# Objective
Fixes#15940
## Solution
Remove the `pub use` and fix the compile errors.
Make `bevy_image` available as `bevy::image`.
## Testing
Feature Frenzy would be good here! Maybe I'll learn how to use it if I
have some time this weekend, or maybe a reviewer can use it.
## Migration Guide
Use `bevy_image` instead of `bevy_render::texture` items.
---------
Co-authored-by: chompaa <antony.m.3012@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- wgpu 0.20 made workgroup vars stop being zero-init by default. this
broke some applications (cough foresight cough) and now we workaround
it. wgpu exposes a compilation option that zero initializes workgroup
memory by default, but bevy does not expose it.
## Solution
- expose the compilation option wgpu gives us
## Testing
- ran examples: 3d_scene, compute_shader_game_of_life, gpu_readback,
lines, specialized_mesh_pipeline. they all work
- confirmed fix for our own problems
---
</details>
## Migration Guide
- add `zero_initialize_workgroup_memory: false,` to
`ComputePipelineDescriptor` or `RenderPipelineDescriptor` structs to
preserve 0.14 functionality, add `zero_initialize_workgroup_memory:
true,` to restore bevy 0.13 functionality.
# Objective
#14273 changed `Msaa` to be a component rather than a resource. However,
the documentation still says that it is a resource. This tripped me up
during migration to 0.15 until I looked at the type definition.
Additionally, the docs have some unnecessary repetition and some grammar
mistakes, and they don't link to camera documentation.
## Solution
Fix up the docs!
# Objective
- Fixes#16122
When the wayland feature is not enabled, xwayland is used on wayland.
Nvidia drivers are somewhat bugged on linux and return outdated surfaces
on xwayland for seemingly no reason. Oftentimes at startup we get into
an infine loop where the surface is permanently outdated and nothing (or
sometimes only the first frame) is drawn on the screen.
## Solution
After experimenting I found that we can safely call configure again and
the issue seems to resolve itsef. After this change I couldn't reproduce
the original issue after many tries. More testing is probably needed
though.
The main issue is that `get_current_texture` fails sometimes because the
surface remains outdated even after configuring. It would be better to
just properly handle and never panic when `get_current_texture` fails.
This way we always call configure when outdated and bail when getting
the swapchain fails instead of crashing. The number of special cases is
also reduced.
## Testing
I tested the example "rotation" manually by trying to move around.
It works with X11 and Xwayland and the non panicing code paths didn't
change so other platforms aren't affected.
# Objective
- Display message for `AsBindGroupError::InvalidSamplerType` was not
correctly displaying the binding index
## Solution
- Simple typo fix
## Testing
- Tested locally
# Objective
Bevy seems to want to standardize on "American English" spellings. Not
sure if this is laid out anywhere in writing, but see also #15947.
While perusing the docs for `typos`, I noticed that it has a `locale`
config option and tried it out.
## Solution
Switch to `en-us` locale in the `typos` config and run `typos -w`
## Migration Guide
The following methods or fields have been renamed from `*dependants*` to
`*dependents*`.
- `ProcessorAssetInfo::dependants`
- `ProcessorAssetInfos::add_dependant`
- `ProcessorAssetInfos::non_existent_dependants`
- `AssetInfo::dependants_waiting_on_load`
- `AssetInfo::dependants_waiting_on_recursive_dep_load`
- `AssetInfos::loader_dependants`
- `AssetInfos::remove_dependants_and_labels`
# Objective
Switch to retained render world causes the extracted cameras in render
world to not be removed until camera in main world is despawned. When
extracting data from main world inactive cameras are skipped. Therefore
camera that was active and became inactive has a retained
`ExtractedCamera` component from previous frames (when it was active)
and is processed the same way as if it were active (there is no `active`
field on `ExtractedCamera`). This breakes switching between cameras in
`render_primitives` example.
Fixes#15822
## Solution
Fix it by removing `ExtractedCamera` and related components from
inactive cameras.
Note that despawning inactive camera seems to be bad option because they
are spawned using `SyncToRenderWorld` component.
## Testing
Switching camera in `render_primitives` example now works correctly.
---------
Co-authored-by: akimakinai <105044389+akimakinai@users.noreply.github.com>
# Objective
Fixes#15791.
As raised in #11022, scaling orthographic cameras is confusing! In Bevy
0.14, there were multiple completely redundant ways to do this, and no
clear guidance on which to use.
As a result, #15075 removed the `scale` field from
`OrthographicProjection` completely, solving the redundancy issue.
However, this resulted in an unintuitive API and a painful migration, as
discussed in #15791. Users simply want to change a single parameter to
zoom, rather than deal with the irrelevant details of how the camera is
being scaled.
## Solution
This PR reverts #15075, and takes an alternate, more nuanced approach to
the redundancy problem. `ScalingMode::WindowSize` was by far the biggest
offender. This was the default variant, and stored a float that was
*fully* redundant to setting `scale`.
All of the other variants contained meaningful semantic information and
had an intuitive scale. I could have made these unitless, storing an
aspect ratio, but this would have been a worse API and resulted in a
pointlessly painful migration.
In the course of this work I've also:
- improved the documentation to explain that you should just set `scale`
to zoom cameras
- swapped to named fields for all of the variants in `ScalingMode` for
more clarity about the parameter meanings
- substantially improved the `projection_zoom` example
- removed the footgunny `Mul` and `Div` impls for `ScalingMode`,
especially since these no longer have the intended effect on
`ScalingMode::WindowSize`.
- removed a rounding step because this is now redundant 🎉
## Testing
I've tested these changes as part of my work in the `projection_zoom`
example, and things seem to work fine.
## Migration Guide
`ScalingMode` has been refactored for clarity, especially on how to zoom
orthographic cameras and their projections:
- `ScalingMode::WindowSize` no longer stores a float, and acts as if its
value was 1. Divide your camera's scale by any previous value to achieve
identical results.
- `ScalingMode::FixedVertical` and `FixedHorizontal` now use named
fields.
---------
Co-authored-by: MiniaczQ <xnetroidpl@gmail.com>
Fixes#15834
## Migration Guide
The APIs of `Time`, `Timer` and `Stopwatch` have been cleaned up for
consistency with each other and the standard library's `Duration` type.
