# Objective
Expand the existing `Query` API to support more dynamic use cases i.e.
scripting.
## Prior Art
- #6390
- #8308
- #10037
## Solution
- Create a `QueryBuilder` with runtime methods to define the set of
component accesses for a built query.
- Create new `WorldQueryData` implementations `FilteredEntityMut` and
`FilteredEntityRef` as variants of `EntityMut` and `EntityRef` that
provide run time checked access to the components included in a given
query.
- Add new methods to `Query` to create "query lens" with a subset of the
access of the initial query.
### Query Builder
The `QueryBuilder` API allows you to define a query at runtime. At it's
most basic use it will simply create a query with the corresponding type
signature:
```rust
let query = QueryBuilder::<Entity, With<A>>::new(&mut world).build();
// is equivalent to
let query = QueryState::<Entity, With<A>>::new(&mut world);
```
Before calling `.build()` you also have the opportunity to add
additional accesses and filters. Here is a simple example where we add
additional filter terms:
```rust
let entity_a = world.spawn((A(0), B(0))).id();
let entity_b = world.spawn((A(0), C(0))).id();
let mut query_a = QueryBuilder::<Entity>::new(&mut world)
.with::<A>()
.without::<C>()
.build();
assert_eq!(entity_a, query_a.single(&world));
```
This alone is useful in that allows you to decide which archetypes your
query will match at runtime. However it is also very limited, consider a
case like the following:
```rust
let query_a = QueryBuilder::<&A>::new(&mut world)
// Add an additional access
.data::<&B>()
.build();
```
This will grant the query an additional read access to component B
however we have no way of accessing the data while iterating as the type
signature still only includes &A. For an even more concrete example of
this consider dynamic components:
```rust
let query_a = QueryBuilder::<Entity>::new(&mut world)
// Adding a filter is easy since it doesn't need be read later
.with_id(component_id_a)
// How do I access the data of this component?
.ref_id(component_id_b)
.build();
```
With this in mind the `QueryBuilder` API seems somewhat incomplete by
itself, we need some way method of accessing the components dynamically.
So here's one:
### Query Transmutation
If the problem is not having the component in the type signature why not
just add it? This PR also adds transmute methods to `QueryBuilder` and
`QueryState`. Here's a simple example:
```rust
world.spawn(A(0));
world.spawn((A(1), B(0)));
let mut query = QueryBuilder::<()>::new(&mut world)
.with::<B>()
.transmute::<&A>()
.build();
query.iter(&world).for_each(|a| assert_eq!(a.0, 1));
```
The `QueryState` and `QueryBuilder` transmute methods look quite similar
but are different in one respect. Transmuting a builder will always
succeed as it will just add the additional accesses needed for the new
terms if they weren't already included. Transmuting a `QueryState` will
panic in the case that the new type signature would give it access it
didn't already have, for example:
```rust
let query = QueryState::<&A, Option<&B>>::new(&mut world);
/// This is fine, the access for Option<&A> is less restrictive than &A
query.transmute::<Option<&A>>(&world);
/// Oh no, this would allow access to &B on entities that might not have it, so it panics
query.transmute::<&B>(&world);
/// This is right out
query.transmute::<&C>(&world);
```
This is quite an appealing API to also have available on `Query` however
it does pose one additional wrinkle: In order to to change the iterator
we need to create a new `QueryState` to back it. `Query` doesn't own
it's own state though, it just borrows it, so we need a place to borrow
it from. This is why `QueryLens` exists, it is a place to store the new
state so it can be borrowed when you call `.query()` leaving you with an
API like this:
```rust
fn function_that_takes_a_query(query: &Query<&A>) {
// ...
}
fn system(query: Query<(&A, &B)>) {
let lens = query.transmute_lens::<&A>();
let q = lens.query();
function_that_takes_a_query(&q);
}
```
Now you may be thinking: Hey, wait a second, you introduced the problem
with dynamic components and then described a solution that only works
for static components! Ok, you got me, I guess we need a bit more:
### Filtered Entity References
Currently the only way you can access dynamic components on entities
through a query is with either `EntityMut` or `EntityRef`, however these
can access all components and so conflict with all other accesses. This
PR introduces `FilteredEntityMut` and `FilteredEntityRef` as
alternatives that have additional runtime checking to prevent accessing
components that you shouldn't. This way you can build a query with a
`QueryBuilder` and actually access the components you asked for:
```rust
let mut query = QueryBuilder::<FilteredEntityRef>::new(&mut world)
.ref_id(component_id_a)
.with(component_id_b)
.build();
let entity_ref = query.single(&world);
// Returns Some(Ptr) as we have that component and are allowed to read it
let a = entity_ref.get_by_id(component_id_a);
// Will return None even though the entity does have the component, as we are not allowed to read it
let b = entity_ref.get_by_id(component_id_b);
```
For the most part these new structs have the exact same methods as their
non-filtered equivalents.
Putting all of this together we can do some truly dynamic ECS queries,
check out the `dynamic` example to see it in action:
```
Commands:
comp, c Create new components
spawn, s Spawn entities
query, q Query for entities
Enter a command with no parameters for usage.
> c A, B, C, Data 4
Component A created with id: 0
Component B created with id: 1
Component C created with id: 2
Component Data created with id: 3
> s A, B, Data 1
Entity spawned with id: 0v0
> s A, C, Data 0
Entity spawned with id: 1v0
> q &Data
0v0: Data: [1, 0, 0, 0]
1v0: Data: [0, 0, 0, 0]
> q B, &mut Data
0v0: Data: [2, 1, 1, 1]
> q B || C, &Data
0v0: Data: [2, 1, 1, 1]
1v0: Data: [0, 0, 0, 0]
```
## Changelog
- Add new `transmute_lens` methods to `Query`.
- Add new types `QueryBuilder`, `FilteredEntityMut`, `FilteredEntityRef`
and `QueryLens`
- `update_archetype_component_access` has been removed, archetype
component accesses are now determined by the accesses set in
`update_component_access`
- Added method `set_access` to `WorldQuery`, this is called before
`update_component_access` for queries that have a restricted set of
accesses, such as those built by `QueryBuilder` or `QueryLens`. This is
primarily used by the `FilteredEntity*` variants and has an empty trait
implementation.
