# 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>
Addresses:
```sh
$ cargo build --release --example lighting --target wasm32-unknown-unknown --features webgl
error: none of the selected packages contains these features: webgl, did you mean: webgl2, webp?
```
# Objective
- When following the instructions for the web examples.
- Document clearly the generated file `./target/wasm_example.js`, since
it didn't appear on `git grep` (missing extension)
## Solution
- Follow the feature rename on the docs.
---------
Signed-off-by: Seb Ospina <kraige@gmail.com>
# Objective
My attempt at implementing #7515
## Solution
Added struct `Pitch` and implemented on it `Source` trait.
## Changelog
### Added
- File pitch.rs to bevy_audio crate
- Struct `Pitch` and type aliases for `AudioSourceBundle<Pitch>` and
`SpatialAudioSourceBundle<Pitch>`
- New example showing how to use `PitchBundle`
### Changed
- `AudioPlugin` now adds system for `Pitch` audio
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Fixes#4922
## Solution
- Add an example that maps a custom texture on a 3D mesh.
---
## Changelog
> Added the texture itself (confirmed with mod on discord before it
should be ok) to the assets folder, added to the README and Cargo.toml.
---------
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Sélène Amanita <134181069+Selene-Amanita@users.noreply.github.com>
# Objective
- Add morph targets to `bevy_pbr` (closes#5756) & load them from glTF
- Supersedes #3722
- Fixes#6814
[Morph targets][1] (also known as shape interpolation, shape keys, or
blend shapes) allow animating individual vertices with fine grained
controls. This is typically used for facial expressions. By specifying
multiple poses as vertex offset, and providing a set of weight of each
pose, it is possible to define surprisingly realistic transitions
between poses. Blending between multiple poses also allow composition.
Morph targets are part of the [gltf standard][2] and are a feature of
Unity and Unreal, and babylone.js, it is only natural to implement them
in bevy.
## Solution
This implementation of morph targets uses a 3d texture where each pixel
is a component of an animated attribute. Each layer is a different
target. We use a 2d texture for each target, because the number of
attribute×components×animated vertices is expected to always exceed the
maximum pixel row size limit of webGL2. It copies fairly closely the way
skinning is implemented on the CPU side, while on the GPU side, the
shader morph target implementation is a relatively trivial detail.
We add an optional `morph_texture` to the `Mesh` struct. The
`morph_texture` is built through a method that accepts an iterator over
attribute buffers.
The `MorphWeights` component, user-accessible, controls the blend of
poses used by mesh instances (so that multiple copy of the same mesh may
have different weights), all the weights are uploaded to a uniform
buffer of 256 `f32`. We limit to 16 poses per mesh, and a total of 256
poses.
More literature:
* Old babylone.js implementation (vertex attribute-based):
https://www.eternalcoding.com/dev-log-1-morph-targets/
* Babylone.js implementation (similar to ours):
https://www.youtube.com/watch?v=LBPRmGgU0PE
* GPU gems 3:
https://developer.nvidia.com/gpugems/gpugems3/part-i-geometry/chapter-3-directx-10-blend-shapes-breaking-limits
* Development discord thread
https://discord.com/channels/691052431525675048/1083325980615114772https://user-images.githubusercontent.com/26321040/231181046-3bca2ab2-d4d9-472e-8098-639f1871ce2e.mp4https://github.com/bevyengine/bevy/assets/26321040/d2a0c544-0ef8-45cf-9f99-8c3792f5a258
## Acknowledgements
* Thanks to `storytold` for sponsoring the feature
* Thanks to `superdump` and `james7132` for guidance and help figuring
out stuff
## Future work
- Handling of less and more attributes (eg: animated uv, animated
arbitrary attributes)
- Dynamic pose allocation (so that zero-weighted poses aren't uploaded
to GPU for example, enables much more total poses)
- Better animation API, see #8357
----
## Changelog
- Add morph targets to bevy meshes
- Support up to 64 poses per mesh of individually up to 116508 vertices,
animation currently strictly limited to the position, normal and tangent
attributes.
- Load a morph target using `Mesh::set_morph_targets`
- Add `VisitMorphTargets` and `VisitMorphAttributes` traits to
`bevy_render`, this allows defining morph targets (a fairly complex and
nested data structure) through iterators (ie: single copy instead of
passing around buffers), see documentation of those traits for details
- Add `MorphWeights` component exported by `bevy_render`
- `MorphWeights` control mesh's morph target weights, blending between
various poses defined as morph targets.
- `MorphWeights` are directly inherited by direct children (single level
of hierarchy) of an entity. This allows controlling several mesh
primitives through a unique entity _as per GLTF spec_.
- Add `MorphTargetNames` component, naming each indices of loaded morph
targets.
- Load morph targets weights and buffers in `bevy_gltf`
- handle morph targets animations in `bevy_animation` (previously, it
was a `warn!` log)
- Add the `MorphStressTest.gltf` asset for morph targets testing, taken
from the glTF samples repo, CC0.
- Add morph target manipulation to `scene_viewer`
- Separate the animation code in `scene_viewer` from the rest of the
code, reducing `#[cfg(feature)]` noise
- Add the `morph_targets.rs` example to show off how to manipulate morph
targets, loading `MorpStressTest.gltf`
## Migration Guide
- (very specialized, unlikely to be touched by 3rd parties)
- `MeshPipeline` now has a single `mesh_layouts` field rather than
separate `mesh_layout` and `skinned_mesh_layout` fields. You should
handle all possible mesh bind group layouts in your implementation
- You should also handle properly the new `MORPH_TARGETS` shader def and
mesh pipeline key. A new function is exposed to make this easier:
`setup_moprh_and_skinning_defs`
- The `MeshBindGroup` is now `MeshBindGroups`, cached bind groups are
now accessed through the `get` method.
[1]: https://en.wikipedia.org/wiki/Morph_target_animation
[2]:
https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#morph-targets
---------
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
This adds support for using texture atlas sprites in UI. From
discussions today in the ui-dev discord it seems this is a much wanted
feature.
This was previously attempted in #5070 by @ManevilleF however that was
blocked #5103. This work can be easily modified to support #5103 changes
after that merges.
## Solution
I created a new UI bundle that reuses the existing texture atlas
infrastructure. I create a new atlas image component to prevent it from
being drawn by the existing non-UI systems and to remove unused
parameters.
In extract I added new system to calculate the required values for the
texture atlas image, this extracts into the same resource as the
existing UI Image and Text components.
This should have minimal performance impact because if texture atlas is
not present then the exact same code path is followed. Also there should
be no unintended behavior changes because without the new components the
existing systems write the extract same resulting data.
I also added an example showing the sprite working and a system to
advance the animation on space bar presses.
Naming is hard and I would accept any feedback on the bundle name!
---
## Changelog
> Added TextureAtlasImageBundle
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
# Objective
Implement borders for UI nodes.
Relevant discussion: #7785
Related: #5924, #3991
<img width="283" alt="borders"
src="https://user-images.githubusercontent.com/27962798/220968899-7661d5ec-6f5b-4b0f-af29-bf9af02259b5.PNG">
## Solution
Add an extraction function to draw the borders.
---
Can only do one colour rectangular borders due to the limitations of the
Bevy UI renderer.
Maybe it can be combined with #3991 eventually to add curved border
support.
## Changelog
* Added a component `BorderColor`.
* Added the `extract_uinode_borders` system to the UI Render App.
* Added the UI example `borders`
---------
Co-authored-by: Nico Burns <nico@nicoburns.com>
# Objective
- `apply_system_buffers` is an unhelpful name: it introduces a new
internal-only concept
- this is particularly rough for beginners as reasoning about how
commands work is a critical stumbling block
## Solution
- rename `apply_system_buffers` to the more descriptive `apply_deferred`
- rename related fields, arguments and methods in the internals fo
bevy_ecs for consistency
- update the docs
## Changelog
`apply_system_buffers` has been renamed to `apply_deferred`, to more
clearly communicate its intent and relation to `Deferred` system
parameters like `Commands`.
## Migration Guide
- `apply_system_buffers` has been renamed to `apply_deferred`
- the `apply_system_buffers` method on the `System` trait has been
renamed to `apply_deferred`
- the `is_apply_system_buffers` function has been replaced by
`is_apply_deferred`
- `Executor::set_apply_final_buffers` is now
`Executor::set_apply_final_deferred`
- `Schedule::apply_system_buffers` is now `Schedule::apply_deferred`
---------
Co-authored-by: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
# Objective
- Support WebGPU
- alternative to #5027 that doesn't need any async / await
- fixes#8315
- Surprise fix#7318
## Solution
### For async renderer initialisation
- Update the plugin lifecycle:
- app builds the plugin
- calls `plugin.build`
- registers the plugin
- app starts the event loop
- event loop waits for `ready` of all registered plugins in the same
order
- returns `true` by default
- then call all `finish` then all `cleanup` in the same order as
registered
- then execute the schedule
In the case of the renderer, to avoid anything async:
- building the renderer plugin creates a detached task that will send
back the initialised renderer through a mutex in a resource
- `ready` will wait for the renderer to be present in the resource
- `finish` will take that renderer and place it in the expected
resources by other plugins
- other plugins (that expect the renderer to be available) `finish` are
called and they are able to set up their pipelines
- `cleanup` is called, only custom one is still for pipeline rendering
### For WebGPU support
- update the `build-wasm-example` script to support passing `--api
webgpu` that will build the example with WebGPU support
- feature for webgl2 was always enabled when building for wasm. it's now
in the default feature list and enabled on all platforms, so check for
this feature must also check that the target_arch is `wasm32`
---
## Migration Guide
- `Plugin::setup` has been renamed `Plugin::cleanup`
- `Plugin::finish` has been added, and plugins adding pipelines should
do it in this function instead of `Plugin::build`
```rust
// Before
impl Plugin for MyPlugin {
fn build(&self, app: &mut App) {
app.insert_resource::<MyResource>
.add_systems(Update, my_system);
let render_app = match app.get_sub_app_mut(RenderApp) {
Ok(render_app) => render_app,
Err(_) => return,
};
render_app
.init_resource::<RenderResourceNeedingDevice>()
.init_resource::<OtherRenderResource>();
}
}
// After
impl Plugin for MyPlugin {
fn build(&self, app: &mut App) {
app.insert_resource::<MyResource>
.add_systems(Update, my_system);
let render_app = match app.get_sub_app_mut(RenderApp) {
Ok(render_app) => render_app,
Err(_) => return,
};
render_app
.init_resource::<OtherRenderResource>();
}
fn finish(&self, app: &mut App) {
let render_app = match app.get_sub_app_mut(RenderApp) {
Ok(render_app) => render_app,
Err(_) => return,
};
render_app
.init_resource::<RenderResourceNeedingDevice>();
}
}
```
# Objective
Provide the ability to trigger controller rumbling (force-feedback) with
a cross-platform API.
