# Objective
When dragging the slider thumb the thumb is only highlighted while the
pointer is hovering the widget. If the pointer moves off the widget
during a drag the thumb reverts to its normal unhovered colour.
## Solution
Query for `CoreSliderDragState` in the slider update systems and set the
lighter color if the thumb is dragged or hovered.
# Objective
This PR introduces Bevy Feathers, an opinionated widget toolkit and
theming system intended for use by the Bevy Editor, World Inspector, and
other tools.
The `bevy_feathers` crate is incomplete and hidden behind an
experimental feature flag. The API is going to change significantly
before release.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Fix https://github.com/bevyengine/bevy/issues/19617
# Solution
Add newlines before all impl blocks.
I suspect that at least some of these will be objectionable! If there's
a desired Bevy style for this then I'll update the PR. If not then we
can just close it - it's the work of a single find and replace.
Click to focus is now a global observer.
# Objective
Previously, the "click to focus" behavior was implemented in each
individual headless widget, producing redundant logic.
## Solution
The new scheme is to have a global observer which looks for pointer down
events and triggers an `AcquireFocus` event on the target. This event
bubbles until it finds an entity with `TabIndex`, and then focuses it.
## Testing
Tested the changes using the various examples that have focusable
widgets. (This will become easier to test when I add focus ring support
to the examples, but that's for another day. For now you just have to
know which keys to press.)
## Migration
This change is backwards-compatible. People who want the new behavior
will need to install the new plugin.
# Objective
Add support for interpolation in OKLab and OKLCH color spaces for UI
gradients.
## Solution
* New `InterpolationColorSpace` enum with `OkLab`, `OkLch`, `OkLchLong`,
`Srgb` and `LinearRgb` variants.
* Added a color space specialization to the gradients pipeline.
* Added support for interpolation in OkLCH and OkLAB color spaces to the
gradients shader. OKLCH interpolation supports both short and long hue
paths. This is mostly based on the conversion functions from
`bevy_color` except that interpolation in polar space uses radians.
* Added `color_space` fields to each gradient type.
## Testing
The `gradients` example has been updated to demonstrate the different
color interpolation methods.
Press space to cycle through the different options.
---
## Showcase
# Objective
This is part of the "core widgets" effort:
https://github.com/bevyengine/bevy/issues/19236.
## Solution
This adds the "core checkbox" widget type.
## Testing
Tested using examples core_widgets and core_widgets_observers.
Note to reviewers: I reorganized the code in the examples, so the diffs
are large because of code moves.
# Objective
- Fixes#19627
- Tackles part of #19644
- Supersedes #19629
- `Window` has become a very very very big component
- As such, our change detection does not *really* work on it, as e.g.
moving the mouse will cause a change for the entire window
- We circumvented this with a cache
- But, some things *shouldn't* be cached as they can be changed from
outside the user's control, notably the cursor grab mode on web
- So, we need to disable the cache for that
- But because change detection is broken, that would result in the
cursor grab mode being set every frame the mouse is moved
- That is usually *not* what a dev wants, as it forces the cursor to be
locked even when the end-user is trying to free the cursor on the
browser
- the cache in this situation is invalid due to #8949
## Solution
- Split `Window` into multiple components, each with working change
detection
- Disable caching of the cursor grab mode
- This will only attempt to force the grab mode when the `CursorOptions`
were touched by the user, which is *much* rarer than simply moving the
mouse.
- If this PR is merged, I'll do the exact same for the other
constituents of `Window` as a follow-up
## Testing
- Ran all the changed examples
# Objective
Getting access to the original target of an entity-event is really
helpful when working with bubbled / propagated events.
`bevy_picking` special-cases this, but users have requested this for all
sorts of bubbled events.
The existing naming convention was also very confusing. Fixes
https://github.com/bevyengine/bevy/issues/17112, but also see #18982.
## Solution
1. Rename `ObserverTrigger::target` -> `current_target`.
1. Store `original_target: Option<Entity>` in `ObserverTrigger`.
1. Wire it up so this field gets set correctly.
1. Remove the `target` field on the `Pointer` events from
`bevy_picking`.
Closes https://github.com/bevyengine/bevy/pull/18710, which attempted
the same thing. Thanks @emfax!
## Testing
I've modified an existing test to check that the entities returned
during event bubbling / propagation are correct.
## Notes to reviewers
It's a little weird / sad that you can no longer access this infromation
via the buffered events for `Pointer`. That said, you already couldn't
access any bubbled target. We should probably remove the `BufferedEvent`
form of `Pointer` to reduce confusion and overhead, but I didn't want to
do so here.
Observer events can be trivially converted into buffered events (write
an observer with an EventWriter), and I suspect that that is the better
migration if you want the controllable timing or performance
characteristics of buffered events for your specific use case.
## Future work
It would be nice to not store this data at all (and not expose any
methods) if propagation was disabled. That involves more trait
shuffling, and I don't think we should do it here for reviewability.
---------
Co-authored-by: Joona Aalto <jondolf.dev@gmail.com>
# Objective
Closes#19564.
The current `Event` trait looks like this:
```rust
pub trait Event: Send + Sync + 'static {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
The `Event` trait is used by both buffered events
(`EventReader`/`EventWriter`) and observer events. If they are observer
events, they can optionally be targeted at specific `Entity`s or
`ComponentId`s, and can even be propagated to other entities.
However, there has long been a desire to split the trait semantically
for a variety of reasons, see #14843, #14272, and #16031 for discussion.
Some reasons include:
- It's very uncommon to use a single event type as both a buffered event
and targeted observer event. They are used differently and tend to have
distinct semantics.
- A common footgun is using buffered events with observers or event
readers with observer events, as there is no type-level error that
prevents this kind of misuse.
- #19440 made `Trigger::target` return an `Option<Entity>`. This
*seriously* hurts ergonomics for the general case of entity observers,
as you need to `.unwrap()` each time. If we could statically determine
whether the event is expected to have an entity target, this would be
unnecessary.
There's really two main ways that we can categorize events: push vs.
pull (i.e. "observer event" vs. "buffered event") and global vs.
targeted:
| | Push | Pull |
| ------------ | --------------- | --------------------------- |
| **Global** | Global observer | `EventReader`/`EventWriter` |
| **Targeted** | Entity observer | - |
There are many ways to approach this, each with their tradeoffs.
Ultimately, we kind of want to split events both ways:
- A type-level distinction between observer events and buffered events,
to prevent people from using the wrong kind of event in APIs
- A statically designated entity target for observer events to avoid
accidentally using untargeted events for targeted APIs
This PR achieves these goals by splitting event traits into `Event`,
`EntityEvent`, and `BufferedEvent`, with `Event` being the shared trait
implemented by all events.
## `Event`, `EntityEvent`, and `BufferedEvent`
`Event` is now a very simple trait shared by all events.
```rust
pub trait Event: Send + Sync + 'static {
// Required for observer APIs
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
You can call `trigger` for *any* event, and use a global observer for
listening to the event.
