Commit graph

96 commits

Author SHA1 Message Date
Christian Hughes
e939d6c33f
Remove remnant EntityHash and related types from bevy_utils (#15039)
# Objective

`EntityHash` and related types were moved from `bevy_utils` to
`bevy_ecs` in #11498, but seemed to have been accidentally reintroduced
a week later in #11707.

## Solution

Remove the old leftover code.

---

## Migration Guide

- Uses of `bevy::utils::{EntityHash, EntityHasher, EntityHashMap,
EntityHashSet}` now have to be imported from `bevy::ecs::entity`.
2024-09-09 15:24:17 +00:00
Zachary Harrold
bc13161416
Migrated NonZero* to NonZero<*> (#14978)
# Objective

- Fixes #14974

## Solution

- Replace all* instances of `NonZero*` with `NonZero<*>`

## Testing

- CI passed locally.

---

## Notes

Within the `bevy_reflect` implementations for `std` types,
`impl_reflect_value!()` will continue to use the type aliases instead,
as it inappropriately parses the concrete type parameter as a generic
argument. If the `ZeroablePrimitive` trait was stable, or the macro
could be modified to accept a finite list of types, then we could fully
migrate.
2024-08-30 02:37:47 +00:00
Lubba64
f9fbd08f9f
Implement Reflect for std::ops::Bound (#14861)
# Objective

- Fixes #14844

## Solution

- implement reflect using the `impl_reflect_value` macro

## Testing

- I wrote a test locally to understand and learn how reflection worked
on a basic level and to confirm that yes indeed the bound struct could
use the reflection traits that have been implemented for it.

note: I did remove a line that asked for bound to not have reflect
implemented in a test, since that's the point of this PR and the test
worked without the line so I am not sure what that was about, not sure
if that uncovers a deeper issue or not.
2024-08-22 23:01:38 +00:00
EdJoPaTo
938d810766
Apply unused_qualifications lint (#14828)
# Objective

Fixes #14782

## Solution

Enable the lint and fix all upcoming hints (`--fix`). Also tried to
figure out the false-positive (see review comment). Maybe split this PR
up into multiple parts where only the last one enables the lint, so some
can already be merged resulting in less many files touched / less
potential for merge conflicts?

Currently, there are some cases where it might be easier to read the
code with the qualifier, so perhaps remove the import of it and adapt
its cases? In the current stage it's just a plain adoption of the
suggestions in order to have a base to discuss.

## Testing

`cargo clippy` and `cargo run -p ci` are happy.
2024-08-21 12:29:33 +00:00
radiish
6ab8767d3b
reflect: implement the unique reflect rfc (#7207)
# Objective

- Implements the [Unique Reflect
RFC](https://github.com/nicopap/rfcs/blob/bevy-reflect-api/rfcs/56-better-reflect.md).

## Solution

- Implements the RFC.
- This implementation differs in some ways from the RFC:
- In the RFC, it was suggested `Reflect: Any` but `PartialReflect:
?Any`. During initial implementation I tried this, but we assume the
`PartialReflect: 'static` in a lot of places and the changes required
crept out of the scope of this PR.
- `PartialReflect::try_into_reflect` originally returned `Option<Box<dyn
Reflect>>` but i changed this to `Result<Box<dyn Reflect>, Box<dyn
PartialReflect>>` since the method takes by value and otherwise there
would be no way to recover the type. `as_full` and `as_full_mut` both
still return `Option<&(mut) dyn Reflect>`.

---

## Changelog

- Added `PartialReflect`.
- `Reflect` is now a subtrait of `PartialReflect`.
- Moved most methods on `Reflect` to the new `PartialReflect`.
- Added `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect}`.
- Added `PartialReflect::{try_as_reflect, try_as_reflect_mut,
try_into_reflect}`.
- Added `<dyn PartialReflect>::{try_downcast_ref, try_downcast_mut,
try_downcast, try_take}` supplementing the methods on `dyn Reflect`.

## Migration Guide

- Most instances of `dyn Reflect` should be changed to `dyn
PartialReflect` which is less restrictive, however trait bounds should
generally stay as `T: Reflect`.
- The new `PartialReflect::{as_partial_reflect, as_partial_reflect_mut,
into_partial_reflect, try_as_reflect, try_as_reflect_mut,
try_into_reflect}` methods as well as `Reflect::{as_reflect,
as_reflect_mut, into_reflect}` will need to be implemented for manual
implementors of `Reflect`.

## Future Work

- This PR is designed to be followed up by another "Unique Reflect Phase
2" that addresses the following points:
- Investigate making serialization revolve around `Reflect` instead of
`PartialReflect`.
- [Remove the `try_*` methods on `dyn PartialReflect` since they are
stop
gaps](https://github.com/bevyengine/bevy/pull/7207#discussion_r1083476050).
- Investigate usages like `ReflectComponent`. In the places they
currently use `PartialReflect`, should they be changed to use `Reflect`?
- Merging this opens the door to lots of reflection features we haven't
been able to implement.
- We could re-add [the `Reflectable`
trait](8e3488c880/crates/bevy_reflect/src/reflect.rs (L337-L342))
and make `FromReflect` a requirement to improve [`FromReflect`
ergonomics](https://github.com/bevyengine/rfcs/pull/59). This is
currently not possible because dynamic types cannot sensibly be
`FromReflect`.
  - Since this is an alternative to #5772, #5781 would be made cleaner.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-08-12 17:01:41 +00:00
recatek
87b63af864
bevy_reflect: Adding support for Atomic values (#14419)
Fixes #14418

Note that this does not add AtomicPtr, which would need its own special
casing support, just the regular value types.
Also, I was forced to be opinionated about which Ordering to use, so I
chose SeqCst as the strictest by default.
2024-07-29 23:33:18 +00:00
Robert Walter
52a2a3b146
Dedicated Reflect implementation for Set-like things (#13014)
# Objective

I just wanted to inspect `HashSet`s in `bevy-inspector-egui` but I
noticed that it didn't work for some reason. A few minutes later I found
myself looking into the bevy reflect impls noticing that `HashSet`s have
been covered only rudimentary up until now.

## Solution

I'm not sure if this is overkill (especially the first bullet), but
here's a list of the changes:

- created a whole new trait and enum variants for `ReflectRef` and the
like called `Set`
- mostly oriented myself at the `Map` trait and made the necessary
changes until RA was happy
- create macro `impl_reflect_for_hashset!` and call it on `std::HashSet`
and `hashbrown::HashSet`

Extra notes:

- no `get_mut` or `get_mut_at` mirroring the `std::HashSet`
- `insert[_boxed]` and `remove` return `bool` mirroring `std::HashSet`,
additionally that bool is reflect as I thought that would be how we
handle things in bevy reflect, but I'm not sure on this
- ser/de are handled via `SeqAccess`
- I'm not sure about the general deduplication property of this impl of
`Set` that is generally expected? I'm also not sure yet if `Map` does
provide this. This mainly refers to the `Dynamic[...]` structs
- I'm not sure if there are other methods missing from the `trait`, I
felt like `contains` or the set-operations (union/diff/...) could've
been helpful, but I wanted to get out the bare minimum for feedback
first

---

## Changelog

### Added
- `Set` trait for `bevy_reflect`

### Changed
- `std::collections::HashSet` and `bevy_utils::hashbrown::HashSet` now
implement a more complete set of reflect functionalities instead of
"just" `reflect_value`
- `TypeInfo` contains a new variant `Set` that contains `SetInfo`
- `ReflectKind` contains a new variant `Set`
- `ReflectRef` contains a new variant `Set`
- `ReflectMut` contains a new variant `Set`
- `ReflectOwned` contains a new variant `Set`

## Migration Guide

- The new `Set` variants on the enums listed in the change section
should probably be considered by people working with this level of the
lib
### Help wanted! 

I'm not sure if this change is able to break code. From my understanding
it shouldn't since we just add functionality but I'm not sure yet if
theres anything missing from my impl that would be normally provided by
`impl_reflect_value!`
2024-07-24 19:43:26 +00:00
Gino Valente
aa241672e1
bevy_reflect: Nested TypeInfo getters (#13321)
# Objective

Right now, `TypeInfo` can be accessed directly from a type using either
`Typed::type_info` or `Reflect::get_represented_type_info`.

However, once that `TypeInfo` is accessed, any nested types must be
accessed via the `TypeRegistry`.

```rust
#[derive(Reflect)]
struct Foo {
  bar: usize
}

let registry = TypeRegistry::default();

let TypeInfo::Struct(type_info) = Foo::type_info() else {
  panic!("expected struct info");
};

let field = type_info.field("bar").unwrap();

let field_info = registry.get_type_info(field.type_id()).unwrap();
assert!(field_info.is::<usize>());;
```

## Solution

Enable nested types within a `TypeInfo` to be retrieved directly.

```rust
#[derive(Reflect)]
struct Foo {
  bar: usize
}

let TypeInfo::Struct(type_info) = Foo::type_info() else {
  panic!("expected struct info");
};

let field = type_info.field("bar").unwrap();

let field_info = field.type_info().unwrap();
assert!(field_info.is::<usize>());;
```

The particular implementation was chosen for two reasons.

Firstly, we can't just store `TypeInfo` inside another `TypeInfo`
directly. This is because some types are recursive and would result in a
deadlock when trying to create the `TypeInfo` (i.e. it has to create the
`TypeInfo` before it can use it, but it also needs the `TypeInfo` before
it can create it). Therefore, we must instead store the function so it
can be retrieved lazily.

I had considered also using a `OnceLock` or something to lazily cache
the info, but I figured we can look into optimizations later. The API
should remain the same with or without the `OnceLock`.

Secondly, a new wrapper trait had to be introduced: `MaybeTyped`. Like
`RegisterForReflection`, this trait is `#[doc(hidden)]` and only exists
so that we can properly handle dynamic type fields without requiring
them to implement `Typed`. We don't want dynamic types to implement
`Typed` due to the fact that it would make the return type
`Option<&'static TypeInfo>` for all types even though only the dynamic
types ever need to return `None` (see #6971 for details).

Users should never have to interact with this trait as it has a blanket
impl for all `Typed` types. And `Typed` is automatically implemented
when deriving `Reflect` (as it is required).

The one downside is we do need to return `Option<&'static TypeInfo>`
from all these new methods so that we can handle the dynamic cases. If
we didn't have to, we'd be able to get rid of the `Option` entirely. But
I think that's an okay tradeoff for this one part of the API, and keeps
the other APIs intact.

## Testing

This PR contains tests to verify everything works as expected. You can
test locally by running:

```
cargo test --package bevy_reflect
```

---

## Changelog

### Public Changes

- Added `ArrayInfo::item_info` method
- Added `NamedField::type_info` method
- Added `UnnamedField::type_info` method
- Added `ListInfo::item_info` method
- Added `MapInfo::key_info` method
- Added `MapInfo::value_info` method
- All active fields now have a `Typed` bound (remember that this is
automatically satisfied for all types that derive `Reflect`)

### Internal Changes

- Added `MaybeTyped` trait

## Migration Guide

All active fields for reflected types (including lists, maps, tuples,
etc.), must implement `Typed`. For the majority of users this won't have
any visible impact.

However, users implementing `Reflect` manually may need to update their
types to implement `Typed` if they weren't already.

Additionally, custom dynamic types will need to implement the new hidden
`MaybeTyped` trait.
2024-07-15 00:40:07 +00:00
Gino Valente
99c9218b56
bevy_reflect: Feature-gate function reflection (#14174)
# Objective

Function reflection requires a lot of macro code generation in the form
of several `all_tuples!` invocations, as well as impls generated in the
`Reflect` derive macro.

Seeing as function reflection is currently a bit more niche, it makes
sense to gate it all behind a feature.

## Solution

Add a `functions` feature to `bevy_reflect`, which can be enabled in
Bevy using the `reflect_functions` feature.

## Testing

You can test locally by running:

```
cargo test --package bevy_reflect
```

That should ensure that everything still works with the feature
disabled.

To test with the feature on, you can run:

```
cargo test --package bevy_reflect --features functions
```

---

## Changelog

- Moved function reflection behind a Cargo feature
(`bevy/reflect_functions` and `bevy_reflect/functions`)
- Add `IntoFunction` export in `bevy_reflect::prelude`

## Internal Migration Guide

> [!important]
> Function reflection was introduced as part of the 0.15 dev cycle. This
migration guide was written for developers relying on `main` during this
cycle, and is not a breaking change coming from 0.14.

Function reflection is now gated behind a feature. To use function
reflection, enable the feature:
- If using `bevy_reflect` directly, enable the `functions` feature
- If using `bevy`, enable the `reflect_functions` feature
2024-07-14 15:55:31 +00:00
Gino Valente
276dd04001
bevy_reflect: Function reflection (#13152)
# Objective

We're able to reflect types sooooooo... why not functions?

The goal of this PR is to make functions callable within a dynamic
context, where type information is not readily available at compile
time.

For example, if we have a function:

```rust
fn add(left: i32, right: i32) -> i32 {
  left + right
}
```

And two `Reflect` values we've already validated are `i32` types:

```rust
let left: Box<dyn Reflect> = Box::new(2_i32);
let right: Box<dyn Reflect> = Box::new(2_i32);
```

We should be able to call `add` with these values:

```rust
// ?????
let result: Box<dyn Reflect> = add.call_dynamic(left, right);
```

And ideally this wouldn't just work for functions, but methods and
closures too!

Right now, users have two options:

1. Manually parse the reflected data and call the function themselves
2. Rely on registered type data to handle the conversions for them

For a small function like `add`, this isn't too bad. But what about for
more complex functions? What about for many functions?

At worst, this process is error-prone. At best, it's simply tedious.

And this is assuming we know the function at compile time. What if we
want to accept a function dynamically and call it with our own
arguments?

