think the approach in this PR is a better solve for Bevy's specific "asset system requirements". ### Doesn't async-fs just shim requests to "sync" `std::fs`? What is the point? "True async file io" has limited / spotty platform support. async-fs (and the rust async ecosystem generally ... ex Tokio) currently use async wrappers over std::fs that offload blocking requests to separate threads. This may feel unsatisfying, but it _does_ still provide value because it prevents our task pools from blocking on file system operations (which would prevent progress when there are many tasks to do, but all threads in a pool are currently blocking on file system ops). Additionally, using async APIs for our AssetReaders and AssetWriters also provides value because we can later add support for "true async file io" for platforms that support it. _And_ we can implement other "true async io" asset backends (such as networked asset io). ## Draft TODO - [x] Fill in missing filesystem event APIs: file removed event (which is expressed as dangling RenameFrom events in some cases), file/folder renamed event - [x] Assets without loaders are not moved to the processed folder. This breaks things like referenced `.bin` files for GLTFs. This should be configurable per-non-asset-type. - [x] Initial implementation of Reflect and FromReflect for Handle. The "deserialization" parity bar is low here as this only worked with static UUIDs in the old impl ... this is a non-trivial problem. Either we add a Handle::AssetPath variant that gets "upgraded" to a strong handle on scene load or we use a separate AssetRef type for Bevy scenes (which is converted to a runtime Handle on load). This deserves its own discussion in a different pr. - [x] Populate read_asset_bytes hash when run by the processor (a bit of a special case .. when run by the processor the processed meta will contain the hash so we don't need to compute it on the spot, but we don't want/need to read the meta when run by the main AssetServer) - [x] Delay hot reloading: currently filesystem events are handled immediately, which creates timing issues in some cases. For example hot reloading images can sometimes break because the image isn't finished writing. We should add a delay, likely similar to the [implementation in this PR](https://github.com/bevyengine/bevy/pull/8503). - [x] Port old platform-specific AssetIo implementations to the new AssetReader interface (currently missing Android and web) - [x] Resolve on_loaded unsafety (either by removing the API entirely or removing the unsafe) - [x] Runtime loader setting overrides - [x] Remove remaining unwraps that should be error-handled. There are number of TODOs here - [x] Pretty AssetPath Display impl - [x] Document more APIs - [x] Resolve spurious "reloading because it has changed" events (to repro run load_gltf with `processed_dev()`) - [x] load_dependency hot reloading currently only works for processed assets. If processing is disabled, load_dependency changes are not hot reloaded. - [x] Replace AssetInfo dependency load/fail counters with `loading_dependencies: HashSet<UntypedAssetId>` to prevent reloads from (potentially) breaking counters. Storing this will also enable "dependency reloaded" events (see [Next Steps](#next-steps)) - [x] Re-add filesystem watcher cargo feature gate (currently it is not optional) - [ ] Migration Guide - [ ] Changelog ## Followup TODO - [ ] Replace "eager unchanged processed asset loading" behavior with "don't returned unchanged processed asset until dependencies have been checked". - [ ] Add true `Ignore` AssetAction that does not copy the asset to the imported_assets folder. - [ ] Finish "live asset unloading" (ex: free up CPU asset memory after uploading an image to the GPU), rethink RenderAssets, and port renderer features. The `Assets` collection uses `Option<T>` for asset storage to support its removal. (1) the Option might not actually be necessary ... might be able to just remove from the collection entirely (2) need to finalize removal apis - [ ] Try replacing the "channel based" asset id recycling with something a bit more efficient (ex: we might be able to use raw atomic ints with some cleverness) - [ ] Consider adding UUIDs to processed assets (scoped just to helping identify moved assets ... not exposed to load queries ... see [Next Steps](#next-steps)) - [ ] Store "last modified" source asset and meta timestamps in processed meta files to enable skipping expensive hashing when the file wasn't changed - [ ] Fix "slow loop" handle drop fix - [ ] Migrate to TypeName - [x] Handle "loader preregistration". See #9429 ## Next Steps * **Configurable per-type defaults for AssetMeta**: It should be possible to add configuration like "all png image meta should default to using nearest sampling" (currently this hard-coded per-loader/processor Settings::default() impls). Also see the "Folder Meta" bullet point. * **Avoid Reprocessing on Asset Renames / Moves**: See the "canonical asset ids" discussion in [Open Questions](#open-questions) and the relevant bullet point in [Draft TODO](#draft-todo). Even without canonical ids, folder renames could avoid reprocessing in some cases. * **Multiple Asset Sources**: Expand AssetPath to support "asset source names" and support multiple AssetReaders in the asset server (ex: `webserver://some_path/image.png` backed by an Http webserver AssetReader). The "default" asset reader would use normal `some_path/image.png` paths. Ideally this works in combination with multiple AssetWatchers for hot-reloading * **Stable Type Names**: this pr removes the TypeUuid requirement from assets in favor of `std::any::type_name`. This makes defining assets easier (no need to generate a new uuid / use weird proc macro syntax). It also makes reading meta files easier (because things have "friendly names"). We also use type names for components in scene files. If they are good enough for components, they are good enough for assets. And consistency across Bevy pillars is desirable. However, `std::any::type_name` is not guaranteed to be stable (although in practice it is). We've developed a [stable type path](https://github.com/bevyengine/bevy/pull/7184) to resolve this, which should be adopted when it is ready. * **Command Line Interface**: It should be possible to run the asset processor in a separate process from the command line. This will also require building a network-server-backed AssetReader to communicate between the app and the processor. We've been planning to build a "bevy cli" for awhile. This seems like a good excuse to build it. * **Asset Packing**: This is largely an additive feature, so it made sense to me to punt this until we've laid the foundations in this PR. * **Per-Platform Processed Assets**: It should be possible to generate assets for multiple platforms by supporting multiple "processor profiles" per asset (ex: compress with format X on PC and Y on iOS). I think there should probably be arbitrary "profiles" (which can be separate from actual platforms), which are then assigned to a given platform when generating the final asset distribution for that platform. Ex: maybe devs want a "Mobile" profile that is shared between iOS and Android. Or a "LowEnd" profile shared between web and mobile. * **Versioning and Migrations**: Assets, Loaders, Savers, and Processors need to have versions to determine if their schema is valid. If an asset / loader version is incompatible with the current version expected at runtime, the processor should be able to migrate them. I think we should try using Bevy Reflect for this, as it would allow us to load the old version as a dynamic Reflect type without actually having the old Rust type. It would also allow us to define "patches" to migrate between versions (Bevy Reflect devs are currently working on patching). The `.meta` file