```rust
#[derive(Event)]
struct Speak {
message: String,
}
// ...
app.add_observer(|trigger: On<Speak>| {
println!("{}", trigger.message);
});
// ...
commands.trigger(Speak {
message: "Y'all like these reworked events?".to_string(),
});
```
To allow an event to be targeted at entities and even propagated
further, you can additionally implement the `EntityEvent` trait:
```rust
pub trait EntityEvent: Event {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
}
```
This lets you call `trigger_targets`, and to use targeted observer APIs
like `EntityCommands::observe`:
```rust
#[derive(Event, EntityEvent)]
#[entity_event(traversal = &'static ChildOf, auto_propagate)]
struct Damage {
amount: f32,
}
// ...
let enemy = commands.spawn((Enemy, Health(100.0))).id();
// Spawn some armor as a child of the enemy entity.
// When the armor takes damage, it will bubble the event up to the enemy.
let armor_piece = commands
.spawn((ArmorPiece, Health(25.0), ChildOf(enemy)))
.observe(|trigger: On<Damage>, mut query: Query<&mut Health>| {
// Note: `On::target` only exists because this is an `EntityEvent`.
let mut health = query.get(trigger.target()).unwrap();
health.0 -= trigger.amount();
});
commands.trigger_targets(Damage { amount: 10.0 }, armor_piece);
```
> [!NOTE]
> You *can* still also trigger an `EntityEvent` without targets using
`trigger`. We probably *could* make this an either-or thing, but I'm not
sure that's actually desirable.
To allow an event to be used with the buffered API, you can implement
`BufferedEvent`:
```rust
pub trait BufferedEvent: Event {}
```
The event can then be used with `EventReader`/`EventWriter`:
```rust
#[derive(Event, BufferedEvent)]
struct Message(String);
fn write_hello(mut writer: EventWriter<Message>) {
writer.write(Message("I hope these examples are alright".to_string()));
}
fn read_messages(mut reader: EventReader<Message>) {
// Process all buffered events of type `Message`.
for Message(message) in reader.read() {
println!("{message}");
}
}
```
In summary:
- Need a basic event you can trigger and observe? Derive `Event`!
- Need the event to be targeted at an entity? Derive `EntityEvent`!
- Need the event to be buffered and support the
`EventReader`/`EventWriter` API? Derive `BufferedEvent`!
## Alternatives
I'll now cover some of the alternative approaches I have considered and
briefly explored. I made this section collapsible since it ended up
being quite long :P
<details>
<summary>Expand this to see alternatives</summary>
### 1. Unified `Event` Trait
One option is not to have *three* separate traits (`Event`,
`EntityEvent`, `BufferedEvent`), and to instead just use associated
constants on `Event` to determine whether an event supports targeting
and buffering or not:
```rust
pub trait Event: Send + Sync + 'static {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
const TARGETED: bool = false;
const BUFFERED: bool = false;
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
Methods can then use bounds like `where E: Event<TARGETED = true>` or
`where E: Event<BUFFERED = true>` to limit APIs to specific kinds of
events.
This would keep everything under one `Event` trait, but I don't think
it's necessarily a good idea. It makes APIs harder to read, and docs
can't easily refer to specific types of events. You can also create
weird invariants: what if you specify `TARGETED = false`, but have
`Traversal` and/or `AUTO_PROPAGATE` enabled?
### 2. `Event` and `Trigger`
Another option is to only split the traits between buffered events and
observer events, since that is the main thing people have been asking
for, and they have the largest API difference.
If we did this, I think we would need to make the terms *clearly*
separate. We can't really use `Event` and `BufferedEvent` as the names,
since it would be strange that `BufferedEvent` doesn't implement
`Event`. Something like `ObserverEvent` and `BufferedEvent` could work,
but it'd be more verbose.
For this approach, I would instead keep `Event` for the current
`EventReader`/`EventWriter` API, and call the observer event a
`Trigger`, since the "trigger" terminology is already used in the
observer context within Bevy (both as a noun and a verb). This is also
what a long [bikeshed on
Discord](https://discord.com/channels/691052431525675048/749335865876021248/1298057661878898791)
seemed to land on at the end of last year.
```rust
// For `EventReader`/`EventWriter`
pub trait Event: Send + Sync + 'static {}
// For observers
pub trait Trigger: Send + Sync + 'static {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
const TARGETED: bool = false;
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
```
The problem is that "event" is just a really good term for something
that "happens". Observers are rapidly becoming the more prominent API,
so it'd be weird to give them the `Trigger` name and leave the good
`Event` name for the less common API.
So, even though a split like this seems neat on the surface, I think it
ultimately wouldn't really work. We want to keep the `Event` name for
observer events, and there is no good alternative for the buffered
variant. (`Message` was suggested, but saying stuff like "sends a
collision message" is weird.)
### 3. `GlobalEvent` + `TargetedEvent`
What if instead of focusing on the buffered vs. observed split, we
*only* make a distinction between global and targeted events?
```rust
// A shared event trait to allow global observers to work
pub trait Event: Send + Sync + 'static {
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
// For buffered events and non-targeted observer events
pub trait GlobalEvent: Event {}
// For targeted observer events
pub trait TargetedEvent: Event {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
}
```
This is actually the first approach I implemented, and it has the neat
characteristic that you can only use non-targeted APIs like `trigger`
with a `GlobalEvent` and targeted APIs like `trigger_targets` with a
`TargetedEvent`. You have full control over whether the entity should or
should not have a target, as they are fully distinct at the type-level.
However, there's a few problems:
- There is no type-level indication of whether a `GlobalEvent` supports
buffered events or just non-targeted observer events
- An `Event` on its own does literally nothing, it's just a shared trait
required to make global observers accept both non-targeted and targeted
events
- If an event is both a `GlobalEvent` and `TargetedEvent`, global
observers again have ambiguity on whether an event has a target or not,
undermining some of the benefits
- The names are not ideal
### 4. `Event` and `EntityEvent`
We can fix some of the problems of Alternative 3 by accepting that
targeted events can also be used in non-targeted contexts, and simply
having the `Event` and `EntityEvent` traits:
```rust
// For buffered events and non-targeted observer events
pub trait Event: Send + Sync + 'static {
fn register_component_id(world: &mut World) -> ComponentId { ... }
fn component_id(world: &World) -> Option<ComponentId> { ... }
}
// For targeted observer events
pub trait EntityEvent: Event {
type Traversal: Traversal<Self>;
const AUTO_PROPAGATE: bool = false;
}
```
This is essentially identical to this PR, just without a dedicated
`BufferedEvent`. The remaining major "problem" is that there is still
zero type-level indication of whether an `Event` event *actually*
supports the buffered API. This leads us to the solution proposed in
this PR, using `Event`, `EntityEvent`, and `BufferedEvent`.
</details>
## Conclusion
The `Event` + `EntityEvent` + `BufferedEvent` split proposed in this PR
aims to solve all the common problems with Bevy's current event model
while keeping the "weirdness" factor minimal. It splits in terms of both
the push vs. pull *and* global vs. targeted aspects, while maintaining a
shared concept for an "event".
### Why I Like This
- The term "event" remains as a single concept for all the different
kinds of events in Bevy.
