# Objective
- Fixes https://github.com/bevyengine/bevy/issues/2096
## Solution
- This PR enables the drag-and-drop feature for winit on windows again, as the collision issue between cpal and winit has been fixed in https://github.com/RustAudio/cpal/pull/597. I confirmed the drag and drop example working on windows 10 with this change.
- ~~It also bumps the rodio version, though this is not strictly necessary.~~
# Objective
- While playing with animated models, I noticed some were a little off
## Solution
- Some animations curves only have one keyframe, they are used to set a transform to a given value
- Those were ignored as we're never exactly at the ts 0.0 of an animation. going there explicitly (`.set_elapsed(0.0).pause()`) would crash
- Special case this as there isn't much to animate in this case
https://en.wikipedia.org/wiki/HSL_and_HSV#From_RGB
# Objective
Fixes#4382
## Solution
- Describe the solution used to achieve the objective above.
Fixed conversion formula to account for red and green component being max and equal
---
## Changelog
Fixed RGB -> HSL colorspace conversion
## Migration Guide
Co-authored-by: Francesco Giordana <fgiordana@netflix.com>
# Objective
- Part of the splitting process of #3503.
## Solution
- Remove the `face_toward.rs` file containing the `FaceToward` trait.
## Reasons
- It is unused inside of `bevy`.
- The method `Mat4::face_toward` of the trait is identical to `Mat4::look_at_rh` (see https://docs.rs/glam/latest/glam/f32/struct.Mat4.html#method.look_at_rh).
- Discussion in #3503.
## Changelog
### Removed
- The `FaceToward` trait got removed.
## Migration Guide
- The `FaceToward` trait got removed. To migrate you just have to change every occurrence of `Mat4::face_toward` to `Mat4::look_at_rh`.
# Objective
- Since #4224, using labels which only refer to one system doesn't make sense.
## Solution
- Remove some of those.
## Future work
- We should remove the ability to use strings as system labels entirely. I haven't in this PR because there are tests which use this, and that's a lot of code to change.
- The only use cases for labels are either intra-crate, which use #4224, or inter-crate, which should either use #4224 or explicit types. Neither of those should use strings.
# Objective
- std's new APIs do the same thing as `Query::get_multiple_mut`, but are called `get_many`: https://github.com/rust-lang/rust/pull/83608
## Solution
- Find and replace `get_multiple` with `get_many`
# Objective
Make it so that loading in a mesh without normals that is not a `TriangleList` succeeds.
## Solution
Flat normals can only be calculated on a mesh made of triangles.
Check whether the mesh is a `TriangleList` before trying to compute missing normals.
## Additional changes
The panic condition in `duplicate_vertices` did not make sense to me. I moved it to `compute_flat_normals` where the algorithm would produce incorrect results if the mesh is not a `TriangleList`.
Co-authored-by: devil-ira <justthecooldude@gmail.com>
# Objective
- Clarify `RemovedComponents` are flushed in `CoreStage::Last` and systems relying on that should run before that stage
## Solution
- Update `RemovedComponents` doc comment
# Objective
make bevy ecs a lil bit less unsound
## Solution
make unsound API unsafe so that there is an unsafe block to blame:
```rust
use bevy_ecs::prelude::*;
#[derive(Debug, Component)]
struct Foo(u8);
fn main() {
let mut world = World::new();
let e1 = world.spawn().id();
let e2 = world.spawn().insert(Foo(2)).id();
world.entities_mut().meta[0] = world.entities_mut().meta[1].clone();
let foo = world.entity(e1).get::<Foo>().unwrap();
// whoo i love having components i dont have
dbg!(foo);
}
```
This is not _strictly_ speaking UB, however:
- `Query::get_multiple` cannot work if this is allowed
- bevy_ecs is a pile of unsafe code whose soundness generally depends on the world being in a "correct" state with "no funny business" so it seems best to disallow this
- it is trivial to get bevy to panic inside of functions with safety invariants that have been violated (the entity location is not valid)
- it seems to violate what the safety invariant on `Entities::flush` is trying to ensure
# Objective
An entity spawned with `MaterialMesh2dBundle<M>` cannot be saved and spawned using `DynamicScene` because the `Mesh2dHandle` component does not `impl Reflect`.
## Solution
Add `#[derive(Reflect)]` and `#[reflect(Component)]` to `Mesh2dHandle`, and call `register_type` in `SpritePlugin`. Also add `#[derive(Debug)]` since I'm touching the `derive`s anyway.