- Added method `get_state` to `WorldQuery` as a fallible version of
`init_state` when you don't have `&mut World` access.
## Future Work
Improve performance of `FilteredEntityMut` and `FilteredEntityRef`,
currently they have to determine the accesses a query has in a given
archetype during iteration which is far from ideal, especially since we
already did the work when matching the archetype in the first place. To
avoid making more internal API changes I have left it out of this PR.
---------
Co-authored-by: Mike Hsu <mike.hsu@gmail.com>
Rebased and finished version of
https://github.com/bevyengine/bevy/pull/8407. Huge thanks to @GitGhillie
for adjusting all the examples, and the many other people who helped
write this PR (@superdump , @coreh , among others) :)
Fixes https://github.com/bevyengine/bevy/issues/8369
---
## Changelog
- Added a `brightness` control to `Skybox`.
- Added an `intensity` control to `EnvironmentMapLight`.
- Added `ExposureSettings` and `PhysicalCameraParameters` for
controlling exposure of 3D cameras.
- Removed the baked-in `DirectionalLight` exposure Bevy previously
hardcoded internally.
## Migration Guide
- If using a `Skybox` or `EnvironmentMapLight`, use the new `brightness`
and `intensity` controls to adjust their strength.
- All 3D scene will now have different apparent brightnesses due to Bevy
implementing proper exposure controls. You will have to adjust the
intensity of your lights and/or your camera exposure via the new
`ExposureSettings` component to compensate.
---------
Co-authored-by: Robert Swain <robert.swain@gmail.com>
Co-authored-by: GitGhillie <jillisnoordhoek@gmail.com>
Co-authored-by: Marco Buono <thecoreh@gmail.com>
Co-authored-by: vero <email@atlasdostal.com>
Co-authored-by: atlas dostal <rodol@rivalrebels.com>
# Objective
This PR is heavily inspired by
https://github.com/bevyengine/bevy/pull/7682
It aims to solve the same problem: allowing the user to extend the
tracing subscriber with extra layers.
(in my case, I'd like to use `use
metrics_tracing_context::{MetricsLayer, TracingContextLayer};`)
## Solution
I'm proposing a different api where the user has the opportunity to take
the existing `subscriber` and apply any transformations on it.
---
## Changelog
- Added a `update_subscriber` option on the `LogPlugin` that lets the
user modify the `subscriber` (for example to extend it with more tracing
`Layers`
## Migration Guide
> This section is optional. If there are no breaking changes, you can
delete this section.
- Added a new field `update_subscriber` in the `LogPlugin`
---------
Co-authored-by: Charles Bournhonesque <cbournhonesque@snapchat.com>
# Objective
Re this comment:
https://github.com/bevyengine/bevy/pull/11141#issuecomment-1872455313
Since https://github.com/bevyengine/bevy/pull/9822, Bevy automatically
inserts `apply_deferred` between systems with dependencies where needed,
so manually inserted `apply_deferred` doesn't to anything useful, and in
current state this example does more harm than good.
## Solution
The example can be modified with removal of automatic `apply_deferred`
insertion, but that would immediately upgrade this example from beginner
level, to upper intermediate. Most users don't need to disable automatic
sync point insertion, and remaining few who do probably already know how
it works.
CC @hymm
# Objective
- Make it possible to react to arbitrary state changes
- this will be useful regardless of the other changes to states
currently being discussed
## Solution
- added `StateTransitionEvent<S>` struct
- previously, this would have been impossible:
```rs
#[derive(States, Eq, PartialEq, Hash, Copy, Clone, Default)]
enum MyState {
#[default]
Foo,
Bar(MySubState),
}
enum MySubState {
Spam,
Eggs,
}
app.add_system(Update, on_enter_bar);
fn on_enter_bar(trans: EventReader<StateTransition<MyState>>){
for (befoare, after) in trans.read() {
match before, after {
MyState::Foo, MyState::Bar(_) => info!("detected transition foo => bar");
_, _ => ();
}
}
}
```
---
## Changelog
- Added
- `StateTransitionEvent<S>` - Fired on state changes of `S`
## Migration Guide
N/A no breaking changes
---------
Co-authored-by: Federico Rinaldi <gisquerin@gmail.com>
# Motivation
When spawning entities into a scene, it is very common to create assets
like meshes and materials and to add them via asset handles. A common
setup might look like this:
```rust
fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
commands.spawn(PbrBundle {
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
material: materials.add(StandardMaterial::from(Color::RED)),
..default()
});
}
```
Let's take a closer look at the part that adds the assets using `add`.
```rust
mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
material: materials.add(StandardMaterial::from(Color::RED)),
```
Here, "mesh" and "material" are both repeated three times. It's very
explicit, but I find it to be a bit verbose. In addition to being more
code to read and write, the extra characters can sometimes also lead to
the code being formatted to span multiple lines even though the core
task, adding e.g. a primitive mesh, is extremely simple.
A way to address this is by using `.into()`:
```rust
mesh: meshes.add(shape::Cube { size: 1.0 }.into()),
material: materials.add(Color::RED.into()),
```
This is fine, but from the names and the type of `meshes`, we already
know what the type should be. It's very clear that `Cube` should be
turned into a `Mesh` because of the context it's used in. `.into()` is
just seven characters, but it's so common that it quickly adds up and
gets annoying.
It would be nice if you could skip all of the conversion and let Bevy
handle it for you:
```rust
mesh: meshes.add(shape::Cube { size: 1.0 }),
material: materials.add(Color::RED),
```
# Objective
Make adding assets more ergonomic by making `Assets::add` take an `impl
Into<A>` instead of `A`.
## Solution
`Assets::add` now takes an `impl Into<A>` instead of `A`, so e.g. this
works:
```rust
commands.spawn(PbrBundle {
mesh: meshes.add(shape::Cube { size: 1.0 }),
material: materials.add(Color::RED),
..default()
});
```
I also changed all examples to use this API, which increases consistency
as well because `Mesh::from` and `into` were being used arbitrarily even
in the same file. This also gets rid of some lines of code because
formatting is nicer.