## Solution
This adds the `GamepadRumbleRequest` event to `bevy_input` and adds a
system in `bevy_gilrs` to read them and rumble controllers accordingly.
It's a relatively primitive API with a `duration` in seconds and
`GamepadRumbleIntensity` with values for the weak and strong gamepad
motors. It's is an almost 1-to-1 mapping to platform APIs. Some
platforms refer to these motors as left and right, and low frequency and
high frequency, but by convention, they're usually the same.
I used #3868 as a starting point, updated to main, removed the low-level
gilrs effect API, and moved the requests to `bevy_input` and exposed the
strong and weak intensities.
I intend this to hopefully be a non-controversial cross-platform
starting point we can build upon to eventually support more fine-grained
control (closer to the gilrs effect API)
---
## Changelog
### Added
- Gamepads can now be rumbled by sending the `GamepadRumbleRequest`
event.
---------
Co-authored-by: Nicola Papale <nico@nicopap.ch>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
Co-authored-by: Bruce Reif (Buswolley) <bruce.reif@dynata.com>
# Objective
The objective is to be able to load data from "application-specific"
(see glTF spec 3.7.2.1.) vertex attribute semantics from glTF files into
Bevy meshes.
## Solution
Rather than probe the glTF for the specific attributes supported by
Bevy, this PR changes the loader to iterate through all the attributes
and map them onto `MeshVertexAttribute`s. This mapping includes all the
previously supported attributes, plus it is now possible to add mappings
using the `add_custom_vertex_attribute()` method on `GltfPlugin`.
## Changelog
- Add support for loading custom vertex attributes from glTF files.
- Add the `custom_gltf_vertex_attribute.rs` example to illustrate
loading custom vertex attributes.
## Migration Guide
- If you were instantiating `GltfPlugin` using the unit-like struct
syntax, you must instead use `GltfPlugin::default()` as the type is no
longer unit-like.
Fixes https://github.com/bevyengine/bevy/issues/1207
# Objective
Right now, it's impossible to capture a screenshot of the entire window
without forking bevy. This is because
- The swapchain texture never has the COPY_SRC usage
- It can't be accessed without taking ownership of it
- Taking ownership of it breaks *a lot* of stuff
## Solution
- Introduce a dedicated api for taking a screenshot of a given bevy
window, and guarantee this screenshot will always match up with what
gets put on the screen.
---
## Changelog
- Added the `ScreenshotManager` resource with two functions,
`take_screenshot` and `save_screenshot_to_disk`
# Objective
Split the UI overflow enum so that overflow can be set for each axis
separately.
## Solution
Change `Overflow` from an enum to a struct with `x` and `y`
`OverflowAxis` fields, where `OverflowAxis` is an enum with `Clip` and
`Visible` variants. Modify `update_clipping` to calculate clipping for
each axis separately. If only one axis is clipped, the other axis is
given infinite bounds.
<img width="642" alt="overflow"
src="https://user-images.githubusercontent.com/27962798/227592983-568cf76f-7e40-48c4-a511-43c886f5e431.PNG">
---
## Changelog
* Split the UI overflow implementation so overflow can be set for each
axis separately.
* Added the enum `OverflowAxis` with `Clip` and `Visible` variants.
* Changed `Overflow` to a struct with `x` and `y` fields of type
`OverflowAxis`.
* `Overflow` has new methods `visible()` and `hidden()` that replace its
previous `Clip` and `Visible` variants.
* Added `Overflow` helper methods `clip_x()` and `clip_y()` that return
a new `Overflow` value with the given axis clipped.
* Modified `update_clipping` so it calculates clipping for each axis
separately. If a node is only clipped on a single axis, the other axis
is given `-f32::INFINITY` to `f32::INFINITY` clipping bounds.
## Migration Guide
The `Style` property `Overflow` is now a struct with `x` and `y` fields,
that allow for per-axis overflow control.
Use these helper functions to replace the variants of `Overflow`:
* Replace `Overflow::Visible` with `Overflow::visible()`
* Replace `Overflow::Hidden` with `Overflow::clip()`
# Objective
An easy way to create 2D grid layouts
## Solution
Enable the `grid` feature in Taffy and add new style types for defining
grids.
## Notes
- ~I'm having a bit of trouble getting `#[derive(Reflect)]` to work
properly. Help with that would be appreciated (EDIT: got it to compile
by ignoring the problematic fields, but this presumably can't be
merged).~ This is now fixed
- ~The alignment types now have a `Normal` variant because I couldn't
get reflect to work with `Option`.~ I've decided to stick with the
flattened variant, as it saves a level of wrapping when authoring
styles. But I've renamed the variants from `Normal` to `Default`.
- ~This currently exposes a simplified API on top of grid. In particular
the following is not currently supported:~
- ~Negative grid indices~ Now supported.
- ~Custom `end` values for grid placement (you can only use `start` and
`span`)~ Now supported
- ~`minmax()` track sizing functions~ minmax is now support through a
`GridTrack::minmax()` constructor
- ~`repeat()`~ repeat is now implemented as `RepeatedGridTrack`
- ~Documentation still needs to be improved.~ An initial pass over the
documentation has been completed.
## Screenshot
<img width="846" alt="Screenshot 2023-03-10 at 17 56 21"
src="https://user-images.githubusercontent.com/1007307/224435332-69aa9eac-123d-4856-b75d-5449d3f1d426.png">
---
## Changelog
- Support for CSS Grid layout added to `bevy_ui`
---------
Co-authored-by: Rob Parrett <robparrett@gmail.com>
Co-authored-by: Andreas Weibye <13300393+Weibye@users.noreply.github.com>
# Objective
Examples on how to use the freshly merged `Bezier` struct ( #7653 ) are
missing.
## Solution
- Added a `bezier_curve.rs` example in the `animation/` folder.
---------
Co-authored-by: ira <JustTheCoolDude@gmail.com>
Co-authored-by: Aevyrie <aevyrie@gmail.com>
# Objective
Bevy provides an easy way to build the `examples/README.md` page, but
it's difficult to discover.
By adding instructions in `CONTRIBUTING.md`, it's easier to find that
it's possible to avoid this error-prone manual process.
Precisely: #8405 took me about 1 additional hour searching what command
to use to generate automatically the file. (I could have manually edited
the README, but that's beyond the point…)
# Objective
- The old post processing example doesn't use the actual post processing
features of bevy. It also has some issues with resizing. It's also
causing some confusion for people because accessing the prepass textures
from it is not easy.
- There's already a render to texture example
- At this point, it's mostly obsolete since the post_process_pass
example is more complete and shows the recommended way to do post
processing in bevy. It's a bit more complicated, but it's well
documented and I'm working on simplifying it even more
## Solution
- Remove the old post_processing example
- Rename post_process_pass to post_processing
## Reviewer Notes
The diff is really noisy because of the rename, but I didn't change any
code in the example.
---------
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
- Add a new example that helps debug different UI overflow scenarios
- This example tests the clipping behavior for images and text when the
node is moved, scaled or rotated.
## Solution
- Add a new `overflow_debug` example
# Preview
**Note:** Only top-left is working properly right now.
https://user-images.githubusercontent.com/188612/227629093-26c94c67-1781-437d-8410-e854b6f1adc1.mp4
---
Related #8095, #8167
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
# Objective
- Implement an alternative antialias technique
- TAA scales based off of view resolution, not geometry complexity
- TAA filters textures, firefly pixels, and other aliasing not covered
by MSAA
- TAA additionally will reduce noise / increase quality in future
stochastic rendering techniques
- Closes https://github.com/bevyengine/bevy/issues/3663
## Solution
- Add a temporal jitter component
- Add a motion vector prepass
- Add a TemporalAntialias component and plugin
- Combine existing MSAA and FXAA examples and add TAA
## Followup Work
- Prepass motion vector support for skinned meshes
- Move uniforms needed for motion vectors into a separate bind group,
instead of using different bind group layouts
- Reuse previous frame's GPU view buffer for motion vectors, instead of
recomputing
- Mip biasing for sharper textures, and or unjitter texture UVs
https://github.com/bevyengine/bevy/issues/7323
- Compute shader for better performance
- Investigate FSR techniques
- Historical depth based disocclusion tests, for geometry disocclusion
- Historical luminance/hue based tests, for shading disocclusion
- Pixel "locks" to reduce blending rate / revamp history confidence
mechanism
- Orthographic camera support for TemporalJitter
- Figure out COD's 1-tap bicubic filter
---
## Changelog
- Added MotionVectorPrepass and TemporalJitter
- Added TemporalAntialiasPlugin, TemporalAntialiasBundle, and
TemporalAntialiasSettings
---------
Co-authored-by: IceSentry <c.giguere42@gmail.com>
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
Co-authored-by: Robert Swain <robert.swain@gmail.com>
Co-authored-by: Daniel Chia <danstryder@gmail.com>
Co-authored-by: robtfm <50659922+robtfm@users.noreply.github.com>
Co-authored-by: Brandon Dyer <brandondyer64@gmail.com>
Co-authored-by: Edgar Geier <geieredgar@gmail.com>
# Objective
- Rename `text_layout` example to `flex_layout` to better reflect the
example purpose
- `AlignItems`/`JustifyContent` is not related to text layout, it's
about child nodes positioning
## Solution
- Rename the example
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Add a convenient immediate mode drawing API for visual debugging.
Fixes#5619
Alternative to #1625
Partial alternative to #5734
Based off https://github.com/Toqozz/bevy_debug_lines with some changes:
* Simultaneous support for 2D and 3D.
* Methods for basic shapes; circles, spheres, rectangles, boxes, etc.
* 2D methods.
* Removed durations. Seemed niche, and can be handled by users.
<details>
<summary>Performance</summary>
Stress tested using Bevy's recommended optimization settings for the dev
profile with the
following command.