The following methods have been renamed:
- `Stowatch::paused` -> `Stopwatch::is_paused`
- `Time::elapsed_seconds` -> `Time::elasped_secs` (including `_f64` and
`_wrapped` variants)
# Objective
- `C: ExtractComponent` inserts `C::Out` instead of `C`, so we need to
remove `C::Out`. cc #15904.
## Solution
- `C` -> `C::Out`
## Testing
- CAS has `<ContrastAdaptiveSharpening as ExtractComponent>::Out =
(DenoiseCas, CasUniform)`. Setting its strength to zero correctly
removes the effect after this change.
# Objective
Closes#15799.
Many rendering people and maintainers are in favor of reverting default
mesh materials added in #15524, especially as the migration to required
component is already large and heavily breaking.
## Solution
Revert default mesh materials, and adjust docs accordingly.
- Remove `extract_default_materials`
- Remove `clear_material_instances`, and move the logic back into
`extract_mesh_materials`
- Remove `HasMaterial2d` and `HasMaterial3d`
- Change default material handles back to pink instead of white
- 2D uses `Color::srgb(1.0, 0.0, 1.0)`, while 3D uses `Color::srgb(1.0,
0.0, 0.5)`. Not sure if this is intended.
There is now no indication at all about missing materials for `Mesh2d`
and `Mesh3d`. Having a mesh without a material renders nothing.
## Testing
I ran `2d_shapes`, `mesh2d_manual`, and `3d_shapes`, with and without
mesh material components.
# Objective
Fixes#15730.
## Solution
As part of #15586, we made a constant to store all the supported image
formats. However since the `ImageFormat` does actually include Hdr and
OpenExr, it also included the `"hdr"` and `"exr"` file extensions. These
are supported by separate loaders though: `HdrTextureLoader` and
`ExrTextureLoader`. This led to a warning about duplicate asset loaders.
Therefore, instead of having the constant for `ImageFormat`, I made the
constant just for `ImageLoader`. This lets us correctly remove `"hdr"`
and `"exr"` from the image formats supported by `ImageLoader`, returning
us to having a single asset loader for every image format.
Note: we could have just removed `hdr` and `exr` from
`ImageFormat::SUPPORTED_FILE_EXTENSIONS`, but this would be very
confusing. Then the list of `ImageFormat`s would not match the list of
supported formats!
## Testing
- I ran the `sprite` example and got no warning! I also replaced the
sprite in that example with an HDR file and everything worked as
expected.
# Objective
Ensure that components that are conditionally extracted do not linger in
the render world when not extracted from the main world.
## Solution
If the `ExtractComponent` returns `None`, we'll remove the render world
component. I think this is the most sensible behavior here. In the
future if there really is a use case for keeping the previous render
component around, we could add a `Option<Self::Out>` parameter for the
previous render component to the method, or something similar. I think
that this follows the principle of least surprise here relative to what
`None` would suggest and the way that render nodes are typically
written. The alternative would be to add an `enabled` field to pretty
much every camera settings component, or duplicate the extraction
condition as #15856 does.
## Testing
`transmission` no longer crashes.
## Migration Guide
Components that implement `ExtractComponent` and return `None` will
cause the extracted component to be removed from the render world.
# Objective
This is a follow-up to #15650. While the core `Image` stuff moved from
`bevy_render` to `bevy_image`, the `ImageLoader` and the
`CompressedImageSaver` remained in `bevy_render`.
## Solution
I moved `ImageLoader` and `CompressedImageSaver` to `bevy_image` and
re-exported everything out from `bevy_render`. The second step isn't
strictly necessary, but `bevy_render` is already doing this for all the
other `bevy_image` types, so I kept it the same for consistency.
Unfortunately I had to give `ImageLoader` a constructor so I can keep
the `RenderDevice` stuff in `bevy_render`.
## Testing
It compiles!
## Migration Guide
- `ImageLoader` can no longer be initialized directly through
`init_asset_loader`. Now you must use
`app.register_asset_loader(ImageLoader::new(supported_compressed_formats))`
(check out the implementation of `bevy_render::ImagePlugin`). This only
affects you if you are initializing the loader manually and does not
affect users of `bevy_render::ImagePlugin`.
## Followup work
- We should be able to move most of the `ImagePlugin` to `bevy_image`.
This would likely require an `ImagePlugin` and a `RenderImagePlugin` or
something though.
# Objective
Another clippy-lint fix: the goal is so that `ci lints` actually
displays the problems that a contributor caused, and not a bunch of
existing stuff in the repo. (when run on nightly)
## Solution
This fixes all but the `clippy::needless_lifetimes` lint, which will
result in substantially more fixes and be in other PR(s). I also
explicitly allow `non_local_definitions` since it is [not working
correctly, but will be
fixed](https://github.com/rust-lang/rust/issues/131643).
A few things were manually fixed: for example, some places had an
explicitly defined `div_ceil` function that was used, which is no longer
needed since this function is stable on unsigned integers. Also, empty
lines in doc comments were handled individually.
## Testing
I ran `cargo clippy --workspace --all-targets --all-features --fix
--allow-staged` with the `clippy::needless_lifetimes` lint marked as
`allow` in `Cargo.toml` to avoid fixing that too. It now passes with all
but the listed lint.
# Objective
#15320 is a particularly painful breaking change, and the new
`RenderEntity` in particular is very noisy, with a lot of `let entity =
entity.id()` spam.
## Solution
Implement `WorldQuery`, `QueryData` and `ReadOnlyQueryData` for
`RenderEntity` and `WorldEntity`.
These work the same as the `Entity` impls from a user-facing
perspective: they simply return an owned (copied) `Entity` identifier.
This dramatically reduces noise and eases migration.
Under the hood, these impls defer to the implementations for `&T` for
everything other than the "call .id() for the user" bit, as they involve
read-only access to component data. Doing it this way (as opposed to
implementing a custom fetch, as tried in the first commit) dramatically
reduces the maintenance risk of complex unsafe code outside of
`bevy_ecs`.
To make this easier (and encourage users to do this themselves!), I've
made `ReadFetch` and `WriteFetch` slightly more public: they're no
longer `doc(hidden)`. This is a good change, since trying to vendor the
logic is much worse than just deferring to the existing tested impls.
## Testing
I've run a handful of rendering examples (breakout, alien_cake_addict,
auto_exposure, fog_volumes, box_shadow) and nothing broke.
## Follow-up
We should lint for the uses of `&RenderEntity` and `&MainEntity` in
queries: this is just less nice for no reason.
