# Objective
- Users are often confused when their command effects are not visible in
the next system. This PR auto inserts sync points if there are deferred
buffers on a system and there are dependents on that system (systems
with after relationships).
- Manual sync points can lead to users adding more than needed and it's
hard for the user to have a global understanding of their system graph
to know which sync points can be merged. However we can easily calculate
which sync points can be merged automatically.
## Solution
1. Add new edge types to allow opting out of new behavior
2. Insert an sync point for each edge whose initial node has deferred
system params.
3. Reuse nodes if they're at the number of sync points away.
* add opt outs for specific edges with `after_ignore_deferred`,
`before_ignore_deferred` and `chain_ignore_deferred`. The
`auto_insert_apply_deferred` boolean on `ScheduleBuildSettings` can be
set to false to opt out for the whole schedule.
## Perf
This has a small negative effect on schedule build times.
```text
group auto-sync main-for-auto-sync
----- ----------- ------------------
build_schedule/1000_schedule 1.06 2.8±0.15s ? ?/sec 1.00 2.7±0.06s ? ?/sec
build_schedule/1000_schedule_noconstraints 1.01 26.2±0.88ms ? ?/sec 1.00 25.8±0.36ms ? ?/sec
build_schedule/100_schedule 1.02 13.1±0.33ms ? ?/sec 1.00 12.9±0.28ms ? ?/sec
build_schedule/100_schedule_noconstraints 1.08 505.3±29.30µs ? ?/sec 1.00 469.4±12.48µs ? ?/sec
build_schedule/500_schedule 1.00 485.5±6.29ms ? ?/sec 1.00 485.5±9.80ms ? ?/sec
build_schedule/500_schedule_noconstraints 1.00 6.8±0.10ms ? ?/sec 1.02 6.9±0.16ms ? ?/sec
```
---
## Changelog
- Auto insert sync points and added `after_ignore_deferred`,
`before_ignore_deferred`, `chain_no_deferred` and
`auto_insert_apply_deferred` APIs to opt out of this behavior
## Migration Guide
- `apply_deferred` points are added automatically when there is ordering
relationship with a system that has deferred parameters like `Commands`.
If you want to opt out of this you can switch from `after`, `before`,
and `chain` to the corresponding `ignore_deferred` API,
`after_ignore_deferred`, `before_ignore_deferred` or
`chain_ignore_deferred` for your system/set ordering.
- You can also set `ScheduleBuildSettings::auto_insert_sync_points` to
`false` if you want to do it for the whole schedule. Note that in this
mode you can still add `apply_deferred` points manually.
- For most manual insertions of `apply_deferred` you should remove them
as they cannot be merged with the automatically inserted points and
might reduce parallelizability of the system graph.
## TODO
- [x] remove any apply_deferred used in the engine
- [x] ~~decide if we should deprecate manually using apply_deferred.~~
We'll still allow inserting manual sync points for now for whatever edge
cases users might have.
- [x] Update migration guide
- [x] rerun schedule build benchmarks
---------
Co-authored-by: Joseph <21144246+JoJoJet@users.noreply.github.com>
# Objective
- Finish the work done in #8942 .
## Solution
- Rebase the changes made in #8942 and fix the issues stopping it from
being merged earlier
---------
Co-authored-by: Thomas <1234328+thmsgntz@users.noreply.github.com>
# Objective
Make direction construction a bit more ergonomic.
## Solution
Add `Direction2d::from_xy` and `Direction3d::from_xyz`, similar to
`Transform::from_xyz`:
```rust
let dir2 = Direction2d::from_xy(0.5, 0.5).unwrap();
let dir3 = Direction3d::from_xyz(0.5, 0.5, 0.5).unwrap();
```
This can be a bit cleaner than using `new`:
```rust
let dir2 = Direction2d::new(Vec2::new(0.5, 0.5)).unwrap();
let dir3 = Direction3d::new(Vec3::new(0.5, 0.5, 0.5)).unwrap();
```
Fixes https://github.com/bevyengine/bevy/issues/10974
# Objective
Duplicate the ordering logic of the `Main` schedule into the `FixedMain`
schedule.
---
## Changelog
- `FixedUpdate` is no longer the main schedule ran in
`RunFixedUpdateLoop`, `FixedMain` has replaced this and has a similar
structure to `Main`.
## Migration Guide
- Usage of `RunFixedUpdateLoop` should be renamed to `RunFixedMainLoop`.