```bash
cargo run --example many_debug_lines \
--config "profile.dev.package.\"*\".opt-level=3" \
--config "profile.dev.opt-level=1"
```
I dipped to 65-70 FPS at 300,000 lines
CPU: 3700x
RAM Speed: 3200 Mhz
GPU: 2070 super - probably not very relevant, mostly cpu/memory bound
</details>
<details>
<summary>Fancy bloom screenshot</summary>
</details>
## Changelog
* Added `GizmoPlugin`
* Added `Gizmos` system parameter for drawing lines and wireshapes.
### TODO
- [ ] Update changelog
- [x] Update performance numbers
- [x] Add credit to PR description
### Future work
- Cache rendering primitives instead of constructing them out of line
segments each frame.
- Support for drawing solid meshes
- Interactions. (See
[bevy_mod_gizmos](https://github.com/LiamGallagher737/bevy_mod_gizmos))
- Fancier line drawing. (See
[bevy_polyline](https://github.com/ForesightMiningSoftwareCorporation/bevy_polyline))
- Support for `RenderLayers`
- Display gizmos for a certain duration. Currently everything displays
for one frame (ie. immediate mode)
- Changing settings per drawn item like drawing on top or drawing to
different `RenderLayers`
Co-Authored By: @lassade <felipe.jorge.pereira@gmail.com>
Co-Authored By: @The5-1 <agaku@hotmail.de>
Co-Authored By: @Toqozz <toqoz@hotmail.com>
Co-Authored By: @nicopap <nico@nicopap.ch>
---------
Co-authored-by: Robert Swain <robert.swain@gmail.com>
Co-authored-by: IceSentry <c.giguere42@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Simple text pipeline benchmark. It's quite expensive but current examples don't capture the performance of `queue_text` as it only runs on changes to the text.
Huge credit to @StarLederer, who did almost all of the work on this. We're just reusing this PR to keep everything in one place.
# Objective
1. Make bloom more physically based.
1. Improve artistic control.
1. Allow to use bloom as screen blur.
1. Fix#6634.
1. Address #6655 (although the author makes incorrect conclusions).
## Solution
1. Set the default threshold to 0.
2. Lerp between bloom textures when `composite_mode: BloomCompositeMode::EnergyConserving`.
1. Use [a parametric function](https://starlederer.github.io/bloom) to control blend levels for each bloom texture. In the future this can be controlled per-pixel for things like lens dirt.
3. Implement BloomCompositeMode::Additive` for situations where the old school look is desired.
## Changelog
* Bloom now looks different.
* Added `BloomSettings:lf_boost`, `BloomSettings:lf_boost_curvature`, `BloomSettings::high_pass_frequency` and `BloomSettings::composite_mode`.
* `BloomSettings::scale` removed.
* `BloomSettings::knee` renamed to `BloomPrefilterSettings::softness`.
* `BloomSettings::threshold` renamed to `BloomPrefilterSettings::threshold`.
* The bloom example has been renamed to bloom_3d and improved. A bloom_2d example was added.
## Migration Guide
* Refactor mentions of `BloomSettings::knee` and `BloomSettings::threshold` as `BloomSettings::prefilter_settings` where knee is now `softness`.
* If defined without `..default()` add `..default()` to definitions of `BloomSettings` instances or manually define missing fields.
* Adapt to Bloom looking visually different (if needed).
Co-authored-by: Herman Lederer <germans.lederers@gmail.com>
# Objective
- Use the prepass textures in webgl
## Solution
- Bind the prepass textures even when using webgl, but only if msaa is disabled
- Also did some refactors to centralize how textures are bound, similar to the EnvironmentMapLight PR
- ~~Also did some refactors of the example to make it work in webgl~~
- ~~To make the example work in webgl, I needed to use a sampler for the depth texture, the resulting code looks a bit weird, but it's simple enough and I think it's worth it to show how it works when using webgl~~
# Objective
This PR adds an example that shows how to use `apply_system_buffers` and how to order it with respect to the relevant systems. It also shows how not ordering the systems can lead to unexpected behaviours.
## Solution
Add the example.
# Objective
- Add basic spatial audio support to Bevy
- this is what rodio supports, so no HRTF, just simple stereo channel manipulation
- no "built-in" ECS support: `Emitter` and `Listener` should be components that would automatically update the positions
This PR goal is to just expose rodio functionality, made possible with the recent update to rodio 0.16. A proper ECS integration opens a lot more questions, and would probably require an RFC
Also updates rodio and fixes#6122
# Objective
Splits tone mapping from https://github.com/bevyengine/bevy/pull/6677 into a separate PR.
Address https://github.com/bevyengine/bevy/issues/2264.
Adds tone mapping options:
- None: Bypasses tonemapping for instances where users want colors output to match those set.
- Reinhard
- Reinhard Luminance: Bevy's exiting tonemapping
- [ACES](https://github.com/TheRealMJP/BakingLab/blob/master/BakingLab/ACES.hlsl) (Fitted version, based on the same implementation that Godot 4 uses) see https://github.com/bevyengine/bevy/issues/2264
- [AgX](https://github.com/sobotka/AgX)
- SomewhatBoringDisplayTransform
- TonyMcMapface
- Blender Filmic
This PR also adds support for EXR images so they can be used to compare tonemapping options with reference images.
## Migration Guide
- Tonemapping is now an enum with NONE and the various tonemappers.
- The DebandDither is now a separate component.
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
# Objective
- Merge the examples on iOS and Android
- Make sure they both work from the same code
## Solution
- don't create window when not in an active state (from #6830)
- exit on suspend on Android (from #6830)
- automatically enable dependency feature of bevy_audio on android so that it works out of the box
- don't inverse y position of touch events
- reuse the same example for both Android and iOS
Fixes#4616Fixes#4103Fixes#3648Fixes#3458Fixes#3249Fixes#86
Huge thanks to @maniwani, @devil-ira, @hymm, @cart, @superdump and @jakobhellermann for the help with this PR.
# Objective
- Followup #6587.
- Minimal integration for the Stageless Scheduling RFC: https://github.com/bevyengine/rfcs/pull/45
## Solution
- [x] Remove old scheduling module
- [x] Migrate new methods to no longer use extension methods
- [x] Fix compiler errors
- [x] Fix benchmarks
- [x] Fix examples
- [x] Fix docs
- [x] Fix tests
## Changelog
### Added
- a large number of methods on `App` to work with schedules ergonomically
- the `CoreSchedule` enum
- `App::add_extract_system` via the `RenderingAppExtension` trait extension method
- the private `prepare_view_uniforms` system now has a public system set for scheduling purposes, called `ViewSet::PrepareUniforms`
### Removed
- stages, and all code that mentions stages
- states have been dramatically simplified, and no longer use a stack
- `RunCriteriaLabel`
- `AsSystemLabel` trait
- `on_hierarchy_reports_enabled` run criteria (now just uses an ad hoc resource checking run condition)
- systems in `RenderSet/Stage::Extract` no longer warn when they do not read data from the main world
- `RunCriteriaLabel`
- `transform_propagate_system_set`: this was a nonstandard pattern that didn't actually provide enough control. The systems are already `pub`: the docs have been updated to ensure that the third-party usage is clear.
### Changed
- `System::default_labels` is now `System::default_system_sets`.
- `App::add_default_labels` is now `App::add_default_sets`
- `CoreStage` and `StartupStage` enums are now `CoreSet` and `StartupSet`
- `App::add_system_set` was renamed to `App::add_systems`
- The `StartupSchedule` label is now defined as part of the `CoreSchedules` enum
- `.label(SystemLabel)` is now referred to as `.in_set(SystemSet)`
- `SystemLabel` trait was replaced by `SystemSet`
- `SystemTypeIdLabel<T>` was replaced by `SystemSetType<T>`
- The `ReportHierarchyIssue` resource now has a public constructor (`new`), and implements `PartialEq`
- Fixed time steps now use a schedule (`CoreSchedule::FixedTimeStep`) rather than a run criteria.
- Adding rendering extraction systems now panics rather than silently failing if no subapp with the `RenderApp` label is found.
- the `calculate_bounds` system, with the `CalculateBounds` label, is now in `CoreSet::Update`, rather than in `CoreSet::PostUpdate` before commands are applied.
- `SceneSpawnerSystem` now runs under `CoreSet::Update`, rather than `CoreStage::PreUpdate.at_end()`.
- `bevy_pbr::add_clusters` is no longer an exclusive system
- the top level `bevy_ecs::schedule` module was replaced with `bevy_ecs::scheduling`
- `tick_global_task_pools_on_main_thread` is no longer run as an exclusive system. Instead, it has been replaced by `tick_global_task_pools`, which uses a `NonSend` resource to force running on the main thread.
## Migration Guide
- Calls to `.label(MyLabel)` should be replaced with `.in_set(MySet)`
- Stages have been removed. Replace these with system sets, and then add command flushes using the `apply_system_buffers` exclusive system where needed.
- The `CoreStage`, `StartupStage, `RenderStage` and `AssetStage` enums have been replaced with `CoreSet`, `StartupSet, `RenderSet` and `AssetSet`. The same scheduling guarantees have been preserved.
- Systems are no longer added to `CoreSet::Update` by default. Add systems manually if this behavior is needed, although you should consider adding your game logic systems to `CoreSchedule::FixedTimestep` instead for more reliable framerate-independent behavior.
- Similarly, startup systems are no longer part of `StartupSet::Startup` by default. In most cases, this won't matter to you.
- For example, `add_system_to_stage(CoreStage::PostUpdate, my_system)` should be replaced with
- `add_system(my_system.in_set(CoreSet::PostUpdate)`
- When testing systems or otherwise running them in a headless fashion, simply construct and run a schedule using `Schedule::new()` and `World::run_schedule` rather than constructing stages
- Run criteria have been renamed to run conditions. These can now be combined with each other and with states.
- Looping run criteria and state stacks have been removed. Use an exclusive system that runs a schedule if you need this level of control over system control flow.
- For app-level control flow over which schedules get run when (such as for rollback networking), create your own schedule and insert it under the `CoreSchedule::Outer` label.
- Fixed timesteps are now evaluated in a schedule, rather than controlled via run criteria. The `run_fixed_timestep` system runs this schedule between `CoreSet::First` and `CoreSet::PreUpdate` by default.
- Command flush points introduced by `AssetStage` have been removed. If you were relying on these, add them back manually.
- Adding extract systems is now typically done directly on the main app. Make sure the `RenderingAppExtension` trait is in scope, then call `app.add_extract_system(my_system)`.