---
## Changelog
- `Assets::add` now takes an `impl Into<A>` instead of `A`
- Examples don't use `T::from(K)` or `K.into()` when adding assets
## Migration Guide
Some `into` calls that worked previously might now be broken because of
the new trait bounds. You need to either remove `into` or perform the
conversion explicitly with `from`:
```rust
// Doesn't compile
let mesh_handle = meshes.add(shape::Cube { size: 1.0 }.into()),
// These compile
let mesh_handle = meshes.add(shape::Cube { size: 1.0 }),
let mesh_handle = meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
```
## Concerns
I believe the primary concerns might be:
1. Is this too implicit?
2. Does this increase codegen bloat?
Previously, the two APIs were using `into` or `from`, and now it's
"nothing" or `from`. You could argue that `into` is slightly more
explicit than "nothing" in cases like the earlier examples where a
`Color` gets converted to e.g. a `StandardMaterial`, but I personally
don't think `into` adds much value even in this case, and you could
still see the actual type from the asset type.
As for codegen bloat, I doubt it adds that much, but I'm not very
familiar with the details of codegen. I personally value the user-facing
code reduction and ergonomics improvements that these changes would
provide, but it might be worth checking the other effects in more
detail.
Another slight concern is migration pain; apps might have a ton of
`into` calls that would need to be removed, and it did take me a while
to do so for Bevy itself (maybe around 20-40 minutes). However, I think
the fact that there *are* so many `into` calls just highlights that the
API could be made nicer, and I'd gladly migrate my own projects for it.
# Objective
Fix#10731.
## Solution
Rename `App::add_state<T>(&mut self)` to `init_state`, and add
`App::insert_state<T>(&mut self, state: T)`. I decided on these names
because they are more similar to `init_resource` and `insert_resource`.
I also removed the `States` trait's requirement for `Default`. Instead,
`init_state` requires `FromWorld`.
---
## Changelog
- Renamed `App::add_state` to `init_state`.
- Added `App::insert_state`.
- Removed the `States` trait's requirement for `Default`.
## Migration Guide
- Renamed `App::add_state` to `init_state`.
# Objective
- Update winit dependency to 0.29
## Changelog
### KeyCode changes
- Removed `ScanCode`, as it was [replaced by
KeyCode](https://github.com/rust-windowing/winit/blob/master/CHANGELOG.md#0292).
- `ReceivedCharacter.char` is now a `SmolStr`, [relevant
doc](https://docs.rs/winit/latest/winit/event/struct.KeyEvent.html#structfield.text).
- Changed most `KeyCode` values, and added more.
KeyCode has changed meaning. With this PR, it refers to physical
position on keyboard rather than the printed letter on keyboard keys.
In practice this means:
- On QWERTY keyboard layouts, nothing changes
- On any other keyboard layout, `KeyCode` no longer reflects the label
on key.
- This is "good". In bevy 0.12, when you used WASD for movement, users
with non-QWERTY keyboards couldn't play your game! This was especially
bad for non-latin keyboards. Now, WASD represents the physical keys. A
French player will press the ZQSD keys, which are near each other,
Kyrgyz players will use "Цфыв".
- This is "bad" as well. You can't know in advance what the label of the
key for input is. Your UI says "press WASD to move", even if in reality,
they should be pressing "ZQSD" or "Цфыв". You also no longer can use
`KeyCode` for text inputs. In any case, it was a pretty bad API for text
input. You should use `ReceivedCharacter` now instead.
### Other changes
- Use `web-time` rather than `instant` crate.
(https://github.com/rust-windowing/winit/pull/2836)
- winit did split `run_return` in `run_onDemand` and `pump_events`, I
did the same change in bevy_winit and used `pump_events`.
- Removed `return_from_run` from `WinitSettings` as `winit::run` now
returns on supported platforms.
- I left the example "return_after_run" as I think it's still useful.
- This winit change is done partly to allow to create a new window after
quitting all windows: https://github.com/emilk/egui/issues/1918 ; this
PR doesn't address.
- added `width` and `height` properties in the `canvas` from wasm
example
(https://github.com/bevyengine/bevy/pull/10702#discussion_r1420567168)
## Known regressions (important follow ups?)
- Provide an API for reacting when a specific key from current layout
was released.
- possible solutions: use winit::Key from winit::KeyEvent ; mapping
between KeyCode and Key ; or .
- We don't receive characters through alt+numpad (e.g. alt + 151 = "ù")
anymore ; reproduced on winit example "ime". maybe related to
https://github.com/rust-windowing/winit/issues/2945
- (windows) Window content doesn't refresh at all when resizing. By
reading https://github.com/rust-windowing/winit/issues/2900 ; I suspect
we should just fire a `window.request_redraw();` from `AboutToWait`, and
handle actual redrawing within `RedrawRequested`. I'm not sure how to
move all that code so I'd appreciate it to be a follow up.
- (windows) unreleased winit fix for using set_control_flow in
AboutToWait https://github.com/rust-windowing/winit/issues/3215 ; ⚠️ I'm
not sure what the implications are, but that feels bad 🤔
## Follow up
I'd like to avoid bloating this PR, here are a few follow up tasks
worthy of a separate PR, or new issue to track them once this PR is
closed, as they would either complicate reviews, or at risk of being
controversial:
- remove CanvasParentResizePlugin
(https://github.com/bevyengine/bevy/pull/10702#discussion_r1417068856)
- avoid mentionning explicitly winit in docs from bevy_window ?
- NamedKey integration on bevy_input:
https://github.com/rust-windowing/winit/pull/3143 introduced a new
NamedKey variant. I implemented it only on the converters but we'd
benefit making the same changes to bevy_input.
- Add more info in KeyboardInput
https://github.com/bevyengine/bevy/pull/10702#pullrequestreview-1748336313
- https://github.com/bevyengine/bevy/pull/9905 added a workaround on a
bug allegedly fixed by winit 0.29. We should check if it's still
necessary.
