Some hardware and driver combos, such as Intel Iris Xe, have low limits
on the numbers of samplers per shader, causing an overflow. With
first-class bindless arrays, `wgpu` should be able to work around this
limitation eventually, but for now we need to disable bindless materials
on those platforms.
This is an alternative to PR #17107 that calculates the precise number
of samplers needed and compares to the hardware sampler limit,
transparently falling back to non-bindless if the limit is exceeded.
Fixes#16988.
# Objective
- Contributes to #11478
- Contributes to #16877
## Solution
- Removed everything except `Instant` from `bevy_utils::time`
## Testing
- CI
---
## Migration Guide
If you relied on any of the following from `bevy_utils::time`:
- `Duration`
- `TryFromFloatSecsError`
Import these directly from `core::time` regardless of platform target
(WASM, mobile, etc.)
If you relied on any of the following from `bevy_utils::time`:
- `SystemTime`
- `SystemTimeError`
Instead import these directly from either `std::time` or `web_time` as
appropriate for your target platform.
## Notes
`Duration` and `TryFromFloatSecsError` are both re-exports from
`core::time` regardless of whether they are used from `web_time` or
`std::time`, so there is no value gained from re-exporting them from
`bevy_utils::time` as well. As for `SystemTime` and `SystemTimeError`,
no Bevy internal crates or examples rely on these types. Since Bevy
doesn't have a `Time<Wall>` resource for interacting with wall-time (and
likely shouldn't need one), I think removing these from `bevy_utils`
entirely and waiting for a use-case to justify inclusion is a reasonable
path forward.
# Objective
- https://github.com/bevyengine/bevy/issues/17111
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_audio` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
`cargo clippy`, `cargo clippy --package bevy_dev_tools` and cargo test
--package bevy_dev_tools` were run, and no errors were encountered.
(Except for one warning from bevy_sprite, but I plan to fix that when I
get to bevy_sprite)
# Objective
Optimization for sprite picking
## Solution
Use `radsort` for the sort.
We already have `radsort` in tree for sorting various phase items
(including `Transparent2d` / sprites). It's a stable parallel radix
sort.
## Testing
Tested on an M1 Max.
`cargo run --example sprite_picking`
`cargo run --example bevymark --release --features=trace,trace_tracy --
--waves 100 --per-wave 1000 --benchmark`
<img width="983" alt="image"
src="https://github.com/user-attachments/assets/0f7a8c3a-006b-4323-a2ed-03788918dffa"
/>
# Objective
While checking over https://github.com/bevyengine/bevy/pull/17160, it
occurred to me that rust-analyzer will copy the method signature
exactly, when using tab completion trait methods. This includes provided
trait methods that use underscores to silence the `unused_variables`
lint. This probably isn't good for users, seeing as how they'll have to
remove the underscore if they want to use the parameters.
(I mean, they technically don't have to remove the underscore... but
usually you don't keep a leading underscore on parameters you're using.)
## Solution
Changes `bevy_reflect::RegisterForReflection::__register()` to
`#[expect(unused_variables)]`, and removes the underscores from its
parameter names.
## Testing
N/A
# Objective
- `GetPath` `path` related methods allow an empty string as the
parameter, but this is not included as a test or in documentation. This
PR adds both.
- Fixes#13459
## Solution
- Updates the `bevy_reflect` `GetPath` documentation and unit tests
## Testing
- `cargo run -p ci`
Derived `Default` for all public unit structs that already derive from
`Component`. This allows them to be used more easily as required
components.
To avoid clutter in tests/examples, only public components were
affected, but this could easily be expanded to affect all unit
components.
Fixes#17052.
# Objective
Improve DAG building for virtual geometry
## Solution
- Use METIS to group triangles into meshlets which lets us minimize
locked vertices which improves simplification, instead of using meshopt
which prioritizes culling efficiency. Also some other minor tweaks.
- Currently most meshlets have 126 triangles, and not 128. Fixing this
might involve calling METIS recursively ourselves to manually bisect the
graph, not sure. Not going to attempt to fix this in this PR.