- the `calculate_bounds` system, with the `CalculateBounds` label, is now in `CoreSet::Update`, rather than in `CoreSet::PostUpdate` before commands are applied. You may need to order your movement systems to occur before this system in order to avoid system order ambiguities in culling behavior.
- the `RenderLabel` `AppLabel` was renamed to `RenderApp` for clarity
- `App::add_state` now takes 0 arguments: the starting state is set based on the `Default` impl.
- Instead of creating `SystemSet` containers for systems that run in stages, simply use `.on_enter::<State::Variant>()` or its `on_exit` or `on_update` siblings.
- `SystemLabel` derives should be replaced with `SystemSet`. You will also need to add the `Debug`, `PartialEq`, `Eq`, and `Hash` traits to satisfy the new trait bounds.
- `with_run_criteria` has been renamed to `run_if`. Run criteria have been renamed to run conditions for clarity, and should now simply return a bool.
- States have been dramatically simplified: there is no longer a "state stack". To queue a transition to the next state, call `NextState::set`
## TODO
- [x] remove dead methods on App and World
- [x] add `App::add_system_to_schedule` and `App::add_systems_to_schedule`
- [x] avoid adding the default system set at inappropriate times
- [x] remove any accidental cycles in the default plugins schedule
- [x] migrate benchmarks
- [x] expose explicit labels for the built-in command flush points
- [x] migrate engine code
- [x] remove all mentions of stages from the docs
- [x] verify docs for States
- [x] fix uses of exclusive systems that use .end / .at_start / .before_commands
- [x] migrate RenderStage and AssetStage
- [x] migrate examples
- [x] ensure that transform propagation is exported in a sufficiently public way (the systems are already pub)
- [x] ensure that on_enter schedules are run at least once before the main app
- [x] re-enable opt-in to execution order ambiguities
- [x] revert change to `update_bounds` to ensure it runs in `PostUpdate`
- [x] test all examples
- [x] unbreak directional lights
- [x] unbreak shadows (see 3d_scene, 3d_shape, lighting, transparaency_3d examples)
- [x] game menu example shows loading screen and menu simultaneously
- [x] display settings menu is a blank screen
- [x] `without_winit` example panics
- [x] ensure all tests pass
- [x] SubApp doc test fails
- [x] runs_spawn_local tasks fails
- [x] [Fix panic_when_hierachy_cycle test hanging](https://github.com/alice-i-cecile/bevy/pull/120)
## Points of Difficulty and Controversy
**Reviewers, please give feedback on these and look closely**
1. Default sets, from the RFC, have been removed. These added a tremendous amount of implicit complexity and result in hard to debug scheduling errors. They're going to be tackled in the form of "base sets" by @cart in a followup.
2. The outer schedule controls which schedule is run when `App::update` is called.
3. I implemented `Label for `Box<dyn Label>` for our label types. This enables us to store schedule labels in concrete form, and then later run them. I ran into the same set of problems when working with one-shot systems. We've previously investigated this pattern in depth, and it does not appear to lead to extra indirection with nested boxes.
4. `SubApp::update` simply runs the default schedule once. This sucks, but this whole API is incomplete and this was the minimal changeset.
5. `time_system` and `tick_global_task_pools_on_main_thread` no longer use exclusive systems to attempt to force scheduling order
6. Implemetnation strategy for fixed timesteps
7. `AssetStage` was migrated to `AssetSet` without reintroducing command flush points. These did not appear to be used, and it's nice to remove these bottlenecks.
8. Migration of `bevy_render/lib.rs` and pipelined rendering. The logic here is unusually tricky, as we have complex scheduling requirements.
## Future Work (ideally before 0.10)
- Rename schedule_v3 module to schedule or scheduling
- Add a derive macro to states, and likely a `EnumIter` trait of some form
- Figure out what exactly to do with the "systems added should basically work by default" problem
- Improve ergonomics for working with fixed timesteps and states
- Polish FixedTime API to match Time
- Rebase and merge #7415
- Resolve all internal ambiguities (blocked on better tools, especially #7442)
- Add "base sets" to replace the removed default sets.
# Objective
- Bevy should not have any "internal" execution order ambiguities. These clutter the output of user-facing error reporting, and can result in nasty, nondetermistic, very difficult to solve bugs.
- Verifying this currently involves repeated non-trivial manual work.
## Solution
- [x] add an example to quickly check this
- ~~[ ] ensure that this example panics if there are any unresolved ambiguities~~
- ~~[ ] run the example in CI 😈~~
There's one tricky ambiguity left, between UI and animation. I don't have the tools to fix this without system set configuration, so the remaining work is going to be left to #7267 or another PR after that.
```
2023-01-27T18:38:42.989405Z INFO bevy_ecs::schedule::ambiguity_detection: Execution order ambiguities detected, you might want to add an explicit dependency relation between some of these systems:
* Parallel systems:
-- "bevy_animation::animation_player" and "bevy_ui::flex::flex_node_system"
conflicts: ["bevy_transform::components::transform::Transform"]
```
## Changelog
Resolved internal execution order ambiguities for:
1. Transform propagation (ignored, we need smarter filter checking).
2. Gamepad processing (fixed).
3. bevy_winit's window handling (fixed).
4. Cascaded shadow maps and perspectives (fixed).
Also fixed a desynchronized state bug that could occur when the `Window` component is removed and then added to the same entity in a single frame.
# Objective
- Fix#7315
- Add IME support
## Solution
- Add two new fields to `Window`, to control if IME is enabled and the candidate box position
This allows the use of dead keys which are needed in French, or the full IME experience to type using Pinyin
I also added a basic general text input example that can handle IME input.
https://user-images.githubusercontent.com/8672791/213941353-5ed73a73-5dd1-4e66-a7d6-a69b49694c52.mp4
<img width="1392" alt="image" src="https://user-images.githubusercontent.com/418473/203873533-44c029af-13b7-4740-8ea3-af96bd5867c9.png">
<img width="1392" alt="image" src="https://user-images.githubusercontent.com/418473/203873549-36be7a23-b341-42a2-8a9f-ceea8ac7a2b8.png">
# Objective
- Add support for the “classic” distance fog effect, as well as a more advanced atmospheric fog effect.
## Solution
This PR:
- Introduces a new `FogSettings` component that controls distance fog per-camera.
- Adds support for three widely used “traditional” fog falloff modes: `Linear`, `Exponential` and `ExponentialSquared`, as well as a more advanced `Atmospheric` fog;
- Adds support for directional light influence over fog color;
- Extracts fog via `ExtractComponent`, then uses a prepare system that sets up a new dynamic uniform struct (`Fog`), similar to other mesh view types;
- Renders fog in PBR material shader, as a final adjustment to the `output_color`, after PBR is computed (but before tone mapping);
- Adds a new `StandardMaterial` flag to enable fog; (`fog_enabled`)
- Adds convenience methods for easier artistic control when creating non-linear fog types;
- Adds documentation around fog.
---
## Changelog
### Added
- Added support for distance-based fog effects for PBR materials, controllable per-camera via the new `FogSettings` component;
- Added `FogFalloff` enum for selecting between three widely used “traditional” fog falloff modes: `Linear`, `Exponential` and `ExponentialSquared`, as well as a more advanced `Atmospheric` fog;
# Objective
I found several words in code and docs are incorrect. This should be fixed.
## Solution
- Fix several minor typos
Co-authored-by: Chris Ohk <utilforever@gmail.com>
# Objective
Fixes#6952
## Solution
- Request WGPU capabilities `SAMPLED_TEXTURE_AND_STORAGE_BUFFER_ARRAY_NON_UNIFORM_INDEXING`, `SAMPLER_NON_UNIFORM_INDEXING` and `UNIFORM_BUFFER_AND_STORAGE_TEXTURE_ARRAY_NON_UNIFORM_INDEXING` when corresponding features are enabled.
- Add an example (`shaders/texture_binding_array`) illustrating (and testing) the use of non-uniform indexed textures and samplers.
## Changelog
- Added new capabilities for shader validation.
- Added example `shaders/texture_binding_array`.
# Objective
- This PR adds support for blend modes to the PBR `StandardMaterial`.
<img width="1392" alt="Screenshot 2022-11-18 at 20 00 56" src="https://user-images.githubusercontent.com/418473/202820627-0636219a-a1e5-437a-b08b-b08c6856bf9c.png">
<img width="1392" alt="Screenshot 2022-11-18 at 20 01 01" src="https://user-images.githubusercontent.com/418473/202820615-c8d43301-9a57-49c4-bd21-4ae343c3e9ec.png">
## Solution
- The existing `AlphaMode` enum is extended, adding three more modes: `AlphaMode::Premultiplied`, `AlphaMode::Add` and `AlphaMode::Multiply`;
- All new modes are rendered in the existing `Transparent3d` phase;
- The existing mesh flags for alpha mode are reorganized for a more compact/efficient representation, and new values are added;
- `MeshPipelineKey::TRANSPARENT_MAIN_PASS` is refactored into `MeshPipelineKey::BLEND_BITS`.
- `AlphaMode::Opaque` and `AlphaMode::Mask(f32)` share a single opaque pipeline key: `MeshPipelineKey::BLEND_OPAQUE`;
- `Blend`, `Premultiplied` and `Add` share a single premultiplied alpha pipeline key, `MeshPipelineKey::BLEND_PREMULTIPLIED_ALPHA`. In the shader, color values are premultiplied accordingly (or not) depending on the blend mode to produce the three different results after PBR/tone mapping/dithering;
- `Multiply` uses its own independent pipeline key, `MeshPipelineKey::BLEND_MULTIPLY`;
- Example and documentation are provided.
---
## Changelog
### Added
- Added support for additive and multiplicative blend modes in the PBR `StandardMaterial`, via `AlphaMode::Add` and `AlphaMode::Multiply`;
- Added support for premultiplied alpha in the PBR `StandardMaterial`, via `AlphaMode::Premultiplied`;
# Objective
- Add a configurable prepass
- A depth prepass is useful for various shader effects and to reduce overdraw. It can be expansive depending on the scene so it's important to be able to disable it if you don't need any effects that uses it or don't suffer from excessive overdraw.
- The goal is to eventually use it for things like TAA, Ambient Occlusion, SSR and various other techniques that can benefit from having a prepass.