already has its own format version. Migrating that to new versions should also be possible. * **Real Copy-on-write AssetPaths**: Rust's actual Cow (clone-on-write type) currently used by AssetPath can still result in String clones that aren't actually necessary (cloning an Owned Cow clones the contents). Bevy's asset system requires cloning AssetPaths in a number of places, which result in actual clones of the internal Strings. This is not efficient. AssetPath internals should be reworked to exhibit truer cow-like-behavior that reduces String clones to the absolute minimum. * **Consider processor-less processing**: In theory the AssetServer could run processors "inline" even if the background AssetProcessor is disabled. If we decide this is actually desirable, we could add this. But I don't think its a priority in the short or medium term. * **Pre-emptive dependency loading**: We could encode dependencies in processed meta files, which could then be used by the Asset Server to kick of dependency loads as early as possible (prior to starting the actual asset load). Is this desirable? How much time would this save in practice? * **Optimize Processor With UntypedAssetIds**: The processor exclusively uses AssetPath to identify assets currently. It might be possible to swap these out for UntypedAssetIds in some places, which are smaller / cheaper to hash and compare. * **One to Many Asset Processing**: An asset source file that produces many assets currently must be processed into a single "processed" asset source. If labeled assets can be written separately they can each have their own configured savers _and_ they could be loaded more granularly. Definitely worth exploring! * **Automatically Track "Runtime-only" Asset Dependencies**: Right now, tracking "created at runtime" asset dependencies requires adding them via `asset_server.load_asset(StandardMaterial::default())`. I think with some cleverness we could also do this for `materials.add(StandardMaterial::default())`, making tracking work "everywhere". There are challenges here relating to change detection / ensuring the server is made aware of dependency changes. This could be expensive in some cases. * **"Dependency Changed" events**: Some assets have runtime artifacts that need to be re-generated when one of their dependencies change (ex: regenerate a material's bind group when a Texture needs to change). We are generating the dependency graph so we can definitely produce these events. Buuuuut generating these events will have a cost / they could be high frequency for some assets, so we might want this to be opt-in for specific cases. * **Investigate Storing More Information In Handles**: Handles can now store arbitrary information, which makes it cheaper and easier to access. How much should we move into them? Canonical asset load states (via atomics)? (`handle.is_loaded()` would be very cool). Should we store the entire asset and remove the `Assets<T>` collection? (`Arc<RwLock<Option<Image>>>`?) * **Support processing and loading files without extensions**: This is a pretty arbitrary restriction and could be supported with very minimal changes. * **Folder Meta**: It would be nice if we could define per folder processor configuration defaults (likely in a `.meta` or `.folder_meta` file). Things like "default to linear filtering for all Images in this folder". * **Replace async_broadcast with event-listener?** This might be approximately drop-in for some uses and it feels more light weight * **Support Running the AssetProcessor on the Web**: Most of the hard work is done here, but there are some easy straggling TODOs (make the transaction log an interface instead of a direct file writer so we can write a web storage backend, implement an AssetReader/AssetWriter that reads/writes to something like LocalStorage). * **Consider identifying and preventing circular dependencies**: This is especially important for "processor dependencies", as processing will silently never finish in these cases. * **Built-in/Inlined Asset Hot Reloading**: This PR regresses "built-in/inlined" asset hot reloading (previously provided by the DebugAssetServer). I'm intentionally punting this because I think it can be cleanly implemented with "multiple asset sources" by registering a "debug asset source" (ex: `debug://bevy_pbr/src/render/pbr.wgsl` asset paths) in combination with an AssetWatcher for that asset source and support for "manually loading pats with asset bytes instead of AssetReaders". The old DebugAssetServer was quite nasty and I'd love to avoid that hackery going forward. * **Investigate ways to remove double-parsing meta files**: Parsing meta files currently involves parsing once with "minimal" versions of the meta file to extract the type name of the loader/processor config, then parsing again to parse the "full" meta. This is suboptimal. We should be able to define custom deserializers that (1) assume the loader/processor type name comes first (2) dynamically looks up the loader/processor registrations to deserialize settings in-line (similar to components in the bevy scene format). Another alternative: deserialize as dynamic Reflect objects and then convert. * **More runtime loading configuration**: Support using the Handle type as a hint to select an asset loader (instead of relying on AssetPath extensions) * **More high level Processor trait implementations**: For example, it might be worth adding support for arbitrary chains of "asset transforms" that modify an in-memory asset representation between loading and saving. (ex: load a Mesh, run a `subdivide_mesh` transform, followed by a `flip_normals` transform, then save the mesh to an efficient compressed format). * **Bevy Scene Handle Deserialization**: (see the relevant [Draft TODO item](#draft-todo) for context) * **Explore High Level Load Interfaces**: See [this discussion](#discuss-on_loaded-high-level-interface) for one prototype. * **Asset Streaming**: It would be great if we could stream Assets (ex: stream a long video file piece by piece) * **ID Exchanging**: In this PR Asset Handles/AssetIds are bigger than they need to be because they have a Uuid enum variant. If we implement an "id exchanging" system that trades Uuids for "efficient runtime ids", we can cut down on the size of AssetIds, making them more efficient. This has some open design questions, such as how to spawn entities with "default" handle values (as these wouldn't have access to the exchange api in the current system). * **Asset Path Fixup Tooling**: Assets that inline asset paths inside them will break when an asset moves. The asset system provides the functionality to detect when paths break. We should build a framework that enables formats to define "path migrations". This is especially important for scene files. For editor-generated files, we should also consider using UUIDs (see other bullet point) to avoid the need to migrate in these cases. --------- Co-authored-by: BeastLe9enD <beastle9end@outlook.de> Co-authored-by: Mike <mike.hsu@gmail.com> Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>	2023-09-07 02:07:27 +00:00
Zachary Harrold	394e2b0c91	Replaced EntityMap with HashMap (#9461) ... # Objective - Fixes #9321 ## Solution - `EntityMap` has been replaced by a simple `HashMap<Entity, Entity>`. --- ## Changelog - `EntityMap::world_scope` has been replaced with `World::world_scope` to avoid creating a new trait. This is a public facing change to the call semantics, but has no effect on results or behaviour. - `EntityMap`, as a `HashMap`, now operates on `&Entity` rather than `Entity`. This changes many standard access functions (e.g, `.get`) in a public-facing way. ## Migration Guide - Calls to `EntityMap::world_scope` can be directly replaced with the following: `map.world_scope(&mut world)` -> `world.world_scope(&mut map)` - Calls to legacy `EntityMap` methods such as `EntityMap::get` must explicitly include de/reference symbols: `let entity = map.get(parent);` -> `let &entity = map.get(&parent);`	2023-08-28 17:18:16 +00:00