# Objective
Animation with shadows crashes with:
```
thread 'main' panicked at 'wgpu error: Validation Error
Caused by:
In Device::create_render_pipeline
note: label = `shadow_pipeline`
error matching VERTEX shader requirements against the pipeline
shader global ResourceBinding { group: 1, binding: 1 } is not available in the layout pipeline layout
visibility flags don't include the shader stage
```
Animation with wireframe crashes with:
```
thread 'main' panicked at 'wgpu error: Validation Error
Caused by:
In Device::create_render_pipeline
note: label = `opaque_mesh_pipeline`
error matching VERTEX shader requirements against the pipeline
shader global ResourceBinding { group: 2, binding: 0 } is not available in the layout pipeline layout
binding is missing from the pipeline layout
```
## Solution
- Fix the bindings
# Objective
- The inability to have multiple active mutable borrows into a query is a common source of borrow-checker pain for users.
- This is a pointless restriction if and only if we can guarantee that the entities they are accessing are unique.
- This could already by bypassed with get_unchecked, but that is an extremely unsafe API.
- Closes https://github.com/bevyengine/bevy/issues/2042.
## Solution
- Add `get_multiple`, `get_multiple_mut` and their unchecked equivalents (`multiple` and `multiple_mut`) to `Query` and `QueryState`.
- Improve the `QueryEntityError` type to provide more useful error information.
## Changelog
- Added `get_multiple`, `get_multiple_mut` and their unchecked equivalents (`multiple` and `multiple_mut`) to Query and QueryState.
## Migration Guide
- The `QueryEntityError` enum now has a `AliasedMutability variant, and returns the offending entity.
## Context
This is a fresh attempt at #3333; rebasing was behaving very badly and it was important to rebase on top of the recent query soundness fixes. Many thanks to all the reviewers in that thread, especially @BoxyUwU for the help with lifetimes.
## To-do
- [x] Add compile fail tests
- [x] Successfully deduplicate code
- [x] Decide what to do about failing doc tests
- [x] Get some reviews for lifetime soundness
# Objective
Add a system parameter `ParamSet` to be used as container for conflicting parameters.
## Solution
Added two methods to the SystemParamState trait, which gives the access used by the parameter. Did the implementation. Added some convenience methods to FilteredAccessSet. Changed `get_conflicts` to return every conflicting component instead of breaking on the first conflicting `FilteredAccess`.
Co-authored-by: bilsen <40690317+bilsen@users.noreply.github.com>
# Objective
Cleans up some duplicated color -> u32 conversion code in `bevy_sprite` and `bevy_ui`
## Solution
Use `as_linear_rgba_u32` which was added recently by #4088
# Objective
Fixes#4344.
## Solution
Add a new component `Text2dBounds` to `Text2dBundle` that specifies the maximum width and height of text. Text will wrap according to this size.
# Objective
- Part of the splitting process of #3692.
## Solution
- Change the `gamepad_connection_system` to run after the `InputSystem` label.
## Reasons
I changed the `gamepad_connection_system` to run after the `InputSystem` instead of in parallel, because this system checks the `GamepadEvent`s which get send inside of the `gamepad_event_system`. This means that the `gamepad_connection_system` could respond to the events one frame later, instead of instantly resulting in one frame lag.
Old possible case:
1. `gamepad_connection_system` (reacts to the `GamepadEvent`s too early)
2. `gamepad_event_system` (sends the `GamepadEvent`s)
New fixed ordering:
1. `gamepad_event_system` (sends the `GamepadEvent`s)
2. `gamepad_connection_system` (reacts to the `GamepadEvent`s)
# Objective
- Closes#335.
- Part of the splitting process of #3503.
## Solution
- Remove the `margins.rs` file containing the `Margins` type.
## Reasons
- It is unused inside of `bevy`.
- The `Rect`/`UiRect` is identical to the `Margins` type and is also used for margins inside of `bevy` (rename of `Rect` happens in #4276)
- Discussion in #3503.
## Changelog
### Removed
- The `Margins` type got removed.
## Migration Guide
- The `Margins` type got removed. To migrate you just have to change every occurrence of `Margins` to `UiRect`.
# Objective
We are currently inserting an `input` into `pressed` even if it is already pressed. This also applies to releasing an input. This is not a big deal, but since we are already checking if the `input` is pressed or not we might as well remove the cost of the value update caused by the `pressed.insert` method.