- Despite all event types being "events", they use fundamentally
different APIs. Instead of assuming that you can use an event type with
any pattern (when only one is typically supported), you explicitly opt
in to each one with dedicated traits.
- Using separate traits for each type of event helps with documentation
and clearer function signatures.
- I can safely make assumptions on expected usage.
- If I see that an event is an `EntityEvent`, I can assume that I can
use `observe` on it and get targeted events.
- If I see that an event is a `BufferedEvent`, I can assume that I can
use `EventReader` to read events.
- If I see both `EntityEvent` and `BufferedEvent`, I can assume that
both APIs are supported.
In summary: This allows for a unified concept for events, while limiting
the different ways to use them with opt-in traits. No more guess-work
involved when using APIs.
### Problems?
- Because `BufferedEvent` implements `Event` (for more consistent
semantics etc.), you can still use all buffered events for non-targeted
observers. I think this is fine/good. The important part is that if you
see that an event implements `BufferedEvent`, you know that the
`EventReader`/`EventWriter` API should be supported. Whether it *also*
supports other APIs is secondary.
- I currently only support `trigger_targets` for an `EntityEvent`.
However, you can technically target components too, without targeting
any entities. I consider that such a niche and advanced use case that
it's not a huge problem to only support it for `EntityEvent`s, but we
could also split `trigger_targets` into `trigger_entities` and
`trigger_components` if we wanted to (or implement components as
entities :P).
- You can still trigger an `EntityEvent` *without* targets. I consider
this correct, since `Event` implements the non-targeted behavior, and
it'd be weird if implementing another trait *removed* behavior. However,
it does mean that global observers for entity events can technically
return `Entity::PLACEHOLDER` again (since I got rid of the
`Option<Entity>` added in #19440 for ergonomics). I think that's enough
of an edge case that it's not a huge problem, but it is worth keeping in
mind.
- ~~Deriving both `EntityEvent` and `BufferedEvent` for the same type
currently duplicates the `Event` implementation, so you instead need to
manually implement one of them.~~ Changed to always requiring `Event` to
be derived.
## Related Work
There are plans to implement multi-event support for observers,
especially for UI contexts. [Cart's
example](https://github.com/bevyengine/bevy/issues/14649#issuecomment-2960402508)
API looked like this:
```rust
// Truncated for brevity
trigger: Trigger<(
OnAdd<Pressed>,
OnRemove<Pressed>,
OnAdd<InteractionDisabled>,
OnRemove<InteractionDisabled>,
OnInsert<Hovered>,
)>,
```
I believe this shouldn't be in conflict with this PR. If anything, this
PR might *help* achieve the multi-event pattern for entity observers
with fewer footguns: by statically enforcing that all of these events
are `EntityEvent`s in the context of `EntityCommands::observe`, we can
avoid misuse or weird cases where *some* events inside the trigger are
targeted while others are not.
# Objective
This is part of the "core widgets" effort: #19236.
## Solution
This PR adds the "core slider" widget to the collection.
## Testing
Tested using examples `core_widgets` and `core_widgets_observers`.
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
# Objective
Currently, the observer API looks like this:
```rust
app.add_observer(|trigger: Trigger<Explode>| {
info!("Entity {} exploded!", trigger.target());
});
```
Future plans for observers also include "multi-event observers" with a
trigger that looks like this (see [Cart's
example](https://github.com/bevyengine/bevy/issues/14649#issuecomment-2960402508)):
```rust
trigger: Trigger<(
OnAdd<Pressed>,
OnRemove<Pressed>,
OnAdd<InteractionDisabled>,
OnRemove<InteractionDisabled>,
OnInsert<Hovered>,
)>,
```
In scenarios like this, there is a lot of repetition of `On`. These are
expected to be very high-traffic APIs especially in UI contexts, so
ergonomics and readability are critical.
By renaming `Trigger` to `On`, we can make these APIs read more cleanly
and get rid of the repetition:
```rust
app.add_observer(|trigger: On<Explode>| {
info!("Entity {} exploded!", trigger.target());
});
```
```rust
trigger: On<(
Add<Pressed>,
Remove<Pressed>,
Add<InteractionDisabled>,
Remove<InteractionDisabled>,
Insert<Hovered>,
)>,
```
Names like `On<Add<Pressed>>` emphasize the actual event listener nature
more than `Trigger<OnAdd<Pressed>>`, and look cleaner. This *also* frees
up the `Trigger` name if we want to use it for the observer event type,
splitting them out from buffered events (bikeshedding this is out of
scope for this PR though).
For prior art:
[`bevy_eventlistener`](https://github.com/aevyrie/bevy_eventlistener)
used
[`On`](https://docs.rs/bevy_eventlistener/latest/bevy_eventlistener/event_listener/struct.On.html)
for its event listener type. Though in our case, the observer is the
event listener, and `On` is just a type containing information about the
triggered event.
## Solution
Steal from `bevy_event_listener` by @aevyrie and use `On`.
- Rename `Trigger` to `On`
- Rename `OnAdd` to `Add`
- Rename `OnInsert` to `Insert`
- Rename `OnReplace` to `Replace`
- Rename `OnRemove` to `Remove`
- Rename `OnDespawn` to `Despawn`
## Discussion
### Naming Conflicts??
Using a name like `Add` might initially feel like a very bad idea, since
it risks conflict with `core::ops::Add`. However, I don't expect this to
be a big problem in practice.
- You rarely need to actually implement the `Add` trait, especially in
modules that would use the Bevy ECS.
- In the rare cases where you *do* get a conflict, it is very easy to
fix by just disambiguating, for example using `ops::Add`.
- The `Add` event is a struct while the `Add` trait is a trait (duh), so
the compiler error should be very obvious.
For the record, renaming `OnAdd` to `Add`, I got exactly *zero* errors
or conflicts within Bevy itself. But this is of course not entirely
representative of actual projects *using* Bevy.
You might then wonder, why not use `Added`? This would conflict with the
`Added` query filter, so it wouldn't work. Additionally, the current
naming convention for observer events does not use past tense.
### Documentation
This does make documentation slightly more awkward when referring to
`On` or its methods. Previous docs often referred to `Trigger::target`
or "sends a `Trigger`" (which is... a bit strange anyway), which would
now be `On::target` and "sends an observer `Event`".
You can see the diff in this PR to see some of the effects. I think it
should be fine though, we may just need to reword more documentation to
read better.
# Objective
- Update the scroll example to use the latest API.
## Solution
- It now uses the 'children![]' API.
## Testing
- I manually verified that the scrolling was working
## Limitations
- Unfortunately, I couldn't find a way to spawn observers targeting the
entity inside the "fn() -> impl Bundle" function.
# Objective
#19366 implemented core button widgets, which included the `Depressed`
state component.
`Depressed` was chosen instead of `Pressed` to avoid conflict with the
`Pointer<Pressed>` event, but it is problematic and awkward in many
ways:
- Using the word "depressed" for such a high-traffic type is not great
due to the obvious connection to "depressed" as in depression.
- "Depressed" is not what I would search for if I was looking for a
component like this, and I'm not aware of any other engine or UI
framework using the term.