- update to raw_window_handle 0.6
- blocked by wgpu
- Rename `KeyCode` to `PhysicalKeyCode`
https://github.com/bevyengine/bevy/pull/10702#discussion_r1404595015
- remove `instant` dependency, [replaced
by](https://github.com/rust-windowing/winit/pull/2836) `web_time`), we'd
need to update to :
- fastrand >= 2.0
- [`async-executor`](https://github.com/smol-rs/async-executor) >= 1.7
- [`futures-lite`](https://github.com/smol-rs/futures-lite) >= 2.0
- Verify license, see
[discussion](https://github.com/bevyengine/bevy/pull/8745#discussion_r1402439800)
- we might be missing a short notice or description of changes made
- Consider using https://github.com/rust-windowing/cursor-icon directly
rather than vendoring it in bevy.
- investigate [this
unwrap](https://github.com/bevyengine/bevy/pull/8745#discussion_r1387044986)
(`winit_window.canvas().unwrap();`)
- Use more good things about winit's update
- https://github.com/bevyengine/bevy/pull/10689#issuecomment-1823560428
## Migration Guide
This PR should have one.
# 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
- Shorten paths by removing unnecessary prefixes
## Solution
- Remove the prefixes from many paths which do not need them. Finding
the paths was done automatically using built-in refactoring tools in
Jetbrains RustRover.
# Objective
- Fixes#7680
- This is an updated for https://github.com/bevyengine/bevy/pull/8899
which had the same objective but fell a long way behind the latest
changes
## Solution
The traits `WorldQueryData : WorldQuery` and `WorldQueryFilter :
WorldQuery` have been added and some of the types and functions from
`WorldQuery` has been moved into them.
`ReadOnlyWorldQuery` has been replaced with `ReadOnlyWorldQueryData`.
`WorldQueryFilter` is safe (as long as `WorldQuery` is implemented
safely).
`WorldQueryData` is unsafe - safely implementing it requires that
`Self::ReadOnly` is a readonly version of `Self` (this used to be a
safety requirement of `WorldQuery`)
The type parameters `Q` and `F` of `Query` must now implement
`WorldQueryData` and `WorldQueryFilter` respectively.
This makes it impossible to accidentally use a filter in the data
position or vice versa which was something that could lead to bugs.
~~Compile failure tests have been added to check this.~~
It was previously sometimes useful to use `Option<With<T>>` in the data
position. Use `Has<T>` instead in these cases.
The `WorldQuery` derive macro has been split into separate derive macros
for `WorldQueryData` and `WorldQueryFilter`.
Previously it was possible to derive both `WorldQuery` for a struct that
had a mixture of data and filter items. This would not work correctly in
some cases but could be a useful pattern in others. *This is no longer
possible.*
---
## Notes
- The changes outside of `bevy_ecs` are all changing type parameters to
the new types, updating the macro use, or replacing `Option<With<T>>`
with `Has<T>`.
- All `WorldQueryData` types always returned `true` for `IS_ARCHETYPAL`
so I moved it to `WorldQueryFilter` and
replaced all calls to it with `true`. That should be the only logic
change outside of the macro generation code.
- `Changed<T>` and `Added<T>` were being generated by a macro that I
have expanded. Happy to revert that if desired.
- The two derive macros share some functions for implementing
`WorldQuery` but the tidiest way I could find to implement them was to
give them a ton of arguments and ask clippy to ignore that.
## Changelog
### Changed
- Split `WorldQuery` into `WorldQueryData` and `WorldQueryFilter` which
now have separate derive macros. It is not possible to derive both for
the same type.
- `Query` now requires that the first type argument implements
`WorldQueryData` and the second implements `WorldQueryFilter`
## Migration Guide
- Update derives
```rust
// old
#[derive(WorldQuery)]
#[world_query(mutable, derive(Debug))]
struct CustomQuery {
entity: Entity,
a: &'static mut ComponentA
}
#[derive(WorldQuery)]
struct QueryFilter {
_c: With<ComponentC>
}
// new
#[derive(WorldQueryData)]
#[world_query_data(mutable, derive(Debug))]
struct CustomQuery {
entity: Entity,
a: &'static mut ComponentA,
}
#[derive(WorldQueryFilter)]
struct QueryFilter {
_c: With<ComponentC>
}
```
- Replace `Option<With<T>>` with `Has<T>`
```rust
/// old
fn my_system(query: Query<(Entity, Option<With<ComponentA>>)>)
{
for (entity, has_a_option) in query.iter(){
let has_a:bool = has_a_option.is_some();
//todo!()
}
}
/// new
fn my_system(query: Query<(Entity, Has<ComponentA>)>)
{
for (entity, has_a) in query.iter(){
//todo!()
}
}
```
- Fix queries which had filters in the data position or vice versa.
```rust
// old
fn my_system(query: Query<(Entity, With<ComponentA>)>)
{
for (entity, _) in query.iter(){
//todo!()
}
}
// new
fn my_system(query: Query<Entity, With<ComponentA>>)
{
for entity in query.iter(){
//todo!()
}
}
// old
fn my_system(query: Query<AnyOf<(&ComponentA, With<ComponentB>)>>)
{
for (entity, _) in query.iter(){
//todo!()
}
}
// new
fn my_system(query: Query<Option<&ComponentA>, Or<(With<ComponentA>, With<ComponentB>)>>)
{
for entity in query.iter(){
//todo!()
}
}
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
The `nondeterministic_system_order` example doesn't actually detect and
log its deliberate order ambiguities! It should, tho.
## Solution
Update the schedule label, and explain in a comment that you can't turn
it on for the whole `Main` schedule in one go (alas, that would be nice,
but it makes sense that it doesn't work that way).
# Objective
- Fix adding `#![allow(clippy::type_complexity)]` everywhere. like #9796
## Solution
- Use the new [lints] table that will land in 1.74
(https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#lints)
- inherit lint to the workspace, crates and examples.