## Solution
The prepass node is inserted before the main pass. It runs for each `Camera3d` with a prepass component (`DepthPrepass`, `NormalPrepass`). The presence of one of those components is used to determine which textures are generated in the prepass. When any prepass is enabled, the depth buffer generated will be used by the main pass to reduce overdraw.
The prepass runs for each `Material` created with the `MaterialPlugin::prepass_enabled` option set to `true`. You can overload the shader used by the prepass by using `Material::prepass_vertex_shader()` and/or `Material::prepass_fragment_shader()`. It will also use the `Material::specialize()` for more advanced use cases. It is enabled by default on all materials.
The prepass works on opaque materials and materials using an alpha mask. Transparent materials are ignored.
The `StandardMaterial` overloads the prepass fragment shader to support alpha mask and normal maps.
---
## Changelog
- Add a new `PrepassNode` that runs before the main pass
- Add a `PrepassPlugin` to extract/prepare/queue the necessary data
- Add a `DepthPrepass` and `NormalPrepass` component to control which textures will be created by the prepass and available in later passes.
- Add a new `prepass_enabled` flag to the `MaterialPlugin` that will control if a material uses the prepass or not.
- Add a new `prepass_enabled` flag to the `PbrPlugin` to control if the StandardMaterial uses the prepass. Currently defaults to false.
- Add `Material::prepass_vertex_shader()` and `Material::prepass_fragment_shader()` to control the prepass from the `Material`
## Notes
In bevy's sample 3d scene, the performance is actually worse when enabling the prepass, but on more complex scenes the performance is generally better. I would like more testing on this, but @DGriffin91 has reported a very noticeable improvements in some scenes.
The prepass is also used by @JMS55 for TAA and GTAO
discord thread: <https://discord.com/channels/691052431525675048/1011624228627419187>
This PR was built on top of the work of multiple people
Co-Authored-By: @superdump
Co-Authored-By: @robtfm
Co-Authored-By: @JMS55
Co-authored-by: Charles <IceSentry@users.noreply.github.com>
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
# Objective
- Fixes#6361
- Fixes#6362
- Fixes#6364
## Solution
- Added an example for creating a custom `Decodable` type
- Clarified the documentation on `Decodable`
- Added an `AddAudioSource` trait and implemented it for `App`
Co-authored-by: dis-da-moe <84386186+dis-da-moe@users.noreply.github.com>
# Objective
Add useful information about cursor position relative to a UI node. Fixes#7079.
## Solution
- Added a new `RelativeCursorPosition` component
---
## Changelog
- Added
- `RelativeCursorPosition`
- an example showcasing the new component
Co-authored-by: Dawid Piotrowski <41804418+Pietrek14@users.noreply.github.com>
# Objective
It is possible to manually update `GlobalTransform`.
The engine actually assumes this is not possible.
For example, `propagate_transform` does not update children
of an `Entity` which **`GlobalTransform`** changed,
leading to unexpected behaviors.
A `GlobalTransform` set by the user may also be blindly
overwritten by the propagation system.
## Solution
- Remove `translation_mut`
- Explain to users that they shouldn't manually update the `GlobalTransform`
- Remove `global_vs_local.rs` example, since it misleads users
in believing that it is a valid use-case to manually update the
`GlobalTransform`
---
## Changelog
- Remove `GlobalTransform::translation_mut`
## Migration Guide
`GlobalTransform::translation_mut` has been removed without alternative,
if you were relying on this, update the `Transform` instead. If the given entity
had children or parent, you may need to remove its parent to make its transform
independent (in which case the new `Commands::set_parent_in_place` and
`Commands::remove_parent_in_place` may be of interest)
Bevy may add in the future a way to toggle transform propagation on
an entity basis.
# Objective
This PR reorganizes majority of the scene viewer example into a module of plugins which then allows reuse of functionality among new or existing examples. In addition, this enables the scene viewer to be more succinct and showcase the distinct cases of camera control and scene control.
This work is to support future work in organization and future examples. A more complicated 3D scene example has been requested by the community (#6551) which requests functionality currently included in scene_viewer, but previously inaccessible. The future example can now just utilize the two plugins created here. The existing example [animated_fox example] can utilize the scene creation and animation control functionality of `SceneViewerPlugin`.
## Solution
- Created a `scene_viewer` module inside the `tools` example folder.
- Created two plugins: `SceneViewerPlugin` (gltf scene loading, animation control, camera tracking control, light control) and `CameraControllerPlugin` (controllable camera).
- Original `scene_viewer.rs` moved to `scene_viewer/main.rs` and now utilizes the two plugins.
# Objective
- Bevy should be usable to create 'overlay' type apps, where the input is not captured by Bevy, but passed down/into a target app, or to allow passive displays/widgets etc.
## Solution
- the `winit:🪟:Window` already has a `set_cursor_hittest()` which basically does this for mouse input events, so I've exposed it (trying to copy the style laid out in the existing wrappings, and added a simple demo.
---
## Changelog
- Added `hittest` to `WindowAttributes`
- Added the `hittest`'s setters/getters
- Modified the `WindowBuilder`
- Modifed the `WindowDescriptor`'s `Default` impl.
- Added an example `cargo run --example fallthrough`
# Objective
- Adds a bloom pass for HDR-enabled Camera3ds.
- Supersedes (and all credit due to!) https://github.com/bevyengine/bevy/pull/3430 and https://github.com/bevyengine/bevy/pull/2876
## Solution
- A threshold is applied to isolate emissive samples, and then a series of downscale and upscaling passes are applied and composited together.
- Bloom is applied to 2d or 3d Cameras with hdr: true and a BloomSettings component.
---
## Changelog
- Added a `core_pipeline::bloom::BloomSettings` component.
- Added `BloomNode` that runs between the main pass and tonemapping.
- Added a `BloomPlugin` that is loaded as part of CorePipelinePlugin.
- Added a bloom example project.
Co-authored-by: JMS55 <47158642+JMS55@users.noreply.github.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Co-authored-by: DGriffin91 <github@dgdigital.net>
# Objective
Add consistent UI rendering and interaction where deep nodes inside two different hierarchies will never render on top of one-another by default and offer an escape hatch (z-index) for nodes to change their depth.
## The problem with current implementation
The current implementation of UI rendering is broken in that regard, mainly because [it sets the Z value of the `Transform` component based on a "global Z" space](https://github.com/bevyengine/bevy/blob/main/crates/bevy_ui/src/update.rs#L43) shared by all nodes in the UI. This doesn't account for the fact that each node's final `GlobalTransform` value will be relative to its parent. This effectively makes the depth unpredictable when two deep trees are rendered on top of one-another.
At the moment, it's also up to each part of the UI code to sort all of the UI nodes. The solution that's offered here does the full sorting of UI node entities once and offers the result through a resource so that all systems can use it.
## Solution
### New ZIndex component
This adds a new optional `ZIndex` enum component for nodes which offers two mechanism:
- `ZIndex::Local(i32)`: Overrides the depth of the node relative to its siblings.
- `ZIndex::Global(i32)`: Overrides the depth of the node relative to the UI root. This basically allows any node in the tree to "escape" the parent and be ordered relative to the entire UI.
Note that in the current implementation, omitting `ZIndex` on a node has the same result as adding `ZIndex::Local(0)`. Additionally, the "global" stacking context is essentially a way to add your node to the root stacking context, so using `ZIndex::Local(n)` on a root node (one without parent) will share that space with all nodes using `Index::Global(n)`.
### New UiStack resource
This adds a new `UiStack` resource which is calculated from both hierarchy and `ZIndex` during UI update and contains a vector of all node entities in the UI, ordered by depth (from farthest from camera to closest). This is exposed publicly by the bevy_ui crate with the hope that it can be used for consistent ordering and to reduce the amount of sorting that needs to be done by UI systems (i.e. instead of sorting everything by `global_transform.z` in every system, this array can be iterated over).
### New z_index example
This also adds a new z_index example that showcases the new `ZIndex` component. It's also a good general demo of the new UI stack system, because making this kind of UI was very broken with the old system (e.g. nodes would render on top of each other, not respecting hierarchy or insert order at all).
---
## Changelog
- Added the `ZIndex` component to bevy_ui.
- Added the `UiStack` resource to bevy_ui, and added implementation in a new `stack.rs` module.
- Removed the previous Z updating system from bevy_ui, because it was replaced with the above.
- Changed bevy_ui rendering to use UiStack instead of z ordering.
- Changed bevy_ui focus/interaction system to use UiStack instead of z ordering.
- Added a new z_index example.
## ZIndex demo
Here's a demo I wrote to test these features
https://user-images.githubusercontent.com/1060971/188329295-d7beebd6-9aee-43ab-821e-d437df5dbe8a.mp4
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Add post processing passes for FXAA (Fast Approximate Anti-Aliasing)
- Add example comparing MSAA and FXAA
## Solution
When the FXAA plugin is added, passes for FXAA are inserted between the main pass and the tonemapping pass. Supports using either HDR or LDR output from the main pass.
---
## Changelog
- Add a new FXAANode that runs after the main pass when the FXAA plugin is added.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
To be consistent like other examples, it's better to keep file name and example name same, so we don't need to find correct example name in Cargo.toml.
## Solution
Rename example file scaling.rs to ui_scaling.rs.
# Objective
> System chaining is a confusing name: it implies the ability to construct non-linear graphs, and suggests a sense of system ordering that is only incidentally true. Instead, it actually works by passing data from one system to the next, much like the pipe operator.
> In the accepted [stageless RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/45-stageless.md), this concept is renamed to piping, and "system chaining" is used to construct groups of systems with ordering dependencies between them.
Fixes#6225.
## Changelog
System chaining has been renamed to system piping to improve clarity (and free up the name for new ordering APIs).
## Migration Guide
The `.chain(handler_system)` method on systems is now `.pipe(handler_system)`.
The `IntoChainSystem` trait is now `IntoPipeSystem`, and the `ChainSystem` struct is now `PipeSystem`.
# Objective
I was about to submit a PR to add these two examples to `bevy-website` and re-discovered the inconsistency.
Although it's not a major issue on the website where only the filenames are shown, this would help to visually distinguish the two examples in the list because the names are very prominent.
This also helps out when fuzzy-searching the codebase for these files.
## Solution
Rename `shapes` to `2d_shapes`. Now the filename matches the example name, and the naming structure matches the 3d example.
## Notes
@Nilirad proposed this in https://github.com/bevyengine/bevy/pull/4613#discussion_r862455631 but it had slipped away from my brain at that time.