Related to #4209
## Solution
Only insert or remove input if needed.
related: https://github.com/bevyengine/bevy/pull/3289
In addition to validating shaders early when debug assertions are enabled, use the new [error scopes](https://gpuweb.github.io/gpuweb/#error-scopes) API when creating a shader module.
I chose to keep the early validation (and thereby parsing twice) when debug assertions are enabled in, because it lets as handle errors ourselves and display them with pretty colors, while the error scopes API just gives us a string we can display.
This change pulls in `futures-util` as a new dependency for `future.now_or_never()`. I can inline that part of futures-lite into `bevy_render` to keep the compilation time lower if that's preferred.
# Objective
Fixes `StandardMaterial` texture update (see sample code below).
Most probably fixes#3674 (did not test)
## Solution
Material updates, such as PBR update, reference the underlying `GpuImage`. Like here: 9a7852db0f/crates/bevy_pbr/src/pbr_material.rs (L177)
However, currently the `GpuImage` update may actually happen *after* the material update fetches the gpu image. Resulting in the material actually not being updated for the correct gpu image.
In this pull req, I introduce new systemlabels for the renderassetplugin. Also assigned the RenderAssetPlugin::<Image> to the `PreAssetExtract` stage, so that it is executed before any material updates.
Code to test.
Expected behavior:
* should update to red texture
Unexpected behavior (before this merge):
* texture stays randomly as green one (depending on the execution order of systems)
```rust
use bevy::{
prelude::*,
render::render_resource::{Extent3d, TextureDimension, TextureFormat},
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_startup_system(setup)
.add_system(changes)
.run();
}
struct Iteration(usize);
#[derive(Component)]
struct MyComponent;
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
mut images: ResMut<Assets<Image>>,
) {
commands.spawn_bundle(PointLightBundle {
point_light: PointLight {
..Default::default()
},
transform: Transform::from_xyz(4.0, 8.0, 4.0),
..Default::default()
});
commands.spawn_bundle(PerspectiveCameraBundle {
transform: Transform::from_xyz(-2.0, 0.0, 5.0)
.looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
..Default::default()
});
commands.insert_resource(Iteration(0));
commands
.spawn_bundle(PbrBundle {
mesh: meshes.add(Mesh::from(shape::Quad::new(Vec2::new(3., 2.)))),
material: materials.add(StandardMaterial {
base_color_texture: Some(images.add(Image::new(
Extent3d {
width: 600,
height: 400,
depth_or_array_layers: 1,
},
TextureDimension::D2,
[0, 255, 0, 128].repeat(600 * 400), // GREEN
TextureFormat::Rgba8Unorm,
))),
..Default::default()
}),
..Default::default()
})
.insert(MyComponent);
}
fn changes(
mut materials: ResMut<Assets<StandardMaterial>>,
mut images: ResMut<Assets<Image>>,
mut iteration: ResMut<Iteration>,
webview_query: Query<&Handle<StandardMaterial>, With<MyComponent>>,
) {
if iteration.0 == 2 {
let material = materials.get_mut(webview_query.single()).unwrap();
let image = images
.get_mut(material.base_color_texture.as_ref().unwrap())
.unwrap();
image
.data
.copy_from_slice(&[255, 0, 0, 255].repeat(600 * 400));
}
iteration.0 += 1;
}
```
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Load skeletal weights and indices from GLTF files. Animate meshes.
## Solution
- Load skeletal weights and indices from GLTF files.
- Added `SkinnedMesh` component and ` SkinnedMeshInverseBindPose` asset
- Added `extract_skinned_meshes` to extract joint matrices.
- Added queue phase systems for enqueuing the buffer writes.
Some notes:
- This ports part of # #2359 to the current main.
- This generates new `BufferVec`s and bind groups every frame. The expectation here is that the number of `Query::get` calls during extract is probably going to be the stronger bottleneck, with up to 256 calls per skinned mesh. Until that is optimized, caching buffers and bind groups is probably a non-concern.
- Unfortunately, due to the uniform size requirements, this means a 16KB buffer is allocated for every skinned mesh every frame. There's probably a few ways to get around this, but most of them require either compute shaders or storage buffers, which are both incompatible with WebGL2.