```
[lints]
workspace = true
```
## Changelog
- Bump rust version to 1.74
- Enable lints table for the workspace
```toml
[workspace.lints.clippy]
type_complexity = "allow"
```
- Allow type complexity for all crates and examples
```toml
[lints]
workspace = true
```
---------
Co-authored-by: Martín Maita <47983254+mnmaita@users.noreply.github.com>
When `cargo doc -Zunstable-options -Zrustdoc-scrape-examples` (trying to
figure out why it doesn't work with bevy), I had the following warnings:
```
warning: unresolved link to `Quad`
--> examples/2d/mesh2d.rs:1:66
|
1 | //! Shows how to render a polygonal [`Mesh`], generated from a [`Quad`] primitive, in a 2D scene.
| ^^^^ no item named `Quad` in scope
|
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
warning: `bevy` (example "mesh2d") generated 1 warning
warning: unresolved link to `update_weights`
--> examples/animation/morph_targets.rs:6:17
|
6 | //! See the [`update_weights`] system for details.
| ^^^^^^^^^^^^^^ no item named `update_weights` in scope
|
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
warning: public documentation for `morph_targets` links to private item `name_morphs`
--> examples/animation/morph_targets.rs:7:43
|
7 | //! - How to read morph target names in [`name_morphs`].
| ^^^^^^^^^^^ this item is private
|
= note: this link will resolve properly if you pass `--document-private-items`
= note: `#[warn(rustdoc::private_intra_doc_links)]` on by default
warning: public documentation for `morph_targets` links to private item `setup_animations`
--> examples/animation/morph_targets.rs:8:48
|
8 | //! - How to play morph target animations in [`setup_animations`].
| ^^^^^^^^^^^^^^^^ this item is private
|
= note: this link will resolve properly if you pass `--document-private-items`
warning: `bevy` (example "morph_targets") generated 3 warnings
warning: unresolved link to `Quad`
--> examples/2d/mesh2d_vertex_color_texture.rs:1:66
|
1 | //! Shows how to render a polygonal [`Mesh`], generated from a [`Quad`] primitive, in a 2D scene.
| ^^^^ no item named `Quad` in scope
|
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
warning: `bevy` (example "mesh2d_vertex_color_texture") generated 1 warning
warning: unresolved link to `UIScale`
--> examples/ui/ui_scaling.rs:1:36
|
1 | //! This example illustrates the [`UIScale`] resource from `bevy_ui`.
| ^^^^^^^ no item named `UIScale` in scope
|
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
warning: `bevy` (example "ui_scaling") generated 1 warning
warning: unresolved link to `dependencies`
--> examples/app/headless.rs:5:6
|
5 | //! [dependencies]
| ^^^^^^^^^^^^ no item named `dependencies` in scope
|
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
warning: `bevy` (example "headless") generated 1 warning
warning: unresolved link to `Material2d`
--> examples/2d/mesh2d_manual.rs:3:26
|
3 | //! It doesn't use the [`Material2d`] abstraction, but changes the vertex buffer to include verte...
| ^^^^^^^^^^ no item named `Material2d` in scope
|
= help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`
= note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
warning: `bevy` (example "mesh2d_manual") generated 1 warning
```
# Objective
- Fixes#10133
## Solution
- Add a new example that focuses on using `Virtual` time
## Changelog
### Added
- new `virtual_time` example
### Changed
- moved `time` & `timers` examples to the new `examples/time` folder
# Objective
Current `FixedTime` and `Time` have several problems. This pull aims to
fix many of them at once.
- If there is a longer pause between app updates, time will jump forward
a lot at once and fixed time will iterate on `FixedUpdate` for a large
number of steps. If the pause is merely seconds, then this will just
mean jerkiness and possible unexpected behaviour in gameplay. If the
pause is hours/days as with OS suspend, the game will appear to freeze
until it has caught up with real time.
- If calculating a fixed step takes longer than specified fixed step
period, the game will enter a death spiral where rendering each frame
takes longer and longer due to more and more fixed step updates being
run per frame and the game appears to freeze.
- There is no way to see current fixed step elapsed time inside fixed
steps. In order to track this, the game designer needs to add a custom
system inside `FixedUpdate` that calculates elapsed or step count in a
resource.
- Access to delta time inside fixed step is `FixedStep::period` rather
than `Time::delta`. This, coupled with the issue that `Time::elapsed`
isn't available at all for fixed steps, makes it that time requiring
systems are either implemented to be run in `FixedUpdate` or `Update`,
but rarely work in both.
- Fixes#8800
- Fixes#8543
- Fixes#7439
- Fixes#5692
## Solution
- Create a generic `Time<T>` clock that has no processing logic but
which can be instantiated for multiple usages. This is also exposed for
users to add custom clocks.
- Create three standard clocks, `Time<Real>`, `Time<Virtual>` and
`Time<Fixed>`, all of which contain their individual logic.
- Create one "default" clock, which is just `Time` (or `Time<()>`),
which will be overwritten from `Time<Virtual>` on each update, and
`Time<Fixed>` inside `FixedUpdate` schedule. This way systems that do
not care specifically which time they track can work both in `Update`
and `FixedUpdate` without changes and the behaviour is intuitive.
- Add `max_delta` to virtual time update, which limits how much can be
added to virtual time by a single update. This fixes both the behaviour
after a long freeze, and also the death spiral by limiting how many
fixed timestep iterations there can be per update. Possible future work
could be adding `max_accumulator` to add a sort of "leaky bucket" time
processing to possibly smooth out jumps in time while keeping frame rate
stable.
- Many minor tweaks and clarifications to the time functions and their
documentation.
## Changelog
- `Time::raw_delta()`, `Time::raw_elapsed()` and related methods are
moved to `Time<Real>::delta()` and `Time<Real>::elapsed()` and now match
`Time` API
- `FixedTime` is now `Time<Fixed>` and matches `Time` API.
- `Time<Fixed>` default timestep is now 64 Hz, or 15625 microseconds.
- `Time` inside `FixedUpdate` now reflects fixed timestep time, making
systems portable between `Update ` and `FixedUpdate`.
- `Time::pause()`, `Time::set_relative_speed()` and related methods must
now be called as `Time<Virtual>::pause()` etc.
- There is a new `max_delta` setting in `Time<Virtual>` that limits how
much the clock can jump by a single update. The default value is 0.25
seconds.
- Removed `on_fixed_timer()` condition as `on_timer()` does the right
thing inside `FixedUpdate` now.
## Migration Guide
- Change all `Res<Time>` instances that access `raw_delta()`,
`raw_elapsed()` and related methods to `Res<Time<Real>>` and `delta()`,
`elapsed()`, etc.
- Change access to `period` from `Res<FixedTime>` to `Res<Time<Fixed>>`
and use `delta()`.