# Objective
Fixes#10968
## Solution
Pull startup schedules from a list of `ScheduleLabel`s in the same way
the update schedules are handled.
---
## Changelog
- Added `MainScheduleOrder::startup_labels` to allow the editing of the
startup schedule order.
## Migration Guide
- Added a new field to `MainScheduleOrder`, `startup_labels`, for
editing the startup schedule order.
# Objective
Keep up to date with wgpu.
## Solution
Update the wgpu version.
Currently blocked on naga_oil updating to naga 0.14 and releasing a new
version.
3d scenes (or maybe any scene with lighting?) currently don't render
anything due to
```
error: naga_oil bug, please file a report: composer failed to build a valid header: Type [2] '' is invalid
= Capability Capabilities(CUBE_ARRAY_TEXTURES) is required
```
I'm not sure what should be passed in for `wgpu::InstanceFlags`, or if we want to make the gles3minorversion configurable (might be useful for debugging?)
Currently blocked on https://github.com/bevyengine/naga_oil/pull/63, and https://github.com/gfx-rs/wgpu/issues/4569 to be fixed upstream in wgpu first.
## Known issues
Amd+windows+vulkan has issues with texture_binding_arrays (see the image [here](https://github.com/bevyengine/bevy/pull/10266#issuecomment-1819946278)), but that'll be fixed in the next wgpu/naga version, and you can just use dx12 as a workaround for now (Amd+linux mesa+vulkan texture_binding_arrays are fixed though).
---
## Changelog
Updated wgpu to 0.18, naga to 0.14.2, and naga_oil to 0.11.
- Windows desktop GL should now be less painful as it no longer requires Angle.
- You can now toggle shader validation and debug information for debug and release builds using `WgpuSettings.instance_flags` and [InstanceFlags](https://docs.rs/wgpu/0.18.0/wgpu/struct.InstanceFlags.html)
## Migration Guide
- `RenderPassDescriptor` `color_attachments` (as well as `RenderPassColorAttachment`, and `RenderPassDepthStencilAttachment`) now use `StoreOp::Store` or `StoreOp::Discard` instead of a `boolean` to declare whether or not they should be stored.
- `RenderPassDescriptor` now have `timestamp_writes` and `occlusion_query_set` fields. These can safely be set to `None`.
- `ComputePassDescriptor` now have a `timestamp_writes` field. This can be set to `None` for now.
- See the [wgpu changelog](https://github.com/gfx-rs/wgpu/blob/trunk/CHANGELOG.md#v0180-2023-10-25) for additional details
# Objective
- Make the implementation order consistent between all sources to fit
the order in the trait.
## Solution
- Change the implementation order.
# Objective
A workaround for a webgl issue was introduced in #9383 but one function
for mesh2d was missed.
## Solution
Applied the migration guide from #9383 in
`mesh2d_normal_local_to_world()
Note: I'm not using normals so I have not tested the bug & fix
# Objective
The documentation for `AnimationPlayer::play` mentions a non-existent
`transition_duration` argument from an old iteration of the API. It's
confusing.
## Solution
Remove the offending sentence.
# Objective
Since #10776 split `WorldQuery` to `WorldQueryData` and
`WorldQueryFilter`, it should be clear that the query is actually
composed of two parts. It is not factually correct to call "query" only
the data part. Therefore I suggest to rename the `Q` parameter to `D` in
`Query` and related items.
As far as I know, there shouldn't be breaking changes from renaming
generic type parameters.
## Solution
I used a combination of rust-analyzer go to reference and `Ctrl-F`ing
various patterns to catch as many cases as possible. Hopefully I got
them all. Feel free to check if you're concerned of me having missed
some.
## Notes
This and #10779 have many lines in common, so merging one will cause a
lot of merge conflicts to the other.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- The example in the docs is unsound.
Demo:
```rust
#[derive(Resource)]
struct MyRes(u32);
fn main() {
let mut w = World::new();
w.insert_resource(MyRes(0));
let (mut res, comp) = split_world_access(&mut w);
let mut r1 = res.get_resource_mut::<MyRes>().unwrap();
let mut r2 = res.get_resource_mut::<MyRes>().unwrap();
*r1 = MyRes(1);
*r2 = MyRes(2);
}
```
The API in the example allows aliasing mutable references to the same
resource. Miri also complains when running this.
## Solution
- Change the example API to make the returned `Mut` borrow from the
`OnlyResourceAccessWorld` instead of borrowing from the world via `'w`.
This prevents obtaining more than one `Mut` at the same time from it.