- `Depressed` is not a very natural pair to the `Pointer<Pressed>`
event.
- It might be because I'm not a native English speaker, but I have very
rarely heard someone say "a button is depressed". Seeing it, my mind
initially goes from "depression??" to "oh, de-pressed, meaning released"
and definitely not "is pressed", even though that *is* also a valid
meaning for it.
A related problem is that the current `Pointer<Pressed>` and
`Pointer<Released>` event names use a different verb tense than all of
our other observer events such as `Pointer<Click>` or
`Pointer<DragStart>`. By fixing this and renaming `Pressed` (and
`Released`), we can then use `Pressed` instead of `Depressed` for the
state component.
Additionally, the `IsHovered` and `IsDirectlyHovered` components added
in #19366 use an inconsistent naming; the other similar components don't
use an `Is` prefix. It also makes query filters like `Has<IsHovered>`
and `With<IsHovered>` a bit more awkward.
This is partially related to Cart's [picking concept
proposal](https://gist.github.com/cart/756e48a149db2838028be600defbd24a?permalink_comment_id=5598154).
## Solution
- Rename `Pointer<Pressed>` to `Pointer<Press>`
- Rename `Pointer<Released>` to `Pointer<Release>`
- Rename `Depressed` to `Pressed`
- Rename `IsHovered` to `Hovered`
- Rename `IsDirectlyHovered` to `DirectlyHovered`
# Objective
Part of #19236
## Solution
Adds a new `bevy_core_widgets` crate containing headless widget
implementations. This PR adds a single `CoreButton` widget, more widgets
to be added later once this is approved.
## Testing
There's an example, ui/core_widgets.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Rename `JustifyText`:
* The name `JustifyText` is just ugly.
* It's inconsistent since no other `bevy_text` types have a `Text-`
suffix, only prefix.
* It's inconsistent with the other text layout enum `Linebreak` which
doesn't have a prefix or suffix.
Fixes#19521.
## Solution
Rename `JustifyText` to `Justify`.
Without other context, it's natural to assume the name `Justify` refers
to text justification.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
`Entity::PLACEHOLDER` acts as a magic number that will *probably* never
really exist, but it certainly could. And, `Entity` has a niche, so the
only reason to use `PLACEHOLDER` is as an alternative to `MaybeUninit`
that trades safety risks for logic risks.
As a result, bevy has generally advised against using `PLACEHOLDER`, but
we still use if for a lot internally. This pr starts removing internal
uses of it, starting from observers.
## Solution
Change all trigger target related types from `Entity` to
`Option<Entity>`
Small migration guide to come.
## Testing
CI
## Future Work
This turned a lot of code from
```rust
trigger.target()
```
to
```rust
trigger.target().unwrap()
```
The extra panic is no worse than before; it's just earlier than
panicking after passing the placeholder to something else.
But this is kinda annoying.
I would like to add a `TriggerMode` or something to `Event` that would
restrict what kinds of targets can be used for that event. Many events
like `Removed` etc, are always triggered with a target. We can make
those have a way to assume Some, etc. But I wanted to save that for a
future pr.
# Objective
Add specialized UI transform `Component`s and fix some related problems:
* Animating UI elements by modifying the `Transform` component of UI
nodes doesn't work very well because `ui_layout_system` overwrites the
translations each frame. The `overflow_debug` example uses a horrible
hack where it copies the transform into the position that'll likely
cause a panic if any users naively copy it.
* Picking ignores rotation and scaling and assumes UI nodes are always
axis aligned.
* The clipping geometry stored in `CalculatedClip` is wrong for rotated
and scaled elements.
* Transform propagation is unnecessary for the UI, the transforms can be
updated during layout updates.
* The UI internals use both object-centered and top-left-corner-based
coordinates systems for UI nodes. Depending on the context you have to
add or subtract the half-size sometimes before transforming between
coordinate spaces. We should just use one system consistantly so that
the transform can always be directly applied.
* `Transform` doesn't support responsive coordinates.
## Solution
* Unrequire `Transform` from `Node`.
* New components `UiTransform`, `UiGlobalTransform`:
- `Node` requires `UiTransform`, `UiTransform` requires
`UiGlobalTransform`
- `UiTransform` is a 2d-only equivalent of `Transform` with a
translation in `Val`s.
- `UiGlobalTransform` newtypes `Affine2` and is updated in
`ui_layout_system`.
* New helper functions on `ComputedNode` for mapping between viewport
and local node space.
* The cursor position is transformed to local node space during picking
so that it respects rotations and scalings.
* To check if the cursor hovers a node recursively walk up the tree to
the root checking if any of the ancestor nodes clip the point at the
cursor. If the point is clipped the interaction is ignored.
* Use object-centered coordinates for UI nodes.
* `RelativeCursorPosition`'s coordinates are now object-centered with
(0,0) at the the center of the node and the corners at (±0.5, ±0.5).
* Replaced the `normalized_visible_node_rect: Rect` field of
`RelativeCursorPosition` with `cursor_over: bool`, which is set to true
when the cursor is over an unclipped point on the node. The visible area
of the node is not necessarily a rectangle, so the previous
implementation didn't work.
This should fix all the logical bugs with non-axis aligned interactions
and clipping. Rendering still needs changes but they are far outside the
scope of this PR.
Tried and abandoned two other approaches:
* New `transform` field on `Node`, require `GlobalTransform` on `Node`,
and unrequire `Transform` on `Node`. Unrequiring `Transform` opts out of
transform propagation so there is then no conflict with updating the
`GlobalTransform` in `ui_layout_system`. This was a nice change in its
simplicity but potentially confusing for users I think, all the
`GlobalTransform` docs mention `Transform` and having special rules for
how it's updated just for the UI is unpleasently surprising.
* New `transform` field on `Node`. Unrequire `Transform` on `Node`. New
`transform: Affine2` field on `ComputedNode`.
This was okay but I think most users want a separate specialized UI
transform components. The fat `ComputedNode` doesn't work well with
change detection.
Fixes#18929, #18930
## Testing
There is an example you can look at:
```
cargo run --example ui_transform
```
Sometimes in the example if you press the rotate button couple of times
the first glyph from the top label disappears , I'm not sure what's
causing it yet but I don't think it's related to this PR.
## Migration Guide
New specialized 2D UI transform components `UiTransform` and
`UiGlobalTransform`. `UiTransform` is a 2d-only equivalent of
`Transform` with a translation in `Val`s. `UiGlobalTransform` newtypes
`Affine2` and is updated in `ui_layout_system`.
`Node` now requires `UiTransform` instead of `Transform`. `UiTransform`
requires `UiGlobalTransform`.
In previous versions of Bevy `ui_layout_system` would overwrite UI
node's `Transform::translation` each frame. `UiTransform`s aren't
overwritten and there is no longer any need for systems that cache and
rewrite the transform for translated UI elements.
`RelativeCursorPosition`'s coordinates are now object-centered with
(0,0) at the the center of the node and the corners at (±0.5, ±0.5). Its
`normalized_visible_node_rect` field has been removed and replaced with
a new `cursor_over: bool` field which is set to true when the cursor is
hovering an unclipped area of the UI node.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
When running the `gradient` example, part of the content doesn't fit
within the initial window:
The UI requires 1830×930 pixels, but the initial window size is
1280×720.