## Testing
- Did you test these changes? If so, how?
- Tested on bunny.glb and cliff.glb
- Are there any parts that need more testing?
- No
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
- Download the new bunny asset, run the meshlet example.
---
## Showcase
New
Old
---------
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
# Objective
- As stated in the linked issue, if a Mesh2D is drawn with elements with
a positive Z value, resulting gizmos get drawn behind instead of in
front of them.
- Fixes#17053
## Solution
- Similar to the change done for the `SpritePipeline` in the relevant
commit (5abc32ceda), this PR changes both
line gizmos to avoid writing to the depth buffer and always pass the
depth test to ensure they are not filtered out.
## Testing
- Tested with the provided snippet in #17053
- I looked over the `2d_gizmos` example, but it seemed like adding more
elements there to demonstrate this might not be the best idea? Looking
for guidance here on if that should be updated or if a new gizmo example
needs to be made.
# Objective
- https://github.com/bevyengine/bevy/issues/17111
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_audio` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
I ran `cargo clippy`, and received no errors.
## Objective
The error `EntityFetchError::NoSuchEntity` has an `UnsafeWorldCell`
inside it, which it uses to call
`Entities::entity_does_not_exist_error_details_message` when being
printed. That method returns a `String` that, if the `track_location`
feature is enabled, contains the location of whoever despawned the
relevant entity.
I initially had to modify this error while working on #17043. The
`UnsafeWorldCell` was causing borrow problems when being returned from a
command, so I tried replacing it with the `String` that the method
returns, since that was the world cell's only purpose.
Unfortunately, `String`s are slow, and it significantly impacted
performance (on top of that PR's performance hit):
<details>
<summary>17043 benchmarks</summary>
### With `String`
### No `String`
</details>
For that PR, I just removed the error details entirely, but I figured
I'd try to find a way to keep them around.
## Solution
- Replace the `String` with a helper struct that holds the location, and
only turn it into a string when someone actually wants to print it.
- Replace the `UnsafeWorldCell` with the aforementioned struct.
- Do the same for `QueryEntityError::NoSuchEntity`.
## Benchmarking
This had some interesting performance impact:
<details>
<summary>This PR vs main</summary>
</details>
## Other work
`QueryEntityError::QueryDoesNotMatch` also has an `UnsafeWorldCell`
inside it. This one would be more complicated to rework while keeping
the same functionality.
## Migration Guide
The errors `EntityFetchError::NoSuchEntity` and
`QueryEntityError::NoSuchEntity` now contain an
`EntityDoesNotExistDetails` struct instead of an `UnsafeWorldCell`. If
you were just printing these, they should work identically.
---------
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
# Objective
Fixes#17098
It seems that it's not totally obvious how to fix this, but that
reverting might be part of the solution anyway.
Let's get the repo back into a working state.
## Solution
Revert the [recent
optimization](https://github.com/bevyengine/bevy/pull/17078) that broke
"many-to-one main->render world entities" for 2d.
## Testing
`cargo run --example text2d`
`cargo run --example sprite_slice`
# Objective
Fixes#3450
## Solution
Scale the input to account for the range
## Testing
Updated unit tests
## Migration Guide
`GamepadButtonChangedEvent.value` is now linearly rescaled to be from
`0.0..=1.0` (instead of `low..=high`) and
`GamepadAxisChangedEvent.value` is now linearly rescaled to be from
`-1.0..=0.0`/`0.0..=1.0` (accounting for the deadzone).
# Objective
We want to deny the following lints:
* `clippy::allow_attributes` - Because there's no reason to
`#[allow(...)]` an attribute if it wouldn't lint against anything; you
should always use `#[expect(...)]`
* `clippy::allow_attributes_without_reason` - Because documenting the
reason for allowing/expecting a lint is always good
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_reflect` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
I ran `cargo clippy`, and received no errors.
# Objective
Remove the reliance on `#[allow(clippy::excessive_precision)]`.
## Solution
Remove the `#[allow(clippy::excessive_precision)]`, and truncate the
float literals to the value rustc would normally truncate them to.