I didn't notice minus where vertices are generated, so could not
understand the order there.
Adding a comment to help the next person who is going to understand Bevy
by reading its code.
# Objective
- Reduce nesting in `process_handle_drop_internal()`.
- Related to #10896.
## Solution
- Use early returns when possible.
- Reduced from 9 levels of indents to 4.
# Objective
add `RenderLayers` awareness to lights. lights default to
`RenderLayers::layer(0)`, and must intersect the camera entity's
`RenderLayers` in order to affect the camera's output.
note that lights already use renderlayers to filter meshes for shadow
casting. this adds filtering lights per view based on intersection of
camera layers and light layers.
fixes#3462
## Solution
PointLights and SpotLights are assigned to individual views in
`assign_lights_to_clusters`, so we simply cull the lights which don't
match the view layers in that function.
DirectionalLights are global, so we
- add the light layers to the `DirectionalLight` struct
- add the view layers to the `ViewUniform` struct
- check for intersection before processing the light in
`apply_pbr_lighting`
potential issue: when mesh/light layers are smaller than the view layers
weird results can occur. e.g:
camera = layers 1+2
light = layers 1
mesh = layers 2
the mesh does not cast shadows wrt the light as (1 & 2) == 0.
the light affects the view as (1+2 & 1) != 0.
the view renders the mesh as (1+2 & 2) != 0.
so the mesh is rendered and lit, but does not cast a shadow.
this could be fixed (so that the light would not affect the mesh in that
view) by adding the light layers to the point and spot light structs,
but i think the setup is pretty unusual, and space is at a premium in
those structs (adding 4 bytes more would reduce the webgl point+spot
light max count to 240 from 256).
I think typical usage is for cameras to have a single layer, and
meshes/lights to maybe have multiple layers to render to e.g. minimaps
as well as primary views.
if there is a good use case for the above setup and we should support
it, please let me know.
---
## Migration Guide
Lights no longer affect all `RenderLayers` by default, now like cameras
and meshes they default to `RenderLayers::layer(0)`. To recover the
previous behaviour and have all lights affect all views, add a
`RenderLayers::all()` component to the light entity.
# Objective
Printing `DynamicStruct` with a debug format does not show the contained
type anymore. For instance, in `examples/reflection/reflection.rs`,
adding `dbg!(&reflect_value);` to line 96 will print:
```rust
[examples/reflection/reflection.rs:96] &reflect_value = DynamicStruct(bevy_reflect::DynamicStruct {
a: 4,
nested: DynamicStruct(bevy_reflect::DynamicStruct {
b: 8,
}),
})
```
## Solution
Show the represented type instead (`reflection::Foo` and
`reflection::Bar` in this case):
```rust
[examples/reflection/reflection.rs:96] &reflect_value = DynamicStruct(reflection::Foo {
a: 4,
nested: DynamicStruct(reflection::Bar {
b: 8,
}),
})
```
---------
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
# Objective
The `Despawn` command breaks the hierarchy whenever you use it if the
despawned entity has a parent or any children. This is a serious footgun
because the `Despawn` command has the shortest name, the behavior is
unexpected and not likely to be what you want, and the crash that it
causes can be very difficult to track down.
## Solution
Until this can be fixed by relations, add a note mentioning the footgun
in the documentation.
## Solution
`Commands.remove` and `.retain` (because I copied `remove`s doc)
referenced `EntityWorldMut.remove` and `retain` for more detail but the
`Commands` docs are much more detailed (which makes sense because it is
the most common api), so I have instead inverted this so that
`EntityWorldMut` docs link to `Commands`.
I also made `EntityWorldMut.despawn` reference `World.despawn` for more
details, like `Commands.despawn` does.
# Objective
Fixes#5891.
For mikktspace normal maps, normals must be renormalized in vertex
shaders to match the way mikktspace bakes vertex tangents and normal
maps so that the exact inverse process is applied when shading.
However, for invalid normals like `vec3<f32>(0.0, 0.0, 0.0)`, this
normalization causes NaN values, and because it's in the vertex shader,
it affects the entire triangle and causes it to be shaded as black:
*A cone with a tip that has a vertex normal of [0, 0, 0], causing the
mesh to be shaded as black.*
In some cases, normals of zero are actually *useful*. For example, a
smoothly shaded cone without creases requires the apex vertex normal to
be zero, because there is no singular normal that works correctly, so
the apex shouldn't contribute to the overall shading. Duplicate vertices
for the apex fix some shading issues, but it causes visible creases and
is more expensive. See #5891 and #10298 for more details.
