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https://github.com/bevyengine/bevy
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3 commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Joseph
|
5876352206
|
Optimize common usages of AssetReader (#14082)
# Objective
The `AssetReader` trait allows customizing the behavior of fetching
bytes for an `AssetPath`, and expects implementors to return `dyn
AsyncRead + AsyncSeek`. This gives implementors of `AssetLoader` great
flexibility to tightly integrate their asset loading behavior with the
asynchronous task system.
However, almost all implementors of `AssetLoader` don't use the async
functionality at all, and just call `AsyncReadExt::read_to_end(&mut
Vec<u8>)`. This is incredibly inefficient, as this method repeatedly
calls `poll_read` on the trait object, filling the vector 32 bytes at a
time. At my work we have assets that are hundreds of megabytes which
makes this a meaningful overhead.
## Solution
Turn the `Reader` type alias into an actual trait, with a provided
method `read_to_end`. This provided method should be more efficient than
the existing extension method, as the compiler will know the underlying
type of `Reader` when generating this function, which removes the
repeated dynamic dispatches and allows the compiler to make further
optimizations after inlining. Individual implementors are able to
override the provided implementation -- for simple asset readers that
just copy bytes from one buffer to another, this allows removing a large
amount of overhead from the provided implementation.
Now that `Reader` is an actual trait, I also improved the ergonomics for
implementing `AssetReader`. Currently, implementors are expected to box
their reader and return it as a trait object, which adds unnecessary
boilerplate to implementations. This PR changes that trait method to
return a pseudo trait alias, which allows implementors to return `impl
Reader` instead of `Box<dyn Reader>`. Now, the boilerplate for boxing
occurs in `ErasedAssetReader`.
## Testing
I made identical changes to my company's fork of bevy. Our app, which
makes heavy use of `read_to_end` for asset loading, still worked
properly after this. I am not aware if we have a more systematic way of
testing asset loading for correctness.
---
## Migration Guide
The trait method `bevy_asset::io::AssetReader::read` (and `read_meta`)
now return an opaque type instead of a boxed trait object. Implementors
of these methods should change the type signatures appropriately
```rust
impl AssetReader for MyReader {
// Before
async fn read<'a>(&'a self, path: &'a Path) -> Result<Box<Reader<'a>>, AssetReaderError> {
let reader = // construct a reader
Box::new(reader) as Box<Reader<'a>>
}
// After
async fn read<'a>(&'a self, path: &'a Path) -> Result<impl Reader + 'a, AssetReaderError> {
// create a reader
}
}
```
`bevy::asset::io::Reader` is now a trait, rather than a type alias for a
trait object. Implementors of `AssetLoader::load` will need to adjust
the method signature accordingly
```rust
impl AssetLoader for MyLoader {
async fn load<'a>(
&'a self,
// Before:
reader: &'a mut bevy::asset::io::Reader,
// After:
reader: &'a mut dyn bevy::asset::io::Reader,
_: &'a Self::Settings,
load_context: &'a mut LoadContext<'_>,
) -> Result<Self::Asset, Self::Error> {
}
```
Additionally, implementors of `AssetReader` that return a type
implementing `futures_io::AsyncRead` and `AsyncSeek` might need to
explicitly implement `bevy::asset::io::Reader` for that type.
```rust
impl bevy::asset::io::Reader for MyAsyncReadAndSeek {}
```
|
||
Arthur Brussee
|
ac49dce4ca
|
Use async-fn in traits rather than BoxedFuture (#12550)
# Objective
Simplify implementing some asset traits without Box::pin(async move{})
shenanigans.
Fixes (in part) https://github.com/bevyengine/bevy/issues/11308
## Solution
Use async-fn in traits when possible in all traits. Traits with return
position impl trait are not object safe however, and as AssetReader and
AssetWriter are both used with dynamic dispatch, you need a Boxed
version of these futures anyway.
In the future, Rust is [adding
](https://blog.rust-lang.org/2023/12/21/async-fn-rpit-in-traits.html)proc
macros to generate these traits automatically, and at some point in the
future dyn traits should 'just work'. Until then.... this seemed liked
the right approach given more ErasedXXX already exist, but, no clue if
there's plans here! Especially since these are public now, it's a bit of
an unfortunate API, and means this is a breaking change.
In theory this saves some performance when these traits are used with
static dispatch, but, seems like most code paths go through dynamic
dispatch, which boxes anyway.
I also suspect a bunch of the lifetime annotations on these function
could be simplified now as the BoxedFuture was often the only thing
returned which needed a lifetime annotation, but I'm not touching that
for now as traits + lifetimes can be so tricky.
This is a revival of
[pull/11362](https://github.com/bevyengine/bevy/pull/11362) after a
spectacular merge f*ckup, with updates to the latest Bevy. Just to recap
some discussion:
- Overall this seems like a win for code quality, especially when
implementing these traits, but a loss for having to deal with ErasedXXX
variants.
- `ConditionalSend` was the preferred name for the trait that might be
Send, to deal with wasm platforms.
- When reviewing be sure to disable whitespace difference, as that's 95%
of the PR.
## Changelog
- AssetReader, AssetWriter, AssetLoader, AssetSaver and Process now use
async-fn in traits rather than boxed futures.
## Migration Guide
- Custom implementations of AssetReader, AssetWriter, AssetLoader,
AssetSaver and Process should switch to async fn rather than returning a
bevy_utils::BoxedFuture.
- Simultaniously, to use dynamic dispatch on these traits you should
instead use dyn ErasedXXX.
|
||
Patrick Walton
|
dfdf2b9ea4
|
Implement the AnimationGraph, allowing for multiple animations to be blended together. (#11989)
This is an implementation of RFC #51: https://github.com/bevyengine/rfcs/blob/main/rfcs/51-animation-composition.md Note that the implementation strategy is different from the one outlined in that RFC, because two-phase animation has now landed. # Objective Bevy needs animation blending. The RFC for this is [RFC 51]. ## Solution This is an implementation of the RFC. Note that the implementation strategy is different from the one outlined there, because two-phase animation has now landed. This is just a draft to get the conversation started. Currently we're missing a few things: - [x] A fully-fleshed-out mechanism for transitions - [x] A serialization format for `AnimationGraph`s - [x] Examples are broken, other than `animated_fox` - [x] Documentation --- ## Changelog ### Added * The `AnimationPlayer` has been reworked to support blending multiple animations together through an `AnimationGraph`, and as such will no longer function unless a `Handle<AnimationGraph>` has been added to the entity containing the player. See [RFC 51] for more details. * Transition functionality has moved from the `AnimationPlayer` to a new component, `AnimationTransitions`, which works in tandem with the `AnimationGraph`. ## Migration Guide * `AnimationPlayer`s can no longer play animations by themselves and need to be paired with a `Handle<AnimationGraph>`. Code that was using `AnimationPlayer` to play animations will need to create an `AnimationGraph` asset first, add a node for the clip (or clips) you want to play, and then supply the index of that node to the `AnimationPlayer`'s `play` method. * The `AnimationPlayer::play_with_transition()` method has been removed and replaced with the `AnimationTransitions` component. If you were previously using `AnimationPlayer::play_with_transition()`, add all animations that you were playing to the `AnimationGraph`, and create an `AnimationTransitions` component to manage the blending between them. [RFC 51]: https://github.com/bevyengine/rfcs/blob/main/rfcs/51-animation-composition.md --------- Co-authored-by: Rob Parrett <robparrett@gmail.com> |