# Objective
The pointer types introduced in #3001 are useful not just in `bevy_ecs`, but also in crates like `bevy_reflect` (#4475) or even outside of bevy.
## Solution
Extract `Ptr<'a>`, `PtrMut<'a>`, `OwnedPtr<'a>`, `ThinSlicePtr<'a, T>` and `UnsafeCellDeref` from `bevy_ecs::ptr` into `bevy_ptr`.
**Note:** `bevy_ecs` still reexports the `bevy_ptr` as `bevy_ecs::ptr` so that crates like `bevy_transform` can use the `Bundle` derive without needing to depend on `bevy_ptr` themselves.
# Objective
- `RunOnce` was a manual `System` implementation.
- Adding run criteria to stages was yet to be systemyoten
## Solution
- Make it a normal function
- yeet
## Changelog
- Replaced `RunOnce` with `ShouldRun::once`
## Migration guide
The run criterion `RunOnce`, which would make the controlled systems run only once, has been replaced with a new run criterion function `ShouldRun::once`. Replace all instances of `RunOnce` with `ShouldRun::once`.
# Objective
The `Ptr` types gives free access to the underlying `NonNull<u8>`, which adds more publicly visible pointer wrangling than there needs to be. There are also a few edge cases where Ptr types could be more readily utilized for properly validating the soundness of ECS operations.
## Solution
- Replace `*Ptr(Mut)::inner` with `cast` which requires a concrete type to give the pointer. This function could also have a `debug_assert` with an alignment check to ensure that the pointer is aligned properly, but is currently not included.
- Use `OwningPtr::read` in ECS macros over casting the inner pointer around.
# Objective
- After #3412, `Camera::world_to_screen` got a little bit uglier to use by needing to provide both `Windows` and `Assets<Image>`, even though only one would be needed b697e73c3d/crates/bevy_render/src/camera/camera.rs (L117-L123)
- Some time, exact coordinates are not needed but normalized device coordinates is enough
## Solution
- Add a function to just get NDC
### Problem
It currently isn't possible to construct the default value of a reflected type. Because of that, it isn't possible to use `add_component` of `ReflectComponent` to add a new component to an entity because you can't know what the initial value should be.
### Solution
1. add `ReflectDefault` type
```rust
#[derive(Clone)]
pub struct ReflectDefault {
default: fn() -> Box<dyn Reflect>,
}
impl ReflectDefault {
pub fn default(&self) -> Box<dyn Reflect> {
(self.default)()
}
}
impl<T: Reflect + Default> FromType<T> for ReflectDefault {
fn from_type() -> Self {
ReflectDefault {
default: || Box::new(T::default()),
}
}
}
```
2. add `#[reflect(Default)]` to all component types that implement `Default` and are user facing (so not `ComputedSize`, `CubemapVisibleEntities` etc.)
This makes it possible to add the default value of a component to an entity without any compile-time information:
```rust
fn main() {
let mut app = App::new();
app.register_type::<Camera>();
let type_registry = app.world.get_resource::<TypeRegistry>().unwrap();
let type_registry = type_registry.read();
let camera_registration = type_registry.get(std::any::TypeId::of::<Camera>()).unwrap();
let reflect_default = camera_registration.data::<ReflectDefault>().unwrap();
let reflect_component = camera_registration
.data::<ReflectComponent>()
.unwrap()
.clone();
let default = reflect_default.default();
drop(type_registry);
let entity = app.world.spawn().id();
reflect_component.add_component(&mut app.world, entity, &*default);
let camera = app.world.entity(entity).get::<Camera>().unwrap();
dbg!(&camera);
}
```
### Open questions
- should we have `ReflectDefault` or `ReflectFromWorld` or both?
# Objective
- While optimising many_cubes, I noticed that all material handles are extracted regardless of whether the entity to which the handle belongs is visible or not. As such >100k handles are extracted when only <20k are visible.
## Solution
- Only extract material handles of visible entities.
- This improves `many_cubes -- sphere` from ~42fps to ~48fps. It reduces not only the extraction time but also system commands time. `Handle<StandardMaterial>` extraction and its system commands went from 0.522ms + 3.710ms respectively, to 0.267ms + 0.227ms an 88% reduction for this system for this case. It's very view dependent but...
# Objective
- Creating and executing render passes has GPU overhead. If there are no phase items in the render phase to draw, then this overhead should not be incurred as it has no benefit.