It would be much nicer if `bevy_reflect` could alleviate some of the
problems here.

## Solution

Added function reflection!

This adds a `DynamicFunction` type to wrap a function dynamically. This
can be called with an `ArgList`, which is a dynamic list of
`Reflect`-containing `Arg` arguments. It returns a `FunctionResult`
which indicates whether or not the function call succeeded, returning a
`Reflect`-containing `Return` type if it did succeed.

Many functions can be converted into this `DynamicFunction` type thanks
to the `IntoFunction` trait.

Taking our previous `add` example, this might look something like
(explicit types added for readability):

```rust
fn add(left: i32, right: i32) -> i32 {
  left + right
}

let mut function: DynamicFunction = add.into_function();
let args: ArgList = ArgList::new().push_owned(2_i32).push_owned(2_i32);
let result: Return = function.call(args).unwrap();
let value: Box<dyn Reflect> = result.unwrap_owned();
assert_eq!(value.take::<i32>().unwrap(), 4);
```

And it also works on closures:

```rust
let add = |left: i32, right: i32| left + right;

let mut function: DynamicFunction = add.into_function();
let args: ArgList = ArgList::new().push_owned(2_i32).push_owned(2_i32);
let result: Return = function.call(args).unwrap();
let value: Box<dyn Reflect> = result.unwrap_owned();
assert_eq!(value.take::<i32>().unwrap(), 4);
```

As well as methods:

```rust
#[derive(Reflect)]
struct Foo(i32);

impl Foo {
  fn add(&mut self, value: i32) {
    self.0 += value;
  }
}

let mut foo = Foo(2);

let mut function: DynamicFunction = Foo::add.into_function();
let args: ArgList = ArgList::new().push_mut(&mut foo).push_owned(2_i32);
function.call(args).unwrap();
assert_eq!(foo.0, 4);
```

### Limitations

While this does cover many functions, it is far from a perfect system
and has quite a few limitations. Here are a few of the limitations when
using `IntoFunction`:

1. The lifetime of the return value is only tied to the lifetime of the
first argument (useful for methods). This means you can't have a
function like `(a: i32, b: &i32) -> &i32` without creating the
`DynamicFunction` manually.
2. Only 15 arguments are currently supported. If the first argument is a
(mutable) reference, this number increases to 16.
3. Manual implementations of `Reflect` will need to implement the new
`FromArg`, `GetOwnership`, and `IntoReturn` traits in order to be used
as arguments/return types.

And some limitations of `DynamicFunction` itself:

1. All arguments share the same lifetime, or rather, they will shrink to
the shortest lifetime.
2. Closures that capture their environment may need to have their
`DynamicFunction` dropped before accessing those variables again (there
is a `DynamicFunction::call_once` to make this a bit easier)
3. All arguments and return types must implement `Reflect`. While not a
big surprise coming from `bevy_reflect`, this implementation could
actually still work by swapping `Reflect` out with `Any`. Of course,
that makes working with the arguments and return values a bit harder.
4. Generic functions are not supported (unless they have been manually
monomorphized)

And general, reflection gotchas:

1. `&str` does not implement `Reflect`. Rather, `&'static str`
implements `Reflect` (the same is true for `&Path` and similar types).
This means that `&'static str` is considered an "owned" value for the
sake of generating arguments. Additionally, arguments and return types
containing `&str` will assume it's `&'static str`, which is almost never
the desired behavior. In these cases, the only solution (I believe) is
to use `&String` instead.

### Followup Work

This PR is the first of two PRs I intend to work on. The second PR will
aim to integrate this new function reflection system into the existing
reflection traits and `TypeInfo`. The goal would be to register and call
a reflected type's methods dynamically.

I chose not to do that in this PR since the diff is already quite large.
I also want the discussion for both PRs to be focused on their own
implementation.

Another followup I'd like to do is investigate allowing common container
types as a return type, such as `Option<&[mut] T>` and `Result<&[mut] T,
E>`. This would allow even more functions to opt into this system. I
chose to not include it in this one, though, for the same reasoning as
previously mentioned.

### Alternatives

One alternative I had considered was adding a macro to convert any
function into a reflection-based counterpart. The idea would be that a
struct that wraps the function would be created and users could specify
which arguments and return values should be `Reflect`. It could then be
called via a new `Function` trait.

I think that could still work, but it will be a fair bit more involved,
requiring some slightly more complex parsing. And it of course is a bit
more work for the user, since they need to create the type via macro
invocation.

It also makes registering these functions onto a type a bit more
complicated (depending on how it's implemented).

For now, I think this is a fairly simple, yet powerful solution that
provides the least amount of friction for users.

---

## Showcase

Bevy now adds support for storing and calling functions dynamically
using reflection!

```rust
// 1. Take a standard Rust function
fn add(left: i32, right: i32) -> i32 {
  left + right
}

// 2. Convert it into a type-erased `DynamicFunction` using the `IntoFunction` trait
let mut function: DynamicFunction = add.into_function();
// 3. Define your arguments from reflected values
let args: ArgList = ArgList::new().push_owned(2_i32).push_owned(2_i32);
// 4. Call the function with your arguments
let result: Return = function.call(args).unwrap();
// 5. Extract the return value
let value: Box<dyn Reflect> = result.unwrap_owned();
assert_eq!(value.take::<i32>().unwrap(), 4);
```

## Changelog

#### TL;DR

- Added support for function reflection
- Added a new `Function Reflection` example:
ba727898f2/examples/reflection/function_reflection.rs (L1-L157)

#### Details

Added the following items:

- `ArgError` enum
- `ArgId` enum
- `ArgInfo` struct
- `ArgList` struct
- `Arg` enum
- `DynamicFunction` struct
- `FromArg` trait (derived with `derive(Reflect)`)
- `FunctionError` enum
- `FunctionInfo` struct
- `FunctionResult` alias
- `GetOwnership` trait (derived with `derive(Reflect)`)
- `IntoFunction` trait (with blanket implementation)
- `IntoReturn` trait (derived with `derive(Reflect)`)
- `Ownership` enum
- `ReturnInfo` struct
- `Return` enum

---------

Co-authored-by: Periwink <charlesbour@gmail.com>
2024-07-01 13:49:08 +00:00
Brezak
9c4ac7c297
Finish the work on try_apply (#12646)
# Objective

Finish the `try_apply` implementation started in #6770 by @feyokorenhof.
Supersedes and closes #6770. Closes #6182

## Solution

Add `try_apply` to `Reflect` and implement it in all the places that
implement `Reflect`.

---

## Changelog

Added `try_apply` to `Reflect`.

---------

Co-authored-by: Feyo Korenhof <feyokorenhof@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
2024-05-08 14:26:01 +00:00
Marcel Müller
6d25545c51
Implement Reflect for Result<T, E> as enum (#13182)
# Objective

- Make `Result<T, E>` implement Reflect such that it is an Enum rather
than a Value
- Fixes #13178

## Solution

- Use the correct macro

## Testing

- Did you test these changes? 

I tried it out locally, and it does what it says on the tin. Not sure
how to test it in context of the crate?


---

## Changelog

### Changed

- Result now uses `ReflectKind::Enum` rather than `ReflectKind::Value`,
allowing for inspection of its constituents

## Migration Guide

`Result<T, E>` has had its `Reflect` implementation changed to align it
with `Option<T>` and its intended semantics: A carrier of either an `Ok`
or `Err` value, and the ability to access it. To achieve this it is no
longer a `ReflectKind::Value` but rather a `ReflectKind::Enum` and as
such carries these changes with it:

For `Result<T, E>`
- Both `T` and `E` no longer require to be `Clone` and now require to be
`FromReflect`
- `<Result<T, E> as Reflect>::reflect_*` now returns a
`ReflectKind::Enum`, so any code that previously relied on it being a
`Value` kind will have to be adapted.
- `Result<T, E>` now implements `Enum`

Since the migration is highly dependent on the previous usage, no
automatic upgrade path can be given.

Signed-off-by: Marcel Müller <neikos@neikos.email>
2024-05-02 18:28:24 +00:00
Robert Walter
2532447dcb
impl Reflect for EntityHashSet (#12971)
`EntityHashSet` doesn't seem to implement `Reflect` which seems weird!
Especially since `EntityHashMap` implements `Reflect`.

This PR just added an extra `impl_reflect_value!` for `EntityHashSet`
and this seems to do the trick.

I left out doing the same for `StableHashSet` since it's marked as
deprecated.

---

I'm really wondering what was the issue here. If anyone can explain why
`EntityHashSet` can't use the `Reflect` impl of `bevy_utils::HashSet`
similar to how it's the case with the `...HashMap`s I'd be interested!
2024-04-16 02:48:03 +00:00
BD103
aa2ebbb43f
Fix some nightly Clippy lints (#12927)
# Objective

- I daily drive nightly Rust when developing Bevy, so I notice when new
warnings are raised by `cargo check` and Clippy.
- `cargo +nightly clippy` raises a few of these new warnings.

## Solution

- Fix most warnings from `cargo +nightly clippy`
- I skipped the docs-related warnings because some were covered by
#12692.
- Use `Clone::clone_from` in applicable scenarios, which can sometimes
avoid an extra allocation.
- Implement `Default` for structs that have a `pub const fn new() ->
Self` method.
- Fix an occurrence where generic constraints were defined in both `<C:
Trait>` and `where C: Trait`.
  - Removed generic constraints that were implied by the `Bundle` trait.

---

## Changelog

- `BatchingStrategy`, `NonGenericTypeCell`, and `GenericTypeCell` now
implement `Default`.
2024-04-13 02:05:38 +00:00
Jacques Schutte
fdf2ea7cc5
reflect: remove manual Reflect impls which could be handled by macros (#12596)
# Objective

* Adopted #12025 to fix merge conflicts
* In some cases we used manual impls for certain types, though they are
(at least, now) unnecessary.

## Solution

* Use macros and reflecting-by-value to avoid this clutter.
* Though there were linker issues with Reflect and the CowArc in
AssetPath (see https://github.com/bevyengine/bevy/issues/9747), I
checked these are resolved by using #[reflect_value].

---------

Co-authored-by: soqb <cb.setho@gmail.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: James Liu <contact@jamessliu.com>
2024-03-23 01:45:00 +00:00
Charles Bournhonesque
ea6540dc41
add reflect for BinaryHeap (#12503)
# Objective
I wanted to have reflection for BinaryHeap for a personal project.

I'm running into some issues:
- I wanted to represent BinaryHeap as a reflect::List type since it's
essentially a wrapper around a Vec, however there's no public way to
access the underlying Vec, which makes it hard to implement the
reflect::List methods. I have omitted the reflect::List methods for
now.. I'm not sure if that's a blocker?
- what would be the alternatives? Simply not implement `reflect::List`?
It is possible to implement `FromReflect` without it. Would the type be
`Struct` then?

---------

Co-authored-by: Charles Bournhonesque <cbournhonesque@snapchat.com>
2024-03-17 22:24:04 +00:00
Charles Bournhonesque
24b319f6ec
Add reflect for type id (#12495)
# Objective

Add reflect for `std::any::TypeId`.

I couldn't add ReflectSerialize/ReflectDeserialize for it, it was giving
me an error. I don't really understand why, since it works for
`std::path::PathBuf`.

Co-authored-by: Charles Bournhonesque <cbournhonesque@snapchat.com>
2024-03-15 17:43:26 +00:00
Gino Valente
ccb9d0500f
bevy_reflect: Recursive registration (#5781)
# Objective

Resolves #4154

Currently, registration must all be done manually:

```rust
#[derive(Reflect)]
struct Foo(Bar);

#[derive(Reflect)]
struct Bar(Baz);

#[derive(Reflect)]
struct Baz(usize);

fn main() {
  // ...
  app
    .register_type::<Foo>()
    .register_type::<Bar>()
    .register_type::<Baz>()
    // .register_type::<usize>() <- This one is handled by Bevy, thankfully
  // ...
}
```

This can grow really quickly and become very annoying to add, remove,
and update as types change. It would be great if we could help reduce
the number of types that a user must manually implement themselves.

## Solution

As suggested in #4154, this PR adds automatic recursive registration.
Essentially, when a type is registered, it may now also choose to
register additional types along with it using the new
`GetTypeRegistration::register_type_dependencies` trait method.

The `Reflect` derive macro now automatically does this for all fields in
structs, tuple structs, struct variants, and tuple variants. This is
also done for tuples, arrays, `Vec<T>`, `HashMap<K, V>`, and
`Option<T>`.

This allows us to simplify the code above like:

```rust
#[derive(Reflect)]
struct Foo(Bar);

#[derive(Reflect)]
struct Bar(Baz);

#[derive(Reflect)]
struct Baz(usize);

fn main() {
  // ...
  app.register_type::<Foo>()
  // ...
}
```

This automatic registration only occurs if the type has not yet been
registered. If it has been registered, we simply skip it and move to the
next one. This reduces the cost of registration and prevents overwriting
customized registrations.

## Considerations

While this does improve ergonomics on one front, it's important to look
at some of the arguments against adopting a PR like this.

#### Generic Bounds

~~Since we need to be able to register the fields individually, we need
those fields to implement `GetTypeRegistration`. This forces users to
then add this trait as a bound on their generic arguments. This
annoyance could be relieved with something like #5772.~~

This is no longer a major issue as the `Reflect` derive now adds the
`GetTypeRegistration` bound by default. This should technically be okay,
since we already add the `Reflect` bound.

However, this can also be considered a breaking change for manual
implementations that left out a `GetTypeRegistration` impl ~~or for
items that contain dynamic types (e.g. `DynamicStruct`) since those also
do not implement `GetTypeRegistration`~~.

#### Registration Assumptions

By automatically registering fields, users might inadvertently be
relying on certain types to be automatically registered. If `Foo`
auto-registers `Bar`, but `Foo` is later removed from the code, then
anywhere that previously used or relied on `Bar`'s registration would
now fail.