---------
Co-authored-by: Trashtalk217 <trashtalk217@gmail.com>
# Objective
- Required components replace bundles, but `SpatialBundle` is yet to be
deprecated
## Solution
- Deprecate `SpatialBundle`
- Insert `Transform` and `Visibility` instead in examples using it
- In `spawn` or `insert` inserting a default `Transform` or `Visibility`
with component already requiring either, remove those components from
the tuple
## Testing
- Did you test these changes? If so, how?
Yes, I ran the examples I changed and tests
- Are there any parts that need more testing?
The `gamepad_viewer` and and `custom_shader_instancing` examples don't
work as intended due to entirely unrelated code, didn't check main.
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
Run examples, or just check that all spawned values are identical
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
Linux, wayland trough x11 (cause that's the default feature)
---
## Migration Guide
`SpatialBundle` is now deprecated, insert `Transform` and `Visibility`
instead which will automatically insert all other components that were
in the bundle. If you do not specify these values and any other
components in your `spawn`/`insert` call already requires either of
these components you can leave that one out.
before:
```rust
commands.spawn(SpatialBundle::default());
```
after:
```rust
commands.spawn((Transform::default(), Visibility::default());
```
# Objective
Fixes#15515
## Solution
I went for the simplest solution because "format" in
`shader_format_spirv` didn't sound directly related.
## Testing
The command `cargo b -p bevy --no-default-features -F
spirv_shader_passthrough,x11` failed before, but works now.
# Objective
In the Render World, there are a number of collections that are derived
from Main World entities and are used to drive rendering. The most
notable are:
- `VisibleEntities`, which is generated in the `check_visibility` system
and contains visible entities for a view.
- `ExtractedInstances`, which maps entity ids to asset ids.
In the old model, these collections were trivially kept in sync -- any
extracted phase item could look itself up because the render entity id
was guaranteed to always match the corresponding main world id.
After #15320, this became much more complicated, and was leading to a
number of subtle bugs in the Render World. The main rendering systems,
i.e. `queue_material_meshes` and `queue_material2d_meshes`, follow a
similar pattern:
```rust
for visible_entity in visible_entities.iter::<With<Mesh2d>>() {
let Some(mesh_instance) = render_mesh_instances.get_mut(visible_entity) else {
continue;
};
// Look some more stuff up and specialize the pipeline...
let bin_key = Opaque2dBinKey {
pipeline: pipeline_id,
draw_function: draw_opaque_2d,
asset_id: mesh_instance.mesh_asset_id.into(),
material_bind_group_id: material_2d.get_bind_group_id().0,
};
opaque_phase.add(
bin_key,
*visible_entity,
BinnedRenderPhaseType::mesh(mesh_instance.automatic_batching),
);
}
```
In this case, `visible_entities` and `render_mesh_instances` are both
collections that are created and keyed by Main World entity ids, and so
this lookup happens to work by coincidence. However, there is a major
unintentional bug here: namely, because `visible_entities` is a
collection of Main World ids, the phase item being queued is created
with a Main World id rather than its correct Render World id.
This happens to not break mesh rendering because the render commands
used for drawing meshes do not access the `ItemQuery` parameter, but
demonstrates the confusion that is now possible: our UI phase items are
correctly being queued with Render World ids while our meshes aren't.
Additionally, this makes it very easy and error prone to use the wrong
entity id to look up things like assets. For example, if instead we
ignored visibility checks and queued our meshes via a query, we'd have
to be extra careful to use `&MainEntity` instead of the natural
`Entity`.
## Solution
Make all collections that are derived from Main World data use
`MainEntity` as their key, to ensure type safety and avoid accidentally
looking up data with the wrong entity id:
```rust
pub type MainEntityHashMap<V> = hashbrown::HashMap<MainEntity, V, EntityHash>;
```
Additionally, we make all `PhaseItem` be able to provide both their Main
and Render World ids, to allow render phase implementors maximum
flexibility as to what id should be used to look up data.
You can think of this like tracking at the type level whether something
in the Render World should use it's "primary key", i.e. entity id, or
needs to use a foreign key, i.e. `MainEntity`.
## Testing
##### TODO:
This will require extensive testing to make sure things didn't break!
Additionally, some extraction logic has become more complicated and
needs to be checked for regressions.
## Migration Guide
With the advent of the retained render world, collections that contain
references to `Entity` that are extracted into the render world have
been changed to contain `MainEntity` in order to prevent errors where a
render world entity id is used to look up an item by accident. Custom
rendering code may need to be changed to query for `&MainEntity` in
order to look up the correct item from such a collection. Additionally,
users who implement their own extraction logic for collections of main
world entity should strongly consider extracting into a different
collection that uses `MainEntity` as a key.
Additionally, render phases now require specifying both the `Entity` and
`MainEntity` for a given `PhaseItem`. Custom render phases should ensure
`MainEntity` is available when queuing a phase item.
# Objective
- Another step towards #15716
- Remove trait implementations that are dependent on `Handle<T>` being a
`Component`
## Solution
- Remove unused `ExtractComponent` trait implementation for `Handle<T>`
- Remove unused `ExtractInstance` trait implementation for `AssetId`
- Although the `ExtractInstance` trait wasn't used, the `AssetId`s were
being stored inside of `ExtractedInstances` which has an
`ExtractInstance` trait bound on its contents.
I've upgraded the `RenderMaterialInstances` type alias to be its own
resource, identical to `ExtractedInstances<AssetId<M>>` to get around
that with minimal breakage.
## Testing
Tested `many_cubes`, rendering did not explode
# Objective
- Closes#15752
Calling the functions `App::observe` and `World::observe` doesn't make
sense because you're not "observing" the `App` or `World`, you're adding
an observer that listens for an event that occurs *within* the `World`.
We should rename them to better fit this.
## Solution
Renames:
- `App::observe` -> `App::add_observer`
- `World::observe` -> `World::add_observer`
- `Commands::observe` -> `Commands::add_observer`
- `EntityWorldMut::observe_entity` -> `EntityWorldMut::observe`
(Note this isn't a breaking change as the original rename was introduced
earlier this cycle.)
## Testing
Reusing current tests.
# Objective
- Fixes#15285
## Solution
`winit` sends resized to zero events when the window is minimized only
on Windows OS(rust-windowing/winit#2015).