## Solution
- Check if there are no phase items to draw, and if not, do not construct not execute the render pass
---
## Changelog
- Changed: Do not create nor execute empty render passes
# Objective
- Original objective was to add doc build warning check to the ci local execution
- I somewhat deviated and changed other things...
## Solution
`cargo run -p ci` can now take more parameters:
* `format` - cargo fmt
* `clippy` - clippy
* `compile-fail` - bevy_ecs_compile_fail_tests tests
* `test` - tests but not doc tests and do not build examples
* `doc-test` - doc tests
* `doc-check` - doc build and warnings
* `bench-check` - check that benches build
* `example-check` - check that examples build
* `lints` - group - run lints and format and clippy
* `doc` - group - run doc-test and doc-check
* `compile` - group - run compile-fail and bench-check and example-check
* not providing a parameter will run everything
Ci is using those when possible:
* `build` jobs now don't run doc tests and don't build examples. it makes this job faster, but doc tests and examples are not built for each architecture target
* `ci` job doesn't run the `compile-fail` part but only format and clippy, taking less time
* `check-benches` becomes `check-compiles` and runs the `compile` tasks. It takes longer. I also fixed how it was using cache
* `check-doc` job is now independent and also run the doc tests, so it takes longer. I commented out the deadlinks check as it takes 2.5 minutes (to install) and doesn't work
# Objective
- Example was misleading, as we never import `bevy` itself in the engine (except in integration tests).
## Solution
- Clean up wording.
## Context
Noticed by @mockersf in #4608.
# Objective
1. Previously, the `change_tick` and `last_change_tick` fields on `SystemChangeTick` [were `pub`](https://docs.rs/bevy/0.6.1/bevy/ecs/system/struct.SystemChangeTick.html).
1. This was actively misleading, as while this can be fetched as a `SystemParam`, a copy is returned instead
2. This information could be useful for debugging, but there was no way to investigate when data was changed.
3. There were no docs!
## Solution
1. Move these to a getter method.
2. Add `last_changed` method to the `DetectChanges` trait to enable inspection of when data was last changed.
3. Add docs.
# Changelog
`SystemChangeTick` now provides getter methods for the current and previous change tick, rather than public fields.
This can be combined with `DetectChanges::last_changed()` to debug the timing of changes.
# Migration guide
The `change_tick` and `last_change_tick` fields on `SystemChangeTick` are now private, use the corresponding getter method instead.
# Objective
avoid naming collisions with user structs when deriving ``system_param``.
## Solution
~rename the fetch struct created by ``#[derive(system_param)]`` from ``{}State`` to ``{}SysParamState``.~
place the fetch struct into an anonymous scope.
## Migration Guide
For code that was using a system param's fetch struct, such as ``EventReader``'s ``EventReaderState``, the fetch struct can now be identified via the SystemParam trait associated type ``Fetch``, e.g. for ``EventReader<T>`` it can be identified as ``<EventReader<'static, 'static, T> as SystemParam>::Fetch``
Supercedes https://github.com/bevyengine/bevy/pull/3340, and absorbs the test from there.
# Objective
- Fixes#3329
## Solution
- If the `Children` component has changed, we currently do not have a way to know how it has changed.
- Therefore, we must update the hierarchy downwards from that point to be correct.
Co-authored-by: Daniel McNab <36049421+DJMcNab@users.noreply.github.com>
# Objective
Reflected tuples do not implement `GetTypeRegistration`, preventing us from registering our tuples, like:
```rust
app.register_type::<(i32, i32)>();
```
This is especially important for things like using #4042 to improve the scene format or implementing #4154 to recursively register fields.
## Solution
Added an implementation to the tuple macro:
```rust
impl<$($name: Reflect + for<'de> Deserialize<'de>),*> GetTypeRegistration for ($($name,)*) {
fn get_type_registration() -> TypeRegistration {
let mut registration = TypeRegistration::of::<($($name,)*)>();
registration.insert::<ReflectDeserialize>(FromType::<($($name,)*)>::from_type());
registration
}
}
```
This requires that the tuple's types implement `Deserialize`. This is exactly how `Vec` and `HashMap` handle it:
```rust
impl<T: FromReflect + for<'de> Deserialize<'de>> GetTypeRegistration for Vec<T> {
fn get_type_registration() -> TypeRegistration {
let mut registration = TypeRegistration::of::<Vec<T>>();
registration.insert::<ReflectDeserialize>(FromType::<Vec<T>>::from_type());
registration
}
}
```
This is a replacement for #2106
This adds a `Metadata` struct which contains metadata information about a file, at the moment only the file type.