---

## Changelog

- Added recursive type registration to structs, tuple structs, struct
variants, tuple variants, tuples, arrays, `Vec<T>`, `HashMap<K, V>`, and
`Option<T>`
- Added a new trait in the hidden `bevy_reflect::__macro_exports` module
called `RegisterForReflection`
- Added `GetTypeRegistration` impl for
`bevy_render::render_asset::RenderAssetUsages`

## Migration Guide

All types that derive `Reflect` will now automatically add
`GetTypeRegistration` as a bound on all (unignored) fields. This means
that all reflected fields will need to also implement
`GetTypeRegistration`.

If all fields **derive** `Reflect` or are implemented in `bevy_reflect`,
this should not cause any issues. However, manual implementations of
`Reflect` that excluded a `GetTypeRegistration` impl for their type will
need to add one.

```rust
#[derive(Reflect)]
struct Foo<T: FromReflect> {
  data: MyCustomType<T>
}

// OLD
impl<T: FromReflect> Reflect for MyCustomType<T> {/* ... */}

// NEW
impl<T: FromReflect + GetTypeRegistration> Reflect for MyCustomType<T> {/* ... */}
impl<T: FromReflect + GetTypeRegistration> GetTypeRegistration for MyCustomType<T> {/* ... */}
```

---------

Co-authored-by: James Liu <contact@jamessliu.com>
Co-authored-by: radiish <cb.setho@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2024-03-04 19:04:10 +00:00
Antony
fd0f1a37ad
Remove unnecessary impl_reflect_for_btree_map macro (#12146)
# Objective

To remove the `impl_reflect_for_btree_map` macro as per #12140.

## Solution

Replaced the `impl_reflect_for_btree_map` macro.
2024-02-27 01:04:11 +00:00
Mincong Lu
f45450e26b
Added reflect support for std::HashSet, BTreeSet and BTreeMap. (#12124)
# Objective

Added reflect support for `std::HashSet`, `BTreeSet` and `BTreeMap`.

The set support is limited to `reflect_value` since that's the level of
support prior art `bevy_util::HashSet` got.

## Changelog

Dropped `Hash` Requirement on `MapInfo` since it's not needed on
`BTreeMap`s.
2024-02-26 16:36:04 +00:00
Patrick Walton
5f1dd3918b
Rework animation to be done in two phases. (#11707)
# Objective

Bevy's animation system currently does tree traversals based on `Name`
that aren't necessary. Not only do they require in unsafe code because
tree traversals are awkward with parallelism, but they are also somewhat
slow, brittle, and complex, which manifested itself as way too many
queries in #11670.

# Solution

Divide animation into two phases: animation *advancement* and animation
*evaluation*, which run after one another. *Advancement* operates on the
`AnimationPlayer` and sets the current animation time to match the game
time. *Evaluation* operates on all animation bones in the scene in
parallel and sets the transforms and/or morph weights based on the time
and the clip.

To do this, we introduce a new component, `AnimationTarget`, which the
asset loader places on every bone. It contains the ID of the entity
containing the `AnimationPlayer`, as well as a UUID that identifies
which bone in the animation the target corresponds to. In the case of
glTF, the UUID is derived from the full path name to the bone. The rule
that `AnimationTarget`s are descendants of the entity containing
`AnimationPlayer` is now just a convention, not a requirement; this
allows us to eliminate the unsafe code.

# Migration guide

* `AnimationClip` now uses UUIDs instead of hierarchical paths based on
the `Name` component to refer to bones. This has several consequences:
- A new component, `AnimationTarget`, should be placed on each bone that
you wish to animate, in order to specify its UUID and the associated
`AnimationPlayer`. The glTF loader automatically creates these
components as necessary, so most uses of glTF rigs shouldn't need to
change.
- Moving a bone around the tree, or renaming it, no longer prevents an
`AnimationPlayer` from affecting it.
- Dynamically changing the `AnimationPlayer` component will likely
require manual updating of the `AnimationTarget` components.
* Entities with `AnimationPlayer` components may now possess descendants
that also have `AnimationPlayer` components. They may not, however,
animate the same bones.
* As they aren't specific to `TypeId`s,
`bevy_reflect::utility::NoOpTypeIdHash` and
`bevy_reflect::utility::NoOpTypeIdHasher` have been renamed to
`bevy_reflect::utility::NoOpHash` and
`bevy_reflect::utility::NoOpHasher` respectively.
2024-02-19 14:59:54 +00:00
Doonv
1c67e020f7
Move EntityHash related types into bevy_ecs (#11498)
# Objective

Reduce the size of `bevy_utils`
(https://github.com/bevyengine/bevy/issues/11478)

## Solution

Move `EntityHash` related types into `bevy_ecs`. This also allows us
access to `Entity`, which means we no longer need `EntityHashMap`'s
first generic argument.

---

## Changelog

- Moved `bevy::utils::{EntityHash, EntityHasher, EntityHashMap,
EntityHashSet}` into `bevy::ecs::entity::hash` .
- Removed `EntityHashMap`'s first generic argument. It is now hardcoded
to always be `Entity`.

## Migration Guide

- Uses of `bevy::utils::{EntityHash, EntityHasher, EntityHashMap,
EntityHashSet}` now have to be imported from `bevy::ecs::entity::hash`.
- Uses of `EntityHashMap` no longer have to specify the first generic
parameter. It is now hardcoded to always be `Entity`.
2024-02-12 15:02:24 +00:00
Doonv
054134fba2
Add ReflectKind (#11664)
# Objective

Fix https://github.com/bevyengine/bevy/issues/11657

## Solution

Add a `ReflectKind` enum, add `Reflect::reflect_kind` which returns a
`ReflectKind`, and add `kind` method implementions to `ReflectRef`,
`ReflectMut`, and `ReflectOwned`, which returns a `ReflectKind`.

I also changed `AccessError` to use this new struct instead of it's own
`TypeKind` struct.

---

## Changelog

- Added `ReflectKind`, an enumeration over the kinds of a reflected type
without its data.
- Added `Reflect::reflect_kind` (with default implementation)
- Added implementation for the `kind` method on `ReflectRef`,
`ReflectMut`, and `ReflectOwned` which gives their kind without any
information, as a `ReflectKind`
2024-02-07 00:36:23 +00:00
Gino Valente
71be08af68
bevy_reflect: Reflect &'static str (#11686)
# Objective

`&'static str` doesn't implement `Reflect`. I don't think this was
intentionally excluded.

## Solution

Make `&'static str` implement `Reflect`.

---

## Changelog

- Implement `Reflect` and friends for `&'static str`
- Add missing `Reflect::debug` implementation for `Cow<'static, str>`
2024-02-04 01:32:48 +00:00
John Lewis
cfe4034d25
Add Reflection for Wrapping/Saturating types (#11397)
# Objective

- Extend reflection to the standard library's `Wrapping` and
`Saturating` generic types.

This wasn't my use-case but someone in the discord was surprised that
this wasn't already done. I decided to make a PR because the other
`std::num` items were reflected and if there's a reason to exclude
`Wrapping` and `Saturating`, I am unaware of it.

## Solution

Trivial fix

---

## Changelog

Implemented `Reflect` for `Wrapping<T>` and `Saturating<T>` from
`std::num`.
2024-01-22 15:21:20 +00:00
BD103
056b006d4e
Use static_assertions to check for trait impls (#11407)
# Objective

- Tests are manually checking whether derived types implement certain
traits. (Specifically in `bevy_reflect.)
- #11182 introduces
[`static_assertions`](https://docs.rs/static_assertions/) to
automatically check this.
- Simplifies `Reflect` test in #11195.
- Closes #11196.

## Solution

- Add `static_assertions` and replace current tests.

---

I wasn't sure whether to remove the existing test or not. What do you
think?
2024-01-18 17:21:18 +00:00
Adam
fe68005f71
Implement TypePath for EntityHash (#11195)
# Objective

- Fix #11117 by implementing `Reflect` for `EntityHashMap`

## Solution

- By implementing `TypePath` for `EntityHash`, Bevy will automatically
implement `Reflect` for `EntityHashMap`

---

## Changelog

- `TypePath` is implemented for `EntityHash`
- A test called `entity_hashmap_should_impl_reflect` was created to
verify that #11117 was solved.
2024-01-04 18:28:31 +00:00
Mike
786abbf3f5
Fix ci xvfb (#11143)
# Objective

Fix ci hang, so we can merge pr's again.

## Solution

- switch ppa action to use mesa stable versions
https://launchpad.net/~kisak/+archive/ubuntu/turtle
- use commit from #11123

---------

Co-authored-by: Stepan Koltsov <stepan.koltsov@gmail.com>
2023-12-30 09:07:31 +00:00
Tygyh
1568d4a415
Reorder impl to be the same as the trait (#11076)
# Objective

- Make the implementation order consistent between all sources to fit
the order in the trait.

## Solution

- Change the implementation order.
2023-12-24 17:43:55 +00:00
tygyh
fd308571c4
Remove unnecessary path prefixes (#10749)
# Objective

- Shorten paths by removing unnecessary prefixes

## Solution

- Remove the prefixes from many paths which do not need them. Finding
the paths was done automatically using built-in refactoring tools in
Jetbrains RustRover.
2023-11-28 23:43:40 +00:00
radiish
262846e702
reflect: TypePath part 2 (#8768)
# Objective

- Followup to #7184.
- ~Deprecate `TypeUuid` and remove its internal references.~ No longer
part of this PR.
- Use `TypePath` for the type registry, and (de)serialisation instead of
`std::any::type_name`.
- Allow accessing type path information behind proxies.

## Solution
- Introduce methods on `TypeInfo` and friends for dynamically querying
type path. These methods supersede the old `type_name` methods.
- Remove `Reflect::type_name` in favor of `DynamicTypePath::type_path`
and `TypeInfo::type_path_table`.
- Switch all uses of `std::any::type_name` in reflection, non-debugging
contexts to use `TypePath`.

---

## Changelog

- Added `TypePathTable` for dynamically accessing methods on `TypePath`
through `TypeInfo` and the type registry.
- Removed `type_name` from all `TypeInfo`-like structs.
- Added `type_path` and `type_path_table` methods to all `TypeInfo`-like
structs.
- Removed `Reflect::type_name` in favor of
`DynamicTypePath::reflect_type_path` and `TypeInfo::type_path`.
- Changed the signature of all `DynamicTypePath` methods to return
strings with a static lifetime.

## Migration Guide

- Rely on `TypePath` instead of `std::any::type_name` for all stability
guarantees and for use in all reflection contexts, this is used through
with one of the following APIs:
  - `TypePath::type_path` if you have a concrete type and not a value.
- `DynamicTypePath::reflect_type_path` if you have an `dyn Reflect`
value without a concrete type.
- `TypeInfo::type_path` for use through the registry or if you want to
work with the represented type of a `DynamicFoo`.
  
- Remove `type_name` from manual `Reflect` implementations.
- Use `type_path` and `type_path_table` in place of `type_name` on
`TypeInfo`-like structs.
- Use `get_with_type_path(_mut)` over `get_with_type_name(_mut)`.

## Note to reviewers

I think if anything we were a little overzealous in merging #7184 and we
should take that extra care here.

In my mind, this is the "point of no return" for `TypePath` and while I
think we all agree on the design, we should carefully consider if the
finer details and current implementations are actually how we want them
moving forward.

For example [this incorrect `TypePath` implementation for
`String`](3fea3c6c0b/crates/bevy_reflect/src/impls/std.rs (L90))
(note that `String` is in the default Rust prelude) snuck in completely
under the radar.
2023-10-09 19:33:03 +00:00
Carter Anderson
5eb292dc10
Bevy Asset V2 (#8624)
# Bevy Asset V2 Proposal

## Why Does Bevy Need A New Asset System?

Asset pipelines are a central part of the gamedev process. Bevy's
current asset system is missing a number of features that make it
non-viable for many classes of gamedev. After plenty of discussions and
[a long community feedback
period](https://github.com/bevyengine/bevy/discussions/3972), we've
identified a number missing features:

* **Asset Preprocessing**: it should be possible to "preprocess" /
"compile" / "crunch" assets at "development time" rather than when the
game starts up. This enables offloading expensive work from deployed
apps, faster asset loading, less runtime memory usage, etc.
* **Per-Asset Loader Settings**: Individual assets cannot define their
own loaders that override the defaults. Additionally, they cannot
provide per-asset settings to their loaders. This is a huge limitation,
as many asset types don't provide all information necessary for Bevy
_inside_ the asset. For example, a raw PNG image says nothing about how
it should be sampled (ex: linear vs nearest).
* **Asset `.meta` files**: assets should have configuration files stored
adjacent to the asset in question, which allows the user to configure
asset-type-specific settings. These settings should be accessible during
the pre-processing phase. Modifying a `.meta` file should trigger a
re-processing / re-load of the asset. It should be possible to configure
asset loaders from the meta file.
* **Processed Asset Hot Reloading**: Changes to processed assets (or
their dependencies) should result in re-processing them and re-loading
the results in live Bevy Apps.
* **Asset Dependency Tracking**: The current bevy_asset has no good way
to wait for asset dependencies to load. It punts this as an exercise for
consumers of the loader apis, which is unreasonable and error prone.
There should be easy, ergonomic ways to wait for assets to load and
block some logic on an asset's entire dependency tree loading.
* **Runtime Asset Loading**: it should be (optionally) possible to load
arbitrary assets dynamically at runtime. This necessitates being able to
deploy and run the asset server alongside Bevy Apps on _all platforms_.
For example, we should be able to invoke the shader compiler at runtime,
stream scenes from sources like the internet, etc. To keep deployed
binaries (and startup times) small, the runtime asset server
configuration should be configurable with different settings compared to
the "pre processor asset server".
* **Multiple Backends**: It should be possible to load assets from
arbitrary sources (filesystems, the internet, remote asset serves, etc).
* **Asset Packing**: It should be possible to deploy assets in
compressed "packs", which makes it easier and more efficient to
distribute assets with Bevy Apps.
* **Asset Handoff**: It should be possible to hold a "live" asset
handle, which correlates to runtime data, without actually holding the
asset in memory. Ex: it must be possible to hold a reference to a GPU
mesh generated from a "mesh asset" without keeping the mesh data in CPU
memory
* **Per-Platform Processed Assets**: Different platforms and app
distributions have different capabilities and requirements. Some
platforms need lower asset resolutions or different asset formats to
operate within the hardware constraints of the platform. It should be
possible to define per-platform asset processing profiles. And it should
be possible to deploy only the assets required for a given platform.