This makes updating window viewport size to `(0, 0)` and panicking when
calculating aspect ratio.
~~So, just skip these kinds of events - resizing to (0, 0) when the
window is minimized - on Windows OS~~
Idially, the camera extraction excludes the cameras whose target size
width or height is zero here;
25bfa80e60/crates/bevy_render/src/camera/camera.rs (L1060-L1074)
but it seems that winit event loop sends resize events after extraction
and before post update schedule, so they might panics before the
extraction filters them out.
Alternatively, it might be possible to change event loop evaluating
order or defer them to the right schedule but I'm afraid that it might
cause some breaking changes, so just skip rendering logics for such
windows and they will be all filtered out by the extractions on the next
frame and thereafter.
## Testing
Running the example in the original issue and minimizing causes panic,
or just running `tests/window/minimising.rs` with `cargo run --example
minimising` panics without this PR and doesn't panics with this PR.
I think that we should run it in CI on Windows OS btw
# Objective
- Fixes (partially) #15701.
## Solution
- Use little-endian bytes over native-endian bytes where applicable.
## Testing
- Ran CI.
## Open Questions
- Should we config-gate these for big-endian targets? It looks like
there are [very few
targets](https://doc.rust-lang.org/nightly/rustc/platform-support.html)
that use big-endian.
# Objective
Fixes#15560
Fixes (most of) #15570
Currently a lot of examples (and presumably some user code) depend on
toggling certain render features by adding/removing a single component
to an entity, e.g. `SpotLight` to toggle a light. Because of the
retained render world this no longer works: Extract will add any new
components, but when it is removed the entity persists unchanged in the
render world.
## Solution
Add `SyncComponentPlugin<C: Component>` that registers
`SyncToRenderWorld` as a required component for `C`, and adds a
component hook that will clear all components from the render world
entity when `C` is removed. We add this plugin to
`ExtractComponentPlugin` which fixes most instances of the problem. For
custom extraction logic we can manually add `SyncComponentPlugin` for
that component.
We also rename `WorldSyncPlugin` to `SyncWorldPlugin` so we start a
naming convention like all the `Extract` plugins.
In this PR I also fixed a bunch of breakage related to the retained
render world, stemming from old code that assumed that `Entity` would be
the same in both worlds.
I found that using the `RenderEntity` wrapper instead of `Entity` in
data structures when referring to render world entities makes intent
much clearer, so I propose we make this an official pattern.
## Testing
Run examples like
```
cargo run --features pbr_multi_layer_material_textures --example clearcoat
cargo run --example volumetric_fog
```
and see that they work, and that toggles work correctly. But really we
should test every single example, as we might not even have caught all
the breakage yet.
---
## Migration Guide
The retained render world notes should be updated to explain this edge
case and `SyncComponentPlugin`
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Trashtalk217 <trashtalk217@gmail.com>
The previous fixes were breaking pretty much everything on main due to
naga-oil complaining about the OIT shader not being loaded, since
apparently webgl is a default feature. This fix is a bit messier, but
properly warns the user and is probably what we should have gone for in
the first place.
# Objective
Bevy supports feature gates for each format it supports, but several
formats that it loads via the `image` crate do not have feature gates.
Additionally, the QOI format is supported by the `image` crate and
wasn't available at all. This fixes that.
## Solution
The following feature gates are added:
* `avif`
* `ff` (Farbfeld)
* `gif`
* `ico`
* `qoi`
* `tiff`
None of these formats are enabled by default, despite the fact that all
these formats appeared to be enabled by default before. Since
`default-features` was disabled for the `image` crate, it's likely that
using any of these formats would have errored by default before this
change, although this probably needs additional testing.
## Testing
The changes seemed minimal enough that a compile test would be
sufficient.
## Migration guide
Image formats that previously weren't feature-gated are now
feature-gated, meaning they will have to be enabled if you use them:
* `avif`
* `ff` (Farbfeld)
* `gif`
* `ico`
* `tiff`
Additionally, the `qoi` feature has been added to support loading QOI
format images.
Previously, these formats appeared in the enum by default, but weren't
actually enabled via the `image` crate, potentially resulting in weird
bugs. Now, you should be able to add these features to your projects to
support them properly.
# Objective
After merging retained rendering world #15320, we now have a good way of
creating a link between worlds (*HIYAA intensifies*). This means that
`get_or_spawn` is no longer necessary for that function. Entity should
be opaque as the warning above `get_or_spawn` says. This is also part of
#15459.
I'm deprecating `get_or_spawn_batch` in a different PR in order to keep
the PR small in size.
## Solution
Deprecate `get_or_spawn` and replace it with `get_entity` in most
contexts. If it's possible to query `&RenderEntity`, then the entity is
synced and `render_entity.id()` is initialized in the render world.
## Migration Guide
If you are given an `Entity` and you want to do something with it, use
`Commands.entity(...)` or `World.entity(...)`. If instead you want to
spawn something use `Commands.spawn(...)` or `World.spawn(...)`. If you
are not sure if an entity exists, you can always use `get_entity` and
match on the `Option<...>` that is returned.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Following the pattern established in #15593, we can reduce the API
surface of `World` by providing a single function to grab both a
singular entity reference, or multiple entity references.
## Solution
The following functions can now also take multiple entity IDs and will
return multiple entity references back:
- `World::entity`
- `World::get_entity`
- `World::entity_mut`
- `World::get_entity_mut`
- `DeferredWorld::entity_mut`
- `DeferredWorld::get_entity_mut`
If you pass in X, you receive Y:
- give a single `Entity`, receive a single `EntityRef`/`EntityWorldMut`
(matches current behavior)
- give a `[Entity; N]`/`&[Entity; N]` (array), receive an equally-sized
`[EntityRef; N]`/`[EntityMut; N]`
- give a `&[Entity]` (slice), receive a
`Vec<EntityRef>`/`Vec<EntityMut>`
- give a `&EntityHashSet`, receive a
`EntityHashMap<EntityRef>`/`EntityHashMap<EntityMut>`
Note that `EntityWorldMut` is only returned in the single-entity case,
because having multiple at the same time would lead to UB. Also,
`DeferredWorld` receives an `EntityMut` in the single-entity case
because it does not allow structural access.
## Testing
- Added doc-tests on `World::entity`, `World::entity_mut`, and
`DeferredWorld::entity_mut`
- Added tests for aliased mutability and entity existence
---
## Showcase
<details>
<summary>Click to view showcase</summary>
The APIs for fetching `EntityRef`s and `EntityMut`s from the `World`
have been unified.