Nicola Papale	0294bb191d	Move AppTypeRegistry to bevy_ecs (#8901) ... # Objective - Use `AppTypeRegistry` on API defined in `bevy_ecs` (https://github.com/bevyengine/bevy/pull/8895#discussion_r1234748418) A lot of the API on `Reflect` depends on a registry. When it comes to the ECS. We should use `AppTypeRegistry` in the general case. This is however impossible in `bevy_ecs`, since `AppTypeRegistry` is defined in `bevy_app`. ## Solution - Move `AppTypeRegistry` resource definition from `bevy_app` to `bevy_ecs` - Still add the resource in the `App` plugin, since bevy_ecs itself doesn't know of plugins Note that `bevy_ecs` is a dependency of `bevy_app`, so nothing revolutionary happens. ## Alternative - Define the API as a trait in `bevy_app` over `bevy_ecs`. (though this prevents us from using bevy_ecs internals) - Do not rely on `AppTypeRegistry` for the API in question, requring users to extract themselves the resource and pass it to the API methods. --- ## Changelog - Moved `AppTypeRegistry` resource definition from `bevy_app` to `bevy_ecs` ## Migration Guide - If you were **not** using a `prelude::*` to import `AppTypeRegistry`, you should update your imports: ```diff - use bevy::app::AppTypeRegistry; + use bevy::ecs::reflect::AppTypeRegistry ```	2023-06-21 17:25:01 +00:00
radiish	1efc762924	reflect: stable type path v2 (#7184) ... # Objective - Introduce a stable alternative to [`std::any::type_name`](https://doc.rust-lang.org/std/any/fn.type_name.html). - Rewrite of #5805 with heavy inspiration in design. - On the path to #5830. - Part of solving #3327. ## Solution - Add a `TypePath` trait for static stable type path/name information. - Add a `TypePath` derive macro. - Add a `impl_type_path` macro for implementing internal and foreign types in `bevy_reflect`. --- ## Changelog - Added `TypePath` trait. - Added `DynamicTypePath` trait and `get_type_path` method to `Reflect`. - Added a `TypePath` derive macro. - Added a `bevy_reflect::impl_type_path` for implementing `TypePath` on internal and foreign types in `bevy_reflect`. - Changed `bevy_reflect::utility::(Non)GenericTypeInfoCell` to `(Non)GenericTypedCell<T>` which allows us to be generic over both `TypeInfo` and `TypePath`. - `TypePath` is now a supertrait of `Asset`, `Material` and `Material2d`. - `impl_reflect_struct` needs a `#[type_path = "..."]` attribute to be specified. - `impl_reflect_value` needs to either specify path starting with a double colon (`::core::option::Option`) or an `in my_crate::foo` declaration. - Added `bevy_reflect_derive::ReflectTypePath`. - Most uses of `Ident` in `bevy_reflect_derive` changed to use `ReflectTypePath`. ## Migration Guide - Implementors of `Asset`, `Material` and `Material2d` now also need to derive `TypePath`. - Manual implementors of `Reflect` will need to implement the new `get_type_path` method. ## Open Questions - [x] ~This PR currently does not migrate any usages of `std::any::type_name` to use `bevy_reflect::TypePath` to ease the review process. Should it?~ Migration will be left to a follow-up PR. - [ ] This PR adds a lot of `#[derive(TypePath)]` and `T: TypePath` to satisfy new bounds, mostly when deriving `TypeUuid`. Should we make `TypePath` a supertrait of `TypeUuid`? [Should we remove `TypeUuid` in favour of `TypePath`?](2afbd85532 (r961067892))	2023-06-05 20:31:20 +00:00
Testare	a29d328fe5	Rename map_entities and map_specific_entities (#7570) ... # Objective After fixing dynamic scene to only map specific entities, we want map_entities to default to the less error prone behavior and have the previous behavior renamed to "map_all_entities." As this is a breaking change, it could not be pushed out with the bug fix. ## Solution Simple rename and refactor. ## Changelog ### Changed - `map_entities` now accepts a list of entities to apply to, with `map_all_entities` retaining previous behavior of applying to all entities in the map. ## Migration Guide - In `bevy_ecs`, `ReflectMapEntities::map_entites` now requires an additional `entities` parameter to specify which entities it applies to. To keep the old behavior, use the new `ReflectMapEntities::map_all_entities`, but consider if passing the entities in specifically might be better for your use case to avoid bugs.	2023-05-01 21:40:19 +00:00
Illiux	eebc92a7d4	Make scene handling of entity references robust (#7335) ... # Objective - Handle dangling entity references inside scenes - Handle references to entities with generation > 0 inside scenes - Fix a latent bug in `Parent`'s `MapEntities` implementation, which would, if the parent was outside the scene, cause the scene to be loaded into the new world with a parent reference potentially pointing to some random entity in that new world. - Fixes #4793 and addresses #7235 ## Solution - DynamicScenes now identify entities with a `Entity` instead of a u32, therefore including generation - `World` exposes a new `reserve_generations` function that despawns an entity and advances its generation by some extra amount. - `MapEntities` implementations have a new `get_or_reserve` function available that will always return an `Entity`, establishing a new mapping to a dead entity when the entity they are called with is not in the `EntityMap`. Subsequent calls with that same `Entity` will return the same newly created dead entity reference, preserving equality semantics. - As a result, after loading a scene containing references to dead entities (or entities otherwise outside the scene), those references will all point to different generations on a single entity id in the new world. --- ## Changelog ### Changed - In serialized scenes, entities are now identified by a u64 instead of a u32. - In serialized scenes, components with entity references now have those references serialize as u64s instead of structs. ### Fixed - Scenes containing components with entity references will now deserialize and add to a world reliably. ## Migration Guide - `MapEntities` implementations must change from a `&EntityMap` parameter to a `&mut EntityMapper` parameter and can no longer return a `Result`. Finally, they should switch from calling `EntityMap::get` to calling `EntityMapper::get_or_reserve`. --------- Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>	2023-05-01 15:49:27 +00:00
Testare	3d8c7681a7	Bugfix: Scene reload fix (nonbreaking) (#7951) ... # Objective Fix a bug with scene reload. (This is a copy of #7570 but without the breaking API change, in order to allow the bugfix to be introduced in 0.10.1) When a scene was reloaded, it was corrupting components that weren't native to the scene itself. In particular, when a DynamicScene was created on Entity (A), all components in the scene without parents are automatically added as children of Entity (A). But if that scene was reloaded and the same ID of Entity (A) was a scene ID as well*, that parent component was corrupted, causing the hierarchy to become malformed and bevy to panic. *For example, if Entity (A)'s ID was 3, and the scene contained an entity with ID 3 This issue could affect any components that: * Implemented `MapEntities`, basically components that contained references to other entities * Were added to entities from a scene file but weren't defined in the scene file - Fixes #7529 ## Solution The solution was to keep track of entities+components that had `MapEntities` functionality during scene load, and only apply the entity update behavior to them. They were tracked with a HashMap from the component's TypeID to a vector of entity ID's. Then the `ReflectMapEntities` struct was updated to hold a function that took a list of entities to be applied to, instead of naively applying itself to all values in the EntityMap. (See this PR comment https://github.com/bevyengine/bevy/pull/7570#issuecomment-1432302796 for a story-based explanation of this bug and solution) ## Changelog ### Fixed - Components that implement `MapEntities` added to scene entities after load are not corrupted during scene reload.	2023-03-27 22:18:45 +00:00