These features have architectural implications that are significant
enough to require a full rewrite. The current Bevy Asset implementation
got us this far, but it can take us no farther. This PR defines a brand
new asset system that implements most of these features, while laying
the foundations for the remaining features to be built.

## Bevy Asset V2

Here is a quick overview of the features introduced in this PR.
* **Asset Preprocessing**: Preprocess assets at development time into
more efficient (and configurable) representations
* **Dependency Aware**: Dependencies required to process an asset are
tracked. If an asset's processed dependency changes, it will be
reprocessed
* **Hot Reprocessing/Reloading**: detect changes to asset source files,
reprocess them if they have changed, and then hot-reload them in Bevy
Apps.
* **Only Process Changes**: Assets are only re-processed when their
source file (or meta file) has changed. This uses hashing and timestamps
to avoid processing assets that haven't changed.
* **Transactional and Reliable**: Uses write-ahead logging (a technique
commonly used by databases) to recover from crashes / forced-exits.
Whenever possible it avoids full-reprocessing / only uncompleted
transactions will be reprocessed. When the processor is running in
parallel with a Bevy App, processor asset writes block Bevy App asset
reads. Reading metadata + asset bytes is guaranteed to be transactional
/ correctly paired.
* **Portable / Run anywhere / Database-free**: The processor does not
rely on an in-memory database (although it uses some database techniques
for reliability). This is important because pretty much all in-memory
databases have unsupported platforms or build complications.
* **Configure Processor Defaults Per File Type**: You can say "use this
processor for all files of this type".
* **Custom Processors**: The `Processor` trait is flexible and
unopinionated. It can be implemented by downstream plugins.
* **LoadAndSave Processors**: Most asset processing scenarios can be
expressed as "run AssetLoader A, save the results using AssetSaver X,
and then load the result using AssetLoader B". For example, load this
png image using `PngImageLoader`, which produces an `Image` asset and
then save it using `CompressedImageSaver` (which also produces an
`Image` asset, but in a compressed format), which takes an `Image` asset
as input. This means if you have an `AssetLoader` for an asset, you are
already half way there! It also means that you can share AssetSavers
across multiple loaders. Because `CompressedImageSaver` accepts Bevy's
generic Image asset as input, it means you can also use it with some
future `JpegImageLoader`.
* **Loader and Saver Settings**: Asset Loaders and Savers can now define
their own settings types, which are passed in as input when an asset is
loaded / saved. Each asset can define its own settings.
* **Asset `.meta` files**: configure asset loaders, their settings,
enable/disable processing, and configure processor settings
* **Runtime Asset Dependency Tracking** Runtime asset dependencies (ex:
if an asset contains a `Handle<Image>`) are tracked by the asset server.
An event is emitted when an asset and all of its dependencies have been
loaded
* **Unprocessed Asset Loading**: Assets do not require preprocessing.
They can be loaded directly. A processed asset is just a "normal" asset
with some extra metadata. Asset Loaders don't need to know or care about
whether or not an asset was processed.
* **Async Asset IO**: Asset readers/writers use async non-blocking
interfaces. Note that because Rust doesn't yet support async traits,
there is a bit of manual Boxing / Future boilerplate. This will
hopefully be removed in the near future when Rust gets async traits.
* **Pluggable Asset Readers and Writers**: Arbitrary asset source
readers/writers are supported, both by the processor and the asset
server.
* **Better Asset Handles**
* **Single Arc Tree**: Asset Handles now use a single arc tree that
represents the lifetime of the asset. This makes their implementation
simpler, more efficient, and allows us to cheaply attach metadata to
handles. Ex: the AssetPath of a handle is now directly accessible on the
handle itself!
* **Const Typed Handles**: typed handles can be constructed in a const
context. No more weird "const untyped converted to typed at runtime"
patterns!
* **Handles and Ids are Smaller / Faster To Hash / Compare**: Typed
`Handle<T>` is now much smaller in memory and `AssetId<T>` is even
smaller.
* **Weak Handle Usage Reduction**: In general Handles are now considered
to be "strong". Bevy features that previously used "weak `Handle<T>`"
have been ported to `AssetId<T>`, which makes it statically clear that
the features do not hold strong handles (while retaining strong type
information). Currently Handle::Weak still exists, but it is very
possible that we can remove that entirely.
* **Efficient / Dense Asset Ids**: Assets now have efficient dense
runtime asset ids, which means we can avoid expensive hash lookups.
Assets are stored in Vecs instead of HashMaps. There are now typed and
untyped ids, which means we no longer need to store dynamic type
information in the ID for typed handles. "AssetPathId" (which was a
nightmare from a performance and correctness standpoint) has been
entirely removed in favor of dense ids (which are retrieved for a path
on load)
* **Direct Asset Loading, with Dependency Tracking**: Assets that are
defined at runtime can still have their dependencies tracked by the
Asset Server (ex: if you create a material at runtime, you can still
wait for its textures to load). This is accomplished via the (currently
optional) "asset dependency visitor" trait. This system can also be used
to define a set of assets to load, then wait for those assets to load.
* **Async folder loading**: Folder loading also uses this system and
immediately returns a handle to the LoadedFolder asset, which means
folder loading no longer blocks on directory traversals.
* **Improved Loader Interface**: Loaders now have a specific "top level
asset type", which makes returning the top-level asset simpler and
statically typed.
* **Basic Image Settings and Processing**: Image assets can now be
processed into the gpu-friendly Basic Universal format. The ImageLoader
now has a setting to define what format the image should be loaded as.
Note that this is just a minimal MVP ... plenty of additional work to do
here. To demo this, enable the `basis-universal` feature and turn on
asset processing.
* **Simpler Audio Play / AudioSink API**: Asset handle providers are
cloneable, which means the Audio resource can mint its own handles. This
means you can now do `let sink_handle = audio.play(music)` instead of
`let sink_handle = audio_sinks.get_handle(audio.play(music))`. Note that
this might still be replaced by
https://github.com/bevyengine/bevy/pull/8424.
**Removed Handle Casting From Engine Features**: Ex: FontAtlases no
longer use casting between handle types

## Using The New Asset System

### Normal Unprocessed Asset Loading

By default the `AssetPlugin` does not use processing. It behaves pretty
much the same way as the old system.

If you are defining a custom asset, first derive `Asset`:

```rust
#[derive(Asset)]
struct Thing {
    value: String,
}
```

Initialize the asset:
```rust
app.init_asset:<Thing>()
```

Implement a new `AssetLoader` for it:

```rust
#[derive(Default)]
struct ThingLoader;

#[derive(Serialize, Deserialize, Default)]
pub struct ThingSettings {
    some_setting: bool,
}

impl AssetLoader for ThingLoader {
    type Asset = Thing;
    type Settings = ThingSettings;

    fn load<'a>(
        &'a self,
        reader: &'a mut Reader,
        settings: &'a ThingSettings,
        load_context: &'a mut LoadContext,
    ) -> BoxedFuture<'a, Result<Thing, anyhow::Error>> {
        Box::pin(async move {
            let mut bytes = Vec::new();
            reader.read_to_end(&mut bytes).await?;
            // convert bytes to value somehow
            Ok(Thing {
                value 
            })
        })
    }

    fn extensions(&self) -> &[&str] {
        &["thing"]
    }
}
```

Note that this interface will get much cleaner once Rust gets support
for async traits. `Reader` is an async futures_io::AsyncRead. You can
stream bytes as they come in or read them all into a `Vec<u8>`,
depending on the context. You can use `let handle =
load_context.load(path)` to kick off a dependency load, retrieve a
handle, and register the dependency for the asset.

Then just register the loader in your Bevy app:

```rust
app.init_asset_loader::<ThingLoader>()
```

Now just add your `Thing` asset files into the `assets` folder and load
them like this:

```rust
fn system(asset_server: Res<AssetServer>) {
    let handle = Handle<Thing> = asset_server.load("cool.thing");
}
```

You can check load states directly via the asset server:

```rust
if asset_server.load_state(&handle) == LoadState::Loaded { }
```

You can also listen for events:

```rust
fn system(mut events: EventReader<AssetEvent<Thing>>, handle: Res<SomeThingHandle>) {
    for event in events.iter() {
        if event.is_loaded_with_dependencies(&handle) {
        }
    }
}
```

Note the new `AssetEvent::LoadedWithDependencies`, which only fires when
the asset is loaded _and_ all dependencies (and their dependencies) have
loaded.

Unlike the old asset system, for a given asset path all `Handle<T>`
values point to the same underlying Arc. This means Handles can cheaply
hold more asset information, such as the AssetPath:

```rust
// prints the AssetPath of the handle
info!("{:?}", handle.path())
```

### Processed Assets

Asset processing can be enabled via the `AssetPlugin`. When developing
Bevy Apps with processed assets, do this:

```rust
app.add_plugins(DefaultPlugins.set(AssetPlugin::processed_dev()))
```

This runs the `AssetProcessor` in the background with hot-reloading. It
reads assets from the `assets` folder, processes them, and writes them
to the `.imported_assets` folder. Asset loads in the Bevy App will wait
for a processed version of the asset to become available. If an asset in
the `assets` folder changes, it will be reprocessed and hot-reloaded in
the Bevy App.

When deploying processed Bevy apps, do this:

```rust
app.add_plugins(DefaultPlugins.set(AssetPlugin::processed()))
```

This does not run the `AssetProcessor` in the background. It behaves
like `AssetPlugin::unprocessed()`, but reads assets from
`.imported_assets`.

When the `AssetProcessor` is running, it will populate sibling `.meta`
files for assets in the `assets` folder. Meta files for assets that do
not have a processor configured look like this:

```rust
(
    meta_format_version: "1.0",
    asset: Load(
        loader: "bevy_render::texture::image_loader::ImageLoader",
        settings: (
            format: FromExtension,
        ),
    ),
)
```

This is metadata for an image asset. For example, if you have
`assets/my_sprite.png`, this could be the metadata stored at
`assets/my_sprite.png.meta`. Meta files are totally optional. If no
metadata exists, the default settings will be used.

In short, this file says "load this asset with the ImageLoader and use
the file extension to determine the image type". This type of meta file
is supported in all AssetPlugin modes. If in `Unprocessed` mode, the
asset (with the meta settings) will be loaded directly. If in
`ProcessedDev` mode, the asset file will be copied directly to the
`.imported_assets` folder. The meta will also be copied directly to the
`.imported_assets` folder, but with one addition:

```rust
(
    meta_format_version: "1.0",
    processed_info: Some((
        hash: 12415480888597742505,
        full_hash: 14344495437905856884,
        process_dependencies: [],
    )),
    asset: Load(
        loader: "bevy_render::texture::image_loader::ImageLoader",
        settings: (
            format: FromExtension,
        ),
    ),
)
```

`processed_info` contains `hash` (a direct hash of the asset and meta
bytes), `full_hash` (a hash of `hash` and the hashes of all
`process_dependencies`), and `process_dependencies` (the `path` and
`full_hash` of every process_dependency). A "process dependency" is an
asset dependency that is _directly_ used when processing the asset.
Images do not have process dependencies, so this is empty.

When the processor is enabled, you can use the `Process` metadata
config:

```rust
(
    meta_format_version: "1.0",
    asset: Process(
        processor: "bevy_asset::processor::process::LoadAndSave<bevy_render::texture::image_loader::ImageLoader, bevy_render::texture::compressed_image_saver::CompressedImageSaver>",
        settings: (
            loader_settings: (
                format: FromExtension,
            ),
            saver_settings: (
                generate_mipmaps: true,
            ),
        ),
    ),
)
```

This configures the asset to use the `LoadAndSave` processor, which runs
an AssetLoader and feeds the result into an AssetSaver (which saves the
given Asset and defines a loader to load it with). (for terseness
LoadAndSave will likely get a shorter/friendlier type name when [Stable
Type Paths](#7184) lands). `LoadAndSave` is likely to be the most common
processor type, but arbitrary processors are supported.

`CompressedImageSaver` saves an `Image` in the Basis Universal format
and configures the ImageLoader to load it as basis universal. The
`AssetProcessor` will read this meta, run it through the LoadAndSave
processor, and write the basis-universal version of the image to
`.imported_assets`. The final metadata will look like this:

```rust
(
    meta_format_version: "1.0",
    processed_info: Some((
        hash: 905599590923828066,
        full_hash: 9948823010183819117,
        process_dependencies: [],
    )),
    asset: Load(
        loader: "bevy_render::texture::image_loader::ImageLoader",
        settings: (
            format: Format(Basis),
        ),
    ),
)
```

To try basis-universal processing out in Bevy examples, (for example
`sprite.rs`), change `add_plugins(DefaultPlugins)` to
`add_plugins(DefaultPlugins.set(AssetPlugin::processed_dev()))` and run
with the `basis-universal` feature enabled: `cargo run
--features=basis-universal --example sprite`.