For correctly shaded cones and other similar low-density shapes with
sharp tips, vertex normals of zero can not be normalized in the vertex
shader.
## Solution
Only normalize the vertex normals and tangents in the vertex shader if
the normal isn't [0, 0, 0]. This way, mikktspace normal maps should
still work for everything except the zero normals, and the zero normals
will only be normalized in the fragment shader.
This allows us to render cones correctly:
Notice how there is still a weird shadow banding effect in one area. I
noticed that it can be fixed by normalizing
[here](d2614f2d80/crates/bevy_pbr/src/render/pbr_functions.wgsl (L51)),
which produces a perfectly smooth cone without duplicate vertices:
I didn't add this change yet, because it seems a bit arbitrary. I can
add it here if that'd be useful or make another PR though.
# Objective
`update_accessibility_nodes` is one of the most nested functions in the
entire Bevy repository, with a maximum of 9 levels of indentations. This
PR refactors it down to 3 levels of indentations, while improving
readability on other fronts. The result is a function that is actually
understandable at a first glance.
- This is a proof of concept to demonstrate that it is possible to
gradually lower the nesting limit proposed by #10896.
PS: I read AccessKit's documentation, but I don't have experience with
it. Therefore, naming of variables and subroutines may be a bit off.
PS2: I don't know if the test suite covers the functionality of this
system, but since I've spent quite some time on it and the changes were
simple, I'm pretty confident the refactor is functionally equivalent to
the original.
## Solution
I documented each change with a commit, but as a summary I did the
following to reduce nesting:
- I moved from `if-let` blocks to `let-else` statements where
appropriate to reduce rightward shift
- I extracted the closure body to a new function `update_adapter`
- I factored out parts of `update_adapter` into new functions
`queue_node_for_update` and `add_children_nodes`
**Note for reviewers:** GitHub's diff viewer is not the greatest in
showing horizontal code shifts, therefore you may want to use a
different tool like VSCode to review some commits, especially the second
one (anyway, that commit is very straightforward, despite changing many
lines).
# Objective
A nodes outline should be clipped using its own clipping rect, not its
parents.
fixes#10921
## Solution
Clip outlines by the node's own clipping rect, not the parent's.
If you compare the `overflow` ui example in main with this PR, you'll
see that the outlines that appear when you hover above the images are
now clipped along with the images.
---
## Changelog
* Outlines are now clipped using the node's own clipping rect, not the
parent's.
# Objective
- Improve readability.
- Somewhat relates to #10896.
## Solution
- Use early returns to minimize nesting.
- Change `emitter_translation` to use `if let` instead of `map`.
# Objective
The `update_emitter_positions`, and `update_listener_positions` systems
are added for every call to `add_audio_source`.
Instead, add them once in the `AudioPlugin` directly.
Also merged the calls to `add_systems`.
Caught while working on my schedule visualizer c:
# Objective
Test more complex function signatures for exclusive systems, and test
that `StaticSystemParam` is indeed a `SystemParam`.
I mean, it currently works, but might as well add a test for it.
# Objective
- Resolves#10853
## Solution
- ~~Changed the name of `Input` struct to `PressableInput`.~~
- Changed the name of `Input` struct to `ButtonInput`.
## Migration Guide
- Breaking Change: Users need to rename `Input` to `ButtonInput` in
their projects.
# Objective
A better alternative version of #10843.
Currently, Bevy has a single `Ray` struct for 3D. To allow better
interoperability with Bevy's primitive shapes (#10572) and some third
party crates (that handle e.g. spatial queries), it would be very useful
to have separate versions for 2D and 3D respectively.
## Solution
Separate `Ray` into `Ray2d` and `Ray3d`. These new structs also take
advantage of the new primitives by using `Direction2d`/`Direction3d` for
the direction:
```rust
pub struct Ray2d {
pub origin: Vec2,
pub direction: Direction2d,
}
pub struct Ray3d {
pub origin: Vec3,
pub direction: Direction3d,
}
```
and by using `Plane2d`/`Plane3d` in `intersect_plane`:
```rust
impl Ray2d {
// ...
pub fn intersect_plane(&self, plane_origin: Vec2, plane: Plane2d) -> Option<f32> {
// ...