Francesco	7b38de0a64	(De) serialize resources in scenes (#6846) ... # Objective Co-Authored-By: davier [bricedavier@gmail.com](mailto:bricedavier@gmail.com) Fixes #3576. Adds a `resources` field in scene serialization data to allow de/serializing resources that have reflection enabled. ## Solution Most of this code is taken from a previous closed PR: https://github.com/bevyengine/bevy/pull/3580. Most of the credit goes to @Davier , what I did was mostly getting it to work on the latest main branch of Bevy, along with adding a few asserts in the currently existing tests to be sure everything is working properly. This PR changes the scene format to include resources in this way: ``` ( resources: { // List of resources here, keyed by resource type name. }, entities: [ // Previous scene format here ], ) ``` An example taken from the tests: ``` ( resources: { "bevy_scene::serde::tests::MyResource": ( foo: 123, ), }, entities: { // Previous scene format here }, ) ``` For this, a `resources` fields has been added on the `DynamicScene` and the `DynamicSceneBuilder` structs. The latter now also has a method named `extract_resources` to properly extract the existing resources registered in the local type registry, in a similar way to `extract_entities`. --- ## Changelog Added: Reflect resources registered in the type registry used by dynamic scenes will now be properly de/serialized in scene data. ## Migration Guide Since the scene format has been changed, the user may not be able to use scenes saved prior to this PR due to the `resources` scene field being missing. ~~To preserve backwards compatibility, I will try to make the `resources` fully optional so that old scenes can be loaded without issue.~~ ## TODOs - [x] I may have to update a few doc blocks still referring to dynamic scenes as mere container of entities, since they now include resources as well. - [x] ~~I want to make the `resources` key optional, as specified in the Migration Guide, so that old scenes will be compatible with this change.~~ Since this would only be trivial for ron format, I think it might be better to consider it in a separate PR/discussion to figure out if it could be done for binary serialization too. - [x] I suppose it might be a good idea to add a resources in the scene example so that users will quickly notice they can serialize resources just like entities. --------- Co-authored-by: Carter Anderson <mcanders1@gmail.com>	2023-03-20 21:17:02 +00:00
James Liu	fe7ebd4326	Clean up Fetch code (#4800) ... # Objective Clean up code surrounding fetch by pulling out the common parts into the iteration code. ## Solution Merge `Fetch::table_fetch` and `Fetch::archetype_fetch` into a single API: `Fetch::fetch(&mut self, entity: &Entity, table_row: &usize)`. This provides everything any fetch requires to internally decide which storage to read from and get the underlying data. All of these functions are marked as `#[inline(always)]` and the arguments are passed as references to attempt to optimize out the argument that isn't being used. External to `Fetch`, Query iteration has been changed to keep track of the table row and entity outside of fetch, which moves a lot of the expensive bookkeeping `Fetch` structs had previously done internally into the outer loop. ~~TODO: Benchmark, docs~~ Done. --- ## Changelog Changed: `Fetch::table_fetch` and `Fetch::archetype_fetch` have been merged into a single `Fetch::fetch` function. ## Migration Guide TODO Co-authored-by: Brian Merchant <bhmerchang@gmail.com> Co-authored-by: Saverio Miroddi <saverio.pub2@gmail.com>	2022-10-28 09:25:50 +00:00
François	b09b2c1056	Create a scene from a dynamic scene (#6229) ... # Objective - Add a method to create a `Scene` from a `DynamicScene`	2022-10-17 16:25:12 +00:00
Carter Anderson	01aedc8431	Spawn now takes a Bundle (#6054) ... # Objective Now that we can consolidate Bundles and Components under a single insert (thanks to #2975 and #6039), almost 100% of world spawns now look like `world.spawn().insert((Some, Tuple, Here))`. Spawning an entity without any components is an extremely uncommon pattern, so it makes sense to give spawn the "first class" ergonomic api. This consolidated api should be made consistent across all spawn apis (such as World and Commands). ## Solution All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input: ```rust // before: commands .spawn() .insert((A, B, C)); world .spawn() .insert((A, B, C); // after commands.spawn((A, B, C)); world.spawn((A, B, C)); ``` All existing instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api. A new `spawn_empty` has been added, replacing the old `spawn` api. By allowing `world.spawn(some_bundle)` to replace `world.spawn().insert(some_bundle)`, this opened the door to removing the initial entity allocation in the "empty" archetype / table done in `spawn()` (and subsequent move to the actual archetype in `.insert(some_bundle)`). This improves spawn performance by over 10%:  To take this measurement, I added a new `world_spawn` benchmark. Unfortunately, optimizing `Commands::spawn` is slightly less trivial, as Commands expose the Entity id of spawned entities prior to actually spawning. Doing the optimization would (naively) require assurances that the `spawn(some_bundle)` command is applied before all other commands involving the entity (which would not necessarily be true, if memory serves). Optimizing `Commands::spawn` this way does feel possible, but it will require careful thought (and maybe some additional checks), which deserves its own PR. For now, it has the same performance characteristics of the current `Commands::spawn_bundle` on main. **Note that 99% of this PR is simple renames and refactors. The only code that needs careful scrutiny is the new `World::spawn()` impl, which is relatively straightforward, but it has some new unsafe code (which re-uses battle tested BundlerSpawner code path).** --- ## Changelog - All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input - All instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api - World and Commands now have `spawn_empty()`, which is equivalent to the old `spawn()` behavior. ## Migration Guide ```rust // Old (0.8): commands .spawn() .insert_bundle((A, B, C)); // New (0.9) commands.spawn((A, B, C)); // Old (0.8): commands.spawn_bundle((A, B, C)); // New (0.9) commands.spawn((A, B, C)); // Old (0.8): let entity = commands.spawn().id(); // New (0.9) let entity = commands.spawn_empty().id(); // Old (0.8) let entity = world.spawn().id(); // New (0.9) let entity = world.spawn_empty(); ```	2022-09-23 19:55:54 +00:00
François	e8041150ee	can clone a scene (#5855) ... # Objective - Easier to work with model assets - Models are often one mesh, many textures. This can be hard to use in Bevy as it's not possible to clone the scene to have one scene for each material. It's still possible to instantiate the texture-less scene, then modify the texture material once spawned but that means happening during play and is quite more painful ## Solution - Expose the code to clone a scene. This code already existed but was only possible to use to spawn the scene	2022-09-02 11:56:21 +00:00