To create a custom processor, there are two main paths:
1. Use the `LoadAndSave` processor with an existing `AssetLoader`.
Implement the `AssetSaver` trait, register the processor using
`asset_processor.register_processor::<LoadAndSave<ImageLoader,
CompressedImageSaver>>(image_saver.into())`.
2. Implement the `Process` trait directly and register it using:
`asset_processor.register_processor(thing_processor)`.

You can configure default processors for file extensions like this:

```rust
asset_processor.set_default_processor::<ThingProcessor>("thing")
```

There is one more metadata type to be aware of:

```rust
(
    meta_format_version: "1.0",
    asset: Ignore,
)
```

This will ignore the asset during processing / prevent it from being
written to `.imported_assets`.

The AssetProcessor stores a transaction log at `.imported_assets/log`
and uses it to gracefully recover from unexpected stops. This means you
can force-quit the processor (and Bevy Apps running the processor in
parallel) at arbitrary times!

`.imported_assets` is "local state". It should _not_ be checked into
source control. It should also be considered "read only". In practice,
you _can_ modify processed assets and processed metadata if you really
need to test something. But those modifications will not be represented
in the hashes of the assets, so the processed state will be "out of
sync" with the source assets. The processor _will not_ fix this for you.
Either revert the change after you have tested it, or delete the
processed files so they can be re-populated.

## Open Questions

There are a number of open questions to be discussed. We should decide
if they need to be addressed in this PR and if so, how we will address
them:

### Implied Dependencies vs Dependency Enumeration

There are currently two ways to populate asset dependencies:
* **Implied via AssetLoaders**: if an AssetLoader loads an asset (and
retrieves a handle), a dependency is added to the list.
* **Explicit via the optional Asset::visit_dependencies**: if
`server.load_asset(my_asset)` is called, it will call
`my_asset.visit_dependencies`, which will grab dependencies that have
been manually defined for the asset via the Asset trait impl (which can
be derived).

This means that defining explicit dependencies is optional for "loaded
assets". And the list of dependencies is always accurate because loaders
can only produce Handles if they register dependencies. If an asset was
loaded with an AssetLoader, it only uses the implied dependencies. If an
asset was created at runtime and added with
`asset_server.load_asset(MyAsset)`, it will use
`Asset::visit_dependencies`.

However this can create a behavior mismatch between loaded assets and
equivalent "created at runtime" assets if `Assets::visit_dependencies`
doesn't exactly match the dependencies produced by the AssetLoader. This
behavior mismatch can be resolved by completely removing "implied loader
dependencies" and requiring `Asset::visit_dependencies` to supply
dependency data. But this creates two problems:
* It makes defining loaded assets harder and more error prone: Devs must
remember to manually annotate asset dependencies with `#[dependency]`
when deriving `Asset`. For more complicated assets (such as scenes), the
derive likely wouldn't be sufficient and a manual `visit_dependencies`
impl would be required.
* Removes the ability to immediately kick off dependency loads: When
AssetLoaders retrieve a Handle, they also immediately kick off an asset
load for the handle, which means it can start loading in parallel
_before_ the asset finishes loading. For large assets, this could be
significant. (although this could be mitigated for processed assets if
we store dependencies in the processed meta file and load them ahead of
time)

### Eager ProcessorDev Asset Loading

I made a controversial call in the interest of fast startup times ("time
to first pixel") for the "processor dev mode configuration". When
initializing the AssetProcessor, current processed versions of unchanged
assets are yielded immediately, even if their dependencies haven't been
checked yet for reprocessing. This means that
non-current-state-of-filesystem-but-previously-valid assets might be
returned to the App first, then hot-reloaded if/when their dependencies
change and the asset is reprocessed.

Is this behavior desirable? There is largely one alternative: do not
yield an asset from the processor to the app until all of its
dependencies have been checked for changes. In some common cases (load
dependency has not changed since last run) this will increase startup
time. The main question is "by how much" and is that slower startup time
worth it in the interest of only yielding assets that are true to the
current state of the filesystem. Should this be configurable? I'm
starting to think we should only yield an asset after its (historical)
dependencies have been checked for changes + processed as necessary, but
I'm curious what you all think.

### Paths Are Currently The Only Canonical ID / Do We Want Asset UUIDs?

In this implementation AssetPaths are the only canonical asset
identifier (just like the previous Bevy Asset system and Godot). Moving
assets will result in re-scans (and currently reprocessing, although
reprocessing can easily be avoided with some changes). Asset
renames/moves will break code and assets that rely on specific paths,
unless those paths are fixed up.

Do we want / need "stable asset uuids"? Introducing them is very
possible:
1. Generate a UUID and include it in .meta files
2. Support UUID in AssetPath
3. Generate "asset indices" which are loaded on startup and map UUIDs to
paths.
4 (maybe). Consider only supporting UUIDs for processed assets so we can
generate quick-to-load indices instead of scanning meta files.

The main "pro" is that assets referencing UUIDs don't need to be
migrated when a path changes. The main "con" is that UUIDs cannot be
"lazily resolved" like paths. They need a full view of all assets to
answer the question "does this UUID exist". Which means UUIDs require
the AssetProcessor to fully finish startup scans before saying an asset
doesnt exist. And they essentially require asset pre-processing to use
in apps, because scanning all asset metadata files at runtime to resolve
a UUID is not viable for medium-to-large apps. It really requires a
pre-generated UUID index, which must be loaded before querying for
assets.

I personally think this should be investigated in a separate PR. Paths
aren't going anywhere ... _everyone_ uses filesystems (and
filesystem-like apis) to manage their asset source files. I consider
them permanent canonical asset information. Additionally, they behave
well for both processed and unprocessed asset modes. Given that Bevy is
supporting both, this feels like the right canonical ID to start with.
UUIDS (and maybe even other indexed-identifier types) can be added later
as necessary.

### Folder / File Naming Conventions

All asset processing config currently lives in the `.imported_assets`
folder. The processor transaction log is in `.imported_assets/log`.
Processed assets are added to `.imported_assets/Default`, which will
make migrating to processed asset profiles (ex: a
`.imported_assets/Mobile` profile) a non-breaking change. It also allows
us to create top-level files like `.imported_assets/log` without it
being interpreted as an asset. Meta files currently have a `.meta`
suffix. Do we like these names and conventions?

### Should the `AssetPlugin::processed_dev` configuration enable
`watch_for_changes` automatically?

Currently it does (which I think makes sense), but it does make it the
only configuration that enables watch_for_changes by default.

### Discuss on_loaded High Level Interface:

This PR includes a very rough "proof of concept" `on_loaded` system
adapter that uses the `LoadedWithDependencies` event in combination with
`asset_server.load_asset` dependency tracking to support this pattern

```rust
fn main() {
    App::new()
        .init_asset::<MyAssets>()
        .add_systems(Update, on_loaded(create_array_texture))
        .run();
}

#[derive(Asset, Clone)]
struct MyAssets {
    #[dependency]
    picture_of_my_cat: Handle<Image>,
    #[dependency]
    picture_of_my_other_cat: Handle<Image>,
}

impl FromWorld for ArrayTexture {
    fn from_world(world: &mut World) -> Self {
        picture_of_my_cat: server.load("meow.png"),
        picture_of_my_other_cat: server.load("meeeeeeeow.png"),
    }
}

fn spawn_cat(In(my_assets): In<MyAssets>, mut commands: Commands) {
    commands.spawn(SpriteBundle {
        texture: my_assets.picture_of_my_cat.clone(),  
        ..default()
    });
    
    commands.spawn(SpriteBundle {
        texture: my_assets.picture_of_my_other_cat.clone(),  
        ..default()
    });
}

```

The implementation is _very_ rough. And it is currently unsafe because
`bevy_ecs` doesn't expose some internals to do this safely from inside
`bevy_asset`. There are plenty of unanswered questions like:
* "do we add a Loadable" derive? (effectively automate the FromWorld
implementation above)
* Should `MyAssets` even be an Asset? (largely implemented this way
because it elegantly builds on `server.load_asset(MyAsset { .. })`
dependency tracking).

We should think hard about what our ideal API looks like (and if this is
a pattern we want to support). Not necessarily something we need to
solve in this PR. The current `on_loaded` impl should probably be
removed from this PR before merging.

## Clarifying Questions

### What about Assets as Entities?

This Bevy Asset V2 proposal implementation initially stored Assets as
ECS Entities. Instead of `AssetId<T>` + the `Assets<T>` resource it used
`Entity` as the asset id and Asset values were just ECS components.
There are plenty of compelling reasons to do this:
1. Easier to inline assets in Bevy Scenes (as they are "just" normal
entities + components)
2. More flexible queries: use the power of the ECS to filter assets (ex:
`Query<Mesh, With<Tree>>`).
3. Extensible. Users can add arbitrary component data to assets.
4. Things like "component visualization tools" work out of the box to
visualize asset data.

However Assets as Entities has a ton of caveats right now:
* We need to be able to allocate entity ids without a direct World
reference (aka rework id allocator in Entities ... i worked around this
in my prototypes by just pre allocating big chunks of entities)
* We want asset change events in addition to ECS change tracking ... how
do we populate them when mutations can come from anywhere? Do we use
Changed queries? This would require iterating over the change data for
all assets every frame. Is this acceptable or should we implement a new
"event based" component change detection option?
* Reconciling manually created assets with asset-system managed assets
has some nuance (ex: are they "loaded" / do they also have that
component metadata?)
* "how do we handle "static" / default entity handles" (ties in to the
Entity Indices discussion:
https://github.com/bevyengine/bevy/discussions/8319). This is necessary
for things like "built in" assets and default handles in things like
SpriteBundle.
* Storing asset information as a component makes it easy to "invalidate"
asset state by removing the component (or forcing modifications).
Ideally we have ways to lock this down (some combination of Rust type
privacy and ECS validation)

In practice, how we store and identify assets is a reasonably
superficial change (porting off of Assets as Entities and implementing
dedicated storage + ids took less than a day). So once we sort out the
remaining challenges the flip should be straightforward. Additionally, I
do still have "Assets as Entities" in my commit history, so we can reuse
that work. I personally think "assets as entities" is a good endgame,
but it also doesn't provide _significant_ value at the moment and it
certainly isn't ready yet with the current state of things.

### Why not Distill?

[Distill](https://github.com/amethyst/distill) is a high quality fully
featured asset system built in Rust. It is very natural to ask "why not
just use Distill?".

It is also worth calling out that for awhile, [we planned on adopting
Distill / I signed off on
it](https://github.com/bevyengine/bevy/issues/708).

However I think Bevy has a number of constraints that make Distill
adoption suboptimal:
* **Architectural Simplicity:**
* Distill's processor requires an in-memory database (lmdb) and RPC
networked API (using Cap'n Proto). Each of these introduces API
complexity that increases maintenance burden and "code grokability".
Ignoring tests, documentation, and examples, Distill has 24,237 lines of
Rust code (including generated code for RPC + database interactions). If
you ignore generated code, it has 11,499 lines.
* Bevy builds the AssetProcessor and AssetServer using pluggable
AssetReader/AssetWriter Rust traits with simple io interfaces. They do
not necessitate databases or RPC interfaces (although Readers/Writers
could use them if that is desired). Bevy Asset V2 (at the time of
writing this PR) is 5,384 lines of Rust code (ignoring tests,
documentation, and examples). Grain of salt: Distill does have more
features currently (ex: Asset Packing, GUIDS, remote-out-of-process
asset processor). I do plan to implement these features in Bevy Asset V2
and I personally highly doubt they will meaningfully close the 6115
lines-of-code gap.
* This complexity gap (which while illustrated by lines of code, is much
bigger than just that) is noteworthy to me. Bevy should be hackable and
there are pillars of Distill that are very hard to understand and
extend. This is a matter of opinion (and Bevy Asset V2 also has
complicated areas), but I think Bevy Asset V2 is much more approachable
for the average developer.
* Necessary disclaimer: counting lines of code is an extremely rough
complexity metric. Read the code and form your own opinions.
* **Optional Asset Processing:** Not all Bevy Apps (or Bevy App
developers) need / want asset preprocessing. Processing increases the
complexity of the development environment by introducing things like
meta files, imported asset storage, running processors in the
background, waiting for processing to finish, etc. Distill _requires_
preprocessing to work. With Bevy Asset V2 processing is fully opt-in.
The AssetServer isn't directly aware of asset processors at all.
AssetLoaders only care about converting bytes to runtime Assets ... they
don't know or care if the bytes were pre-processed or not. Processing is
"elegantly" (forgive my self-congratulatory phrasing) layered on top and
builds on the existing Asset system primitives.
* **Direct Filesystem Access to Processed Asset State:** Distill stores
processed assets in a database. This makes debugging / inspecting the
processed outputs harder (either requires special tooling to query the
database or they need to be "deployed" to be inspected). Bevy Asset V2,
on the other hand, stores processed assets in the filesystem (by default
... this is configurable). This makes interacting with the processed
state more natural. Note that both Godot and Unity's new asset system
store processed assets in the filesystem.
* **Portability**: Because Distill's processor uses lmdb and RPC
networking, it cannot be run on certain platforms (ex: lmdb is a
non-rust dependency that cannot run on the web, some platforms don't
support running network servers). Bevy should be able to process assets
everywhere (ex: run the Bevy Editor on the web, compile + process
shaders on mobile, etc). Distill does partially mitigate this problem by
supporting "streaming" assets via the RPC protocol, but this is not a
full solve from my perspective. And Bevy Asset V2 can (in theory) also
stream assets (without requiring RPC, although this isn't implemented
yet)

Note that I _do_ still think Distill would be a solid asset system for
Bevy. But I think the approach in this PR is a better solve for Bevy's
specific "asset system requirements".

### Doesn't async-fs just shim requests to "sync" `std::fs`? What is the
point?

"True async file io" has limited / spotty platform support. async-fs
(and the rust async ecosystem generally ... ex Tokio) currently use
async wrappers over std::fs that offload blocking requests to separate
threads. This may feel unsatisfying, but it _does_ still provide value
because it prevents our task pools from blocking on file system
operations (which would prevent progress when there are many tasks to
do, but all threads in a pool are currently blocking on file system
ops).