```rust
// This code will be referred to by subsequent code blocks.
let world = World::new();
let e1 = world.spawn_empty().id();
let e2 = world.spawn_empty().id();
let e3 = world.spawn_empty().id();
```
Querying for a single entity remains mostly the same:
```rust
// 0.14
let eref: EntityRef = world.entity(e1);
let emut: EntityWorldMut = world.entity_mut(e1);
let eref: Option<EntityRef> = world.get_entity(e1);
let emut: Option<EntityWorldMut> = world.get_entity_mut(e1);
// 0.15
let eref: EntityRef = world.entity(e1);
let emut: EntityWorldMut = world.entity_mut(e1);
let eref: Result<EntityRef, Entity> = world.get_entity(e1);
let emut: Result<EntityWorldMut, Entity> = world.get_entity_mut(e1);
```
Querying for multiple entities with an array has changed:
```rust
// 0.14
let erefs: [EntityRef; 2] = world.many_entities([e1, e2]);
let emuts: [EntityMut; 2] = world.many_entities_mut([e1, e2]);
let erefs: Result<[EntityRef; 2], Entity> = world.get_many_entities([e1, e2]);
let emuts: Result<[EntityMut; 2], QueryEntityError> = world.get_many_entities_mut([e1, e2]);
// 0.15
let erefs: [EntityRef; 2] = world.entity([e1, e2]);
let emuts: [EntityMut; 2] = world.entity_mut([e1, e2]);
let erefs: Result<[EntityRef; 2], Entity> = world.get_entity([e1, e2]);
let emuts: Result<[EntityMut; 2], EntityFetchError> = world.get_entity_mut([e1, e2]);
```
Querying for multiple entities with a slice has changed:
```rust
let ids = vec![e1, e2, e3]);
// 0.14
let erefs: Result<Vec<EntityRef>, Entity> = world.get_many_entities_dynamic(&ids[..]);
let emuts: Result<Vec<EntityMut>, QueryEntityError> = world.get_many_entities_dynamic_mut(&ids[..]);
// 0.15
let erefs: Result<Vec<EntityRef>, Entity> = world.get_entity(&ids[..]);
let emuts: Result<Vec<EntityMut>, EntityFetchError> = world.get_entity_mut(&ids[..]);
let erefs: Vec<EntityRef> = world.entity(&ids[..]); // Newly possible!
let emuts: Vec<EntityMut> = world.entity_mut(&ids[..]); // Newly possible!
```
Querying for multiple entities with an `EntityHashSet` has changed:
```rust
let set = EntityHashSet::from_iter([e1, e2, e3]);
// 0.14
let emuts: Result<Vec<EntityMut>, QueryEntityError> = world.get_many_entities_from_set_mut(&set);
// 0.15
let emuts: Result<EntityHashMap<EntityMut>, EntityFetchError> = world.get_entity_mut(&set);
let erefs: Result<EntityHashMap<EntityRef>, EntityFetchError> = world.get_entity(&set); // Newly possible!
let emuts: EntityHashMap<EntityMut> = world.entity_mut(&set); // Newly possible!
let erefs: EntityHashMap<EntityRef> = world.entity(&set); // Newly possible!
```
</details>
## Migration Guide
- `World::get_entity` now returns `Result<_, Entity>` instead of
`Option<_>`.
- Use `world.get_entity(..).ok()` to return to the previous behavior.
- `World::get_entity_mut` and `DeferredWorld::get_entity_mut` now return
`Result<_, EntityFetchError>` instead of `Option<_>`.
- Use `world.get_entity_mut(..).ok()` to return to the previous
behavior.
- Type inference for `World::entity`, `World::entity_mut`,
`World::get_entity`, `World::get_entity_mut`,
`DeferredWorld::entity_mut`, and `DeferredWorld::get_entity_mut` has
changed, and might now require the input argument's type to be
explicitly written when inside closures.
- The following functions have been deprecated, and should be replaced
as such:
- `World::many_entities` -> `World::entity::<[Entity; N]>`
- `World::many_entities_mut` -> `World::entity_mut::<[Entity; N]>`
- `World::get_many_entities` -> `World::get_entity::<[Entity; N]>`
- `World::get_many_entities_dynamic` -> `World::get_entity::<&[Entity]>`
- `World::get_many_entities_mut` -> `World::get_entity_mut::<[Entity;
N]>`
- The equivalent return type has changed from `Result<_,
QueryEntityError>` to `Result<_, EntityFetchError>`
- `World::get_many_entities_dynamic_mut` ->
`World::get_entity_mut::<&[Entity]>1
- The equivalent return type has changed from `Result<_,
QueryEntityError>` to `Result<_, EntityFetchError>`
- `World::get_many_entities_from_set_mut` ->
`World::get_entity_mut::<&EntityHashSet>`
- The equivalent return type has changed from `Result<Vec<EntityMut>,
QueryEntityError>` to `Result<EntityHashMap<EntityMut>,
EntityFetchError>`. If necessary, you can still convert the
`EntityHashMap` into a `Vec`.
# Objective
- `bevy_render` should not depend on `bevy_winit`
- Fixes#15565
## Solution
- `bevy_render` no longer depends on `bevy_winit`
- The following is behind the `custom_cursor` feature
- Move custom cursor code from `bevy_render` to `bevy_winit` behind the
`custom_cursor` feature
- `bevy_winit` now depends on `bevy_render` (for `Image` and
`TextureFormat`)
- `bevy_winit` now depends on `bevy_asset` (for `Assets`, `Handle` and
`AssetId`)
- `bevy_winit` now depends on `bytemuck` (already in tree)
- Custom cursor code in `bevy_winit` reworked to use `AssetId` (other
than that it is taken over 1:1)
- Rework `bevy_winit` custom cursor interface visibility now that the
logic is all contained in `bevy_winit`
## Testing
- I ran the screenshot and window_settings examples
- Tested on linux wayland so far
---
## Migration Guide
`CursorIcon` and `CustomCursor` previously provided by
`bevy::render::view::cursor` is now available from `bevy::winit`.
A new feature `custom_cursor` enables this functionality (default
feature).