## Testing
I ran `cargo test -p bevy_color`, and received no errors.
# Objective
Use the latest version of `typos` and fix the typos that it now detects
# Additional Info
By the way, `typos` has a "low priority typo suggestions issue" where we
can throw typos we find that `typos` doesn't catch.
(This link may go stale) https://github.com/crate-ci/typos/issues/1200
# Background
In `no_std` compatible crates, there is often an `std` feature which
will allow access to the standard library. Currently, with the `std`
feature _enabled_, the
[`std::prelude`](https://doc.rust-lang.org/std/prelude/index.html) is
implicitly imported in all modules. With the feature _disabled_, instead
the [`core::prelude`](https://doc.rust-lang.org/core/prelude/index.html)
is implicitly imported. This creates a subtle and pervasive issue where
`alloc` items _may_ be implicitly included (if `std` is enabled), or
must be explicitly included (if `std` is not enabled).
# Objective
- Make the implicit imports for `no_std` crates consistent regardless of
what features are/not enabled.
## Solution
- Replace the `cfg_attr` "double negative" `no_std` attribute with
conditional compilation to _include_ `std` as an external crate.
```rust
// Before
#![cfg_attr(not(feature = "std"), no_std)]
// After
#![no_std]
#[cfg(feature = "std")]
extern crate std;
```
- Fix imports that are currently broken but are only now visible with
the above fix.
## Testing
- CI
## Notes
I had previously used the "double negative" version of `no_std` based on
general consensus that it was "cleaner" within the Rust embedded
community. However, this implicit prelude issue likely was considered
when forming this consensus. I believe the reason why is the items most
affected by this issue are provided by the `alloc` crate, which is
rarely used within embedded but extensively used within Bevy.
# Objective
We want to deny the following lints:
* `clippy::allow_attributes` - Because there's no reason to
`#[allow(...)]` an attribute if it wouldn't lint against anything; you
should always use `#[expect(...)]`
* `clippy::allow_attributes_without_reason` - Because documenting the
reason for allowing/expecting a lint is always good
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_tasks` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
I ran `cargo clippy`, and received no errors.
# Objective
Fix incorrect comment on `IntoSystemSetConfigs::after` likely caused by
copy-paste error. It said "before" instead of "after".
## Solution
Update the comment to the correct text.
## Testing
CI tests pass. This is just updating a comment.
# Objective
We want to deny the following lints:
* `clippy::allow_attributes` - Because there's no reason to
`#[allow(...)]` an attribute if it wouldn't lint against anything; you
should always use `#[expect(...)]`
* `clippy::allow_attributes_without_reason` - Because documenting the
reason for allowing/expecting a lint is always good
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_math` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
I ran `cargo clippy`, and received no errors.
---------
Co-authored-by: IQuick 143 <IQuick143cz@gmail.com>
# Objective
We want to deny the following lints:
* `clippy::allow_attributes` - Because there's no reason to
`#[allow(...)]` an attribute if it wouldn't lint against anything; you
should always use `#[expect(...)]`
* `clippy::allow_attributes_without_reason` - Because documenting the
reason for allowing/expecting a lint is always good
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_a11y` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
I ran `cargo clippy`, and received no errors.
# Objective
We want to deny the following lints:
* `clippy::allow_attributes` - Because there's no reason to
`#[allow(...)]` an attribute if it wouldn't lint against anything; you
should always use `#[expect(...)]`
* `clippy::allow_attributes_without_reason` - Because documenting the
reason for allowing/expecting a lint is always good
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_animation` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
I ran `cargo clippy`, and received no errors.
# Objective
We want to deny the following lints:
* `clippy::allow_attributes` - Because there's no reason to
`#[allow(...)]` an attribute if it wouldn't lint against anything; you
should always use `#[expect(...)]`
* `clippy::allow_attributes_without_reason` - Because documenting the
reason for allowing/expecting a lint is always good
## Solution
Set the `clippy::allow_attributes` and
`clippy::allow_attributes_without_reason` lints to `deny`, and bring
`bevy_reflect` in line with the new restrictions.