It also adds a `get_metadata` to `AssetIo` trait and an `asset_io` accessor method to `AssetServer` and `LoadContext`
I am not sure about the changes in `AndroidAssetIo ` and `WasmAssetIo`.
# Objective
- Manually running systems is a somewhat obscure process: systems must be initialized before they are run
- The unwrap is rather hard to debug.
## Solution
- Replace unwraps in `FunctionSystem` methods with expects (progress towards #3892).
- Briefly document this requirement.
# Objective
- As requested here: https://github.com/bevyengine/bevy/pull/4520#issuecomment-1109302039
- Make it easier to spot issues with built-in shapes
## Solution
https://user-images.githubusercontent.com/200550/165624709-c40dfe7e-0e1e-4bd3-ae52-8ae66888c171.mp4
- Add an example showcasing the built-in 3d shapes with lighting/shadows
- Rotate objects in such a way that all faces are seen by the camera
- Add a UV debug texture
## Discussion
I'm not sure if this is what @alice-i-cecile had in mind, but I adapted the little "torus playground" from the issue linked above to include all built-in shapes.
This exact arrangement might not be particularly scalable if many more shapes are added. Maybe a slow camera pan, or cycling with the keyboard or on a timer, or a sidebar with buttons would work better. If one of the latter options is used, options for showing wireframes or computed flat normals might add some additional utility.
Ideally, I think we'd have a better way of visualizing normals.
Happy to rework this or close it if there's not a consensus around it being useful.
# Objective
- Part of the splitting process of #3692.
## Solution
- Remove / change the tuple structs inside of `gamepad.rs` of `bevy_input` to normal structs.
## Reasons
- It made the `gamepad_connection_system` cleaner.
- It made the `gamepad_input_events.rs` example cleaner (which is probably the most notable change for the user facing API).
- Tuple structs are not descriptive (`.0`, `.1`).
- Using tuple structs for more than 1 field is a bad idea (This means that the `Gamepad` type might be fine as a tuple struct, but I still prefer normal structs over tuple structs).
Feel free to discuss this change as this is more or less just a matter of taste.
## Changelog
### Changed
- The `Gamepad`, `GamepadButton`, `GamepadAxis`, `GamepadEvent` and `GamepadEventRaw` types are now normal structs instead of tuple structs and have a `new()` function.
## Migration Guide
- The `Gamepad`, `GamepadButton`, `GamepadAxis`, `GamepadEvent` and `GamepadEventRaw` types are now normal structs instead of tuple structs and have a `new()` function. To migrate change every instantiation to use the `new()` function instead and use the appropriate field names instead of `.0` and `.1`.
# Objective
- Clean up duplicate code in the add_before/add_after functions in PluginGroupBuilder.
## Solution
- moved index retrieval code to a private function index_of() for the PluginGroupBuilder.
- change is just tidying up. No real change to functionality.
# Objective
This code currently fails to compile with error ``the name `T` is already used for a generic parameter in this item's generic parameters``, because `T` is also used in code generated by `derive(Bundle)`.
```rust
#[derive(Bundle)]
struct MyBundle<T: Component> {
component: T,
}
```
## Solution
Add double underscores to type parameter names in `derive(Bundle)`.
# Objective
- Meshes are queued in opaque phase instead of transparent phase when drawing wireframes.
- There is a name mismatch.
## Solution
- Rename `transparent_phase` to `opaque_phase` in `wireframe.rs`.
The only tests we had for `derive(WorldQuery)` checked that the derive doesnt panic/emit a `compiler_error!`. This PR adds tests that actually assert the returned values of a query using the derived `WorldQuery` impl. Also adds a compile fail test to check that we correctly error on read only world queries containing mutable world queries.
# Objective
`bevy_ecs` has large amounts of unsafe code which is hard to get right and makes it difficult to audit for soundness.
## Solution
Introduce lifetimed, type-erased pointers: `Ptr<'a>` `PtrMut<'a>` `OwningPtr<'a>'` and `ThinSlicePtr<'a, T>` which are newtypes around a raw pointer with a lifetime and conceptually representing strong invariants about the pointee and validity of the pointer.