## Solution
Make ui elements smaller:
Alternative: Use a larger initial window size. I decided against this
because that would make the examples less uniform, make the code less
focused on gradients and not help on web.
# Objective
Minimal effort to address feedback here:
https://github.com/bevyengine/bevy/pull/19345#discussion_r2107844018
more thoroughly.
## Solution
- Remove hardcoded label string comparisons and make more use of the new
enum added during review
- Resist temptation to let this snowball this into a huge refactor
- Maybe come back later for a few other small improvements
## Testing
`cargo run --example box_shadow`
# Objective
Renames `Timer::finished` and `Timer::paused` to `Timer::is_finished`
and `Timer::is_paused` to align the public APIs for `Time`, `Timer`, and
`Stopwatch`.
Fixes#19110
# Objective
Fixes#19385
Note: this has shader errors due to #19383 and should probably be merged
after #19384
## Solution
- Move the example to the UI testbed
- Adjust label contents and cell size so that every test case fits on
the screen
- Minor tidying, slightly less harsh colors while preserving the
intentional debug coloring
## Testing
`cargo run --example testbed_ui`
---------
Co-authored-by: François Mockers <mockersf@gmail.com>
# Objective
- Addresses the previous example's lack of visual appeal and clarity. It
was missing labels for clear distinction of the shadow settings used on
each of the shapes. The suggestion in the linked issue was to either
just visually update and add labels or to collapse example to a single
node with adjustable settings.
- Fixes#19240
## Solution
- Replace the previous static example with a single, central node with
adjustable settings as per issue suggestion.
- Implement button-based setting adjustments. Unfortunately slider
widgets don't seem available yet and I didn't want to further bloat the
example.
- Improve overall aesthetics of the example -- although color pallette
could still be improved. flat gray tones are probably not the best
choice as a contrast to the shadow, but the white border does help in
that aspect.
- Dynamically recolor shadows for visual clarity when increasing shadow
count.
- Add Adjustable Settings:
- Shape selection
- Shadow X/Y offset, blur, spread, and count
- Add Reset button to restore default settings
The disadvantage of this solution is that the old example code would
have probably been easier to digest as the new example is quite bloated
in comparison. Alternatively I could also just implement labels and fix
aesthetics of the old example without adding functionality for
adjustable settings, _but_ I personally feel like interactive examples
are more engaging to users.
## Testing
- Did you test these changes? If so, how? `cargo run --example
box_shadow` and functionality of all features of the example.
- Are there any parts that need more testing? Not that I am aware of.
- How can other people (reviewers) test your changes? Is there anything
specific they need to know? Not really, it should be pretty
straightforward just running the new example and testing the feats.
---
## Showcase
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
# Objective
Improve the `tab_navigation` example.
## Solution
* Set different `TabIndex`s for the buttons of each group.
* Label each button with its associated `TabIndex`.
* Reduce the code duplication using a loop.
I tried to flatten it further using the new spawning APIs and
`children!` macro but not sure what the current best way to attach the
observers is.
# Objective
The new viewport example allocates a texture in main memory, even though
it's only needed on the GPU. Also fix an unnecessary warning when a
viewport's texture doesn't exist CPU-side.
## Testing
Run the `viewport_node` example.
# Objective
allow specifying the left/top/right/bottom border colors separately for
ui elements
fixes#14773
## Solution
- change `BorderColor` to
```rs
pub struct BorderColor {
pub left: Color,
pub top: Color,
pub right: Color,
pub bottom: Color,
}
```
- generate one ui node per distinct border color, set flags for the
active borders
- render only the active borders
i chose to do this rather than adding multiple colors to the
ExtractedUiNode in order to minimize the impact for the common case
where all border colors are the same.
## Testing
modified the `borders` example to use separate colors:
the behaviour is a bit weird but it mirrors html/css border behaviour.
---
## Migration:
To keep the existing behaviour, just change `BorderColor(color)` into
`BorderColor::all(color)`.
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
# Objective
Accessibility features don't work with the UI `button` example because
`InputFocus` must be set for the accessibility systems to recognise the
button.
Fixes#18760
## Solution
* Set the button entity as the `InputFocus` when it is hovered or
pressed.
* Call `set_changed` on the `Button` component when the button's state
changes to hovered or pressed (the accessibility system's only update
the button's state when the `Button` component is marked as changed).
## Testing
Install NVDA, it should say "hover" when the button is hovered and
"pressed" when the button is pressed.
The bounds of the accessibility node are reported incorrectly. I thought
we fixed this, I'll take another look at it. It's not a problem with
this PR.
# Objective
Allowing drawing of UI nodes with a gradient instead of a flat color.
## Solution
The are three gradient structs corresponding to the three types of
gradients supported: `LinearGradient`, `ConicGradient` and
`RadialGradient`. These are then wrapped in a `Gradient` enum
discriminator which has `Linear`, `Conic` and `Radial` variants.
Each gradient type consists of the geometric properties for that
gradient and a list of color stops.
Color stops consist of a color, a position or angle and an optional
hint. If no position is specified for a stop, it's evenly spaced between
the previous and following stops. Color stop positions are absolute, if
you specify a list of stops:
```vec
Conic gradients can be used to draw simple pie charts like in CSS:
# Objective
Add a viewport widget.
## Solution
- Add a new `ViewportNode` component to turn a UI node into a viewport.
- Add `viewport_picking` to pass pointer inputs from other pointers to
the viewport's pointer.
- Notably, this is somewhat functionally different from the viewport
widget in [the editor
prototype](https://github.com/bevyengine/bevy_editor_prototypes/pull/110/files#L124),
which just moves the pointer's location onto the render target. Viewport
widgets have their own pointers.
- Care is taken to handle dragging in and out of viewports.
- Add `update_viewport_render_target_size` to update the viewport node's
render target's size if the node size changes.
- Feature gate picking-related viewport items behind
`bevy_ui_picking_backend`.