# Objective
- Adopted from #3836
- Example showcases how to request a new resolution
- Example showcases how to react to resolution changes
Co-authored-by: Andreas Weibye <13300393+Weibye@users.noreply.github.com>
# Objective
- Allow users to change the scaling of the UI
- Adopted from #2808
## Solution
- This is an accessibility feature for fixed-size UI elements, allowing the developer to expose a range of UI scales for the player to set a scale that works for their needs.
> - The user can modify the UiScale struct to change the scaling at runtime. This multiplies the Px values by the scale given, while not touching any others.
> - The example showcases how this even allows for fluid transitions
> Here's how the example looks like:
https://user-images.githubusercontent.com/1631166/132979069-044161a9-8e85-45ab-9e93-fcf8e3852c2b.mp4
---
## Changelog
- Added a `UiScale` which can be used to scale all of UI
Co-authored-by: Andreas Weibye <13300393+Weibye@users.noreply.github.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Fix / support KTX2 array / cubemap / cubemap array textures
- Fixes#4495 . Supersedes #4514 .
## Solution
- Add `Option<TextureViewDescriptor>` to `Image` to enable configuration of the `TextureViewDimension` of a texture.
- This allows users to set `D2Array`, `D3`, `Cube`, `CubeArray` or whatever they need
- Automatically configure this when loading KTX2
- Transcode all layers and faces instead of just one
- Use the UASTC block size of 128 bits, and the number of blocks in x/y for a given mip level in order to determine the offset of the layer and face within the KTX2 mip level data
- `wgpu` wants data ordered as layer 0 mip 0..n, layer 1 mip 0..n, etc. See https://docs.rs/wgpu/latest/wgpu/util/trait.DeviceExt.html#tymethod.create_texture_with_data
- Reorder the data KTX2 mip X layer Y face Z to `wgpu` layer Y face Z mip X order
- Add a `skybox` example to demonstrate / test loading cubemaps from PNG and KTX2, including ASTC 4x4, BC7, and ETC2 compression for support everywhere. Note that you need to enable the `ktx2,zstd` features to be able to load the compressed textures.
---
## Changelog
- Fixed: KTX2 array / cubemap / cubemap array textures
- Fixes: Validation failure for compressed textures stored in KTX2 where the width/height are not a multiple of the block dimensions.
- Added: `Image` now has an `Option<TextureViewDescriptor>` field to enable configuration of the texture view. This is useful for configuring the `TextureViewDimension` when it is not just a plain 2D texture and the loader could/did not identify what it should be.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Add a section to the example's README on how
to reduce generated wasm executable size.
Add a `wasm-release` profile to bevy's `Cargo.toml`
in order to use it when building bevy-website.
Notes:
- We do not recommend `strip = "symbols"` since it breaks bindgen
- see https://github.com/bevyengine/bevy-website/pull/402
# Objective
Bevy need a way to benchmark UI rendering code,
this PR adds a stress test that spawns a lot of buttons.
## Solution
- Add the `many_buttons` stress test.
---
## Changelog
- Add the `many_buttons` stress test.
# Objective
- Showcase how to use a `Material` and `Mesh` to spawn 3d lines
## Solution
- Add an example using a simple `Material` and `Mesh` definition to draw a 3d line
- Shows how to use `LineList` and `LineStrip` in combination with a specialized `Material`
## Notes
This isn't just a primitive shape because it needs a special Material, but I think it's a good showcase of the power of the `Material` and `AsBindGroup` abstractions. All of this is easy to figure out when you know these options are a thing, but I think they are hard to discover which is why I think this should be an example and not shipped with bevy.
Co-authored-by: Charles <IceSentry@users.noreply.github.com>
# Objective
- Reduce confusion as the example opens a window and isn't truly "headless"
- Fixes https://github.com/bevyengine/bevy/issues/5260.
## Solution
- Rename the example and add to the docs that the window is expected.
# Objective
add spotlight support
## Solution / Changelog
- add spotlight angles (inner, outer) to ``PointLight`` struct. emitted light is linearly attenuated from 100% to 0% as angle tends from inner to outer. Direction is taken from the existing transform rotation.
- add spotlight direction (vec3) and angles (f32,f32) to ``GpuPointLight`` struct (60 bytes -> 80 bytes) in ``pbr/render/lights.rs`` and ``mesh_view_bind_group.wgsl``
- reduce no-buffer-support max point light count to 204 due to above
- use spotlight data to attenuate light in ``pbr.wgsl``
- do additional cluster culling on spotlights to minimise cost in ``assign_lights_to_clusters``
- changed one of the lights in the lighting demo to a spotlight
- also added a ``spotlight`` demo - probably not justified but so reviewers can see it more easily
## notes
increasing the size of the GpuPointLight struct on my machine reduces the FPS of ``many_lights -- sphere`` from ~150fps to 140fps.
i thought this was a reasonable tradeoff, and felt better than handling spotlights separately which is possible but would mean introducing a new bind group, refactoring light-assignment code and adding new spotlight-specific code in pbr.wgsl. the FPS impact for smaller numbers of lights should be very small.
the cluster culling strategy reintroduces the cluster aabb code which was recently removed... sorry. the aabb is used to get a cluster bounding sphere, which can then be tested fairly efficiently using the strategy described at the end of https://bartwronski.com/2017/04/13/cull-that-cone/. this works well with roughly cubic clusters (where the cluster z size is close to the same as x/y size), less well for other cases like single Z slice / tiled forward rendering. In the worst case we will end up just keeping the culling of the equivalent point light.
Co-authored-by: François <mockersf@gmail.com>
# Objective
Intended to close#5073
## Solution
Adds a stress test that use TextureAtlas based on the existing many_sprites test using the animated sprite implementation from the sprite_sheet example.
In order to satisfy the goals described in #5073 the animations are all slightly offset.
Of note is that the original stress test was designed to test fullstrum culling. I kept this test similar as to facilitate easy comparisons between the use of TextureAtlas and without.
# Objective
- Make Bevy work on android
## Solution
- Update android metadata and add a few more
- Set the target sdk to 31 as it will soon (in august) be the minimum sdk level for play store
- Remove the custom code to create an activity and use ndk-glue macro instead
- Delay window creation event on android
- Set the example with compatibility settings for wgpu. Those are needed for Bevy to work on my 2019 android tablet
- Add a few details on how to debug in case of failures
- Fix running the example on emulator. This was failing because of the name of the example
Bevy still doesn't work on android with this, audio features need to be disabled because of an ndk-glue version mismatch: rodio depends on 0.6.2, winit on 0.5.2. You can test with:
```
cargo apk run --release --example android_example --no-default-features --features "bevy_winit,render"
```
# Objective
- Make the reusable PBR shading functionality a little more reusable
- Add constructor functions for `StandardMaterial` and `PbrInput` structs to populate them with default values
- Document unclear `PbrInput` members
- Demonstrate how to reuse the bevy PBR shading functionality
- The final important piece from #3969 as the initial shot at making the PBR shader code reusable in custom materials
## Solution
- Add back and rework the 'old' `array_texture` example from pre-0.6.
- Create a custom shader material
- Use a single array texture binding and sampler for the material bind group
- Use a shader that calls `pbr()` from the `bevy_pbr::pbr_functions` import
- Spawn a row of cubes using the custom material
- In the shader, select the array texture layer to sample by using the world position x coordinate modulo the number of array texture layers
<img width="1392" alt="Screenshot 2022-06-23 at 12 28 05" src="https://user-images.githubusercontent.com/302146/175278593-2296f519-f577-4ece-81c0-d842283784a1.png">
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Have information about examples only in one place that can be used for the repo and for the website (and remove the need to keep a list of example to build for wasm in the website 75acb73040/generate-wasm-examples/generate_wasm_examples.sh (L92-L99))
## Solution
- Add metadata about examples in `Cargo.toml`
- Build the `examples/README.md` from a template using those metadata. I used tera as the template engine to use the same tech as the website.
- Make CI fail if an example is missing metadata, or if the readme file needs to be updated (the command to update it is displayed in the failed step in CI)
## Remaining To Do
- After the next release with this merged in, the website will be able to be updated to use those metadata too
- I would like to build the examples in wasm and make them available at http://dev-docs.bevyengine.org/ but that will require more design
- https://github.com/bevyengine/bevy-website/issues/299 for other ToDos
Co-authored-by: Readme <github-actions@github.com>
# Objective
- Add an example showing a custom post processing effect, done after the first rendering pass.
## Solution
- A simple post processing "chromatic aberration" effect. I mixed together examples `3d/render_to_texture`, and `shader/shader_material_screenspace_texture`
- Reading a bit how https://github.com/bevyengine/bevy/pull/3430 was done gave me pointers to apply the main pass to the 2d render rather than using a 3d quad.
This work might be or not be relevant to https://github.com/bevyengine/bevy/issues/2724
<details>
<summary> ⚠️ Click for a video of the render ⚠️ I’ve been told it might hurt the eyes 👀 , maybe we should choose another effect just in case ?</summary>
https://user-images.githubusercontent.com/2290685/169138830-a6dc8a9f-8798-44b9-8d9e-449e60614916.mp4
</details>
# Request for feedbacks
- [ ] Is chromatic aberration effect ok ? (Correct term, not a danger for the eyes ?) I'm open to suggestion to make something different.
- [ ] Is the code idiomatic ? I preferred a "main camera -> **new camera with post processing applied to a quad**" approach to emulate minimum modification to existing code wanting to add global post processing.
---
## Changelog
- Add a full screen post processing shader example
# Objective
Users should be able to render cameras to specific areas of a render target, which enables scenarios like split screen, minimaps, etc.
Builds on the new Camera Driven Rendering added here: #4745Fixes: #202
Alternative to #1389 and #3626 (which are incompatible with the new Camera Driven Rendering)
## Solution
Cameras can now configure an optional "viewport", which defines a rectangle within their render target to draw to. If a `Viewport` is defined, the camera's `CameraProjection`, `View`, and visibility calculations will use the viewport configuration instead of the full render target.