Co-authored-by: james7132 <contact@jamessliu.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
- Improve transform propagation performance
## Solution
- Use `Changed<Transform>` as part of the `root_query` and `transform_query` to avoid the indirection of having to look up the `Entity` in the `changed_transform_query`
- Get rid of the `changed_transform_query` entirely
- `transform_propagate_system` execution time for `many_cubes -- sphere` dropped from 1.07ms to 0.159ms, an 85% reduction for this system. Frame rate increased from ~42fps to ~44fps
# Objective
A common pattern in Rust is the [newtype](https://doc.rust-lang.org/rust-by-example/generics/new_types.html). This is an especially useful pattern in Bevy as it allows us to give common/foreign types different semantics (such as allowing it to implement `Component` or `FromWorld`) or to simply treat them as a "new type" (clever). For example, it allows us to wrap a common `Vec<String>` and do things like:
```rust
#[derive(Component)]
struct Items(Vec<String>);
fn give_sword(query: Query<&mut Items>) {
query.single_mut().0.push(String::from("Flaming Poisoning Raging Sword of Doom"));
}
```
> We could then define another struct that wraps `Vec<String>` without anything clashing in the query.
However, one of the worst parts of this pattern is the ugly `.0` we have to write in order to access the type we actually care about. This is why people often implement `Deref` and `DerefMut` in order to get around this.
Since it's such a common pattern, especially for Bevy, it makes sense to add a derive macro to automatically add those implementations.
## Solution
Added a derive macro for `Deref` and another for `DerefMut` (both exported into the prelude). This works on all structs (including tuple structs) as long as they only contain a single field:
```rust
#[derive(Deref)]
struct Foo(String);
#[derive(Deref, DerefMut)]
struct Bar {
name: String,
}
```
This allows us to then remove that pesky `.0`:
```rust
#[derive(Component, Deref, DerefMut)]
struct Items(Vec<String>);
fn give_sword(query: Query<&mut Items>) {
query.single_mut().push(String::from("Flaming Poisoning Raging Sword of Doom"));
}
```
### Alternatives
There are other alternatives to this such as by using the [`derive_more`](https://crates.io/crates/derive_more) crate. However, it doesn't seem like we need an entire crate just yet since we only need `Deref` and `DerefMut` (for now).
### Considerations
One thing to consider is that the Rust std library recommends _not_ using `Deref` and `DerefMut` for things like this: "`Deref` should only be implemented for smart pointers to avoid confusion" ([reference](https://doc.rust-lang.org/std/ops/trait.Deref.html)). Personally, I believe it makes sense to use it in the way described above, but others may disagree.
### Additional Context
Discord: https://discord.com/channels/691052431525675048/692572690833473578/956648422163746827 (controversiality discussed [here](https://discord.com/channels/691052431525675048/692572690833473578/956711911481835630))
---
## Changelog
- Add `Deref` derive macro (exported to prelude)
- Add `DerefMut` derive macro (exported to prelude)
- Updated most newtypes in examples to use one or both derives
Co-authored-by: MrGVSV <49806985+MrGVSV@users.noreply.github.com>
# Objective
Fixes#1529
Run bevy_ecs in miri
## Solution
- Don't set thread names when running in miri rust-lang/miri/issues/1717
- Update `event-listener` to `2.5.2` as previous versions have UB that is detected by miri: [event-listener commit](1fa31c553e)
- Ignore memory leaks when running in miri as they are impossible to track down rust-lang/miri/issues/1481
- Make `table_add_remove_many` test less "many" because miri is really quite slow :)
- Make CI run `RUSTFLAGS="-Zrandomize-layout" MIRIFLAGS="-Zmiri-ignore-leaks -Zmiri-tag-raw-pointers -Zmiri-disable-isolation" cargo +nightly miri test -p bevy_ecs`
* Refactor assign_lights_to_clusters to always clear + update clusters, even if the screen size isn't available yet / is zero. This fixes#4167. We still avoid the "expensive" per-light work when the screen size isn't available yet. I also consolidated some logic to eliminate some redundancies.
* Removed _a ton_ of (potentially very large) per-frame reallocations
* Removed `Res<VisiblePointLights>` (a vec) in favor of `Res<GlobalVisiblePointLights>` (a hashmap). We were allocating a new hashmap every frame, the collecting it into a vec every frame, then in another system _re-generating the hashmap_. It is always used like a hashmap, might as well embrace that. We now reuse the same hashmap every frame and dont use any intermediate collections.
* We were re-allocating Clusters aabb and light vectors every frame by re-constructing Clusters every frame. We now re-use the existing collections.
* Reuse per-camera VisiblePointLight vecs when possible instead of allocating them every frame. We now only insert VisiblePointLights if the component doesn't exist yet.