François	c6958b3056	add a SceneBundle to spawn a scene (#2424) ... # Objective - Spawning a scene is handled as a special case with a command `spawn_scene` that takes an handle but doesn't let you specify anything else. This is the only handle that works that way. - Workaround for this have been to add the `spawn_scene` on `ChildBuilder` to be able to specify transform of parent, or to make the `SceneSpawner` available to be able to select entities from a scene by their instance id ## Solution Add a bundle ```rust pub struct SceneBundle { pub scene: Handle<Scene>, pub transform: Transform, pub global_transform: GlobalTransform, pub instance_id: Option<InstanceId>, } ``` and instead of ```rust commands.spawn_scene(asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0")); ``` you can do ```rust commands.spawn_bundle(SceneBundle { scene: asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0"), ..Default::default() }); ``` The scene will be spawned as a child of the entity with the `SceneBundle` ~I would like to remove the command `spawn_scene` in favor of this bundle but didn't do it yet to get feedback first~ Co-authored-by: François <8672791+mockersf@users.noreply.github.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>	2022-06-09 20:34:09 +00:00
Carter Anderson	3a2a68852c	Bevy ECS V2 (#1525) ... # Bevy ECS V2 This is a rewrite of Bevy ECS (basically everything but the new executor/schedule, which are already awesome). The overall goal was to improve the performance and versatility of Bevy ECS. Here is a quick bulleted list of changes before we dive into the details: * Complete World rewrite * Multiple component storage types: * Tables: fast cache friendly iteration, slower add/removes (previously called Archetypes) * Sparse Sets: fast add/remove, slower iteration * Stateful Queries (caches query results for faster iteration. fragmented iteration is _fast_ now) * Stateful System Params (caches expensive operations. inspired by @DJMcNab's work in #1364) * Configurable System Params (users can set configuration when they construct their systems. once again inspired by @DJMcNab's work) * Archetypes are now "just metadata", component storage is separate * Archetype Graph (for faster archetype changes) * Component Metadata * Configure component storage type * Retrieve information about component size/type/name/layout/send-ness/etc * Components are uniquely identified by a densely packed ComponentId * TypeIds are now totally optional (which should make implementing scripting easier) * Super fast "for_each" query iterators * Merged Resources into World. Resources are now just a special type of component * EntityRef/EntityMut builder apis (more efficient and more ergonomic) * Fast bitset-backed `Access<T>` replaces old hashmap-based approach everywhere * Query conflicts are determined by component access instead of archetype component access (to avoid random failures at runtime) * With/Without are still taken into account for conflicts, so this should still be comfy to use * Much simpler `IntoSystem` impl * Significantly reduced the amount of hashing throughout the ecs in favor of Sparse Sets (indexed by densely packed ArchetypeId, ComponentId, BundleId, and TableId) * Safety Improvements * Entity reservation uses a normal world reference instead of unsafe transmute * QuerySets no longer transmute lifetimes * Made traits "unsafe" where relevant * More thorough safety docs * WorldCell * Exposes safe mutable access to multiple resources at a time in a World * Replaced "catch all" `System::update_archetypes(world: &World)` with `System::new_archetype(archetype: &Archetype)` * Simpler Bundle implementation * Replaced slow "remove_bundle_one_by_one" used as fallback for Commands::remove_bundle with fast "remove_bundle_intersection" * Removed `Mut<T>` query impl. it is better to only support one way: `&mut T` * Removed with() from `Flags<T>` in favor of `Option<Flags<T>>`, which allows querying for flags to be "filtered" by default * Components now have is_send property (currently only resources support non-send) * More granular module organization * New `RemovedComponents<T>` SystemParam that replaces `query.removed::<T>()` * `world.resource_scope()` for mutable access to resources and world at the same time * WorldQuery and QueryFilter traits unified. FilterFetch trait added to enable "short circuit" filtering. Auto impled for cases that don't need it * Significantly slimmed down SystemState in favor of individual SystemParam state * System Commands changed from `commands: &mut Commands` back to `mut commands: Commands` (to allow Commands to have a World reference) Fixes #1320 ## `World` Rewrite This is a from-scratch rewrite of `World` that fills the niche that `hecs` used to. Yes, this means Bevy ECS is no longer a "fork" of hecs. We're going out our own! (the only shared code between the projects is the entity id allocator, which is already basically ideal) A huge shout out to @SanderMertens (author of [flecs](https://github.com/SanderMertens/flecs)) for sharing some great ideas with me (specifically hybrid ecs storage and archetype graphs). He also helped advise on a number of implementation details. ## Component Storage (The Problem) Two ECS storage paradigms have gained a lot of traction over the years: * **Archetypal ECS**: * Stores components in "tables" with static schemas. Each "column" stores components of a given type. Each "row" is an entity. * Each "archetype" has its own table. Adding/removing an entity's component changes the archetype. * Enables super-fast Query iteration due to its cache-friendly data layout * Comes at the cost of more expensive add/remove operations for an Entity's components, because all components need to be copied to the new archetype's "table" * **Sparse Set ECS**: * Stores components of the same type in densely packed arrays, which are sparsely indexed by densely packed unsigned integers (Entity ids) * Query iteration is slower than Archetypal ECS because each entity's component could be at any position in the sparse set. This "random access" pattern isn't cache friendly. Additionally, there is an extra layer of indirection because you must first map the entity id to an index in the component array. * Adding/removing components is a cheap, constant time operation Bevy ECS V1, hecs, legion, flec, and Unity DOTS are all "archetypal ecs-es". I personally think "archetypal" storage is a good default for game engines. An entity's archetype doesn't need to change frequently in general, and it creates "fast by default" query iteration (which is a much more common operation). It is also "self optimizing". Users don't need to think about optimizing component layouts for iteration performance. It "just works" without any extra boilerplate. Shipyard and EnTT are "sparse set ecs-es". They employ "packing" as a way to work around the "suboptimal by default" iteration performance for specific sets of components. This helps, but I didn't think this was a good choice for a general purpose engine like Bevy because: 1. "packs" conflict with each other. If bevy decides to internally pack the Transform and GlobalTransform components, users are then blocked if they want to pack some custom component with Transform. 