The process of converting bevy_ecs to use these has already caught multiple cases of unsound behavior.
## Changelog
TL;DR for release notes: `bevy_ecs` now uses lifetimed, type-erased pointers internally, significantly improving safety and legibility without sacrificing performance. This should have approximately no end user impact, unless you were meddling with the (unfortunately public) internals of `bevy_ecs`.
- `Fetch`, `FilterFetch` and `ReadOnlyFetch` trait no longer have a `'state` lifetime
- this was unneeded
- `ReadOnly/Fetch` associated types on `WorldQuery` are now on a new `WorldQueryGats<'world>` trait
- was required to work around lack of Generic Associated Types (we wish to express `type Fetch<'a>: Fetch<'a>`)
- `derive(WorldQuery)` no longer requires `'w` lifetime on struct
- this was unneeded, and improves the end user experience
- `EntityMut::get_unchecked_mut` returns `&'_ mut T` not `&'w mut T`
- allows easier use of unsafe API with less footguns, and can be worked around via lifetime transmutery as a user
- `Bundle::from_components` now takes a `ctx` parameter to pass to the `FnMut` closure
- required because closure return types can't borrow from captures
- `Fetch::init` takes `&'world World`, `Fetch::set_archetype` takes `&'world Archetype` and `&'world Tables`, `Fetch::set_table` takes `&'world Table`
- allows types implementing `Fetch` to store borrows into world
- `WorldQuery` trait now has a `shrink` fn to shorten the lifetime in `Fetch::<'a>::Item`
- this works around lack of subtyping of assoc types, rust doesnt allow you to turn `<T as Fetch<'static>>::Item'` into `<T as Fetch<'a>>::Item'`
- `QueryCombinationsIter` requires this
- Most types implementing `Fetch` now have a lifetime `'w`
- allows the fetches to store borrows of world data instead of using raw pointers
## Migration guide
- `EntityMut::get_unchecked_mut` returns a more restricted lifetime, there is no general way to migrate this as it depends on your code
- `Bundle::from_components` implementations must pass the `ctx` arg to `func`
- `Bundle::from_components` callers have to use a fn arg instead of closure captures for borrowing from world
- Remove lifetime args on `derive(WorldQuery)` structs as it is nonsensical
- `<Q as WorldQuery>::ReadOnly/Fetch` should be changed to either `RO/QueryFetch<'world>` or `<Q as WorldQueryGats<'world>>::ReadOnly/Fetch`
- `<F as Fetch<'w, 's>>` should be changed to `<F as Fetch<'w>>`
- Change the fn sigs of `Fetch::init/set_archetype/set_table` to match respective trait fn sigs
- Implement the required `fn shrink` on any `WorldQuery` implementations
- Move assoc types `Fetch` and `ReadOnlyFetch` on `WorldQuery` impls to `WorldQueryGats` impls
- Pass an appropriate `'world` lifetime to whatever fetch struct you are for some reason using
### Type inference regression
in some cases rustc may give spurrious errors when attempting to infer the `F` parameter on a query/querystate this can be fixed by manually specifying the type, i.e. `QueryState:🆕:<_, ()>(world)`. The error is rather confusing:
```rust=
error[E0271]: type mismatch resolving `<() as Fetch<'_>>::Item == bool`
--> crates/bevy_pbr/src/render/light.rs:1413:30
|
1413 | main_view_query: QueryState::new(world),
| ^^^^^^^^^^^^^^^ expected `bool`, found `()`
|
= note: required because of the requirements on the impl of `for<'x> FilterFetch<'x>` for `<() as WorldQueryGats<'x>>::Fetch`
note: required by a bound in `bevy_ecs::query::QueryState::<Q, F>::new`
--> crates/bevy_ecs/src/query/state.rs:49:32
|
49 | for<'x> QueryFetch<'x, F>: FilterFetch<'x>,
| ^^^^^^^^^^^^^^^ required by this bound in `bevy_ecs::query::QueryState::<Q, F>::new`
```
---
Made with help from @BoxyUwU and @alice-i-cecile
Co-authored-by: Boxy <supbscripter@gmail.com>
# Objective
Reduce from scratch build time.
## Solution
Reduce the size of the critical path by removing dependencies between crates where not necessary. For `cargo check --no-default-features` this reduced build time from ~51s to ~45s. For some commits I am not completely sure if the tradeoff between build time reduction and convenience caused by the commit is acceptable. If not, I can drop them.