No code changes have been made - except if a lint that was previously
`allow(...)`'d could be removed via small code changes. For example,
`unused_variables` can be handled by adding a `_` to the beginning of a
field's name.
## Testing
I ran `cargo clippy`, and received no errors.
# Objective
The UI debug overlay draws an outline for every UI node even if it is
invisible or clipped.
Disable debug outlines for hidden and clipped nodes by default and add
options to renable them if needed.
## Solution
* Add `show_hidden` and `show_clipped` fields to `UiDebugOptions`:
```rust
/// Show outlines for non-visible UI nodes
pub show_hidden: bool,
/// Show outlines for clipped sections of UI nodes
pub show_clipped: bool,
```
* Only extract debug outlines for hidden and clipped UI nodes if the
respective field in `UiDebugOptions` is set to `true`.
## Testing
Also added some extra features to the `testbed_ui` example that
demonstrate the new options:
cargo run --example testbed_ui --features "bevy_ui_debug"
<img width="641" alt="show-hidden-and-clipped"
src="https://github.com/user-attachments/assets/16a68600-170c-469e-a3c7-f7dae411dc40"
/>
# Objective
Just being fussy but I hate this `.map(|v|
v.is_some()).unwrap_or(false)` stuff.
## Solution
Reduce it using `and_then`.
---------
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
# Objective
Fix some outdated `bevy_state` documentation examples.
## Solution
- updated some doc examples in `bevy_state` that hadn't been updated
with the API.
- fixed an outdated link in the documentation issue template that
referred to a 404 page instead of the contribution guide.
## Testing
No necessary testing aside from the usual doctests.
---
## Showcase
N/A
## Migration Guide
N/A
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Contributes to #15460
## Solution
- Added the following features:
- `std` (default)
- `bevy_reflect` (default)
- `libm`
## Testing
- CI
## Notes
- `bevy_reflect` was previously always enabled, which isn't how most
other crates handle reflection. I've brought this in line with how most
crates gate `bevy_reflect`. This is where the majority of the changes
come from in this PR.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Fixes https://github.com/bevyengine/bevy/issues/16556
- Closes https://github.com/bevyengine/bevy/issues/11807
## Solution
- Simplify custom projections by using a single source of truth -
`Projection`, removing all existing generic systems and types.
- Existing perspective and orthographic structs are no longer components
- I could dissolve these to simplify further, but keeping them around
was the fast way to implement this.
- Instead of generics, introduce a third variant, with a trait object.
- Do an object safety dance with an intermediate trait to allow cloning
boxed camera projections. This is a normal rust polymorphism papercut.
You can do this with a crate but a manual impl is short and sweet.
## Testing
- Added a custom projection example
---
## Showcase
- Custom projections and projection handling has been simplified.
- Projection systems are no longer generic, with the potential for many
different projection components on the same camera.
- Instead `Projection` is now the single source of truth for camera
projections, and is the only projection component.
- Custom projections are still supported, and can be constructed with
`Projection::custom()`.
## Migration Guide
- `PerspectiveProjection` and `OrthographicProjection` are no longer
components. Use `Projection` instead.
- Custom projections should no longer be inserted as a component.
Instead, simply set the custom projection as a value of `Projection`
with `Projection::custom()`.
# Objective
- As stated in the related issue, this PR is to better align the feature
flag name with what it actually does and the plans for the future.
- Fixes#16852
## Solution
- Simple find / replace
## Testing
- Local run of `cargo run -p ci`
## Migration Guide
The `track_change_detection` feature flag has been renamed to
`track_location` to better reflect its extended capabilities.
# Objective
- Fix sprite rendering performance regression since retained render
world changes
- The retained render world changes moved `ExtractedSprites` from using
the highly-optimised `EntityHasher` with an `Entity` to using
`FixedHasher` with `(Entity, MainEntity)`. This was enough to regress
framerate in bevymark by 25%.