Additionally, using async APIs for our AssetReaders and AssetWriters
also provides value because we can later add support for "true async
file io" for platforms that support it. _And_ we can implement other
"true async io" asset backends (such as networked asset io).

## Draft TODO

- [x] Fill in missing filesystem event APIs: file removed event (which
is expressed as dangling RenameFrom events in some cases), file/folder
renamed event
- [x] Assets without loaders are not moved to the processed folder. This
breaks things like referenced `.bin` files for GLTFs. This should be
configurable per-non-asset-type.
- [x] Initial implementation of Reflect and FromReflect for Handle. The
"deserialization" parity bar is low here as this only worked with static
UUIDs in the old impl ... this is a non-trivial problem. Either we add a
Handle::AssetPath variant that gets "upgraded" to a strong handle on
scene load or we use a separate AssetRef type for Bevy scenes (which is
converted to a runtime Handle on load). This deserves its own discussion
in a different pr.
- [x] Populate read_asset_bytes hash when run by the processor (a bit of
a special case .. when run by the processor the processed meta will
contain the hash so we don't need to compute it on the spot, but we
don't want/need to read the meta when run by the main AssetServer)
- [x] Delay hot reloading: currently filesystem events are handled
immediately, which creates timing issues in some cases. For example hot
reloading images can sometimes break because the image isn't finished
writing. We should add a delay, likely similar to the [implementation in
this PR](https://github.com/bevyengine/bevy/pull/8503).
- [x] Port old platform-specific AssetIo implementations to the new
AssetReader interface (currently missing Android and web)
- [x] Resolve on_loaded unsafety (either by removing the API entirely or
removing the unsafe)
- [x]  Runtime loader setting overrides
- [x] Remove remaining unwraps that should be error-handled. There are
number of TODOs here
- [x] Pretty AssetPath Display impl
- [x] Document more APIs
- [x] Resolve spurious "reloading because it has changed" events (to
repro run load_gltf with `processed_dev()`)
- [x] load_dependency hot reloading currently only works for processed
assets. If processing is disabled, load_dependency changes are not hot
reloaded.
- [x] Replace AssetInfo dependency load/fail counters with
`loading_dependencies: HashSet<UntypedAssetId>` to prevent reloads from
(potentially) breaking counters. Storing this will also enable
"dependency reloaded" events (see [Next Steps](#next-steps))
- [x] Re-add filesystem watcher cargo feature gate (currently it is not
optional)
- [ ] Migration Guide
- [ ] Changelog

## Followup TODO

- [ ] Replace "eager unchanged processed asset loading" behavior with
"don't returned unchanged processed asset until dependencies have been
checked".
- [ ] Add true `Ignore` AssetAction that does not copy the asset to the
imported_assets folder.
- [ ] Finish "live asset unloading" (ex: free up CPU asset memory after
uploading an image to the GPU), rethink RenderAssets, and port renderer
features. The `Assets` collection uses `Option<T>` for asset storage to
support its removal. (1) the Option might not actually be necessary ...
might be able to just remove from the collection entirely (2) need to
finalize removal apis
- [ ] Try replacing the "channel based" asset id recycling with
something a bit more efficient (ex: we might be able to use raw atomic
ints with some cleverness)
- [ ] Consider adding UUIDs to processed assets (scoped just to helping
identify moved assets ... not exposed to load queries ... see [Next
Steps](#next-steps))
- [ ] Store "last modified" source asset and meta timestamps in
processed meta files to enable skipping expensive hashing when the file
wasn't changed
- [ ] Fix "slow loop" handle drop fix 
- [ ] Migrate to TypeName
- [x] Handle "loader preregistration". See #9429

## Next Steps

* **Configurable per-type defaults for AssetMeta**: It should be
possible to add configuration like "all png image meta should default to
using nearest sampling" (currently this hard-coded per-loader/processor
Settings::default() impls). Also see the "Folder Meta" bullet point.
* **Avoid Reprocessing on Asset Renames / Moves**: See the "canonical
asset ids" discussion in [Open Questions](#open-questions) and the
relevant bullet point in [Draft TODO](#draft-todo). Even without
canonical ids, folder renames could avoid reprocessing in some cases.
* **Multiple Asset Sources**: Expand AssetPath to support "asset source
names" and support multiple AssetReaders in the asset server (ex:
`webserver://some_path/image.png` backed by an Http webserver
AssetReader). The "default" asset reader would use normal
`some_path/image.png` paths. Ideally this works in combination with
multiple AssetWatchers for hot-reloading
* **Stable Type Names**: this pr removes the TypeUuid requirement from
assets in favor of `std::any::type_name`. This makes defining assets
easier (no need to generate a new uuid / use weird proc macro syntax).
It also makes reading meta files easier (because things have "friendly
names"). We also use type names for components in scene files. If they
are good enough for components, they are good enough for assets. And
consistency across Bevy pillars is desirable. However,
`std::any::type_name` is not guaranteed to be stable (although in
practice it is). We've developed a [stable type
path](https://github.com/bevyengine/bevy/pull/7184) to resolve this,
which should be adopted when it is ready.
* **Command Line Interface**: It should be possible to run the asset
processor in a separate process from the command line. This will also
require building a network-server-backed AssetReader to communicate
between the app and the processor. We've been planning to build a "bevy
cli" for awhile. This seems like a good excuse to build it.
* **Asset Packing**: This is largely an additive feature, so it made
sense to me to punt this until we've laid the foundations in this PR.
* **Per-Platform Processed Assets**: It should be possible to generate
assets for multiple platforms by supporting multiple "processor
profiles" per asset (ex: compress with format X on PC and Y on iOS). I
think there should probably be arbitrary "profiles" (which can be
separate from actual platforms), which are then assigned to a given
platform when generating the final asset distribution for that platform.
Ex: maybe devs want a "Mobile" profile that is shared between iOS and
Android. Or a "LowEnd" profile shared between web and mobile.
* **Versioning and Migrations**: Assets, Loaders, Savers, and Processors
need to have versions to determine if their schema is valid. If an asset
/ loader version is incompatible with the current version expected at
runtime, the processor should be able to migrate them. I think we should
try using Bevy Reflect for this, as it would allow us to load the old
version as a dynamic Reflect type without actually having the old Rust
type. It would also allow us to define "patches" to migrate between
versions (Bevy Reflect devs are currently working on patching). The
`.meta` file already has its own format version. Migrating that to new
versions should also be possible.
* **Real Copy-on-write AssetPaths**: Rust's actual Cow (clone-on-write
type) currently used by AssetPath can still result in String clones that
aren't actually necessary (cloning an Owned Cow clones the contents).
Bevy's asset system requires cloning AssetPaths in a number of places,
which result in actual clones of the internal Strings. This is not
efficient. AssetPath internals should be reworked to exhibit truer
cow-like-behavior that reduces String clones to the absolute minimum.
* **Consider processor-less processing**: In theory the AssetServer
could run processors "inline" even if the background AssetProcessor is
disabled. If we decide this is actually desirable, we could add this.
But I don't think its a priority in the short or medium term.
* **Pre-emptive dependency loading**: We could encode dependencies in
processed meta files, which could then be used by the Asset Server to
kick of dependency loads as early as possible (prior to starting the
actual asset load). Is this desirable? How much time would this save in
practice?
* **Optimize Processor With UntypedAssetIds**: The processor exclusively
uses AssetPath to identify assets currently. It might be possible to
swap these out for UntypedAssetIds in some places, which are smaller /
cheaper to hash and compare.
* **One to Many Asset Processing**: An asset source file that produces
many assets currently must be processed into a single "processed" asset
source. If labeled assets can be written separately they can each have
their own configured savers _and_ they could be loaded more granularly.
Definitely worth exploring!
* **Automatically Track "Runtime-only" Asset Dependencies**: Right now,
tracking "created at runtime" asset dependencies requires adding them
via `asset_server.load_asset(StandardMaterial::default())`. I think with
some cleverness we could also do this for
`materials.add(StandardMaterial::default())`, making tracking work
"everywhere". There are challenges here relating to change detection /
ensuring the server is made aware of dependency changes. This could be
expensive in some cases.
* **"Dependency Changed" events**: Some assets have runtime artifacts
that need to be re-generated when one of their dependencies change (ex:
regenerate a material's bind group when a Texture needs to change). We
are generating the dependency graph so we can definitely produce these
events. Buuuuut generating these events will have a cost / they could be
high frequency for some assets, so we might want this to be opt-in for
specific cases.
* **Investigate Storing More Information In Handles**: Handles can now
store arbitrary information, which makes it cheaper and easier to
access. How much should we move into them? Canonical asset load states
(via atomics)? (`handle.is_loaded()` would be very cool). Should we
store the entire asset and remove the `Assets<T>` collection?
(`Arc<RwLock<Option<Image>>>`?)
* **Support processing and loading files without extensions**: This is a
pretty arbitrary restriction and could be supported with very minimal
changes.
* **Folder Meta**: It would be nice if we could define per folder
processor configuration defaults (likely in a `.meta` or `.folder_meta`
file). Things like "default to linear filtering for all Images in this
folder".
* **Replace async_broadcast with event-listener?** This might be
approximately drop-in for some uses and it feels more light weight
* **Support Running the AssetProcessor on the Web**: Most of the hard
work is done here, but there are some easy straggling TODOs (make the
transaction log an interface instead of a direct file writer so we can
write a web storage backend, implement an AssetReader/AssetWriter that
reads/writes to something like LocalStorage).
* **Consider identifying and preventing circular dependencies**: This is
especially important for "processor dependencies", as processing will
silently never finish in these cases.
* **Built-in/Inlined Asset Hot Reloading**: This PR regresses
"built-in/inlined" asset hot reloading (previously provided by the
DebugAssetServer). I'm intentionally punting this because I think it can
be cleanly implemented with "multiple asset sources" by registering a
"debug asset source" (ex: `debug://bevy_pbr/src/render/pbr.wgsl` asset
paths) in combination with an AssetWatcher for that asset source and
support for "manually loading pats with asset bytes instead of
AssetReaders". The old DebugAssetServer was quite nasty and I'd love to
avoid that hackery going forward.
* **Investigate ways to remove double-parsing meta files**: Parsing meta
files currently involves parsing once with "minimal" versions of the
meta file to extract the type name of the loader/processor config, then
parsing again to parse the "full" meta. This is suboptimal. We should be
able to define custom deserializers that (1) assume the loader/processor
type name comes first (2) dynamically looks up the loader/processor
registrations to deserialize settings in-line (similar to components in
the bevy scene format). Another alternative: deserialize as dynamic
Reflect objects and then convert.
* **More runtime loading configuration**: Support using the Handle type
as a hint to select an asset loader (instead of relying on AssetPath
extensions)
* **More high level Processor trait implementations**: For example, it
might be worth adding support for arbitrary chains of "asset transforms"
that modify an in-memory asset representation between loading and
saving. (ex: load a Mesh, run a `subdivide_mesh` transform, followed by
a `flip_normals` transform, then save the mesh to an efficient
compressed format).
* **Bevy Scene Handle Deserialization**: (see the relevant [Draft TODO
item](#draft-todo) for context)
* **Explore High Level Load Interfaces**: See [this
discussion](#discuss-on_loaded-high-level-interface) for one prototype.
* **Asset Streaming**: It would be great if we could stream Assets (ex:
stream a long video file piece by piece)
* **ID Exchanging**: In this PR Asset Handles/AssetIds are bigger than
they need to be because they have a Uuid enum variant. If we implement
an "id exchanging" system that trades Uuids for "efficient runtime ids",
we can cut down on the size of AssetIds, making them more efficient.
This has some open design questions, such as how to spawn entities with
"default" handle values (as these wouldn't have access to the exchange
api in the current system).
* **Asset Path Fixup Tooling**: Assets that inline asset paths inside
them will break when an asset moves. The asset system provides the
functionality to detect when paths break. We should build a framework
that enables formats to define "path migrations". This is especially
important for scene files. For editor-generated files, we should also
consider using UUIDs (see other bullet point) to avoid the need to
migrate in these cases.

---------

Co-authored-by: BeastLe9enD <beastle9end@outlook.de>
Co-authored-by: Mike <mike.hsu@gmail.com>
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
2023-09-07 02:07:27 +00:00
ClayenKitten
ffc572728f
Fix typos throughout the project (#9090)
# Objective

Fix typos throughout the project.

## Solution

[`typos`](https://github.com/crate-ci/typos) project was used for
scanning, but no automatic corrections were applied. I checked
everything by hand before fixing.

Most of the changes are documentation/comments corrections. Also, there
are few trivial changes to code (variable name, pub(crate) function name
and a few error/panic messages).

## Unsolved

`bevy_reflect_derive` has
[typo](1b51053f19/crates/bevy_reflect/bevy_reflect_derive/src/type_path.rs (L76))
in enum variant name that I didn't fix. Enum is `pub(crate)`, so there
shouldn't be any trouble if fixed. However, code is tightly coupled with
macro usage, so I decided to leave it for more experienced contributor
just in case.
2023-07-10 00:11:51 +00:00
Gino Valente
aeeb20ec4c
bevy_reflect: FromReflect Ergonomics Implementation (#6056)
# Objective

**This implementation is based on
https://github.com/bevyengine/rfcs/pull/59.**

---

Resolves #4597

Full details and motivation can be found in the RFC, but here's a brief
summary.

`FromReflect` is a very powerful and important trait within the
reflection API. It allows Dynamic types (e.g., `DynamicList`, etc.) to
be formed into Real ones (e.g., `Vec<i32>`, etc.).