## Objective
This fixes#1686.
`size_hint` can be useful even if a little niche. For example,
`collect::<Vec<_>>()` uses the `size_hint` of Iterator it collects from
to pre-allocate a memory slice large enough to not require re-allocating
when pushing all the elements of the iterator.
## Solution
To this effect I made the following changes:
* Add a `IS_ARCHETYPAL` associated constant to the `Fetch` trait,
this constant tells us when it is safe to assume that the `Fetch`
relies exclusively on archetypes to filter queried entities
* Add `IS_ARCHETYPAL` to all the implementations of `Fetch`
* Use that constant in `QueryIter::size_hint` to provide a more useful
## Migration guide
The new associated constant is an API breaking change. For the user,
if they implemented a custom `Fetch`, it means they have to add this
associated constant to their implementation. Either `true` if it doesn't limit
the number of entities returned in a query beyond that of archetypes, or
`false` for when it does.
# Objective
Reduce the catch-all grab-bag of functionality in bevy_core by moving FloatOrd to bevy_utils.
A step in addressing #2931 and splitting bevy_core into more specific locations.
## Solution
Move FloatOrd into bevy_utils. Fix the compile errors.
As a result, bevy_core_pipeline, bevy_pbr, bevy_sprite, bevy_text, and bevy_ui no longer depend on bevy_core (they were only using it for `FloatOrd` previously).
# Objective
- Small change that better facilitates custom animation systems
## Solution
- Added a public access function to `bevy::animation::AnimationClip`, making duration publicly readable
---
# Objective
We keep getting issues where things break at small window sizes, e.g #3368 (caused by #3153), #3596 ('caused' by #3545)
## Solution
- Add a test that we can make small windows.
Currently, this fails on my machine with some quite scary vulkan errors:
```
2022-01-08T22:55:13.770261Z ERROR wgpu_hal::vulkan::instance: VALIDATION [VUID-VkSwapchainCreateInfoKHR-imageExtent-01274 (0x7cd0911d)]
Validation Error: [ VUID-VkSwapchainCreateInfoKHR-imageExtent-01274 ] Object 0: handle = 0x1adbd410a60, type = VK_OBJECT_TYPE_DEVICE; | MessageID = 0x7cd0911d | vkCreateSwapchainKHR() called with imageExtent = (225,60), which is outside the bounds returned by vkGetPhysicalDeviceSurfaceCapabilitiesKHR(): currentExtent = (225,56), minImageExtent = (225,56), maxImageExtent = (225,56). The Vulkan spec states: imageExtent must be between minImageExtent and maxImageExtent, inclusive, where minImageExtent and maxImageExtent are members of the VkSurfaceCapabilitiesKHR structure returned by vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface (https://vulkan.lunarg.com/doc/view/1.2.198.1/windows/1.2-extensions/vkspec.html#VUID-VkSwapchainCreateInfoKHR-imageExtent-01274)
2022-01-08T22:55:13.770808Z ERROR wgpu_hal::vulkan::instance: objects: (type: DEVICE, hndl: 0x1adbd410a60, name: ?)
2022-01-08T22:55:13.787403Z ERROR wgpu_hal::vulkan::instance: VALIDATION [VUID-VkSwapchainCreateInfoKHR-imageExtent-01274 (0x7cd0911d)]
Validation Error: [ VUID-VkSwapchainCreateInfoKHR-imageExtent-01274 ] Object 0: handle = 0x1adbd410a60, type = VK_OBJECT_TYPE_DEVICE; | MessageID = 0x7cd0911d | vkCreateSwapchainKHR() called with imageExtent = (225,56), which is outside the bounds returned by vkGetPhysicalDeviceSurfaceCapabilitiesKHR(): currentExtent = (225,52), minImageExtent = (225,52), maxImageExtent = (225,52). The Vulkan spec states: imageExtent must be between minImageExtent and maxImageExtent, inclusive, where minImageExtent and maxImageExtent are members of the VkSurfaceCapabilitiesKHR structure returned by vkGetPhysicalDeviceSurfaceCapabilitiesKHR for the surface (https://vulkan.lunarg.com/doc/view/1.2.198.1/windows/1.2-extensions/vkspec.html#VUID-VkSwapchainCreateInfoKHR-imageExtent-01274)
```
etc.