}
}
```
---
## Changelog
### Added
- `Ray2d` and `Ray3d`
- `Ray2d::new` and `Ray3d::new` constructors
- `Plane2d::new` and `Plane3d::new` constructors
### Removed
- Removed `Ray` in favor of `Ray3d`
### Changed
- `direction` is now a `Direction2d`/`Direction3d` instead of a vector,
which provides guaranteed normalization
- `intersect_plane` now takes a `Plane2d`/`Plane3d` instead of just a
vector for the plane normal
- `Direction2d` and `Direction3d` now derive `Serialize` and
`Deserialize` to preserve ray (de)serialization
## Migration Guide
`Ray` has been renamed to `Ray3d`.
### Ray creation
Before:
```rust
Ray {
origin: Vec3::ZERO,
direction: Vec3::new(0.5, 0.6, 0.2).normalize(),
}
```
After:
```rust
// Option 1:
Ray3d {
origin: Vec3::ZERO,
direction: Direction3d::new(Vec3::new(0.5, 0.6, 0.2)).unwrap(),
}
// Option 2:
Ray3d::new(Vec3::ZERO, Vec3::new(0.5, 0.6, 0.2))
```
### Plane intersections
Before:
```rust
let result = ray.intersect_plane(Vec2::X, Vec2::Y);
```
After:
```rust
let result = ray.intersect_plane(Vec2::X, Plane2d::new(Vec2::Y));
```
# Objective
Implement `TryFrom<Vec2>`/`TryFrom<Vec3>` for direction primitives as
considered in #10857.
## Solution
Implement `TryFrom` for the direction primitives.
These are all equivalent:
```rust
let dir2d = Direction2d::try_from(Vec2::new(0.5, 0.5)).unwrap();
let dir2d = Vec2::new(0.5, 0.5).try_into().unwrap(); // (assumes that the type is inferred)
let dir2d = Direction2d::new(Vec2::new(0.5, 0.5)).unwrap();
```
For error cases, an `Err(InvalidDirectionError)` is returned. It
contains the type of failure:
```rust
/// An error indicating that a direction is invalid.
#[derive(Debug, PartialEq)]
pub enum InvalidDirectionError {
/// The length of the direction vector is zero or very close to zero.
Zero,
/// The length of the direction vector is `std::f32::INFINITY`.
Infinite,
/// The length of the direction vector is `NaN`.
NaN,
}
```
# Objective
- Resolves#10784
## Solution
- As @ickshonpe mentioned in #10784, this is intended behavior but could
benefit from mentioning it in docs.
- I'm also thinking about adding a helper function to disable os scaling
such as `disable_os_scaling()`, but not sure if it's needed.
---
## Changelog
> Add a comment about scaling behavior that happens, and point user to
how he can avoid that behavior.
# Objective
Adds `EntityCommands.retain` and `EntityWorldMut.retain` to remove all
components except the given bundle from the entity.
Fixes#10865.
## Solution
I added a private unsafe function in `EntityWorldMut` called
`remove_bundle_info` which performs the shared behaviour of `remove` and
`retain`, namely taking a `BundleInfo` of components to remove, and
removing them from the given entity. Then `retain` simply gets all the
components on the entity and filters them by whether they are in the
bundle it was passed, before passing this `BundleInfo` into
`remove_bundle_info`.
`EntityCommands.retain` just creates a new type `Retain` which runs
`EntityWorldMut.retain` when run.
---
## Changelog
Added `EntityCommands.retain` and `EntityWorldMut.retain`, which remove
all components except the given bundle from the entity, they can also be
used to remove all components by passing `()` as the bundle.
# Objective
The name `TextAlignment` is really deceptive and almost every new user
gets confused about the differences between aligning text with
`TextAlignment`, aligning text with `Style` and aligning text with
anchor (when using `Text2d`).
## Solution
* Rename `TextAlignment` to `JustifyText`. The associated helper methods
are also renamed.
* Improve the doc comments for text explaining explicitly how the
`JustifyText` component affects the arrangement of text.
* Add some extra cases to the `text_debug` example that demonstate the
differences between alignment using `JustifyText` and alignment using
`Style`.