This adds the concept of "default labels" for systems (currently scoped to "parallel systems", but this could just as easily be implemented for "exclusive systems"). Function systems now include their function's `SystemTypeIdLabel` by default.
This enables the following patterns:
```rust
// ordering two systems without manually defining labels
app
.add_system(update_velocity)
.add_system(movement.after(update_velocity))
// ordering sets of systems without manually defining labels
app
.add_system(foo)
.add_system_set(
SystemSet::new()
.after(foo)
.with_system(bar)
.with_system(baz)
)
```
Fixes: #4219
Related to: #4220
Credit to @aevyrie @alice-i-cecile @DJMcNab (and probably others) for proposing (and supporting) this idea about a year ago. I was a big dummy that both shut down this (very good) idea and then forgot I did that. Sorry. You all were right!
# Objective
- Fixes#3970
- To support Bevy's shader abstraction(shader defs, shader imports and hot shader reloading) for compute shaders, I have followed carts advice and change the `PipelinenCache` to accommodate both compute and render pipelines.
## Solution
- renamed `RenderPipelineCache` to `PipelineCache`
- Cached Pipelines are now represented by an enum (render, compute)
- split the `SpecializedPipelines` into `SpecializedRenderPipelines` and `SpecializedComputePipelines`
- updated the game of life example
## Open Questions
- should `SpecializedRenderPipelines` and `SpecializedComputePipelines` be merged and how would we do that?
- should the `get_render_pipeline` and `get_compute_pipeline` methods be merged?
- is pipeline specialization for different entry points a good pattern
Co-authored-by: Kurt Kühnert <51823519+Ku95@users.noreply.github.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Add a helper for storage buffers similar to `UniformVec`
## Solution
- Add a `StorageBuffer<T, U>` where `T` is the main body of the shader struct without any final variable-sized array member, and `U` is the type of the items in a variable-sized array.
- Use `()` as the type for unwanted parts, e.g. `StorageBuffer<(), Vec4>::default()` would construct a binding that would work with `struct MyType { data: array<vec4<f32>>; }` in WGSL and `StorageBuffer<MyType, ()>::default()` would work with `struct MyType { ... }` in WGSL as long as there are no variable-sized arrays.
- Std430 requires that there is at most one variable-sized array in a storage buffer, that if there is one it is the last member of the binding, and that it has at least one item. `StorageBuffer` handles all of these constraints.
Add support for removing nodes, edges, and subgraphs. This enables live re-wiring of the render graph.
This was something I did to support the MSAA implementation, but it turned out to be unnecessary there. However, it is still useful so here it is in its own PR.
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
make bevy ecs a lil bit less unsound
## Solution
yeet unsound API `World::components_mut`:
```rust
use bevy_ecs::prelude::*;
#[derive(Component)]
struct Foo(u8);
#[derive(Debug, Component)]
struct Bar([u8; 100]);
fn main() {
let mut world = World::new();
let e = world.spawn().insert(Foo(0)).id();
*world.components_mut() = Default::default();
let bar = world.entity_mut(e).remove::<Bar>().unwrap();
// oopsies reading memory copied from outside allocation
dbg!(bar);
}
```
# Objective
When loading a gltf scene with a camera, bevy will panic at ``thread 'main' panicked at 'scene contains the unregistered type `bevy_render:📷:bundle::Camera3d`. consider registering the type using `app.register_type::<T>()`', /home/jakob/dev/rust/contrib/bevy/bevy/crates/bevy_scene/src/scene_spawner.rs:332:35``.
## Solution
Register the camera types to fix the panic.
# Objective
As described in #4257, registering an Event twice would cause some systems to miss events on some starts, since the event buffer is cleared + swapped multiple times.
Fixes#4257
## Solution
A simple check whether the event is already registered is added, making adding an Event a second time a no-op.
# Objective
- Fixes#4208
## Solution
- Adds a check before inserting into an `Input`'s `just_released` set, in the same way that one exists for adding into the `just_pressed` set.
# Objective
The [glTF spec](8e798b02d2/specification/2.0/Specification.adoc (395-double-sided)) the `doubleSided` has the following to say about the `doubleSided` boolean:
> When this value is false, back-face culling is enabled, i.e., only front-facing triangles are rendered.
> When this value is true, back-face culling is disabled and double sided lighting is enabled. The back-face MUST have its normals reversed before the lighting equation is evaluated.