2. users need to take manual action to optimize Developers selecting an ECS framework are stuck with a hard choice. Select an "archetypal" framework with "fast iteration everywhere" but without the ability to cheaply add/remove components, or select a "sparse set" framework to cheaply add/remove components but with slower iteration performance. ## Hybrid Component Storage (The Solution) In Bevy ECS V2, we get to have our cake and eat it too. It now has _both_ of the component storage types above (and more can be added later if needed): * **Tables** (aka "archetypal" storage) * The default storage. If you don't configure anything, this is what you get * Fast iteration by default * Slower add/remove operations * **Sparse Sets** * Opt-in * Slower iteration * Faster add/remove operations These storage types complement each other perfectly. By default Query iteration is fast. If developers know that they want to add/remove a component at high frequencies, they can set the storage to "sparse set": ```rust world.register_component( ComponentDescriptor:🆕:<MyComponent>(StorageType::SparseSet) ).unwrap(); ``` ## Archetypes Archetypes are now "just metadata" ... they no longer store components directly. They do store: * The `ComponentId`s of each of the Archetype's components (and that component's storage type) * Archetypes are uniquely defined by their component layouts * For example: entities with "table" components `[A, B, C]` _and_ "sparse set" components `[D, E]` will always be in the same archetype. * The `TableId` associated with the archetype * For now each archetype has exactly one table (which can have no components), * There is a 1->Many relationship from Tables->Archetypes. A given table could have any number of archetype components stored in it: * Ex: an entity with "table storage" components `[A, B, C]` and "sparse set" components `[D, E]` will share the same `[A, B, C]` table as an entity with `[A, B, C]` table component and `[F]` sparse set components. * This 1->Many relationship is how we preserve fast "cache friendly" iteration performance when possible (more on this later) * A list of entities that are in the archetype and the row id of the table they are in * ArchetypeComponentIds * unique densely packed identifiers for (ArchetypeId, ComponentId) pairs * used by the schedule executor for cheap system access control * "Archetype Graph Edges" (see the next section) ## The "Archetype Graph" Archetype changes in Bevy (and a number of other archetypal ecs-es) have historically been expensive to compute. First, you need to allocate a new vector of the entity's current component ids, add or remove components based on the operation performed, sort it (to ensure it is order-independent), then hash it to find the archetype (if it exists). And thats all before we get to the _already_ expensive full copy of all components to the new table storage. The solution is to build a "graph" of archetypes to cache these results. @SanderMertens first exposed me to the idea (and he got it from @gjroelofs, who came up with it). They propose adding directed edges between archetypes for add/remove component operations. If `ComponentId`s are densely packed, you can use sparse sets to cheaply jump between archetypes. Bevy takes this one step further by using add/remove `Bundle` edges instead of `Component` edges. Bevy encourages the use of `Bundles` to group add/remove operations. This is largely for "clearer game logic" reasons, but it also helps cut down on the number of archetype changes required. `Bundles` now also have densely-packed `BundleId`s. This allows us to use a _single_ edge for each bundle operation (rather than needing to traverse N edges ... one for each component). Single component operations are also bundles, so this is strictly an improvement over a "component only" graph. As a result, an operation that used to be _heavy_ (both for allocations and compute) is now two dirt-cheap array lookups and zero allocations. ## Stateful Queries World queries are now stateful. This allows us to: 1. Cache archetype (and table) matches * This resolves another issue with (naive) archetypal ECS: query performance getting worse as the number of archetypes goes up (and fragmentation occurs). 2. Cache Fetch and Filter state * The expensive parts of fetch/filter operations (such as hashing the TypeId to find the ComponentId) now only happen once when the Query is first constructed 3. Incrementally build up state * When new archetypes are added, we only process the new archetypes (no need to rebuild state for old archetypes) As a result, the direct `World` query api now looks like this: ```rust let mut query = world.query::<(&A, &mut B)>(); for (a, mut b) in query.iter_mut(&mut world) { } ``` Requiring `World` to generate stateful queries (rather than letting the `QueryState` type be constructed separately) allows us to ensure that _all_ queries are properly initialized (and the relevant world state, such as ComponentIds). This enables QueryState to remove branches from its operations that check for initialization status (and also enables query.iter() to take an immutable world reference because it doesn't need to initialize anything in world). However in systems, this is a non-breaking change. State management is done internally by the relevant SystemParam. ## Stateful SystemParams Like Queries, `SystemParams` now also cache state. For example, `Query` system params store the "stateful query" state mentioned above. Commands store their internal `CommandQueue`. This means you can now safely use as many separate `Commands` parameters in your system as you want. `Local<T>` system params store their `T` value in their state (instead of in Resources). SystemParam state also enabled a significant slim-down of SystemState. It is much nicer to look at now. Per-SystemParam state naturally insulates us from an "aliased mut" class of errors we have hit in the past (ex: using multiple `Commands` system params). (credit goes to @DJMcNab for the initial idea and draft pr here #1364) ## Configurable SystemParams @DJMcNab also had the great idea to make SystemParams configurable. This allows users to provide some initial configuration / values for system parameters (when possible). Most SystemParams have no config (the config type is `()`), but the `Local<T>` param now supports user-provided parameters: ```rust fn foo(value: Local<usize>) { } app.add_system(foo.system().config(|c| c.0 = Some(10))); ``` ## Uber Fast "for_each" Query Iterators Developers now have the choice to use a fast "for_each" iterator, which yields ~1.5-3x iteration speed improvements for "fragmented iteration", and minor ~1.2x iteration speed improvements for unfragmented iteration. ```rust fn system(query: Query<(&A, &mut B)>) { // you now have the option to do this for a speed boost query.for_each_mut(|(a, mut b)| { }); // however normal iterators are still available for (a, mut b) in query.iter_mut() { } } ``` I think in most cases we should continue to encourage "normal" iterators as they are more flexible and more "rust idiomatic". But when that extra "oomf" is needed, it makes sense to use `for_each`. We should also consider using `for_each` for internal bevy systems to give our users a nice speed boost (but that should be a separate pr). ## Component Metadata `World` now has a `Components` collection, which is accessible via `world.components()`. This stores mappings from `ComponentId` to `ComponentInfo`, as well as `TypeId` to `ComponentId` mappings (where relevant). `ComponentInfo` stores information about the component, such as ComponentId, TypeId, memory layout, send-ness (currently limited to resources), and storage type. ## Significantly Cheaper `Access<T>` We used to use `TypeAccess<TypeId>` to manage read/write component/archetype-component access. This was expensive because TypeIds must be hashed and compared individually. The parallel executor got around this by "condensing" type ids into bitset-backed access types. This worked, but it had to be re-generated from the `TypeAccess<TypeId>`sources every time archetypes changed. This pr removes TypeAccess in favor of faster bitset access everywhere. We can do this thanks to the move to densely packed `ComponentId`s and `ArchetypeComponentId`s. ## Merged Resources into World Resources had a lot of redundant functionality with Components. They stored typed data, they had access control, they had unique ids, they were queryable via SystemParams, etc. In fact the _only_ major difference between them was that they were unique (and didn't correlate to an entity). Separate resources also had the downside of requiring a separate set of access controls, which meant the parallel executor needed to