## Solution
- Move the render world entity into a member of `ExtractedSprite` and
change `ExtractedSprites` to use `MainEntityHashMap` for its storage
- Disable sprite picking in bevymark
## Testing
M4 Max. `bevymark --waves 100 --per-wave 1000 --benchmark`. main in
yellow vs PR in red:
<img width="590" alt="Screenshot 2025-01-01 at 16 36 22"
src="https://github.com/user-attachments/assets/1e4ed6ec-3811-4abf-8b30-336153737f89"
/>
20.2% median frame time reduction.
<img width="594" alt="Screenshot 2025-01-01 at 16 38 37"
src="https://github.com/user-attachments/assets/157c2022-cda6-4cf2-bc63-d0bc40528cf0"
/>
49.7% median extract_sprites execution time reduction.
Comparing 0.14.2 yellow vs PR red:
<img width="593" alt="Screenshot 2025-01-01 at 16 40 06"
src="https://github.com/user-attachments/assets/abd59b6f-290a-4eb6-8835-ed110af995f3"
/>
~6.1% median frame time reduction.
---
## Migration Guide
- `ExtractedSprites` is now using `MainEntityHashMap` for storage, which
is keyed on `MainEntity`.
- The render world entity corresponding to an `ExtractedSprite` is now
stored in the `render_entity` member of it.
# Objective
Remove the `atlas_scaling` field from `ExtractedUiItem::Gylphs`.
It's only ever set to `Vec2::ONE`. I don't remember why/if this field
was ever needed, maybe it was useful before the scale factor clean up.
## Migration Guide
The `atlas_scaling` field from `ExtractedUiItem::Gylphs` has been
removed. This shouldn't affect any existing code as it wasn't used for
anything.
# Objective
Tab navigation can fail in all manner of ways. The current API
recognizes this, but merely logs a warning and returns `None`.
We should supply the actual reason for failure to the caller, so they
can handle it in whatever fashion they please (including logging a
warning!).
Swapping to a Result-oriented pattern is also a bit more idiomatic and
makes the code's control flow easier to follow.
## Solution
- Refactor the `tab_navigation` module to return a `Result` rather than
an `Option` from its key APIs.
- Move the logging to the provided prebuilt observer. This leaves the
default behavior largely unchanged, but allows for better user control.
- Make the case where no tab group was found for the currently focused
entity an error branch, but provide enough information that we can still
recover from it.
## Testing
The `tab_navigation` example continues to function as intended.
# Objective
Resolves#17064
## Solution
- Bevy no longer converts asset file extensions to lowercase before
trying to resolve an asset loader
## Testing
- I adapted the `custom_asset` example (see comment in #17064)
- The changes were tested on Linux
As far as I know, Windows has a case-insensitive file system by default,
so case-sensitive asset file extensions are probably bad practice in a
game. But we should be case-sensitive everywhere or handle asset paths
completely case-insensitive.
Before this PR:
* asset loader extensions are case-sensitive
* asset file names are case-sensitive
* asset file extensions are converted to lowercase ⚡
Now everything should be case-sensitive
# Objective
Following #16876, `bevy_input_focus` works with more than just keyboard
inputs! The docs should reflect that.
## Solution
Fix a few missed mentions in the documentation.
Also add a brief reference to navigation frameworks within the module
docs to help give more breadcrumbs.
# Objective
- Support more ergonomic conditional updates for types that can be
modified by `clone_into`.
## Solution
- Use `ToOwned::clone_into` to copy a reference provided by the caller
in `Mut::clone_from_if_neq`.
## Testing
- See doc tests.
# Objective
- #16589 added an enum to switch between fallible and infallible system.
This branching should be unnecessary if we wrap infallible systems in a
function to return `Ok(())`.
## Solution
- Create a wrapper system for `System<(), ()>`s that returns `Ok` on the
call to `run` and `run_unsafe`. The wrapper should compile out, but I
haven't checked.
- I removed the `impl IntoSystemConfigs for BoxedSystem<(), ()>` as I
couldn't figure out a way to keep the impl without double boxing.
## Testing
- ran `many_foxes` example to check if it still runs.
## Migration Guide
- `IntoSystemConfigs` has been removed for `BoxedSystem<(), ()>`. Either
use `InfallibleSystemWrapper` before boxing or make your system return
`bevy::ecs::prelude::Result`.