## Solution
Disable backface culling when `doubleSided: true`.
# Objective
- Make visible how much time is spent building the Opaque3d, AlphaMask3d, and Transparent3d passes
## Solution
- Add a `trace` feature to `bevy_core_pipeline`
- Add tracy spans around the three passes
- I didn't do this for shadows, sprites, etc as they are only one pass in the node. Perhaps it should be split into 3 nodes to allow insertion of other nodes between...?
# Objective
- Reduce time spent in the `check_visibility` system
## Solution
- Use `Vec3A` for all bounding volume types to leverage SIMD optimisations and to avoid repeated runtime conversions from `Vec3` to `Vec3A`
- Inline all bounding volume intersection methods
- Add on-the-fly calculated `Aabb` -> `Sphere` and do `Sphere`-`Frustum` intersection tests before `Aabb`-`Frustum` tests. This is faster for `many_cubes` but could be slower in other cases where the sphere test gives a false-positive that the `Aabb` test discards. Also, I tested precalculating the `Sphere`s and inserting them alongside the `Aabb` but this was slower.
- Do not test meshes against the far plane. Apparently games don't do this anymore with infinite projections, and it's one fewer plane to test against. I made it optional and still do the test for culling lights but that is up for discussion.
- These collectively reduce `check_visibility` execution time in `many_cubes -- sphere` from 2.76ms to 1.48ms and increase frame rate from ~42fps to ~44fps
Tracing added support for "inline span entering", which cuts down on a lot of complexity:
```rust
let span = info_span!("my_span").entered();
```
This adapts our code to use this pattern where possible, and updates our docs to recommend it.
This produces equivalent tracing behavior. Here is a side by side profile of "before" and "after" these changes.
# Objective
- Support compressed textures including 'universal' formats (ETC1S, UASTC) and transcoding of them to
- Support `.dds`, `.ktx2`, and `.basis` files
## Solution
- Fixes https://github.com/bevyengine/bevy/issues/3608 Look there for more details.
- Note that the functionality is all enabled through non-default features. If it is desirable to enable some by default, I can do that.
- The `basis-universal` crate, used for `.basis` file support and for transcoding, is built on bindings against a C++ library. It's not feasible to rewrite in Rust in a short amount of time. There are no Rust alternatives of which I am aware and it's specialised code. In its current state it doesn't support the wasm target, but I don't know for sure. However, it is possible to build the upstream C++ library with emscripten, so there is perhaps a way to add support for web too with some shenanigans.
- There's no support for transcoding from BasisLZ/ETC1S in KTX2 files as it was quite non-trivial to implement and didn't feel important given people could use `.basis` files for ETC1S.
# Objective
- Fixes#3300
- `RunSystem` is messy
## Solution
- Adds the trick theorised in https://github.com/bevyengine/bevy/issues/3300#issuecomment-991791234
P.S. I also want this for an experimental refactoring of `Assets`, to remove the duplication of `Events<AssetEvent<T>>`
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Hierarchy tools are not just used for `Transform`: they are also used for scenes.
- In the future there's interest in using them for other features, such as visiibility inheritance.
- The fact that these tools are found in `bevy_transform` causes a great deal of user and developer confusion
- Fixes#2758.
## Solution
- Split `bevy_transform` into two!
- Make everything work again.
Note that this is a very tightly scoped PR: I *know* there are code quality and docs issues that existed in bevy_transform that I've just moved around. We should fix those in a seperate PR and try to merge this ASAP to reduce the bitrot involved in splitting an entire crate.
## Frustrations
The API around `GlobalTransform` is a mess: we have massive code and docs duplication, no link between the two types and no clear way to extend this to other forms of inheritance.
In the medium-term, I feel pretty strongly that `GlobalTransform` should be replaced by something like `Inherited<Transform>`, which lives in `bevy_hierarchy`:
- avoids code duplication
- makes the inheritance pattern extensible
- links the types at the type-level
- allows us to remove all references to inheritance from `bevy_transform`, making it more useful as a standalone crate and cleaning up its docs
## Additional context
- double-blessed by @cart in https://github.com/bevyengine/bevy/issues/4141#issuecomment-1063592414 and https://github.com/bevyengine/bevy/issues/2758#issuecomment-913810963
- preparation for more advanced / cleaner hierarchy tools: go read https://github.com/bevyengine/rfcs/pull/53 !
- originally attempted by @finegeometer in #2789. It was a great idea, just needed more discussion!
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