```rust
// This camera will render to the first half of the primary window (on the left side).
commands.spawn_bundle(Camera3dBundle {
camera: Camera {
viewport: Some(Viewport {
physical_position: UVec2::new(0, 0),
physical_size: UVec2::new(window.physical_width() / 2, window.physical_height()),
depth: 0.0..1.0,
}),
..default()
},
..default()
});
```
To account for this, the `Camera` component has received a few adjustments:
* `Camera` now has some new getter functions:
* `logical_viewport_size`, `physical_viewport_size`, `logical_target_size`, `physical_target_size`, `projection_matrix`
* All computed camera values are now private and live on the `ComputedCameraValues` field (logical/physical width/height, the projection matrix). They are now exposed on `Camera` via getters/setters This wasn't _needed_ for viewports, but it was long overdue.
---
## Changelog
### Added
* `Camera` components now have a `viewport` field, which can be set to draw to a portion of a render target instead of the full target.
* `Camera` component has some new functions: `logical_viewport_size`, `physical_viewport_size`, `logical_target_size`, `physical_target_size`, and `projection_matrix`
* Added a new split_screen example illustrating how to render two cameras to the same scene
## Migration Guide
`Camera::projection_matrix` is no longer a public field. Use the new `Camera::projection_matrix()` method instead:
```rust
// Bevy 0.7
let projection = camera.projection_matrix;
// Bevy 0.8
let projection = camera.projection_matrix();
```
This adds "high level camera driven rendering" to Bevy. The goal is to give users more control over what gets rendered (and where) without needing to deal with render logic. This will make scenarios like "render to texture", "multiple windows", "split screen", "2d on 3d", "3d on 2d", "pass layering", and more significantly easier.
Here is an [example of a 2d render sandwiched between two 3d renders (each from a different perspective)](https://gist.github.com/cart/4fe56874b2e53bc5594a182fc76f4915):
Users can now spawn a camera, point it at a RenderTarget (a texture or a window), and it will "just work".
Rendering to a second window is as simple as spawning a second camera and assigning it to a specific window id:
```rust
// main camera (main window)
commands.spawn_bundle(Camera2dBundle::default());
// second camera (other window)
commands.spawn_bundle(Camera2dBundle {
camera: Camera {
target: RenderTarget::Window(window_id),
..default()
},
..default()
});
```
Rendering to a texture is as simple as pointing the camera at a texture:
```rust
commands.spawn_bundle(Camera2dBundle {
camera: Camera {
target: RenderTarget::Texture(image_handle),
..default()
},
..default()
});
```
Cameras now have a "render priority", which controls the order they are drawn in. If you want to use a camera's output texture as a texture in the main pass, just set the priority to a number lower than the main pass camera (which defaults to `0`).
```rust
// main pass camera with a default priority of 0
commands.spawn_bundle(Camera2dBundle::default());
commands.spawn_bundle(Camera2dBundle {
camera: Camera {
target: RenderTarget::Texture(image_handle.clone()),
priority: -1,
..default()
},
..default()
});
commands.spawn_bundle(SpriteBundle {
texture: image_handle,
..default()
})
```
Priority can also be used to layer to cameras on top of each other for the same RenderTarget. This is what "2d on top of 3d" looks like in the new system:
```rust
commands.spawn_bundle(Camera3dBundle::default());
commands.spawn_bundle(Camera2dBundle {
camera: Camera {
// this will render 2d entities "on top" of the default 3d camera's render
priority: 1,
..default()
},
..default()
});
```
There is no longer the concept of a global "active camera". Resources like `ActiveCamera<Camera2d>` and `ActiveCamera<Camera3d>` have been replaced with the camera-specific `Camera::is_active` field. This does put the onus on users to manage which cameras should be active.
Cameras are now assigned a single render graph as an "entry point", which is configured on each camera entity using the new `CameraRenderGraph` component. The old `PerspectiveCameraBundle` and `OrthographicCameraBundle` (generic on camera marker components like Camera2d and Camera3d) have been replaced by `Camera3dBundle` and `Camera2dBundle`, which set 3d and 2d default values for the `CameraRenderGraph` and projections.
```rust
// old 3d perspective camera
commands.spawn_bundle(PerspectiveCameraBundle::default())
// new 3d perspective camera
commands.spawn_bundle(Camera3dBundle::default())
```
```rust
// old 2d orthographic camera
commands.spawn_bundle(OrthographicCameraBundle::new_2d())
// new 2d orthographic camera
commands.spawn_bundle(Camera2dBundle::default())
```
```rust
// old 3d orthographic camera
commands.spawn_bundle(OrthographicCameraBundle::new_3d())
// new 3d orthographic camera
commands.spawn_bundle(Camera3dBundle {
projection: OrthographicProjection {
scale: 3.0,
scaling_mode: ScalingMode::FixedVertical,
..default()
}.into(),
..default()
})
```
Note that `Camera3dBundle` now uses a new `Projection` enum instead of hard coding the projection into the type. There are a number of motivators for this change: the render graph is now a part of the bundle, the way "generic bundles" work in the rust type system prevents nice `..default()` syntax, and changing projections at runtime is much easier with an enum (ex for editor scenarios). I'm open to discussing this choice, but I'm relatively certain we will all come to the same conclusion here. Camera2dBundle and Camera3dBundle are much clearer than being generic on marker components / using non-default constructors.
If you want to run a custom render graph on a camera, just set the `CameraRenderGraph` component:
```rust
commands.spawn_bundle(Camera3dBundle {
camera_render_graph: CameraRenderGraph::new(some_render_graph_name),
..default()
})
```
Just note that if the graph requires data from specific components to work (such as `Camera3d` config, which is provided in the `Camera3dBundle`), make sure the relevant components have been added.
Speaking of using components to configure graphs / passes, there are a number of new configuration options:
```rust
commands.spawn_bundle(Camera3dBundle {
camera_3d: Camera3d {
// overrides the default global clear color
clear_color: ClearColorConfig::Custom(Color::RED),
..default()
},
..default()
})
commands.spawn_bundle(Camera3dBundle {
camera_3d: Camera3d {
// disables clearing
clear_color: ClearColorConfig::None,
..default()
},
..default()
})
```
Expect to see more of the "graph configuration Components on Cameras" pattern in the future.
By popular demand, UI no longer requires a dedicated camera. `UiCameraBundle` has been removed. `Camera2dBundle` and `Camera3dBundle` now both default to rendering UI as part of their own render graphs. To disable UI rendering for a camera, disable it using the CameraUi component:
```rust
commands
.spawn_bundle(Camera3dBundle::default())
.insert(CameraUi {
is_enabled: false,
..default()
})
```
## Other Changes
* The separate clear pass has been removed. We should revisit this for things like sky rendering, but I think this PR should "keep it simple" until we're ready to properly support that (for code complexity and performance reasons). We can come up with the right design for a modular clear pass in a followup pr.
* I reorganized bevy_core_pipeline into Core2dPlugin and Core3dPlugin (and core_2d / core_3d modules). Everything is pretty much the same as before, just logically separate. I've moved relevant types (like Camera2d, Camera3d, Camera3dBundle, Camera2dBundle) into their relevant modules, which is what motivated this reorganization.
* I adapted the `scene_viewer` example (which relied on the ActiveCameras behavior) to the new system. I also refactored bits and pieces to be a bit simpler.
* All of the examples have been ported to the new camera approach. `render_to_texture` and `multiple_windows` are now _much_ simpler. I removed `two_passes` because it is less relevant with the new approach. If someone wants to add a new "layered custom pass with CameraRenderGraph" example, that might fill a similar niche. But I don't feel much pressure to add that in this pr.
* Cameras now have `target_logical_size` and `target_physical_size` fields, which makes finding the size of a camera's render target _much_ simpler. As a result, the `Assets<Image>` and `Windows` parameters were removed from `Camera::world_to_screen`, making that operation much more ergonomic.
* Render order ambiguities between cameras with the same target and the same priority now produce a warning. This accomplishes two goals:
1. Now that there is no "global" active camera, by default spawning two cameras will result in two renders (one covering the other). This would be a silent performance killer that would be hard to detect after the fact. By detecting ambiguities, we can provide a helpful warning when this occurs.
2. Render order ambiguities could result in unexpected / unpredictable render results. Resolving them makes sense.
## Follow Up Work
* Per-Camera viewports, which will make it possible to render to a smaller area inside of a RenderTarget (great for something like splitscreen)
* Camera-specific MSAA config (should use the same "overriding" pattern used for ClearColor)
* Graph Based Camera Ordering: priorities are simple, but they make complicated ordering constraints harder to express. We should consider adopting a "graph based" camera ordering model with "before" and "after" relationships to other cameras (or build it "on top" of the priority system).
* Consider allowing graphs to run subgraphs from any nest level (aka a global namespace for graphs). Right now the 2d and 3d graphs each need their own UI subgraph, which feels "fine" in the short term. But being able to share subgraphs between other subgraphs seems valuable.
* Consider splitting `bevy_core_pipeline` into `bevy_core_2d` and `bevy_core_3d` packages. Theres a shared "clear color" dependency here, which would need a new home.
# Objective
- Add Vertex Color support to 2D meshes and ColorMaterial. This extends the work from #4528 (which in turn builds on the excellent tangent handling).
## Solution
- Added `#ifdef` wrapped support for vertex colors in the 2D mesh shader and `ColorMaterial` shader.
- Added an example, `mesh2d_vertex_color_texture` to demonstrate it in action.
---
## Changelog
- Added optional (ifdef wrapped) vertex color support to the 2dmesh and color material systems.
# Objective
Provide a starting point for #3951, or a partial solution.
Providing a few comment blocks to discuss, and hopefully find better one in the process.
## Solution
Since I am pretty new to pretty much anything in this context, I figured I'd just start with a draft for some file level doc blocks. For some of them I found more relevant details (or at least things I considered interessting), for some others there is less.
## Changelog
- Moved some existing comments from main() functions in the 2d examples to the file header level
- Wrote some more comment blocks for most other 2d examples
TODO:
- [x] 2d/sprite_sheet, wasnt able to come up with something good yet
- [x] all other example groups...
Also: Please let me know if the commit style is okay, or to verbose. I could certainly squash these things, or add more details if needed.
I also hope its okay to raise this PR this early, with just a few files changed. Took me long enough and I dont wanted to let it go to waste because I lost motivation to do the whole thing. Additionally I am somewhat uncertain over the style and contents of the commets. So let me know what you thing please.
# Objective
Add support for vertex colors
## Solution
This change is modeled after how vertex tangents are handled, so the shader is conditionally compiled with vertex color support if the mesh has the corresponding attribute set.
Vertex colors are multiplied by the base color. I'm not sure if this is the best for all cases, but may be useful for modifying vertex colors without creating a new mesh.