## Testing
I've been using an example I made to test the widget (and added it as
`viewport_node`):
<details><summary>Code</summary>
```rust
//! A simple scene to demonstrate spawning a viewport widget. The example will demonstrate how to
//! pick entities visible in the widget's view.
use bevy::picking::pointer::PointerInteraction;
use bevy::prelude::*;
use bevy::ui::widget::ViewportNode;
use bevy::{
image::{TextureFormatPixelInfo, Volume},
window::PrimaryWindow,
};
use bevy_render::{
camera::RenderTarget,
render_resource::{
Extent3d, TextureDescriptor, TextureDimension, TextureFormat, TextureUsages,
},
};
fn main() {
App::new()
.add_plugins((DefaultPlugins, MeshPickingPlugin))
.add_systems(Startup, test)
.add_systems(Update, draw_mesh_intersections)
.run();
}
#[derive(Component, Reflect, Debug)]
#[reflect(Component)]
struct Shape;
fn test(
mut commands: Commands,
window: Query<&Window, With<PrimaryWindow>>,
mut images: ResMut<Assets<Image>>,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
) {
// Spawn a UI camera
commands.spawn(Camera3d::default());
// Set up an texture for the 3D camera to render to
let window = window.get_single().unwrap();
let window_size = window.physical_size();
let size = Extent3d {
width: window_size.x,
height: window_size.y,
..default()
};
let format = TextureFormat::Bgra8UnormSrgb;
let image = Image {
data: Some(vec![0; size.volume() * format.pixel_size()]),
texture_descriptor: TextureDescriptor {
label: None,
size,
dimension: TextureDimension::D2,
format,
mip_level_count: 1,
sample_count: 1,
usage: TextureUsages::TEXTURE_BINDING
| TextureUsages::COPY_DST
| TextureUsages::RENDER_ATTACHMENT,
view_formats: &[],
},
..default()
};
let image_handle = images.add(image);
// Spawn the 3D camera
let camera = commands
.spawn((
Camera3d::default(),
Camera {
// Render this camera before our UI camera
order: -1,
target: RenderTarget::Image(image_handle.clone().into()),
..default()
},
))
.id();
// Spawn something for the 3D camera to look at
commands
.spawn((
Mesh3d(meshes.add(Cuboid::new(5.0, 5.0, 5.0))),
MeshMaterial3d(materials.add(Color::WHITE)),
Transform::from_xyz(0.0, 0.0, -10.0),
Shape,
))
// We can observe pointer events on our objects as normal, the
// `bevy::ui::widgets::viewport_picking` system will take care of ensuring our viewport
// clicks pass through
.observe(on_drag_cuboid);
// Spawn our viewport widget
commands
.spawn((
Node {
position_type: PositionType::Absolute,
top: Val::Px(50.0),
left: Val::Px(50.0),
width: Val::Px(200.0),
height: Val::Px(200.0),
border: UiRect::all(Val::Px(5.0)),
..default()
},
BorderColor(Color::WHITE),
ViewportNode::new(camera),
))
.observe(on_drag_viewport);
}
fn on_drag_viewport(drag: Trigger<Pointer<Drag>>, mut node_query: Query<&mut Node>) {
if matches!(drag.button, PointerButton::Secondary) {
let mut node = node_query.get_mut(drag.target()).unwrap();
if let (Val::Px(top), Val::Px(left)) = (node.top, node.left) {
node.left = Val::Px(left + drag.delta.x);
node.top = Val::Px(top + drag.delta.y);
};
}
}
fn on_drag_cuboid(drag: Trigger<Pointer<Drag>>, mut transform_query: Query<&mut Transform>) {
if matches!(drag.button, PointerButton::Primary) {
let mut transform = transform_query.get_mut(drag.target()).unwrap();
transform.rotate_y(drag.delta.x * 0.02);
transform.rotate_x(drag.delta.y * 0.02);
}
}
fn draw_mesh_intersections(
pointers: Query<&PointerInteraction>,
untargetable: Query<Entity, Without<Shape>>,
mut gizmos: Gizmos,
) {
for (point, normal) in pointers
.iter()
.flat_map(|interaction| interaction.iter())
.filter_map(|(entity, hit)| {
if !untargetable.contains(*entity) {
hit.position.zip(hit.normal)
} else {
None
}
})
{
gizmos.arrow(point, point + normal.normalize() * 0.5, Color::WHITE);
}
}
```
</details>
## Showcase
https://github.com/user-attachments/assets/39f44eac-2c2a-4fd9-a606-04171f806dc1
## Open Questions
- <del>Not sure whether the entire widget should be feature gated behind
`bevy_ui_picking_backend` or not? I chose a partial approach since maybe
someone will want to use the widget without any picking being
involved.</del>
- <del>Is `PickSet::Last` the expected set for `viewport_picking`?
Perhaps `PickSet::Input` is more suited.</del>
- <del>Can `dragged_last_frame` be removed in favor of a better dragging
check? Another option that comes to mind is reading `Drag` and `DragEnd`
events, but this seems messier.</del>
---------
Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
Co-authored-by: François Mockers <mockersf@gmail.com>
# Objective
Refactor
[`examples/ui/borders.rs`](7f0490655c/examples/ui/borders.rs)
to use the new spawning/hierarchy APIs in 0.16.
## Solution
This refactor reduces the number of `.spawn` calls from about 16 to 2,
using one spawn for each major feature:
* camera2d
* ui layout
The `Children::spawn` relationship API is used to take advantage of
`SpawnIter` for the borders examples in each block.
Each block of examples now returns a Bundle into its respective
variable, which is then used in combination with the new `label` widget
which makes use of the new `impl Bundle` return capability. This allows
the ui layout to use a single `.spawn` with the `children!` macro.
The blocks of examples are still in separate variables because it felt
like a useful way to organize it still, even without needing to spawn at
those locations.
Functionality of the demo hasn't changed, this is just an API/code
update.
## Showcase
<details>
<summary>Before screenshot</summary>
</details>
---------
Co-authored-by: François Mockers <mockersf@gmail.com>
# Objective
Add background colors for text.
Fixes#18889
## Solution
New component `TextBackgroundColor`, add it to any UI `Text` or
`TextSpan` entity to add a background color to its text.
New field on `TextLayoutInfo` `section_rects` holds the list of bounding
rects for each text section.
The bounding rects are generated in `TextPipeline::queue_text` during
text layout, `extract_text_background_colors` extracts the colored
background rects for rendering.
Didn't include `Text2d` support because of z-order issues.
The section rects can also be used to implement interactions targeting
individual text sections.
## Testing
Includes a basic example that can be used for testing:
```
cargo run --example text_background_colors
```
---
## Showcase
Using a proportional font with kerning the results aren't so tidy (since
the bounds of adjacent glyphs can overlap) but it still works fine:
---------
Co-authored-by: Olle Lukowski <lukowskiolle@gmail.com>
Co-authored-by: Gilles Henaux <ghx_github_priv@fastmail.com>
# Objective
Tripped over the `directional_navigation` one recently while playing
around with that example.
Examples should import items from `bevy` rather than the sub-crates
directly.
## Solution
Use paths re-exported by `bevy`.
## Testing
```
cargo run --example log_diagnostics
cargo run --example directional_navigation
cargo run --example custom_projection
```
# Objective
The goal of `bevy_platform_support` is to provide a set of platform
agnostic APIs, alongside platform-specific functionality. This is a high
traffic crate (providing things like HashMap and Instant). Especially in
light of https://github.com/bevyengine/bevy/discussions/18799, it
deserves a friendlier / shorter name.
Given that it hasn't had a full release yet, getting this change in
before Bevy 0.16 makes sense.
## Solution
- Rename `bevy_platform_support` to `bevy_platform`.
# Objective
In #17905 we swapped to a named field on `ChildOf` to help resolve
variable naming ambiguity of child vs parent (ex: `child_of.parent`
clearly reads as "I am accessing the parent of the child_of
relationship", whereas `child_of.0` is less clear).
Unfortunately this has the side effect of making initialization less
ideal. `ChildOf { parent }` reads just as well as `ChildOf(parent)`, but
`ChildOf { parent: root }` doesn't read nearly as well as
`ChildOf(root)`.