This mainly comes into play concerning deserialization, where the
reflection deserializers both return a `Box<dyn Reflect>` that almost
always contain one of these Dynamic representations of a Real type. To
convert this to our Real type, we need to use `FromReflect`.

It also sneaks up in other ways. For example, it's a required bound for
`T` in `Vec<T>` so that `Vec<T>` as a whole can be made `FromReflect`.
It's also required by all fields of an enum as it's used as part of the
`Reflect::apply` implementation.

So in other words, much like `GetTypeRegistration` and `Typed`, it is
very much a core reflection trait.

The problem is that it is not currently treated like a core trait and is
not automatically derived alongside `Reflect`. This makes using it a bit
cumbersome and easy to forget.

## Solution

Automatically derive `FromReflect` when deriving `Reflect`.

Users can then choose to opt-out if needed using the
`#[reflect(from_reflect = false)]` attribute.

```rust
#[derive(Reflect)]
struct Foo;

#[derive(Reflect)]
#[reflect(from_reflect = false)]
struct Bar;

fn test<T: FromReflect>(value: T) {}

test(Foo); // <-- OK
test(Bar); // <-- Panic! Bar does not implement trait `FromReflect`
```

#### `ReflectFromReflect`

This PR also automatically adds the `ReflectFromReflect` (introduced in
#6245) registration to the derived `GetTypeRegistration` impl— if the
type hasn't opted out of `FromReflect` of course.

<details>
<summary><h4>Improved Deserialization</h4></summary>

> **Warning**
> This section includes changes that have since been descoped from this
PR. They will likely be implemented again in a followup PR. I am mainly
leaving these details in for archival purposes, as well as for reference
when implementing this logic again.

And since we can do all the above, we might as well improve
deserialization. We can now choose to deserialize into a Dynamic type or
automatically convert it using `FromReflect` under the hood.

`[Un]TypedReflectDeserializer::new` will now perform the conversion and
return the `Box`'d Real type.

`[Un]TypedReflectDeserializer::new_dynamic` will work like what we have
now and simply return the `Box`'d Dynamic type.

```rust
// Returns the Real type
let reflect_deserializer = UntypedReflectDeserializer::new(&registry);
let mut deserializer = ron:🇩🇪:Deserializer::from_str(input)?;

let output: SomeStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?;

// Returns the Dynamic type
let reflect_deserializer = UntypedReflectDeserializer::new_dynamic(&registry);
let mut deserializer = ron:🇩🇪:Deserializer::from_str(input)?;

let output: DynamicStruct = reflect_deserializer.deserialize(&mut deserializer)?.take()?;
```

</details>

---

## Changelog

* `FromReflect` is now automatically derived within the `Reflect` derive
macro
* This includes auto-registering `ReflectFromReflect` in the derived
`GetTypeRegistration` impl
* ~~Renamed `TypedReflectDeserializer::new` and
`UntypedReflectDeserializer::new` to
`TypedReflectDeserializer::new_dynamic` and
`UntypedReflectDeserializer::new_dynamic`, respectively~~ **Descoped**
* ~~Changed `TypedReflectDeserializer::new` and
`UntypedReflectDeserializer::new` to automatically convert the
deserialized output using `FromReflect`~~ **Descoped**

## Migration Guide

* `FromReflect` is now automatically derived within the `Reflect` derive
macro. Items with both derives will need to remove the `FromReflect`
one.

  ```rust
  // OLD
  #[derive(Reflect, FromReflect)]
  struct Foo;
  
  // NEW
  #[derive(Reflect)]
  struct Foo;
  ```

If using a manual implementation of `FromReflect` and the `Reflect`
derive, users will need to opt-out of the automatic implementation.

  ```rust
  // OLD
  #[derive(Reflect)]
  struct Foo;
  
  impl FromReflect for Foo {/* ... */}
  
  // NEW
  #[derive(Reflect)]
  #[reflect(from_reflect = false)]
  struct Foo;
  
  impl FromReflect for Foo {/* ... */}
  ```

<details>
<summary><h4>Removed Migrations</h4></summary>

> **Warning**
> This section includes changes that have since been descoped from this
PR. They will likely be implemented again in a followup PR. I am mainly
leaving these details in for archival purposes, as well as for reference
when implementing this logic again.

* The reflect deserializers now perform a `FromReflect` conversion
internally. The expected output of `TypedReflectDeserializer::new` and
`UntypedReflectDeserializer::new` is no longer a Dynamic (e.g.,
`DynamicList`), but its Real counterpart (e.g., `Vec<i32>`).

  ```rust
let reflect_deserializer =
UntypedReflectDeserializer::new_dynamic(&registry);
  let mut deserializer = ron:🇩🇪:Deserializer::from_str(input)?;
  
  // OLD
let output: DynamicStruct = reflect_deserializer.deserialize(&mut
deserializer)?.take()?;
  
  // NEW
let output: SomeStruct = reflect_deserializer.deserialize(&mut
deserializer)?.take()?;
  ```

Alternatively, if this behavior isn't desired, use the
`TypedReflectDeserializer::new_dynamic` and
`UntypedReflectDeserializer::new_dynamic` methods instead:

  ```rust
  // OLD
  let reflect_deserializer = UntypedReflectDeserializer::new(&registry);
  
  // NEW
let reflect_deserializer =
UntypedReflectDeserializer::new_dynamic(&registry);
  ```

</details>

---------

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2023-06-29 01:31:34 +00:00
EliasPrescott
e6b655fb25
adding reflection for Cow<'static, [T]> (#7454)
# Objective

- Implementing reflection for Cow<'static, [T]>
- Hopefully fixes #7429

## Solution

- Implementing Reflect, Typed, GetTypeRegistration, and FromReflect for
Cow<'static, [T]>

---

## Notes

I have not used bevy_reflection much yet, so I may not fully understand
all the use cases. This is also my first attempt at contributing, so I
would appreciate any feedback or recommendations for changes. I tried to
add cases for using Cow<'static, str> and Cow<'static, [u8]> to some of
the bevy_reflect tests, but I can't guarantee those tests are
comprehensive enough.

---------

Co-authored-by: MinerSebas <66798382+MinerSebas@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2023-06-19 14:58:49 +00:00
Carter Anderson
8b9d88f4d0
Reflect now requires DynamicTypePath. Remove Reflect::get_type_path() (#8764)
Followup to #7184

This makes `Reflect: DynamicTypePath` which allows us to remove
`Reflect::get_type_path`, reducing unnecessary codegen and simplifying
`Reflect` implementations.
2023-06-06 17:23:58 +00:00
radiish
1efc762924
reflect: stable type path v2 (#7184)
# Objective

- Introduce a stable alternative to
[`std::any::type_name`](https://doc.rust-lang.org/std/any/fn.type_name.html).
- Rewrite of #5805 with heavy inspiration in design.
- On the path to #5830.
- Part of solving #3327.


## Solution

- Add a `TypePath` trait for static stable type path/name information.
- Add a `TypePath` derive macro.
- Add a `impl_type_path` macro for implementing internal and foreign
types in `bevy_reflect`.

---

## Changelog

- Added `TypePath` trait.
- Added `DynamicTypePath` trait and `get_type_path` method to `Reflect`.
- Added a `TypePath` derive macro.
- Added a `bevy_reflect::impl_type_path` for implementing `TypePath` on
internal and foreign types in `bevy_reflect`.
- Changed `bevy_reflect::utility::(Non)GenericTypeInfoCell` to
`(Non)GenericTypedCell<T>` which allows us to be generic over both
`TypeInfo` and `TypePath`.
- `TypePath` is now a supertrait of `Asset`, `Material` and
`Material2d`.
- `impl_reflect_struct` needs a `#[type_path = "..."]` attribute to be
specified.
- `impl_reflect_value` needs to either specify path starting with a
double colon (`::core::option::Option`) or an `in my_crate::foo`
declaration.
- Added `bevy_reflect_derive::ReflectTypePath`.
- Most uses of `Ident` in `bevy_reflect_derive` changed to use
`ReflectTypePath`.

## Migration Guide

- Implementors of `Asset`, `Material` and `Material2d` now also need to
derive `TypePath`.
- Manual implementors of `Reflect` will need to implement the new
`get_type_path` method.

## Open Questions
- [x] ~This PR currently does not migrate any usages of
`std::any::type_name` to use `bevy_reflect::TypePath` to ease the review
process. Should it?~ Migration will be left to a follow-up PR.
- [ ] This PR adds a lot of `#[derive(TypePath)]` and `T: TypePath` to
satisfy new bounds, mostly when deriving `TypeUuid`. Should we make
`TypePath` a supertrait of `TypeUuid`? [Should we remove `TypeUuid` in
favour of
`TypePath`?](2afbd85532 (r961067892))
2023-06-05 20:31:20 +00:00
Егор Куклин
6b4c7d5d88
Add get_at_mut to bevy_reflect::Map trait (#8691)
# Objective

Fixes #8596 

## Solution

Change interface of the trait Map. Adjust implementations of this trait

---

## Changelog

### Changed
- Interface of Map trait

### Added
- `Map::get_at_mut`

## Migration Guide

Every implementor of Map trait would need to implement `get_at_mut`.
Which, judging by changes in this PR, should be fairly trivial.
2023-06-02 12:24:40 +00:00
Gauthier Acquitter
acf1362b9a
bevy_reflect: Allow construction of MapIter outside of the bevy_reflect crate. (#8723)
# Objective

Right now it's impossible to construct a MapIter outside of the
bevy_reflect crate, making it impossible to implement the Map trait for
custom map types.

## Solution

Addition of a pub constructor to MapIter.
2023-06-01 10:12:57 +00:00
Mincho Paskalev
fe57b9f744
Add Reflect and FromReflect for AssetPath (#8531)
# Objective

- Add Reflect and FromReflect for AssetPath
- Fixes #8458

## Solution

- Straightforward derive of `Reflect` and `FromReflect` for `AssetPath`
- Implement `Reflect` and `FromReflect` for `Cow<'static, Path>` as to
satisfy the 'static lifetime requierments of bevy_reflect.
Implementation is a direct copy of that for `Cow<'static, str>` so maybe
it begs the question that was already asked in #7429 - maybe it would be
benefitial to write a general implementation for `Reflect` for
`Cow<'static, T>`.
2023-05-08 19:19:19 +00:00
Gino Valente
75130bd5ec
bevy_reflect: Better proxies (#6971)
# Objective

> This PR is based on discussion from #6601

The Dynamic types (e.g. `DynamicStruct`, `DynamicList`, etc.) act as
both:
1. Dynamic containers which may hold any arbitrary data
2. Proxy types which may represent any other type

Currently, the only way we can represent the proxy-ness of a Dynamic is
by giving it a name.

```rust
// This is just a dynamic container
let mut data = DynamicStruct::default();

// This is a "proxy"
data.set_name(std::any::type_name::<Foo>());
```

This type name is the only way we check that the given Dynamic is a
proxy of some other type. When we need to "assert the type" of a `dyn
Reflect`, we call `Reflect::type_name` on it. However, because we're
only using a string to denote the type, we run into a few gotchas and
limitations.

For example, hashing a Dynamic proxy may work differently than the type
it proxies:

```rust
#[derive(Reflect, Hash)]
#[reflect(Hash)]
struct Foo(i32);

let concrete = Foo(123);
let dynamic = concrete.clone_dynamic();

let concrete_hash = concrete.reflect_hash();
let dynamic_hash = dynamic.reflect_hash();

// The hashes are not equal because `concrete` uses its own `Hash` impl
// while `dynamic` uses a reflection-based hashing algorithm
assert_ne!(concrete_hash, dynamic_hash);
```

Because the Dynamic proxy only knows about the name of the type, it's
unaware of any other information about it. This means it also differs on
`Reflect::reflect_partial_eq`, and may include ignored or skipped fields
in places the concrete type wouldn't.

## Solution

Rather than having Dynamics pass along just the type name of proxied
types, we can instead have them pass around the `TypeInfo`.

Now all Dynamic types contain an `Option<&'static TypeInfo>` rather than
a `String`:

```diff
pub struct DynamicTupleStruct {
-    type_name: String,
+    represented_type: Option<&'static TypeInfo>,
    fields: Vec<Box<dyn Reflect>>,
}
```

By changing `Reflect::get_type_info` to
`Reflect::represented_type_info`, hopefully we make this behavior a
little clearer. And to account for `None` values on these dynamic types,
`Reflect::represented_type_info` now returns `Option<&'static
TypeInfo>`.

```rust
let mut data = DynamicTupleStruct::default();

// Not proxying any specific type
assert!(dyn_tuple_struct.represented_type_info().is_none());

let type_info = <Foo as Typed>::type_info();
dyn_tuple_struct.set_represented_type(Some(type_info));
// Alternatively:
// let dyn_tuple_struct = foo.clone_dynamic();

// Now we're proxying `Foo`
assert!(dyn_tuple_struct.represented_type_info().is_some());
```

This means that we can have full access to all the static type
information for the proxied type. Future work would include
transitioning more static type information (trait impls, attributes,
etc.) over to the `TypeInfo` so it can actually be utilized by Dynamic
proxies.

### Alternatives & Rationale

> **Note** 
> These alternatives were written when this PR was first made using a
`Proxy` trait. This trait has since been removed.

<details>
<summary>View</summary>

#### Alternative: The `Proxy<T>` Approach

I had considered adding something like a `Proxy<T>` type where `T` would
be the Dynamic and would contain the proxied type information.

This was nice in that it allows us to explicitly determine whether
something is a proxy or not at a type level. `Proxy<DynamicStruct>`
proxies a struct. Makes sense.

The reason I didn't go with this approach is because (1) tuples, (2)
complexity, and (3) `PartialReflect`.