compare more bitsets per system and manage more state. I initially got the "separate resources" idea from `legion`. I think that design was motivated by the fact that it made the direct world query/resource lifetime interactions more manageable. It certainly made our lives easier when using Resources alongside hecs/bevy_ecs. However we already have a construct for safely and ergonomically managing in-world lifetimes: systems (which use `Access<T>` internally). This pr merges Resources into World: ```rust world.insert_resource(1); world.insert_resource(2.0); let a = world.get_resource::<i32>().unwrap(); let mut b = world.get_resource_mut::<f64>().unwrap(); *b = 3.0; ``` Resources are now just a special kind of component. They have their own ComponentIds (and their own resource TypeId->ComponentId scope, so they don't conflict wit components of the same type). They are stored in a special "resource archetype", which stores components inside the archetype using a new `unique_components` sparse set (note that this sparse set could later be used to implement Tags). This allows us to keep the code size small by reusing existing datastructures (namely Column, Archetype, ComponentFlags, and ComponentInfo). This allows us the executor to use a single `Access<ArchetypeComponentId>` per system. It should also make scripting language integration easier. _But_ this merge did create problems for people directly interacting with `World`. What if you need mutable access to multiple resources at the same time? `world.get_resource_mut()` borrows World mutably! ## WorldCell WorldCell applies the `Access<ArchetypeComponentId>` concept to direct world access: ```rust let world_cell = world.cell(); let a = world_cell.get_resource_mut::<i32>().unwrap(); let b = world_cell.get_resource_mut::<f64>().unwrap(); ``` This adds cheap runtime checks (a sparse set lookup of `ArchetypeComponentId` and a counter) to ensure that world accesses do not conflict with each other. Each operation returns a `WorldBorrow<'w, T>` or `WorldBorrowMut<'w, T>` wrapper type, which will release the relevant ArchetypeComponentId resources when dropped. World caches the access sparse set (and only one cell can exist at a time), so `world.cell()` is a cheap operation. WorldCell does _not_ use atomic operations. It is non-send, does a mutable borrow of world to prevent other accesses, and uses a simple `Rc<RefCell<ArchetypeComponentAccess>>` wrapper in each WorldBorrow pointer. The api is currently limited to resource access, but it can and should be extended to queries / entity component access. ## Resource Scopes WorldCell does not yet support component queries, and even when it does there are sometimes legitimate reasons to want a mutable world ref _and_ a mutable resource ref (ex: bevy_render and bevy_scene both need this). In these cases we could always drop down to the unsafe `world.get_resource_unchecked_mut()`, but that is not ideal! Instead developers can use a "resource scope" ```rust world.resource_scope(|world: &mut World, a: &mut A| { }) ``` This temporarily removes the `A` resource from `World`, provides mutable pointers to both, and re-adds A to World when finished. Thanks to the move to ComponentIds/sparse sets, this is a cheap operation. If multiple resources are required, scopes can be nested. We could also consider adding a "resource tuple" to the api if this pattern becomes common and the boilerplate gets nasty. ## Query Conflicts Use ComponentId Instead of ArchetypeComponentId For safety reasons, systems cannot contain queries that conflict with each other without wrapping them in a QuerySet. On bevy `main`, we use ArchetypeComponentIds to determine conflicts. This is nice because it can take into account filters: ```rust // these queries will never conflict due to their filters fn filter_system(a: Query<&mut A, With<B>>, b: Query<&mut B, Without<B>>) { } ``` But it also has a significant downside: ```rust // these queries will not conflict _until_ an entity with A, B, and C is spawned fn maybe_conflicts_system(a: Query<(&mut A, &C)>, b: Query<(&mut A, &B)>) { } ``` The system above will panic at runtime if an entity with A, B, and C is spawned. This makes it hard to trust that your game logic will run without crashing. In this pr, I switched to using `ComponentId` instead. This _is_ more constraining. `maybe_conflicts_system` will now always fail, but it will do it consistently at startup. Naively, it would also _disallow_ `filter_system`, which would be a significant downgrade in usability. Bevy has a number of internal systems that rely on disjoint queries and I expect it to be a common pattern in userspace. To resolve this, I added a new `FilteredAccess<T>` type, which wraps `Access<T>` and adds with/without filters. If two `FilteredAccess` have with/without values that prove they are disjoint, they will no longer conflict. ## EntityRef / EntityMut World entity operations on `main` require that the user passes in an `entity` id to each operation: ```rust let entity = world.spawn((A, )); // create a new entity with A world.get::<A>(entity); world.insert(entity, (B, C)); world.insert_one(entity, D); ``` This means that each operation needs to look up the entity location / verify its validity. The initial spawn operation also requires a Bundle as input. This can be awkward when no components are required (or one component is required). These operations have been replaced by `EntityRef` and `EntityMut`, which are "builder-style" wrappers around world that provide read and read/write operations on a single, pre-validated entity: ```rust // spawn now takes no inputs and returns an EntityMut let entity = world.spawn() .insert(A) // insert a single component into the entity .insert_bundle((B, C)) // insert a bundle of components into the entity .id() // id returns the Entity id // Returns EntityMut (or panics if the entity does not exist) world.entity_mut(entity) .insert(D) .insert_bundle(SomeBundle::default()); { // returns EntityRef (or panics if the entity does not exist) let d = world.entity(entity) .get::<D>() // gets the D component .unwrap(); // world.get still exists for ergonomics let d = world.get::<D>(entity).unwrap(); } // These variants return Options if you want to check existence instead of panicing world.get_entity_mut(entity) .unwrap() .insert(E); if let Some(entity_ref) = world.get_entity(entity) { let d = entity_ref.get::<D>().unwrap(); } ``` This _does not_ affect the current Commands api or terminology. I think that should be a separate conversation as that is a much larger breaking change. ## Safety Improvements * Entity reservation in Commands uses a normal world borrow instead of an unsafe transmute * QuerySets no longer transmutes lifetimes * Made traits "unsafe" when implementing a trait incorrectly could cause unsafety * More thorough safety docs ## RemovedComponents SystemParam The old approach to querying removed components: `query.removed:<T>()` was confusing because it had no connection to the query itself. I replaced it with the following, which is both clearer and allows us to cache the ComponentId mapping in the SystemParamState: ```rust fn system(removed: RemovedComponents<T>) { for entity in removed.iter() { } } ``` ## Simpler Bundle implementation Bundles are no longer responsible for sorting (or deduping) TypeInfo. They are just a simple ordered list of component types / data. This makes the implementation smaller and opens the door to an easy "nested bundle" implementation in the future (which i might even add in this pr). Duplicate detection is now done once per bundle type by World the first time a bundle is used. ## Unified WorldQuery and QueryFilter types (don't worry they are still separate type _parameters_ in Queries .. this is a non-breaking change) WorldQuery and QueryFilter were already basically