<img width="757" alt="text_debug_2"
src="https://github.com/bevyengine/bevy/assets/27962798/9d53e647-93f9-4bc7-8a20-0d9f783304d2">
---
## Changelog
* `TextAlignment` has been renamed to `JustifyText`
* `TextBundle::with_text_alignment` has been renamed to
`TextBundle::with_text_justify`
* `Text::with_alignment` has been renamed to `Text::with_justify`
* The `text_alignment` field of `TextMeasureInfo` has been renamed to
`justification`
## Migration Guide
* `TextAlignment` has been renamed to `JustifyText`
* `TextBundle::with_text_alignment` has been renamed to
`TextBundle::with_text_justify`
* `Text::with_alignment` has been renamed to `Text::with_justify`
* The `text_alignment` field of `TextMeasureInfo` has been renamed to
`justification`
# Objective
- Fixes#10806
## Solution
Replaced `new` and `index` methods for both `TableRow` and `TableId`
with `from_*` and `as_*` methods. These remove the need to perform
casting at call sites, reducing the total number of casts in the Bevy
codebase. Within these methods, an appropriate `debug_assertion` ensures
the cast will behave in an expected manner (no wrapping, etc.). I am
using a `debug_assertion` instead of an `assert` to reduce any possible
runtime overhead, however minimal. This choice is something I am open to
changing (or leaving up to another PR) if anyone has any strong
arguments for it.
---
## Changelog
- `ComponentSparseSet::sparse` stores a `TableRow` instead of a `u32`
(private change)
- Replaced `TableRow::new` and `TableRow::index` methods with
`TableRow::from_*` and `TableRow::as_*`, with `debug_assertions`
protecting any internal casting.
- Replaced `TableId::new` and `TableId::index` methods with
`TableId::from_*` and `TableId::as_*`, with `debug_assertions`
protecting any internal casting.
- All `TableId` methods are now `const`
## Migration Guide
- `TableRow::new` -> `TableRow::from_usize`
- `TableRow::index` -> `TableRow::as_usize`
- `TableId::new` -> `TableId::from_usize`
- `TableId::index` -> `TableId::as_usize`
---
## Notes
I have chosen to remove the `index` and `new` methods for the following
chain of reasoning:
- Across the codebase, `new` was called with a mixture of `u32` and
`usize` values. Likewise for `index`.
- Choosing `new` to either be `usize` or `u32` would break half of these
call-sites, requiring `as` casting at the site.
- Adding a second method `new_u32` or `new_usize` avoids the above, bu
looks visually inconsistent.
- Therefore, they should be replaced with `from_*` and `as_*` methods
instead.
Worth noting is that by updating `ComponentSparseSet`, there are now
zero instances of interacting with the inner value of `TableRow` as a
`u32`, it is exclusively used as a `usize` value (due to interactions
with methods like `len` and slice indexing). I have left the `as_u32`
and `from_u32` methods as the "proper" constructors/getters.
This removes the `From<Vec2/3>` implementations for the direction types.
It doesn't seem right to have when it only works if the vector is
nonzero and finite and produces NaN otherwise.
Added `Direction2d/3d::new` which uses `Vec2/3::try_normalize` to
guarantee it returns either a valid direction or `None`.
This should make it impossible to create an invalid direction, which I
think was the intention with these types.
Bevy builds on a ton of different libraries. Choosing who gets "prime
real estate" in the readme is hard / political. Closing that can of
worms makes a lot of sense to me.
I have also removed the "alternatives" section for similar reasons.
There are a number of engines/libs that aren't credited there, some of
those listed no longer exist / aren't maintained, and it isn't really
our job to be the canonical source. Each alternative listed is a soft
endorsement of the project (and the reverse is true for projects we
don't include). Again, closing this can of worms feels like the right
call.
# Objective
Fixes#10291
This adds a way to easily log messages once within system which are
called every frame.
## Solution
Opted for a macro-based approach. The fact that the 'once' call is
tracked per call site makes the `log_once!()` macro very versatile and
easy-to-use. I suspect it will be very handy for all of us, but
especially beginners, to get some initial feedback from systems without
spamming up the place!
I've made the macro's return its internal `has_fired` state, for
situations in which that might be useful to know (trigger something else
alongside the log, for example).
Please let me know if I placed the macro's in the right location, and if
you would like me to do something more clever with the macro's
themselves, since its looking quite copy-pastey at the moment. I've
tried ways to replace 5 with 1 macro's, but no success yet.
One downside of this approach is: Say you wish to warn the user if a
resource is invalid. In this situation, the
`resource.is_valid()` check would still be performed every frame:
```rust
fn my_system(my_res: Res<MyResource>) {
if !my_res.is_valid() {
warn_once!("resource is invalid!");
}
}
```
If you want to prevent that, you would still need to introduce a local
boolean. I don't think this is a very big deal, as expensive checks
shouldn't be called every frame in any case.
## Changelog
Added: `trace_once!()`, `debug_once!()`, `info_once!()`, `warn_once!()`,
and `error_once!()` log macros which fire only once per call site.