# Objective
- bevy_render is gargantuan
## Solution
- Split out bevy_mesh
## Testing
- Ran some examples, everything looks fine
## Migration Guide
`bevy_render::mesh::morph::inherit_weights` is now
`bevy_render::mesh::inherit_weights`
if you were using `Mesh::compute_aabb`, you will need to `use
bevy_render::mesh::MeshAabb;` now
---------
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
# Objective
Yet another PR for migrating stuff to required components. This time,
cameras!
## Solution
As per the [selected
proposal](https://hackmd.io/tsYID4CGRiWxzsgawzxG_g#Combined-Proposal-1-Selected),
deprecate `Camera2dBundle` and `Camera3dBundle` in favor of `Camera2d`
and `Camera3d`.
Adding a `Camera` without `Camera2d` or `Camera3d` now logs a warning,
as suggested by Cart [on
Discord](https://discord.com/channels/691052431525675048/1264881140007702558/1291506402832945273).
I would personally like cameras to work a bit differently and be split
into a few more components, to avoid some footguns and confusing
semantics, but that is more controversial, and shouldn't block this core
migration.
## Testing
I ran a few 2D and 3D examples, and tried cameras with and without
render graphs.
---
## Migration Guide
`Camera2dBundle` and `Camera3dBundle` have been deprecated in favor of
`Camera2d` and `Camera3d`. Inserting them will now also insert the other
components required by them automatically.
# Objective
- Another step towards #15558
## Solution
- Instead of allocating a Vec and then having wgpu copy it into a
staging buffer, write directly into the staging buffer.
- gets rid of another hidden copy, in `pad_to_alignment`.
future work:
- why is there a gcd implementation in here (and its subpar, use
binary_gcd. its in the hot path, run twice for every mesh, every frame i
think?) make it better and put it in bevy_math
- zero-copy custom mesh api to avoid having to write out a Mesh from a
custom rep
## Testing
- lighting and many_cubes run fine (and slightly faster. havent
benchmarked though)
---
## Showcase
- look ma... no copies
at least when RenderAssetUsage is GPU only :3
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Kristoffer Søholm <k.soeholm@gmail.com>
# Objective
System param validation warnings should be configurable and default to
"warn once" (per system).
Fixes: #15391
## Solution
`SystemMeta` is given a new `ParamWarnPolicy` field.
The policy decides whether warnings will be emitted by each system param
when it fails validation.
The policy is updated by the system after param validation fails.
Example warning:
```
2024-09-30T18:10:04.740749Z WARN bevy_ecs::system::function_system: System fallible_params::do_nothing_fail_validation will not run because it requested inaccessible system parameter Single<(), (With<Player>, With<Enemy>)>
```
Currently, only the first invalid parameter is displayed.
Warnings can be disabled on function systems using
`.param_never_warn()`.
(there is also `.with_param_warn_policy(policy)`)
## Testing
Ran `fallible_params` example.
---------
Co-authored-by: SpecificProtagonist <vincentjunge@posteo.net>
As discussed in #15521
- Partial revert of #14897, reverting the change to the methods to
consume `self`
- The `insert_if` method is kept
The migration guide of #14897 should be removed
Closes#15521
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
A big step in the migration to required components: meshes and
materials!
## Solution
As per the [selected
proposal](https://hackmd.io/@bevy/required_components/%2Fj9-PnF-2QKK0on1KQ29UWQ):
- Deprecate `MaterialMesh2dBundle`, `MaterialMeshBundle`, and
`PbrBundle`.
- Add `Mesh2d` and `Mesh3d` components, which wrap a `Handle<Mesh>`.
- Add `MeshMaterial2d<M: Material2d>` and `MeshMaterial3d<M: Material>`,
which wrap a `Handle<M>`.
- Meshes *without* a mesh material should be rendered with a default
material. The existence of a material is determined by
`HasMaterial2d`/`HasMaterial3d`, which is required by
`MeshMaterial2d`/`MeshMaterial3d`. This gets around problems with the
generics.
Previously:
```rust
commands.spawn(MaterialMesh2dBundle {
mesh: meshes.add(Circle::new(100.0)).into(),
material: materials.add(Color::srgb(7.5, 0.0, 7.5)),
transform: Transform::from_translation(Vec3::new(-200., 0., 0.)),
..default()
});
```
Now:
```rust
commands.spawn((
Mesh2d(meshes.add(Circle::new(100.0))),
MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))),
Transform::from_translation(Vec3::new(-200., 0., 0.)),
));
```
If the mesh material is missing, previously nothing was rendered. Now,
it renders a white default `ColorMaterial` in 2D and a
`StandardMaterial` in 3D (this can be overridden). Below, only every
other entity has a material:
Why white? This is still open for discussion, but I think white makes
sense for a *default* material, while *invalid* asset handles pointing
to nothing should have something like a pink material to indicate that
something is broken (I don't handle that in this PR yet). This is kind
of a mix of Godot and Unity: Godot just renders a white material for
non-existent materials, while Unity renders nothing when no materials
exist, but renders pink for invalid materials. I can also change the
default material to pink if that is preferable though.
## Testing
I ran some 2D and 3D examples to test if anything changed visually. I
have not tested all examples or features yet however. If anyone wants to
test more extensively, it would be appreciated!
## Implementation Notes
- The relationship between `bevy_render` and `bevy_pbr` is weird here.
`bevy_render` needs `Mesh3d` for its own systems, but `bevy_pbr` has all
of the material logic, and `bevy_render` doesn't depend on it. I feel
like the two crates should be refactored in some way, but I think that's
out of scope for this PR.
- I didn't migrate meshlets to required components yet. That can
probably be done in a follow-up, as this is already a huge PR.
- It is becoming increasingly clear to me that we really, *really* want
to disallow raw asset handles as components. They caused me a *ton* of
headache here already, and it took me a long time to find every place
that queried for them or inserted them directly on entities, since there
were no compiler errors for it. If we don't remove the `Component`
derive, I expect raw asset handles to be a *huge* footgun for users as
we transition to wrapper components, especially as handles as components
have been the norm so far. I personally consider this to be a blocker
for 0.15: we need to migrate to wrapper components for asset handles
everywhere, and remove the `Component` derive. Also see
https://github.com/bevyengine/bevy/issues/14124.
---
## Migration Guide
Asset handles for meshes and mesh materials must now be wrapped in the
`Mesh2d` and `MeshMaterial2d` or `Mesh3d` and `MeshMaterial3d`
components for 2D and 3D respectively. Raw handles as components no
longer render meshes.