- The default timestep has been changed from 60 Hz to 64 Hz. If you wish
to restore the old behaviour, use
`app.insert_resource(Time::<Fixed>::from_hz(60.0))`.
- Change `app.insert_resource(FixedTime::new(duration))` to
`app.insert_resource(Time::<Fixed>::from_duration(duration))`
- Change `app.insert_resource(FixedTime::new_from_secs(secs))` to
`app.insert_resource(Time::<Fixed>::from_seconds(secs))`
- Change `system.on_fixed_timer(duration)` to
`system.on_timer(duration)`. Timers in systems placed in `FixedUpdate`
schedule automatically use the fixed time clock.
- Change `ResMut<Time>` calls to `pause()`, `is_paused()`,
`set_relative_speed()` and related methods to `ResMut<Time<Virtual>>`
calls. The API is the same, with the exception that `relative_speed()`
will return the actual last ste relative speed, while
`effective_relative_speed()` returns 0.0 if the time is paused and
corresponds to the speed that was set when the update for the current
frame started.
## Todo
- [x] Update pull name and description
- [x] Top level documentation on usage
- [x] Fix examples
- [x] Decide on default `max_delta` value
- [x] Decide naming of the three clocks: is `Real`, `Virtual`, `Fixed`
good?
- [x] Decide if the three clock inner structures should be in prelude
- [x] Decide on best way to configure values at startup: is manually
inserting a new clock instance okay, or should there be config struct
separately?
- [x] Fix links in docs
- [x] Decide what should be public and what not
- [x] Decide how `wrap_period` should be handled when it is changed
- [x] ~~Add toggles to disable setting the clock as default?~~ No,
separate pull if needed.
- [x] Add tests
- [x] Reformat, ensure adheres to conventions etc.
- [x] Build documentation and see that it looks correct
## Contributors
Huge thanks to @alice-i-cecile and @maniwani while building this pull.
It was a shared effort!
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Cameron <51241057+maniwani@users.noreply.github.com>
Co-authored-by: Jerome Humbert <djeedai@gmail.com>
# Objective
- See fewer warnings when running `cargo clippy` locally.
## Solution
- allow `clippy::type_complexity` in more places, which also signals to
users they should do the same.
I'm adopting this ~~child~~ PR.
# Objective
- Working with exclusive world access is not always easy: in many cases,
a standard system or three is more ergonomic to write, and more
modularly maintainable.
- For small, one-off tasks (commonly handled with scripting), running an
event-reader system incurs a small but flat overhead cost and muddies
the schedule.
- Certain forms of logic (e.g. turn-based games) want very fine-grained
linear and/or branching control over logic.
- SystemState is not automatically cached, and so performance can suffer
and change detection breaks.
- Fixes https://github.com/bevyengine/bevy/issues/2192.
- Partial workaround for https://github.com/bevyengine/bevy/issues/279.
## Solution
- Adds a SystemRegistry resource to the World, which stores initialized
systems keyed by their SystemSet.
- Allows users to call world.run_system(my_system) and
commands.run_system(my_system), without re-initializing or losing state
(essential for change detection).
- Add a Callback type to enable convenient use of dynamic one shot
systems and reduce the mental overhead of working with Box<dyn
SystemSet>.
- Allow users to run systems based on their SystemSet, enabling more
complex user-made abstractions.
## Future work
- Parameterized one-shot systems would improve reusability and bring
them closer to events and commands. The API could be something like
run_system_with_input(my_system, my_input) and use the In SystemParam.
- We should evaluate the unification of commands and one-shot systems
since they are two different ways to run logic on demand over a World.
### Prior attempts
- https://github.com/bevyengine/bevy/pull/2234
- https://github.com/bevyengine/bevy/pull/2417
- https://github.com/bevyengine/bevy/pull/4090
- https://github.com/bevyengine/bevy/pull/7999
This PR continues the work done in
https://github.com/bevyengine/bevy/pull/7999.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Federico Rinaldi <gisquerin@gmail.com>
Co-authored-by: MinerSebas <66798382+MinerSebas@users.noreply.github.com>
Co-authored-by: Aevyrie <aevyrie@gmail.com>
Co-authored-by: Alejandro Pascual Pozo <alejandro.pascual.pozo@gmail.com>
Co-authored-by: Rob Parrett <robparrett@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
Co-authored-by: Dmytro Banin <banind@cs.washington.edu>
Co-authored-by: James Liu <contact@jamessliu.com>
# Objective
Make `bevy_ui` "root" nodes more intuitive to use/style by:
- Removing the implicit flexbox styling (such as stretch alignment) that
is applied to them, and replacing it with more intuitive CSS Grid
styling (notably with stretch alignment disabled in both axes).
- Making root nodes layout independently of each other. Instead of there
being a single implicit "viewport" node that all root nodes are children
of, there is now an implicit "viewport" node *per root node*. And layout
of each tree is computed separately.
## Solution
- Remove the global implicit viewport node, and instead create an
implicit viewport node for each user-specified root node.
- Keep track of both the user-specified root nodes and the implicit
viewport nodes in a separate `Vec`.
- Use the window's size as the `available_space` parameter to
`Taffy.compute_layout` rather than setting it on the implicit viewport
node (and set the viewport to `height: 100%; width: 100%` to make this
"just work").
---
## Changelog
- Bevy UI now lays out root nodes independently of each other in
separate layout contexts.
- The implicit viewport node (which contains each user-specified root
node) is now `Display::Grid` with `align_items` and `justify_items` both
set to `Start`.
## Migration Guide
- Bevy UI now lays out root nodes independently of each other in
separate layout contexts. If you were relying on your root nodes being
able to affect each other's layouts, then you may need to wrap them in a
single root node.
- The implicit viewport node (which contains each user-specified root
node) is now `Display::Grid` with `align_items` and `justify_items` both
set to `Start`. You may need to add `height: Val::Percent(100.)` to your
root nodes if you were previously relying on being implicitly set.
# Objective
Rename RemovedComponents::iter/iter_with_id to read/read_with_id to make
it clear that it consume the data
Fixes#9755.