identical apis. With the addition of `FetchState` and more storage-specific fetch methods, the overlap was even clearer (and the redundancy more painful). QueryFilters are now just `F: WorldQuery where F::Fetch: FilterFetch`. FilterFetch requires `Fetch<Item = bool>` and adds new "short circuit" variants of fetch methods. This enables a filter tuple like `(With<A>, Without<B>, Changed<C>)` to stop evaluating the filter after the first mismatch is encountered. FilterFetch is automatically implemented for `Fetch` implementations that return bool. This forces fetch implementations that return things like `(bool, bool, bool)` (such as the filter above) to manually implement FilterFetch and decide whether or not to short-circuit. ## More Granular Modules World no longer globs all of the internal modules together. It now exports `core`, `system`, and `schedule` separately. I'm also considering exporting `core` submodules directly as that is still pretty "glob-ey" and unorganized (feedback welcome here). ## Remaining Draft Work (to be done in this pr) * ~~panic on conflicting WorldQuery fetches (&A, &mut A)~~ * ~~bevy `main` and hecs both currently allow this, but we should protect against it if possible~~ * ~~batch_iter / par_iter (currently stubbed out)~~ * ~~ChangedRes~~ * ~~I skipped this while we sort out #1313. This pr should be adapted to account for whatever we land on there~~. * ~~The `Archetypes` and `Tables` collections use hashes of sorted lists of component ids to uniquely identify each archetype/table. This hash is then used as the key in a HashMap to look up the relevant ArchetypeId or TableId. (which doesn't handle hash collisions properly)~~ * ~~It is currently unsafe to generate a Query from "World A", then use it on "World B" (despite the api claiming it is safe). We should probably close this gap. This could be done by adding a randomly generated WorldId to each world, then storing that id in each Query. They could then be compared to each other on each `query.do_thing(&world)` operation. This _does_ add an extra branch to each query operation, so I'm open to other suggestions if people have them.~~ * ~~Nested Bundles (if i find time)~~ ## Potential Future Work * Expand WorldCell to support queries. * Consider not allocating in the empty archetype on `world.spawn()` * ex: return something like EntityMutUninit, which turns into EntityMut after an `insert` or `insert_bundle` op * this actually regressed performance last time i tried it, but in theory it should be faster * Optimize SparseSet::insert (see `PERF` comment on insert) * Replace SparseArray `Option<T>` with T::MAX to cut down on branching * would enable cheaper get_unchecked() operations * upstream fixedbitset optimizations * fixedbitset could be allocation free for small block counts (store blocks in a SmallVec) * fixedbitset could have a const constructor * Consider implementing Tags (archetype-specific by-value data that affects archetype identity) * ex: ArchetypeA could have `[A, B, C]` table components and `[D(1)]` "tag" component. ArchetypeB could have `[A, B, C]` table components and a `[D(2)]` tag component. The archetypes are different, despite both having D tags because the value inside D is different. * this could potentially build on top of the `archetype.unique_components` added in this pr for resource storage. * Consider reverting `all_tuples` proc macro in favor of the old `macro_rules` implementation * all_tuples is more flexible and produces cleaner documentation (the macro_rules version produces weird type parameter orders due to parser constraints) * but unfortunately all_tuples also appears to make Rust Analyzer sad/slow when working inside of `bevy_ecs` (does not affect user code) * Consider "resource queries" and/or "mixed resource and entity component queries" as an alternative to WorldCell * this is basically just "systems" so maybe it's not worth it * Add more world ops * `world.clear()` * `world.reserve<T: Bundle>(count: usize)` * Try using the old archetype allocation strategy (allocate new memory on resize and copy everything over). I expect this to improve batch insertion performance at the cost of unbatched performance. But thats just a guess. I'm not an allocation perf pro :) * Adapt Commands apis for consistency with new World apis ## Benchmarks key: * `bevy_old`: bevy `main` branch * `bevy`: this branch * `_foreach`: uses an optimized for_each iterator * ` _sparse`: uses sparse set storage (if unspecified assume table storage) * `_system`: runs inside a system (if unspecified assume test happens via direct world ops) ### Simple Insert (from ecs_bench_suite)  ### Simpler Iter (from ecs_bench_suite)  ### Fragment Iter (from ecs_bench_suite)  ### Sparse Fragmented Iter Iterate a query that matches 5 entities from a single matching archetype, but there are 100 unmatching archetypes  ### Schedule (from ecs_bench_suite)  ### Add Remove Component (from ecs_bench_suite)  ### Add Remove Component Big Same as the test above, but each entity has 5 "large" matrix components and 1 "large" matrix component is added and removed  ### Get Component Looks up a single component value a large number of times 	2021-03-05 07:54:35 +00:00
Carter Anderson	72b2fc9843	Bevy Reflection (#926) ... Bevy Reflection	2020-11-27 16:39:59 -08:00
Carter Anderson	c32e637384	Asset system rework and GLTF scene loading (#693)	2020-10-18 13:48:15 -07:00
Grayson Burton	354d71cc1f	The Great Debuggening (#632) ... The Great Debuggening	2020-10-08 11:43:01 -07:00
Carter Anderson	70ad6671db	ecs: use generational entity ids and other optimizations (#504) ... ecs: use generational entity ids and other optimizations	2020-09-17 17:16:38 -07:00
Carter Anderson	9d0abeb014	fix formatting	2020-09-09 18:54:20 -07:00
Carter Anderson	478fb0649a	use upstream ron	2020-09-09 18:51:59 -07:00
Boxy	57177c9e98	Bump entities to u128 to avoid collisions (#117) (#393)	2020-08-31 11:51:28 -07:00
Victor "multun" Collod	d138647818	enforce cargo fmt --check	2020-08-16 05:02:06 -07:00
Carter Anderson	d67d05db97	add temporary ron fork ... bevy requires changes we contributed to master, but those changes havent been published yet	2020-08-09 18:45:55 -07:00
Carter Anderson	c81ab99dac	cargo fmt	2020-07-10 01:37:06 -07:00
Carter Anderson	950e50bbb1	Bevy ECS migration	2020-07-10 01:06:21 -07:00
Carter Anderson	db27d63b91	upgrade ron	2020-05-29 16:06:23 -07:00
Carter Anderson	651f213570	scene: spawning	2020-05-29 15:51:36 -07:00
Carter Anderson	065a94aca8	scene: hot scene reloading. update load_scene example	2020-05-29 12:56:32 -07:00
Carter Anderson	830565ae2b	scene: type registry refactor. use short type names when possible	2020-05-27 19:27:55 -07:00
Carter Anderson	cb3a863366	component_registry: use FromResources trait instead of Default	2020-05-27 00:23:31 -07:00
Carter Anderson	bb56b07973	scene: use two spaces instead of four	2020-05-26 19:49:46 -07:00
Carter Anderson	f0cbe8cd86	prop: impl prop macro. add impls for glam, legion, smallvec	2020-05-25 17:50:17 -07:00
Carter Anderson	f0f0e3c1a8	move component registry to its own crate. automatically register asset handles	2020-05-25 14:51:38 -07:00
Carter Anderson	0826d74163	props: remove specialization, ignore fields, impl for Handle, fix world round tripping	2020-05-25 12:03:50 -07:00
Carter Anderson	1cd3b4c987	props: add type peeking to ron, support arbitrary property types	2020-05-24 19:36:01 -07:00
Carter Anderson	4c306e6d48	props: migrate scenes to props. loading / saving worlds from / to props.	2020-05-23 22:07:17 -07:00
Carter Anderson	159acf52af	props: rename prop/props to property/properties ... its longer but a bit clearer	2020-05-22 15:36:48 -07:00
Carter Anderson	e514bd14fe	props: dynamic casting. reorganize	2020-05-22 15:25:31 -07:00
Carter Anderson	d920100d35	scenes: deserialization and refactor	2020-05-21 17:21:33 -07:00