I chose `VertexFormat::Float32x4`, but I'd prefer 16-bit floats if/when support is added.
## Changelog
### Added
- Vertex colors can be specified using the `Mesh::ATTRIBUTE_COLOR` mesh attribute.
# Objective
Bevy users often want to create circles and other simple shapes.
All the machinery is in place to accomplish this, and there are external crates that help. But when writing code for e.g. a new bevy example, it's not really possible to draw a circle without bringing in a new asset, writing a bunch of scary looking mesh code, or adding a dependency.
In particular, this PR was inspired by this interaction in another PR: https://github.com/bevyengine/bevy/pull/3721#issuecomment-1016774535
## Solution
This PR adds `shape::RegularPolygon` and `shape::Circle` (which is just a `RegularPolygon` that defaults to a large number of sides)
## Discussion
There's a lot of ongoing discussion about shapes in <https://github.com/bevyengine/rfcs/pull/12> and at least one other lingering shape PR (although it seems incomplete).
That RFC currently includes `RegularPolygon` and `Circle` shapes, so I don't think that having working mesh generation code in the engine for those shapes would add much burden to an author of an implementation.
But if we'd prefer not to add additional shapes until after that's sorted out, I'm happy to close this for now.
## Alternatives for users
For any users stumbling on this issue, here are some plugins that will help if you need more shapes.
https://github.com/Nilirad/bevy_prototype_lyonhttps://github.com/johanhelsing/bevy_smudhttps://github.com/Weasy666/bevy_svghttps://github.com/redpandamonium/bevy_more_shapeshttps://github.com/ForesightMiningSoftwareCorporation/bevy_polyline
# Objective
- As requested here: https://github.com/bevyengine/bevy/pull/4520#issuecomment-1109302039
- Make it easier to spot issues with built-in shapes
## Solution
https://user-images.githubusercontent.com/200550/165624709-c40dfe7e-0e1e-4bd3-ae52-8ae66888c171.mp4
- Add an example showcasing the built-in 3d shapes with lighting/shadows
- Rotate objects in such a way that all faces are seen by the camera
- Add a UV debug texture
## Discussion
I'm not sure if this is what @alice-i-cecile had in mind, but I adapted the little "torus playground" from the issue linked above to include all built-in shapes.
This exact arrangement might not be particularly scalable if many more shapes are added. Maybe a slow camera pan, or cycling with the keyboard or on a timer, or a sidebar with buttons would work better. If one of the latter options is used, options for showing wireframes or computed flat normals might add some additional utility.
Ideally, I think we'd have a better way of visualizing normals.
Happy to rework this or close it if there's not a consensus around it being useful.
# Objective
Fixes https://github.com/bevyengine/bevy/issues/3499
## Solution
Uses a `HashMap` from `RenderTarget` to sampled textures when preparing `ViewTarget`s to ensure that two passes with the same render target get sampled to the same texture.
This builds on and depends on https://github.com/bevyengine/bevy/pull/3412, so this will be a draft PR until #3412 is merged. All changes for this PR are in the last commit.
# Objective
- Several examples are useful for qualitative tests of Bevy's performance
- By contrast, these are less useful for learning material: they are often relatively complex and have large amounts of setup and are performance optimized.
## Solution
- Move bevymark, many_sprites and many_cubes into the new stress_tests example folder
- Move contributors into the games folder: unlike the remaining examples in the 2d folder, it is not focused on demonstrating a clear feature.
# Objective
- Make use of storage buffers, where they are available, for clustered forward bindings to support far more point lights in a scene
- Fixes#3605
- Based on top of #4079
This branch on an M1 Max can keep 60fps with about 2150 point lights of radius 1m in the Sponza scene where I've been testing. The bottleneck is mostly assigning lights to clusters which grows faster than linearly (I think 1000 lights was about 1.5ms and 5000 was 7.5ms). I have seen papers and presentations leveraging compute shaders that can get this up to over 1 million. That said, I think any further optimisations should probably be done in a separate PR.
## Solution
- Add `RenderDevice` to the `Material` and `SpecializedMaterial` trait `::key()` functions to allow setting flags on the keys depending on feature/limit availability
- Make `GpuPointLights` and `ViewClusterBuffers` into enums containing `UniformVec` and `StorageBuffer` variants. Implement the necessary API on them to make usage the same for both cases, and the only difference is at initialisation time.
- Appropriate shader defs in the shader code to handle the two cases
## Context on some decisions / open questions
- I'm using `max_storage_buffers_per_shader_stage >= 3` as a check to see if storage buffers are supported. I was thinking about diving into 'binding resource management' but it feels like we don't have enough use cases to understand the problem yet, and it is mostly a separate concern to this PR, so I think it should be handled separately.
- Should `ViewClusterBuffers` and `ViewClusterBindings` be merged, duplicating the count variables into the enum variants?
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Load skeletal weights and indices from GLTF files. Animate meshes.
## Solution
- Load skeletal weights and indices from GLTF files.
- Added `SkinnedMesh` component and ` SkinnedMeshInverseBindPose` asset
- Added `extract_skinned_meshes` to extract joint matrices.
- Added queue phase systems for enqueuing the buffer writes.
Some notes:
- This ports part of # #2359 to the current main.
- This generates new `BufferVec`s and bind groups every frame. The expectation here is that the number of `Query::get` calls during extract is probably going to be the stronger bottleneck, with up to 256 calls per skinned mesh. Until that is optimized, caching buffers and bind groups is probably a non-concern.
- Unfortunately, due to the uniform size requirements, this means a 16KB buffer is allocated for every skinned mesh every frame. There's probably a few ways to get around this, but most of them require either compute shaders or storage buffers, which are both incompatible with WebGL2.
Co-authored-by: james7132 <contact@jamessliu.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: James Liu <contact@jamessliu.com>
## Objective
There recently was a discussion on Discord about a possible test case for stress-testing transform hierarchies.
## Solution
Create a test case for stress testing transform propagation.
*Edit:* I have scrapped my previous example and built something more functional and less focused on visuals.
There are three test setups:
- `TestCase::Tree` recursively creates a tree with a specified depth and branch width
- `TestCase::NonUniformTree` is the same as `Tree` but omits nodes in a way that makes the tree "lean" towards one side, like this:
<details>
<summary></summary>
</details>
- `TestCase::Humanoids` creates one or more separate hierarchies based on the structure of common humanoid rigs
- this can both insert `active` and `inactive` instances of the human rig
It's possible to parameterize which parts of the hierarchy get updated (transform change) and which remain unchanged. This is based on @james7132 suggestion:
There's a probability to decide which entities should remain static. On top of that these changes can be limited to a certain range in the hierarchy (min_depth..max_depth).
# Objective
- Allow quick and easy testing of scenes
## Solution
- Add a `scene-viewer` tool based on `load_gltf`.
- Run it with e.g. `cargo run --release --example scene_viewer --features jpeg -- ../some/path/assets/models/Sponza/glTF/Sponza.gltf#Scene0`
- Configure the asset path as pointing to the repo root for convenience (paths specified relative to current working directory)
- Copy over the camera controller from the `shadow_biases` example
- Support toggling the light animation
- Support toggling shadows
- Support adjusting the directional light shadow projection (cascaded shadow maps will remove the need for this later)
I don't want to do too much on it up-front. Rather we can add features over time as we need them.
# Add Transform Examples
- Adding examples for moving/rotating entities (with its own section) to resolve#2400
I've stumbled upon this project and been fiddling around a little. Saw the issue and thought I might just add some examples for the proposed transformations.
Mind to check if I got the gist correctly and suggest anything I can improve?
# Objective
- Reduce power usage for games when not focused.
- Reduce power usage to ~0 when a desktop application is minimized (opt-in).
- Reduce power usage when focused, only updating on a `winit` event, or the user sends a redraw request. (opt-in)
https://user-images.githubusercontent.com/2632925/156904387-ec47d7de-7f06-4c6f-8aaf-1e952c1153a2.mp4
Note resource usage in the Task Manager in the above video.
## Solution
- Added a type `UpdateMode` that allows users to specify how the winit event loop is updated, without exposing winit types.
- Added two fields to `WinitConfig`, both with the `UpdateMode` type. One configures how the application updates when focused, and the other configures how the application behaves when it is not focused. Users can modify this resource manually to set the type of event loop control flow they want.
- For convenience, two functions were added to `WinitConfig`, that provide reasonable presets: `game()` (default) and `desktop_app()`.
- The `game()` preset, which is used by default, is unchanged from current behavior with one exception: when the app is out of focus the app updates at a minimum of 10fps, or every time a winit event is received. This has a huge positive impact on power use and responsiveness on my machine, which will otherwise continue running the app at many hundreds of fps when out of focus or minimized.
- The `desktop_app()` preset is fully reactive, only updating when user input (winit event) is supplied or a `RedrawRequest` event is sent. When the app is out of focus, it only updates on `Window` events - i.e. any winit event that directly interacts with the window. What this means in practice is that the app uses *zero* resources when minimized or not interacted with, but still updates fluidly when the app is out of focus and the user mouses over the application.
- Added a `RedrawRequest` event so users can force an update even if there are no events. This is useful in an application when you want to, say, run an animation even when the user isn't providing input.
- Added an example `low_power` to demonstrate these changes
## Usage
Configuring the event loop:
```rs
use bevy::winit::{WinitConfig};
// ...
.insert_resource(WinitConfig::desktop_app()) // preset
// or
.insert_resource(WinitConfig::game()) // preset
// or
.insert_resource(WinitConfig{ .. }) // manual
```
Requesting a redraw:
```rs
use bevy:🪟:RequestRedraw;
// ...
fn request_redraw(mut event: EventWriter<RequestRedraw>) {
event.send(RequestRedraw);
}
```
## Other details
- Because we have a single event loop for multiple windows, every time I've mentioned "focused" above, I more precisely mean, "if at least one bevy window is focused".
- Due to a platform bug in winit (https://github.com/rust-windowing/winit/issues/1619), we can't simply use `Window::request_redraw()`. As a workaround, this PR will temporarily set the window mode to `Poll` when a redraw is requested. This is then reset to the user's `WinitConfig` setting on the next frame.
# Objective
- Add ways to control how audio is played
## Solution
- playing a sound will return a (weak) handle to an asset that can be used to control playback
- if the asset is dropped, it will detach the sink (same behaviour as now)