(It's my first pull request, if i've made any mistake, please let me
know)
## Solution
Refactor RemovedComponents::iter/iter_with_id to read/read_with_id
## Changelog
Refactor RemovedComponents::iter/iter_with_id to read/read_with_id
Deprecate RemovedComponents::iter/iter_with_id
Remove IntoIterator implementation
Update removal_detection example accordingly
---
## Migration Guide
Rename calls of RemovedComponents::iter/iter_with_id to
read/read_with_id
Replace IntoIterator iteration (&mut <RemovedComponents>) with .read()
---------
Co-authored-by: denshi_ika <mojang2824@gmail.com>
# Objective
- The current `EventReader::iter` has been determined to cause confusion
among new Bevy users. It was suggested by @JoJoJet to rename the method
to better clarify its usage.
- Solves #9624
## Solution
- Rename `EventReader::iter` to `EventReader::read`.
- Rename `EventReader::iter_with_id` to `EventReader::read_with_id`.
- Rename `ManualEventReader::iter` to `ManualEventReader::read`.
- Rename `ManualEventReader::iter_with_id` to
`ManualEventReader::read_with_id`.
---
## Changelog
- `EventReader::iter` has been renamed to `EventReader::read`.
- `EventReader::iter_with_id` has been renamed to
`EventReader::read_with_id`.
- `ManualEventReader::iter` has been renamed to
`ManualEventReader::read`.
- `ManualEventReader::iter_with_id` has been renamed to
`ManualEventReader::read_with_id`.
- Deprecated `EventReader::iter`
- Deprecated `EventReader::iter_with_id`
- Deprecated `ManualEventReader::iter`
- Deprecated `ManualEventReader::iter_with_id`
## Migration Guide
- Existing usages of `EventReader::iter` and `EventReader::iter_with_id`
will have to be changed to `EventReader::read` and
`EventReader::read_with_id` respectively.
- Existing usages of `ManualEventReader::iter` and
`ManualEventReader::iter_with_id` will have to be changed to
`ManualEventReader::read` and `ManualEventReader::read_with_id`
respectively.
# Objective
Any time we wish to transform the output of a system, we currently use
system piping to do so:
```rust
my_system.pipe(|In(x)| do_something(x))
```
Unfortunately, system piping is not a zero cost abstraction. Each call
to `.pipe` requires allocating two extra access sets: one for the second
system and one for the combined accesses of both systems. This also adds
extra work to each call to `update_archetype_component_access`, which
stacks as one adds multiple layers of system piping.
## Solution
Add the `AdapterSystem` abstraction: similar to `CombinatorSystem`, this
allows you to implement a trait to generically control how a system is
run and how its inputs and outputs are processed. Unlike
`CombinatorSystem`, this does not have any overhead when computing world
accesses which makes it ideal for simple operations such as inverting or
ignoring the output of a system.
Add the extension method `.map(...)`: this is similar to `.pipe(...)`,
only it accepts a closure as an argument instead of an `In<T>` system.
```rust
my_system.map(do_something)
```
This has the added benefit of making system names less messy: a system
that ignores its output will just be called `my_system`, instead of
`Pipe(my_system, ignore)`
---
## Changelog
TODO
## Migration Guide
The `system_adapter` functions have been deprecated: use `.map` instead,
which is a lightweight alternative to `.pipe`.
```rust
// Before:
my_system.pipe(system_adapter::ignore)
my_system.pipe(system_adapter::unwrap)
my_system.pipe(system_adapter::new(T::from))
// After:
my_system.map(std::mem::drop)
my_system.map(Result::unwrap)
my_system.map(T::from)
// Before:
my_system.pipe(system_adapter::info)
my_system.pipe(system_adapter::dbg)
my_system.pipe(system_adapter::warn)
my_system.pipe(system_adapter::error)
// After:
my_system.map(bevy_utils::info)
my_system.map(bevy_utils::dbg)
my_system.map(bevy_utils::warn)
my_system.map(bevy_utils::error)
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
- Some examples crash in CI because of needing too many resources for
the windows runner
- Some examples have random results making it hard to compare
screenshots
## Solution
- `bloom_3d`: reduce the number of spheres
- `pbr`: use simpler spheres and reuse the mesh
- `tonemapping`: use simpler spheres and reuse the mesh
- `shadow_biases`: reduce the number of spheres
- `spotlight`: use a seeded rng, move more cubes in view while reducing
the total number of cubes, and reuse meshes and materials
- `external_source_external_thread`, `iter_combinations`,
`parallel_query`: use a seeded rng
Examples of errors encountered:
```
Caused by:
In Device::create_bind_group
note: label = `bloom_upsampling_bind_group`
Not enough memory left
```
```
Caused by:
In Queue::write_buffer
Parent device is lost
```
```
ERROR wgpu_core::device::life: Mapping failed Device(Lost)
```
# Objective
The documentation for the `print_when_completed` system stated that this
system would tick the `Timer` component on every entity in the scene.
This was incorrect as this system only ticks the `Timer` on entities
with the `PrintOnCompletionTimer` component.
## Solution
We suggest a modification to the documentation of this system to make it
more clear.
# Objective
The `QueryParIter::for_each_mut` function is required when doing
parallel iteration with mutable queries.
This results in an unfortunate stutter:
`query.par_iter_mut().par_for_each_mut()` ('mut' is repeated).
## Solution
- Make `for_each` compatible with mutable queries, and deprecate
`for_each_mut`. In order to prevent `for_each` from being called
multiple times in parallel, we take ownership of the QueryParIter.
---
## Changelog
- `QueryParIter::for_each` is now compatible with mutable queries.
`for_each_mut` has been deprecated as it is now redundant.
## Migration Guide
The method `QueryParIter::for_each_mut` has been deprecated and is no
longer functional. Use `for_each` instead, which now supports mutable
queries.
```rust
// Before:
query.par_iter_mut().for_each_mut(|x| ...);
// After:
query.par_iter_mut().for_each(|x| ...);
```
The method `QueryParIter::for_each` now takes ownership of the
`QueryParIter`, rather than taking a shared reference.
```rust
// Before:
let par_iter = my_query.par_iter().batching_strategy(my_batching_strategy);
par_iter.for_each(|x| {
// ...Do stuff with x...
par_iter.for_each(|y| {
// ...Do nested stuff with y...