The `DynamicTuple` struct allows us to represent tuples at runtime. It
also allows us to do something you normally can't with tuples: add new
fields. Because of this, adding a field immediately invalidates the
proxy (e.g. our info for `(i32, i32)` doesn't apply to `(i32, i32,
NewField)`). By going with this PR's approach, we can just remove the
type info on `DynamicTuple` when that happens. However, with the
`Proxy<T>` approach, it becomes difficult to represent this behavior—
we'd have to completely control how we access data for `T` for each `T`.

Secondly, it introduces some added complexities (aside from the manual
impls for each `T`). Does `Proxy<T>` impl `Reflect`? Likely yes, if we
want to represent it as `dyn Reflect`. What `TypeInfo` do we give it?
How would we forward reflection methods to the inner type (remember, we
don't have specialization)? How do we separate this from Dynamic types?
And finally, how do all this in a way that's both logical and intuitive
for users?

Lastly, introducing a `Proxy` trait rather than a `Proxy<T>` struct is
actually more inline with the [Unique Reflect
RFC](https://github.com/bevyengine/rfcs/pull/56). In a way, the `Proxy`
trait is really one part of the `PartialReflect` trait introduced in
that RFC (it's technically not in that RFC but it fits well with it),
where the `PartialReflect` serves as a way for proxies to work _like_
concrete types without having full access to everything a concrete
`Reflect` type can do. This would help bridge the gap between the
current state of the crate and the implementation of that RFC.

All that said, this is still a viable solution. If the community
believes this is the better path forward, then we can do that instead.
These were just my reasons for not initially going with it in this PR.

#### Alternative: The Type Registry Approach

The `Proxy` trait is great and all, but how does it solve the original
problem? Well, it doesn't— yet!

The goal would be to start moving information from the derive macro and
its attributes to the generated `TypeInfo` since these are known
statically and shouldn't change. For example, adding `ignored: bool` to
`[Un]NamedField` or a list of impls.

However, there is another way of storing this information. This is, of
course, one of the uses of the `TypeRegistry`. If we're worried about
Dynamic proxies not aligning with their concrete counterparts, we could
move more type information to the registry and require its usage.

For example, we could replace `Reflect::reflect_hash(&self)` with
`Reflect::reflect_hash(&self, registry: &TypeRegistry)`.

That's not the _worst_ thing in the world, but it is an ergonomics loss.

Additionally, other attributes may have their own requirements, further
restricting what's possible without the registry. The `Reflect::apply`
method will require the registry as well now. Why? Well because the
`map_apply` function used for the `Reflect::apply` impls on `Map` types
depends on `Map::insert_boxed`, which (at least for `DynamicMap`)
requires `Reflect::reflect_hash`. The same would apply when adding
support for reflection-based diffing, which will require
`Reflect::reflect_partial_eq`.

Again, this is a totally viable alternative. I just chose not to go with
it for the reasons above. If we want to go with it, then we can close
this PR and we can pursue this alternative instead.

#### Downsides

Just to highlight a quick potential downside (likely needs more
investigation): retrieving the `TypeInfo` requires acquiring a lock on
the `GenericTypeInfoCell` used by the `Typed` impls for generic types
(non-generic types use a `OnceBox which should be faster). I am not sure
how much of a performance hit that is and will need to run some
benchmarks to compare against.

</details>

### Open Questions

1. Should we use `Cow<'static, TypeInfo>` instead? I think that might be
easier for modding? Perhaps, in that case, we need to update
`Typed::type_info` and friends as well?
2. Are the alternatives better than the approach this PR takes? Are
there other alternatives?

---

## Changelog

### Changed

- `Reflect::get_type_info` has been renamed to
`Reflect::represented_type_info`
- This method now returns `Option<&'static TypeInfo>` rather than just
`&'static TypeInfo`

### Added

- Added `Reflect::is_dynamic` method to indicate when a type is dynamic
- Added a `set_represented_type` method on all dynamic types

### Removed

- Removed `TypeInfo::Dynamic` (use `Reflect::is_dynamic` instead)
- Removed `Typed` impls for all dynamic types

## Migration Guide

- The Dynamic types no longer take a string type name. Instead, they
require a static reference to `TypeInfo`:

    ```rust
    #[derive(Reflect)]
    struct MyTupleStruct(f32, f32);
    
    let mut dyn_tuple_struct = DynamicTupleStruct::default();
    dyn_tuple_struct.insert(1.23_f32);
    dyn_tuple_struct.insert(3.21_f32);
    
    // BEFORE:
    let type_name = std::any::type_name::<MyTupleStruct>();
    dyn_tuple_struct.set_name(type_name);
    
    // AFTER:
    let type_info = <MyTupleStruct as Typed>::type_info();
    dyn_tuple_struct.set_represented_type(Some(type_info));
    ```

- `Reflect::get_type_info` has been renamed to
`Reflect::represented_type_info` and now also returns an
`Option<&'static TypeInfo>` (instead of just `&'static TypeInfo`):

    ```rust
    // BEFORE:
    let info: &'static TypeInfo = value.get_type_info();
    // AFTER:
let info: &'static TypeInfo = value.represented_type_info().unwrap();
    ```

- `TypeInfo::Dynamic` and `DynamicInfo` has been removed. Use
`Reflect::is_dynamic` instead:
   
    ```rust
    // BEFORE:
    if matches!(value.get_type_info(), TypeInfo::Dynamic) {
      // ...
    }
    // AFTER:
    if value.is_dynamic() {
      // ...
    }
    ```

---------

Co-authored-by: radiish <cb.setho@gmail.com>
2023-04-26 12:17:46 +00:00
Noah
a9f766ceb2
Fix Box<dyn Reflect> struct with a hashmap in it panicking when clone_value is called on it (#8184)
# Objective

- Fix the issue described in #8183: Box<dyn Reflect> structs with a
hashmap in them will panic when clone_value is called on it
- Fixes: #8183

## Solution

- Updates the implementation of Reflect for Hashmaps to make clone_value
call from_reflect on the key before inserting it into the new struct
2023-04-22 02:55:53 +00:00
TheBigCheese
3d3444b981 impl Reflect for std::collections::HashMap instead of only bevy::utils::HashMap (#7739) (#7782)
# Objective

Implement `Reflect` for `std::collections::HashMap<K, V, S>` as well as `hashbrown::HashMap<K, V, S>` rather than just for `hashbrown::HashMap<K, V, RandomState>`. Fixes #7739.

## Solution

Rather than implementing on `HashMap<K, V>` I instead implemented most of the related traits on `HashMap<K, V, S> where S: BuildHasher + Send + Sync + 'static` and then `FromReflect` also needs the extra bound `S: Default` because it needs to use `with_capacity_and_hasher` so needs to be able to generate a default hasher.

As the API of `hashbrown::HashMap` is identical to `collections::HashMap` making them both work just required creating an `impl_reflect_for_hashmap` macro like the `impl_reflect_for_veclike` above and then applying this to both HashMaps.

---

## Changelog

`std::collections::HashMap` can now be reflected. Also more `State` generics than just `RandomState` can now be reflected for both `hashbrown::HashMap` and `collections::HashMap`
2023-02-27 21:37:36 +00:00
Johan Klokkhammer Helsing
18cfb226db Use a fixed state hasher in bevy_reflect for deterministic Reflect::reflect_hash() across processes (#7583)
# Objective

- bevy_ggrs uses `reflect_hash` in order to produce checksums for its world snapshots. These checksums are sent between clients in order to detect desyncronization.
- However, since we currently use `async::AHasher` with the `std` feature, this means that hashes will always be different for different peers, even if the state is identical.
- This means bevy_ggrs needs a way to get a deterministic (fixed) hash.

## Solution

- ~~Add a feature to use `bevy_utils::FixedState` for the hasher used by bevy_reflect.~~
- Always use `bevy_utils::FixedState` for initializing the bevy_reflect hasher. 

---

## Changelog

- bevy_reflect now uses a fixed state for its hasher, which means the output of `Reflect::reflect_hash` is now deterministic across processes.
2023-02-17 15:37:35 +00:00
Gino Valente
724b36289c bevy_reflect: Decouple List and Array traits (#7467)
# Objective

Resolves #7121

## Solution

Decouples `List` and `Array` by removing `Array` as a supertrait of `List`. Additionally, similar methods from `Array` have been added to `List` so that their usages can remain largely unchanged.

#### Possible Alternatives

##### `Sequence`

My guess for why we originally made `List` a subtrait of `Array` is that they share a lot of common operations. We could potentially move these overlapping methods to a `Sequence` (name taken from #7059) trait and make that a supertrait of both. This would allow functions to contain logic that simply operates on a sequence rather than "list vs array".

However, this means that we'd need to add methods for converting to a `dyn Sequence`. It also might be confusing since we wouldn't add a `ReflectRef::Sequence` or anything like that. Is such a trait worth adding (either in this PR or a followup one)? 

---

## Changelog

- Removed `Array` as supertrait of `List`
  - Added methods to `List` that were previously provided by `Array`

## Migration Guide

The `List` trait is no longer dependent on `Array`. Implementors of `List` can remove the `Array` impl and move its methods into the `List` impl (with only a couple tweaks).

```rust
// BEFORE
impl Array for Foo {
  fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */}
  fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */}
  fn len(&self) -> usize {/* ... */}
  fn is_empty(&self) -> bool {/* ... */}
  fn iter(&self) -> ArrayIter {/* ... */}
  fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */}
  fn clone_dynamic(&self) -> DynamicArray {/* ... */}
}

impl List for Foo {
  fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */}
  fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */}
  fn push(&mut self, value: Box<dyn Reflect>) {/* ... */}
  fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */}
  fn clone_dynamic(&self) -> DynamicList {/* ... */}
}

// AFTER
impl List for Foo {
  fn get(&self, index: usize) -> Option<&dyn Reflect> {/* ... */}
  fn get_mut(&mut self, index: usize) -> Option<&mut dyn Reflect> {/* ... */}
  fn insert(&mut self, index: usize, element: Box<dyn Reflect>) {/* ... */}
  fn remove(&mut self, index: usize) -> Box<dyn Reflect> {/* ... */}
  fn push(&mut self, value: Box<dyn Reflect>) {/* ... */}
  fn pop(&mut self) -> Option<Box<dyn Reflect>> {/* ... */}
  fn len(&self) -> usize {/* ... */}
  fn is_empty(&self) -> bool {/* ... */}
  fn iter(&self) -> ListIter {/* ... */}
  fn drain(self: Box<Self>) -> Vec<Box<dyn Reflect>> {/* ... */}
  fn clone_dynamic(&self) -> DynamicList {/* ... */}
}
```

Some other small tweaks that will need to be made include:
- Use `ListIter` for `List::iter` instead of `ArrayIter` (the return type from `Array::iter`)
- Replace `array_hash` with `list_hash` in `Reflect::reflect_hash` for implementors of `List`
2023-02-13 21:07:53 +00:00
CrystaLamb
4fd092fbec fix typo in bevy_reflect::impls::std GetTypeRegistration for vec like… (#7520)
Implementing GetTypeRegistration in macro impl_reflect_for_veclike! had typos!
It only implement GetTypeRegistration for Vec<T>, but not for VecDeque<T>.
This will cause serialization and deserialization failure.
2023-02-06 12:58:21 +00:00
Elbert Ronnie
615d3d2157 Add constructor new to ArrayIter (#7449)
# Objective

- Fixes #7430.

## Solution

- Changed fields of `ArrayIter` to be private.
- Add a constructor `new` to `ArrayIter`.
- Replace normal struct creation with `new`.

---

## Changelog

- Add a constructor `new` to `ArrayIter`.


Co-authored-by: Elbert Ronnie <103196773+elbertronnie@users.noreply.github.com>
2023-01-31 23:19:19 +00:00
Gino Valente
229d6c686f bevy_reflect: Simplify take-or-else-from_reflect operation (#6566)
# Objective

There are times where we want to simply take an owned `dyn Reflect` and cast it to a type `T`.

Currently, this involves doing:

```rust
let value = value.take::<T>().unwrap_or_else(|value| {
  T::from_reflect(&*value).unwrap_or_else(|| {
    panic!(
      "expected value of type {} to convert to type {}.",
      value.type_name(),
      std::any::type_name::<T>()
    )
  })
});
```

This is a common operation that could be easily be simplified.

## Solution

Add the `FromReflect::take_from_reflect` method. This first tries to `take` the value, calling `from_reflect` iff that fails.

```rust
let value = T::take_from_reflect(value).unwrap_or_else(|value| {
  panic!(
    "expected value of type {} to convert to type {}.",
    value.type_name(),
    std::any::type_name::<T>()
  )
});
```

Based on suggestion from @soqb on [Discord](https://discord.com/channels/691052431525675048/1002362493634629796/1041046880316043374).

---

## Changelog

- Add `FromReflect::take_from_reflect` method
2023-01-11 16:25:37 +00:00
radiish
1b9c156479 reflect: add insert and remove methods to List (#7063)
# Objective

- Fixes #7061

## Solution

- Add and implement `insert` and `remove` methods for `List`.

---

## Changelog

- Added `insert` and `remove` methods to `List`.
- Changed the `push` and `pop` methods on `List` to have default implementations.

## Migration Guide

- Manual implementors of `List` need to implement the new methods `insert` and `remove` and 
consider whether to use the new default implementation of `push` and `pop`.

Co-authored-by: radiish <thesethskigamer@gmail.com>
2023-01-09 19:47:07 +00:00
James Liu
b37a6ca9a2 Add reflection support for VecDeque (#6831)
# Objective
This is an adoption of #5792. Fixes #5791.

## Solution
Implemented all the required reflection traits for `VecDeque`, taking from `Vec`'s impls.

---

## Changelog
Added: `std::collections::VecDeque` now implements `Reflect` and all relevant traits.

Co-authored-by: james7132 <contact@jamessliu.com>
2022-12-11 18:22:08 +00:00