Additionally, `MaterialMesh2dBundle`, `MaterialMeshBundle`, and
`PbrBundle` have been deprecated. Instead, use the mesh and material
components directly.
Previously:
```rust
commands.spawn(MaterialMesh2dBundle {
mesh: meshes.add(Circle::new(100.0)).into(),
material: materials.add(Color::srgb(7.5, 0.0, 7.5)),
transform: Transform::from_translation(Vec3::new(-200., 0., 0.)),
..default()
});
```
Now:
```rust
commands.spawn((
Mesh2d(meshes.add(Circle::new(100.0))),
MeshMaterial2d(materials.add(Color::srgb(7.5, 0.0, 7.5))),
Transform::from_translation(Vec3::new(-200., 0., 0.)),
));
```
If the mesh material is missing, a white default material is now used.
Previously, nothing was rendered if the material was missing.
The `WithMesh2d` and `WithMesh3d` query filter type aliases have also
been removed. Simply use `With<Mesh2d>` or `With<Mesh3d>`.
---------
Co-authored-by: Tim Blackbird <justthecooldude@gmail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- First step towards #15558
## Solution
- Rename `get_vertex_buffer_data` to `create_packed_vertex_buffer_data`
to make it clear that it is not "free" and actually allocates
- Compute length analytically for preallocation instead of creating the
buffer to get its length and immediately discard it
- Use existing vertex attribute size calculation method to reduce code
duplication
- Fix a bug where mesh index data was being replaced by unnecessarily
newly created mesh vertex data in some cases
- Overall reduces mesh copies by two. We still have plenty to go, but
these were the easy ones.
## Testing
- I ran 3d_scene, lighting, and many_cubes, they look fine.
- Benchmarks would be nice, but this is very obviously a win in perf and
correctness.
---
## Migration Guide
- `Mesh::create_packed_vertex_buffer_data` has been renamed
`Mesh::create_packed_vertex_buffer_data` to reflect the fact that it
copies data and allocates.
## Showcase
- look mom, less copies
# Objective
- This PR fixes#12488
## Solution
- This PR adds a new property to `Camera` that emulates the
functionality of the
[setViewOffset()](https://threejs.org/docs/#api/en/cameras/PerspectiveCamera.setViewOffset)
API in three.js.
- When set, the perspective and orthographic projections will restrict
the visible area of the camera to a part of the view frustum defined by
`offset` and `size`.
## Testing
- In the new `camera_sub_view` example, a fixed, moving and control sub
view is created for both perspective and orthographic projection
- Run the example with `cargo run --example camera_sub_view`
- The code can be tested by adding a `SubCameraView` to a camera
---
## Showcase
- Left Half: Perspective Projection
- Right Half: Orthographic Projection
- Small boxes in order:
- Sub view of the left half of the full image
- Sub view moving from the top left to the bottom right of the full
image
- Sub view of the full image (acting as a control)
- Large box: No sub view
<details>
<summary>Shortened camera setup of `camera_sub_view` example</summary>
```rust
// Main perspective Camera
commands.spawn(Camera3dBundle {
transform,
..default()
});
// Perspective camera left half
commands.spawn(Camera3dBundle {
camera: Camera {
sub_camera_view: Some(SubCameraView {
// Set the sub view camera to the left half of the full image
full_size: uvec2(500, 500),
offset: ivec2(0, 0),
size: uvec2(250, 500),
}),
order: 1,
..default()
},
transform,
..default()
});
// Perspective camera moving
commands.spawn((
Camera3dBundle {
camera: Camera {
sub_camera_view: Some(SubCameraView {
// Set the sub view camera to a fifth of the full view and
// move it in another system
full_size: uvec2(500, 500),
offset: ivec2(0, 0),
size: uvec2(100, 100),
}),
order: 2,
..default()
},
transform,
..default()
},
MovingCameraMarker,
));
// Perspective camera control
commands.spawn(Camera3dBundle {
camera: Camera {
sub_camera_view: Some(SubCameraView {
// Set the sub view to the full image, to ensure that it matches
// the projection without sub view
full_size: uvec2(450, 450),
offset: ivec2(0, 0),
size: uvec2(450, 450),
}),
order: 3,
..default()
},
transform,
..default()
});
// Main orthographic camera
commands.spawn(Camera3dBundle {
projection: OrthographicProjection {
...
}
.into(),
camera: Camera {
order: 4,
..default()
},
transform,
..default()
});
// Orthographic camera left half
commands.spawn(Camera3dBundle {
projection: OrthographicProjection {
...
}
.into(),
camera: Camera {
sub_camera_view: Some(SubCameraView {
// Set the sub view camera to the left half of the full image
full_size: uvec2(500, 500),
offset: ivec2(0, 0),
size: uvec2(250, 500),
}),
order: 5,
..default()
},
transform,
..default()
});
// Orthographic camera moving
commands.spawn((
Camera3dBundle {
projection: OrthographicProjection {
...
}
.into(),
camera: Camera {
sub_camera_view: Some(SubCameraView {
// Set the sub view camera to a fifth of the full view and
// move it in another system
full_size: uvec2(500, 500),
offset: ivec2(0, 0),
size: uvec2(100, 100),
}),
order: 6,
..default()
},
transform,
..default()
},
MovingCameraMarker,
));
// Orthographic camera control
commands.spawn(Camera3dBundle {
projection: OrthographicProjection {
...
}
.into(),
camera: Camera {
sub_camera_view: Some(SubCameraView {
// Set the sub view to the full image, to ensure that it matches
// the projection without sub view
full_size: uvec2(450, 450),
offset: ivec2(0, 0),
size: uvec2(450, 450),
}),
order: 7,
..default()
},
transform,
..default()
});
```
</details>
# Objective
Fixes#15541
A bunch of lifetimes were added during the Assets V2 rework, but after
moving to async traits in #12550 they can be elided. That PR mentions
that this might be the case, but apparently it wasn't followed up on at
the time.
~~I ended up grepping for `<'a` and finding a similar case in
`bevy_reflect` which I also fixed.~~ (edit: that one was needed
apparently)
Note that elided lifetimes are unstable in `impl Trait`. If that gets
stabilized then we can elide even more.
## Solution
Remove the extra lifetimes.