## Solution
Move back to `ChildOf(pub Entity)` but add a `child_of.parent()`
function and use it for all accesses. The downside here is that users
are no longer "forced" to access the parent field with `parent`
nomenclature, but I think this strikes the right balance.
Take a look at the diff. I think the results provide strong evidence for
this change. Initialization has the benefit of reading much better _and_
of taking up significantly less space, as many lines go from 3 to 1, and
we're cutting out a bunch of syntax in some cases.
Sadly I do think this should land in 0.16 as the cost of doing this
_after_ the relationships migration is high.
# Objective
@cart noticed some issues with my work in
https://github.com/bevyengine/bevy/pull/17348#discussion_r2001815637,
which I somehow missed before merging the PR.
## Solution
- feature gate the UiPickingPlugin correctly
- don't manually add the picking plugins
## Testing
Ran the debug_picking and sprite_picking examples (for UI and sprites
respectively): both seem to work fine.
# Objective
Currently, our picking backends are inconsistent:
- Mesh picking and sprite picking both have configurable opt in/out
behavior. UI picking does not.
- Sprite picking uses `SpritePickingCamera` and `Pickable` for control,
but mesh picking uses `RayCastPickable`.
- `MeshPickingPlugin` is not a part of `DefaultPlugins`.
`SpritePickingPlugin` and `UiPickingPlugin` are.
## Solution
- Add configurable opt in/out behavior to UI picking (defaults to opt
out).
- Replace `RayCastPickable` with `MeshPickingCamera` and `Pickable`.
- Remove `SpritePickingPlugin` and `UiPickingPlugin` from
`DefaultPlugins`.
## Testing
Ran some examples.
## Migration Guide
`UiPickingPlugin` and `SpritePickingPlugin` are no longer included in
`DefaultPlugins`. They must be explicitly added.
`RayCastPickable` has been replaced in favor of the `MeshPickingCamera`
and `Pickable` components. You should add them to cameras and entities,
respectively, if you have `MeshPickingSettings::require_markers` set to
`true`.
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
Correct spelling
## Solution
Fix typos, specifically ones that I found in folders other than /crates
## Testing
CI
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
There are currently three ways to access the parent stored on a ChildOf
relationship:
1. `child_of.parent` (field accessor)
2. `child_of.get()` (get function)
3. `**child_of` (Deref impl)
I will assert that we should only have one (the field accessor), and
that the existence of the other implementations causes confusion and
legibility issues. The deref approach is heinous, and `child_of.get()`
is significantly less clear than `child_of.parent`.
## Solution
Remove `impl Deref for ChildOf` and `ChildOf::get`.
The one "downside" I'm seeing is that:
```rust
entity.get::<ChildOf>().map(ChildOf::get)
```
Becomes this:
```rust
entity.get::<ChildOf>().map(|c| c.parent)
```
I strongly believe that this is worth the increased clarity and
consistency. I'm also not really a huge fan of the "pass function
pointer to map" syntax. I think most people don't think this way about
maps. They think in terms of a function that takes the item in the
Option and returns the result of some action on it.
## Migration Guide
```rust
// Before
**child_of
// After
child_of.parent
// Before
child_of.get()
// After
child_of.parent
// Before
entity.get::<ChildOf>().map(ChildOf::get)
// After
entity.get::<ChildOf>().map(|c| c.parent)
```
# Objective
fixes#17896
## Solution
Change ChildOf ( Entity ) to ChildOf { parent: Entity }
by doing this we also allow users to use named structs for relationship
derives, When you have more than 1 field in a struct with named fields
the macro will look for a field with the attribute #[relationship] and
all of the other fields should implement the Default trait. Unnamed
fields are still supported.
When u have a unnamed struct with more than one field the macro will
fail.
Do we want to support something like this ?
```rust
#[derive(Component)]
#[relationship_target(relationship = ChildOf)]
pub struct Children (#[relationship] Entity, u8);
```
I could add this, it but doesn't seem nice.
## Testing
crates/bevy_ecs - cargo test
## Showcase
```rust
use bevy_ecs::component::Component;
use bevy_ecs::entity::Entity;
#[derive(Component)]
#[relationship(relationship_target = Children)]
pub struct ChildOf {
#[relationship]
pub parent: Entity,
internal: u8,
};
#[derive(Component)]
#[relationship_target(relationship = ChildOf)]
pub struct Children {
children: Vec<Entity>
};
```
---------
Co-authored-by: Tim Overbeek <oorbecktim@Tims-MacBook-Pro.local>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-042.client.nl.eduvpn.org>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-059.client.nl.eduvpn.org>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-054.client.nl.eduvpn.org>
Co-authored-by: Tim Overbeek <oorbecktim@c-001-001-027.client.nl.eduvpn.org>
# Objective
- Fixes#17960
## Solution
- Followed the [edition upgrade
guide](https://doc.rust-lang.org/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html)
## Testing
- CI
---
## Summary of Changes
### Documentation Indentation
When using lists in documentation, proper indentation is now linted for.
This means subsequent lines within the same list item must start at the
same indentation level as the item.
```rust
/* Valid */
/// - Item 1
/// Run-on sentence.
/// - Item 2
struct Foo;
/* Invalid */
/// - Item 1
/// Run-on sentence.
/// - Item 2
struct Foo;
```
### Implicit `!` to `()` Conversion
`!` (the never return type, returned by `panic!`, etc.) no longer
implicitly converts to `()`. This is particularly painful for systems
with `todo!` or `panic!` statements, as they will no longer be functions
returning `()` (or `Result<()>`), making them invalid systems for
functions like `add_systems`. The ideal fix would be to accept functions
returning `!` (or rather, _not_ returning), but this is blocked on the
[stabilisation of the `!` type
itself](https://doc.rust-lang.org/std/primitive.never.html), which is
not done.
The "simple" fix would be to add an explicit `-> ()` to system
signatures (e.g., `|| { todo!() }` becomes `|| -> () { todo!() }`).
However, this is _also_ banned, as there is an existing lint which (IMO,
incorrectly) marks this as an unnecessary annotation.
So, the "fix" (read: workaround) is to put these kinds of `|| -> ! { ...
}` closuers into variables and give the variable an explicit type (e.g.,
`fn()`).
```rust
// Valid
let system: fn() = || todo!("Not implemented yet!");
app.add_systems(..., system);
// Invalid
app.add_systems(..., || todo!("Not implemented yet!"));
```
### Temporary Variable Lifetimes
The order in which temporary variables are dropped has changed. The
simple fix here is _usually_ to just assign temporaries to a named
variable before use.
### `gen` is a keyword
We can no longer use the name `gen` as it is reserved for a future
generator syntax. This involved replacing uses of the name `gen` with
`r#gen` (the raw-identifier syntax).
### Formatting has changed
Use statements have had the order of imports changed, causing a
substantial +/-3,000 diff when applied. For now, I have opted-out of
this change by amending `rustfmt.toml`
```toml
style_edition = "2021"
```
This preserves the original formatting for now, reducing the size of
this PR. It would be a simple followup to update this to 2024 and run
`cargo fmt`.