# Objective
It is not obvious that one would know these:
```json
{
"id": 1,
"jsonrpc": "2.0",
"result": [
"bevy_animation::AnimationPlayer",
"bevy_animation::AnimationTarget",
"bevy_animation::graph::AnimationGraphHandle",
"bevy_animation::transition::AnimationTransitions",
"bevy_audio::audio::PlaybackSettings",
"bevy_audio::audio::SpatialListener",
"bevy_core_pipeline::bloom::settings::Bloom",
"bevy_core_pipeline::contrast_adaptive_sharpening::ContrastAdaptiveSharpening",
**... snipping for brevity ...**
"bevy_ui::ui_node::Node",
"bevy_ui::ui_node::Outline",
"bevy_ui::ui_node::ScrollPosition",
"bevy_ui::ui_node::TargetCamera",
"bevy_ui::ui_node::UiAntiAlias",
"bevy_ui::ui_node::ZIndex",
"bevy_ui::widget::button::Button",
"bevy_window::monitor::Monitor",
"bevy_window:🪟:PrimaryWindow",
"bevy_window:🪟:Window",
"bevy_winit::cursor::CursorIcon",
"server::Cube"
]
}
```
Especially if you for example, are reading the GH examples because:
If you for example expand these things, due to the number of places bevy
re-exports things you'll find it difficult to find the true path of
something.
i.e you'd probably be forgiven for writing a query (using the
`client.rs` example):
```sh
$ cargo run --example client -- bevy_pbr::mesh_material::MeshMaterial3d | jq
{
"error": {
"code": -23402,
"message": "Unknown component type: `bevy_pbr::mesh_material::MeshMaterial3d`"
},
"id": 1,
"jsonrpc": "2.0"
}
```
which is where
8d9a00f548/crates/bevy_pbr/src/mesh_material.rs (L41)
would lead you to believe it is...
I've worked with bevy a lot, so it's no issue for me, but for others...
?
## Solution
- Add some more docs, including a sample request (`json` and `rust`)
## Testing
N/A
---
## Showcase
N/A
---------
Co-authored-by: Benjamin Brienen <benjamin.brienen@outlook.com>
# Objective
- Make working with immutable components more ergonomic
- Assist #16662
## Solution
Added `modify_component` to `World` and `EntityWorldMut`. This method
"removes" a component from an entity, gives a mutable reference to it to
a provided closure, and then "re-inserts" the component back onto the
entity. This replacement triggers the `OnReplace` and `OnInsert` hooks,
but does _not_ cause an archetype move, as the removal is purely
simulated.
## Testing
- Added doc-tests and a unit test.
---
## Showcase
```rust
use bevy_ecs::prelude::*;
/// An immutable component.
#[derive(Component, PartialEq, Eq, Debug)]
#[component(immutable)]
struct Foo(bool);
let mut world = World::default();
let mut entity = world.spawn(Foo(false));
assert_eq!(entity.get::<Foo>(), Some(&Foo(false)));
// Before the closure is executed, the `OnReplace` hooks/observers are triggered
entity.modify_component(|foo: &mut Foo| {
foo.0 = true;
});
// After the closure is executed, `OnInsert` hooks/observers are triggered
assert_eq!(entity.get::<Foo>(), Some(&Foo(true)));
```
## Notes
- If the component is not available on the entity, the closure and hooks
aren't executed, and `None` is returned. I chose this as an alternative
to returning an error or panicking, but I'm open to changing that based
on feedback.
- This relies on `unsafe`, in particular for accessing the `Archetype`
to trigger hooks. All the unsafe operations are contained within
`DeferredWorld::modify_component`, and I would appreciate that this
function is given special attention to ensure soundness.
- The `OnAdd` hook can never be triggered by this method, since the
component must already be inserted. I have chosen to not trigger
`OnRemove`, as I believe it makes sense that this method is purely a
replacement operation, not an actual removal/insertion.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Malek <50841145+MalekiRe@users.noreply.github.com>