});
});
// After:
my_query.par_iter().batching_strategy(my_batching_strategy).for_each(|x| {
// ...Do stuff with x...
my_query.par_iter().batching_strategy(my_batching_strategy).for_each(|y| {
// ...Do nested stuff with y...
});
});
```
# Objective
- Better consistency with `add_systems`.
- Deprecating `add_plugin` in favor of a more powerful `add_plugins`.
- Allow passing `Plugin` to `add_plugins`.
- Allow passing tuples to `add_plugins`.
## Solution
- `App::add_plugins` now takes an `impl Plugins` parameter.
- `App::add_plugin` is deprecated.
- `Plugins` is a new sealed trait that is only implemented for `Plugin`,
`PluginGroup` and tuples over `Plugins`.
- All examples, benchmarks and tests are changed to use `add_plugins`,
using tuples where appropriate.
---
## Changelog
### Changed
- `App::add_plugins` now accepts all types that implement `Plugins`,
which is implemented for:
- Types that implement `Plugin`.
- Types that implement `PluginGroup`.
- Tuples (up to 16 elements) over types that implement `Plugins`.
- Deprecated `App::add_plugin` in favor of `App::add_plugins`.
## Migration Guide
- Replace `app.add_plugin(plugin)` calls with `app.add_plugins(plugin)`.
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
Be consistent with `Resource`s and `Components` and have `Event` types
be more self-documenting.
Although not susceptible to accidentally using a function instead of a
value due to `Event`s only being initialized by their type, much of the
same reasoning for removing the blanket impl on `Resource` also applies
here.
* Not immediately obvious if a type is intended to be an event
* Prevent invisible conflicts if the same third-party or primitive types
are used as events
* Allows for further extensions (e.g. opt-in warning for missed events)
## Solution
Remove the blanket impl for the `Event` trait. Add a derive macro for
it.
---
## Changelog
- `Event` is no longer implemented for all applicable types. Add the
`#[derive(Event)]` macro for events.
## Migration Guide
* Add the `#[derive(Event)]` macro for events. Third-party types used as
events should be wrapped in a newtype.
# Objective
- `apply_system_buffers` is an unhelpful name: it introduces a new
internal-only concept
- this is particularly rough for beginners as reasoning about how
commands work is a critical stumbling block
## Solution
- rename `apply_system_buffers` to the more descriptive `apply_deferred`
- rename related fields, arguments and methods in the internals fo
bevy_ecs for consistency
- update the docs
## Changelog
`apply_system_buffers` has been renamed to `apply_deferred`, to more
clearly communicate its intent and relation to `Deferred` system
parameters like `Commands`.
## Migration Guide
- `apply_system_buffers` has been renamed to `apply_deferred`
- the `apply_system_buffers` method on the `System` trait has been
renamed to `apply_deferred`
- the `is_apply_system_buffers` function has been replaced by
`is_apply_deferred`
- `Executor::set_apply_final_buffers` is now
`Executor::set_apply_final_deferred`
- `Schedule::apply_system_buffers` is now `Schedule::apply_deferred`
---------
Co-authored-by: JoJoJet <21144246+JoJoJet@users.noreply.github.com>
# Objective
- Showcase the use of `or_else()` as requested. Fixes
https://github.com/bevyengine/bevy/issues/8702
## Solution
- Add an uninitialized resource `Unused`
- Use `or_else()` to evaluate a second run condition
- Add documentation explaining how `or_else()` works
# Objective
- Simplify API and make authoring styles easier
See:
https://github.com/bevyengine/bevy/issues/8540#issuecomment-1536177102
## Solution
- The `size`, `min_size`, `max_size`, and `gap` properties have been
replaced by `width`, `height`, `min_width`, `min_height`, `max_width`,
`max_height`, `row_gap`, and `column_gap` properties
---
## Changelog
- Flattened `Style` properties that have a `Size` value directly into
`Style`
## Migration Guide
- The `size`, `min_size`, `max_size`, and `gap` properties have been
replaced by the `width`, `height`, `min_width`, `min_height`,
`max_width`, `max_height`, `row_gap`, and `column_gap` properties. Use
the new properties instead.
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
# Objective
`ScheduleRunnerPlugin` was still configured via a resource, meaning
users would be able to change the settings while the app is running, but
the changes wouldn't have an effect.
## Solution
Configure plugin directly
---
## Changelog
- Changed: merged `ScheduleRunnerSettings` into `ScheduleRunnerPlugin`
## Migration Guide
- instead of inserting the `ScheduleRunnerSettings` resource, configure
the `ScheduleRunnerPlugin`
Links in the api docs are nice. I noticed that there were several places
where structs / functions and other things were referenced in the docs,
but weren't linked. I added the links where possible / logical.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: François <mockersf@gmail.com>
# Objective
- Have a default font
## Solution
- Add a font based on FiraMono containing only ASCII characters and use
it as the default font
- It is behind a feature `default_font` enabled by default
- I also updated examples to use it, but not UI examples to still show
how to use a custom font
---
## Changelog
* If you display text without using the default handle provided by
`TextStyle`, the text will be displayed
# Objective
Some examples still manually implement the States trait, even though
manual implementation is no longer needed as there is now the derive
macro for that.
---------
Signed-off-by: Natalia Asteria <fortressnordlys@outlook.com>
# Objective
This PR adds an example that shows how to use `apply_system_buffers` and how to order it with respect to the relevant systems. It also shows how not ordering the systems can lead to unexpected behaviours.
## Solution
Add the example.
# Objective
Support the following syntax for adding systems:
```rust
App::new()
.add_system(setup.on_startup())
.add_systems((
show_menu.in_schedule(OnEnter(GameState::Paused)),
menu_ssytem.in_set(OnUpdate(GameState::Paused)),
hide_menu.in_schedule(OnExit(GameState::Paused)),
))
```
## Solution
Add the traits `IntoSystemAppConfig{s}`, which provide the extension methods necessary for configuring which schedule a system belongs to. These extension methods return `IntoSystemAppConfig{s}`, which `App::add_system{s}` uses to choose which schedule to add systems to.
---
## Changelog
+ Added the extension methods `in_schedule(label)` and `on_startup()` for configuring the schedule a system belongs to.
## Future Work
* Replace all uses of `add_startup_system` in the engine.
* Deprecate this method