This might be a new issue here, although I'm surprised it's vulkan giving this error; wgpu should stop it if this is illegal.
# Objective
- Code quality bad
## Solution
- Code quality better
- Using rust-analyzer's inline function and inline variable quick assists, I validated that the call to `AssetServer::new` is exactly the same code as the previous version.
# Objective
- Add benches for run criteria. This is in anticipation of run criteria being redone in stageless.
## Solution
- Benches run criteria that don't access anything to test overhead
- Test run criteria that use a query
- Test run criteria that use a resource
# Objective
Comparing two reflected floating points would always fail:
```rust
let a: &dyn Reflect = &1.23_f32;
let b: &dyn Reflect = &1.23_f32;
// Panics:
assert!(a.reflect_partial_eq(b).unwrap_or_default());
```
The comparison returns `None` since `f32` (and `f64`) does not have a reflected `PartialEq` implementation.
## Solution
Include `PartialEq` in the `impl_reflect_value!` macro call for both `f32` and `f64`.
`Hash` is still excluded since neither implement `Hash`.
Also added equality tests for some of the common types from `std` (including `f32`).
Support for deriving `TypeUuid` for types with generics was initially added in https://github.com/bevyengine/bevy/pull/2044 but later reverted https://github.com/bevyengine/bevy/pull/2204 because it lead to `MyStruct<A>` and `MyStruct<B>` having the same type uuid.
This PR fixes this by generating code like
```rust
#[derive(TypeUuid)]
#[uuid = "69b09733-a21a-4dab-a444-d472986bd672"]
struct Type<T>(T);
impl<T: TypeUuid> TypeUuid for Type<T> {
const TYPE_UUID: TypeUuid = generate_compound_uuid(Uuid::from_bytes([/* 69b0 uuid */]), T::TYPE_UUID);
}
```
where `generate_compound_uuid` will XOR the non-metadata bits of the two UUIDs.
Co-authored-by: XBagon <xbagon@outlook.de>
Co-authored-by: Jakob Hellermann <hellermann@sipgate.de>
# Objective
Fix wonky torus normals.
## Solution
I attempted this previously in #3549, but it looks like I botched it. It seems like I mixed up the y/z axes. Somehow, the result looked okay from that particular camera angle.
This video shows toruses generated with
- [left, orange] original torus mesh code
- [middle, pink] PR 3549
- [right, purple] This PR
https://user-images.githubusercontent.com/200550/164093183-58a7647c-b436-4512-99cd-cf3b705cefb0.mov
# Objective
Make timers update `just_finished` on tick, even if paused.
Fixes#4436
## Solution
`just_finished()` returns `times_finished > 0`. So I:
* Renamed `times_finished` to `times_finished_this_tick` to reduce confusion.
* Set `times_finished_this_tick` to `0` on tick when paused.
* Additionally set `finished` to `false` if the timer is repeating.
Notably this change broke none of the existing tests, so I added a couple for this.
Files changed shows a lot of noise because of the rename. Check the first commit for the relevant changes.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
- Part of the splitting process of #3692.
## Solution
- Document `mouse.rs` inside of `bevy_input`.
Co-authored-by: KDecay <KDecayMusic@protonmail.com>
# Objective
In some cases, you may want to take ownership of the values in `DynamicList` or `DynamicMap`.
I came across this need while trying to implement a custom deserializer, but couldn't get ownership of the values in the list.
## Solution
Implemented `IntoIter` for both `DynamicList` and `DynamicMap`.
# Objective
- Closes#335.
- Related #4285.
- Part of the splitting process of #3503.
## Solution
- Move `Rect` to `bevy_ui` and rename it to `UiRect`.
## Reasons
- `Rect` is only used in `bevy_ui` and therefore calling it `UiRect` makes the intent clearer.
- We have two types that are called `Rect` currently and it's missleading (see `bevy_sprite::Rect` and #335).
- Discussion in #3503.
## Changelog
### Changed
- The `Rect` type got moved from `bevy_math` to `bevy_ui` and renamed to `UiRect`.
## Migration Guide
- The `Rect` type got renamed to `UiRect`. To migrate you just have to change every occurrence of `Rect` to `UiRect`.
Co-authored-by: KDecay <KDecayMusic@protonmail.com>
# Objective
- `EntityRef` and `EntityMut` are surpisingly important public types when working directly with the `World`.
- They're undocumented.
## Solution
- Just add docs!