## Testing
Everything still compiles. If I have messed something up there is a
small risk that some user code stops compiling, but all the examples
still work at least.
---
## Migration Guide
The traits `AssetLoader`, `AssetSaver` and `Process` traits from
`bevy_asset` now use elided lifetimes. If you implement these then
remove the named lifetime.
- Adopted from #14449
- Still fixes#12144.
## Migration Guide
The retained render world is a complex change: migrating might take one
of a few different forms depending on the patterns you're using.
For every example, we specify in which world the code is run. Most of
the changes affect render world code, so for the average Bevy user who's
using Bevy's high-level rendering APIs, these changes are unlikely to
affect your code.
### Spawning entities in the render world
Previously, if you spawned an entity with `world.spawn(...)`,
`commands.spawn(...)` or some other method in the rendering world, it
would be despawned at the end of each frame. In 0.15, this is no longer
the case and so your old code could leak entities. This can be mitigated
by either re-architecting your code to no longer continuously spawn
entities (like you're used to in the main world), or by adding the
`bevy_render::world_sync::TemporaryRenderEntity` component to the entity
you're spawning. Entities tagged with `TemporaryRenderEntity` will be
removed at the end of each frame (like before).
### Extract components with `ExtractComponentPlugin`
```
// main world
app.add_plugins(ExtractComponentPlugin::<ComponentToExtract>::default());
```
`ExtractComponentPlugin` has been changed to only work with synced
entities. Entities are automatically synced if `ComponentToExtract` is
added to them. However, entities are not "unsynced" if any given
`ComponentToExtract` is removed, because an entity may have multiple
components to extract. This would cause the other components to no
longer get extracted because the entity is not synced.
So be careful when only removing extracted components from entities in
the render world, because it might leave an entity behind in the render
world. The solution here is to avoid only removing extracted components
and instead despawn the entire entity.
### Manual extraction using `Extract<Query<(Entity, ...)>>`
```rust
// in render world, inspired by bevy_pbr/src/cluster/mod.rs
pub fn extract_clusters(
mut commands: Commands,
views: Extract<Query<(Entity, &Clusters, &Camera)>>,
) {
for (entity, clusters, camera) in &views {
// some code
commands.get_or_spawn(entity).insert(...);
}
}
```
One of the primary consequences of the retained rendering world is that
there's no longer a one-to-one mapping from entity IDs in the main world
to entity IDs in the render world. Unlike in Bevy 0.14, Entity 42 in the
main world doesn't necessarily map to entity 42 in the render world.
Previous code which called `get_or_spawn(main_world_entity)` in the
render world (`Extract<Query<(Entity, ...)>>` returns main world
entities). Instead, you should use `&RenderEntity` and
`render_entity.id()` to get the correct entity in the render world. Note
that this entity does need to be synced first in order to have a
`RenderEntity`.
When performing manual abstraction, this won't happen automatically
(like with `ExtractComponentPlugin`) so add a `SyncToRenderWorld` marker
component to the entities you want to extract.
This results in the following code:
```rust
// in render world, inspired by bevy_pbr/src/cluster/mod.rs
pub fn extract_clusters(
mut commands: Commands,
views: Extract<Query<(&RenderEntity, &Clusters, &Camera)>>,
) {
for (render_entity, clusters, camera) in &views {
// some code
commands.get_or_spawn(render_entity.id()).insert(...);
}
}
// in main world, when spawning
world.spawn(Clusters::default(), Camera::default(), SyncToRenderWorld)
```
### Looking up `Entity` ids in the render world
As previously stated, there's now no correspondence between main world
and render world `Entity` identifiers.
Querying for `Entity` in the render world will return the `Entity` id in
the render world: query for `MainEntity` (and use its `id()` method) to
get the corresponding entity in the main world.
This is also a good way to tell the difference between synced and
unsynced entities in the render world, because unsynced entities won't
have a `MainEntity` component.
---------
Co-authored-by: re0312 <re0312@outlook.com>
Co-authored-by: re0312 <45868716+re0312@users.noreply.github.com>
Co-authored-by: Periwink <charlesbour@gmail.com>
Co-authored-by: Anselmo Sampietro <ans.samp@gmail.com>
Co-authored-by: Emerson Coskey <56370779+ecoskey@users.noreply.github.com>
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Christian Hughes <9044780+ItsDoot@users.noreply.github.com>
# Objective
* Remove all uses of render_resource_wrapper.
* Make it easier to share a `wgpu::Device` between Bevy and application
code.
## Solution
Removed the `render_resource_wrapper` macro.
To improve the `RenderCreation:: Manual ` API, `ErasedRenderDevice` was
replaced by `Arc`. Unfortunately I had to introduce one more usage of
`WgpuWrapper` which seems like an unwanted constraint on the caller.
## Testing
- Did you test these changes? If so, how?
- Ran `cargo test`.
- Ran a few examples.
- Used `RenderCreation::Manual` in my own project
- Exercised `RenderCreation::Automatic` through examples
- 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?
- Run examples
- Use `RenderCreation::Manual` in their own project
# Objective
- Provide a generic and _reflectable_ way to iterate over contained
entities
## Solution
Adds two new traits:
* `VisitEntities`: Reflectable iteration, accepts a closure rather than
producing an iterator. Implemented by default for `IntoIterator`
implementing types. A proc macro is also provided.
* A `Mut` variant of the above. Its derive macro uses the same field
attribute to avoid repetition.
## Testing
Added a test for `VisitEntities` that also transitively tests its derive
macro as well as the default `MapEntities` impl.
# Objective
Adds a new `Readback` component to request for readback of a
`Handle<Image>` or `Handle<ShaderStorageBuffer>` to the CPU in a future
frame.
## Solution
We track the `Readback` component and allocate a target buffer to write
the gpu resource into and map it back asynchronously, which then fires a
trigger on the entity in the main world. This proccess is asynchronous,
and generally takes a few frames.
## Showcase
```rust
let mut buffer = ShaderStorageBuffer::from(vec![0u32; 16]);
buffer.buffer_description.usage |= BufferUsages::COPY_SRC;
let buffer = buffers.add(buffer);
commands
.spawn(Readback::buffer(buffer.clone()))
.observe(|trigger: Trigger<ReadbackComplete>| {
info!("Buffer data from previous frame {:?}", trigger.event());
});
```
---------
Co-authored-by: Kristoffer Søholm <k.soeholm@gmail.com>
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