### New `use<>` Opt-Out Syntax
Lifetimes are now implicitly included in RPIT types. There was a handful
of instances where it needed to be added to satisfy the borrow checker,
but there may be more cases where it _should_ be added to avoid
breakages in user code.
### `MyUnitStruct { .. }` is an invalid pattern
Previously, you could match against unit structs (and unit enum
variants) with a `{ .. }` destructuring. This is no longer valid.
### Pretty much every use of `ref` and `mut` are gone
Pattern binding has changed to the point where these terms are largely
unused now. They still serve a purpose, but it is far more niche now.
### `iter::repeat(...).take(...)` is bad
New lint recommends using the more explicit `iter::repeat_n(..., ...)`
instead.
## Migration Guide
The lifetimes of functions using return-position impl-trait (RPIT) are
likely _more_ conservative than they had been previously. If you
encounter lifetime issues with such a function, please create an issue
to investigate the addition of `+ use<...>`.
## Notes
- Check the individual commits for a clearer breakdown for what
_actually_ changed.
---------
Co-authored-by: François Mockers <francois.mockers@vleue.com>
Fixes#17856.
## Migration Guide
- `EventWriter::send` has been renamed to `EventWriter::write`.
- `EventWriter::send_batch` has been renamed to
`EventWriter::write_batch`.
- `EventWriter::send_default` has been renamed to
`EventWriter::write_default`.
---------
Co-authored-by: François Mockers <mockersf@gmail.com>
# Objective
Fixes#17851
## Solution
Align the `slider` uniform to 16 bytes by making it a `vec4`.
## Testing
Run the example using:
```
cargo run -p build-wasm-example -- --api webgl2 ui_material
basic-http-server examples/wasm/
```
# Objective
Tidy up a few little things I noticed while working with this example
## Solution
- Fix manual resetting of a repeating timer
- Use atlas image size instead of hardcoded value. Atlases are always
512x512 right now, but hopefully not in the future.
- Pluralize a variable name for a variable holding a `Vec`
## Objective
A major critique of Bevy at the moment is how boilerplatey it is to
compose (and read) entity hierarchies:
```rust
commands
.spawn(Foo)
.with_children(|p| {
p.spawn(Bar).with_children(|p| {
p.spawn(Baz);
});
p.spawn(Bar).with_children(|p| {
p.spawn(Baz);
});
});
```
There is also currently no good way to statically define and return an
entity hierarchy from a function. Instead, people often do this
"internally" with a Commands function that returns nothing, making it
impossible to spawn the hierarchy in other cases (direct World spawns,
ChildSpawner, etc).
Additionally, because this style of API results in creating the
hierarchy bits _after_ the initial spawn of a bundle, it causes ECS
archetype changes (and often expensive table moves).
Because children are initialized after the fact, we also can't count
them to pre-allocate space. This means each time a child inserts itself,
it has a high chance of overflowing the currently allocated capacity in
the `RelationshipTarget` collection, causing literal worst-case
reallocations.
We can do better!
## Solution
The Bundle trait has been extended to support an optional
`BundleEffect`. This is applied directly to World immediately _after_
the Bundle has fully inserted. Note that this is
[intentionally](https://github.com/bevyengine/bevy/discussions/16920)
_not done via a deferred Command_, which would require repeatedly
copying each remaining subtree of the hierarchy to a new command as we
walk down the tree (_not_ good performance).
This allows us to implement the new `SpawnRelated` trait for all
`RelationshipTarget` impls, which looks like this in practice:
```rust
world.spawn((
Foo,
Children::spawn((
Spawn((
Bar,
Children::spawn(Spawn(Baz)),
)),
Spawn((
Bar,
Children::spawn(Spawn(Baz)),
)),
))
))
```
`Children::spawn` returns `SpawnRelatedBundle<Children, L:
SpawnableList>`, which is a `Bundle` that inserts `Children`
(preallocated to the size of the `SpawnableList::size_hint()`).
`Spawn<B: Bundle>(pub B)` implements `SpawnableList` with a size of 1.
`SpawnableList` is also implemented for tuples of `SpawnableList` (same
general pattern as the Bundle impl).
There are currently three built-in `SpawnableList` implementations:
```rust
world.spawn((
Foo,
Children::spawn((
Spawn(Name::new("Child1")),
SpawnIter(["Child2", "Child3"].into_iter().map(Name::new),
SpawnWith(|parent: &mut ChildSpawner| {
parent.spawn(Name::new("Child4"));
parent.spawn(Name::new("Child5"));
})
)),
))
```
We get the benefits of "structured init", but we have nice flexibility
where it is required!
Some readers' first instinct might be to try to remove the need for the
`Spawn` wrapper. This is impossible in the Rust type system, as a tuple
of "child Bundles to be spawned" and a "tuple of Components to be added
via a single Bundle" is ambiguous in the Rust type system. There are two
ways to resolve that ambiguity:
1. By adding support for variadics to the Rust type system (removing the
need for nested bundles). This is out of scope for this PR :)
2. Using wrapper types to resolve the ambiguity (this is what I did in
this PR).
For the single-entity spawn cases, `Children::spawn_one` does also
exist, which removes the need for the wrapper:
```rust
world.spawn((
Foo,
Children::spawn_one(Bar),
))
```
## This works for all Relationships
This API isn't just for `Children` / `ChildOf` relationships. It works
for any relationship type, and they can be mixed and matched!
```rust
world.spawn((
Foo,
Observers::spawn((
Spawn(Observer::new(|trigger: Trigger<FuseLit>| {})),
Spawn(Observer::new(|trigger: Trigger<Exploded>| {})),
)),
OwnerOf::spawn(Spawn(Bar))
Children::spawn(Spawn(Baz))
))
```
## Macros
While `Spawn` is necessary to satisfy the type system, we _can_ remove
the need to express it via macros. The example above can be expressed
more succinctly using the new `children![X]` macro, which internally
produces `Children::spawn(Spawn(X))`:
```rust
world.spawn((
Foo,
children![
(
Bar,
children![Baz],
),
(
Bar,
children![Baz],
),
]
))
```
There is also a `related!` macro, which is a generic version of the
`children!` macro that supports any relationship type:
```rust
world.spawn((
Foo,
related!(Children[
(
Bar,
related!(Children[Baz]),
),
(
Bar,
related!(Children[Baz]),
),
])
))
```
## Returning Hierarchies from Functions
Thanks to these changes, the following pattern is now possible:
```rust
fn button(text: &str, color: Color) -> impl Bundle {
(
Node {
width: Val::Px(300.),
height: Val::Px(100.),
..default()
},
BackgroundColor(color),
children![
Text::new(text),
]
)
}
fn ui() -> impl Bundle {
(
Node {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
..default(),
},
children![
button("hello", BLUE),
button("world", RED),
]
)
}
// spawn from a system
fn system(mut commands: Commands) {
commands.spawn(ui());
}
// spawn directly on World
world.spawn(ui());
```
## Additional Changes and Notes
* `Bundle::from_components` has been split out into
`BundleFromComponents::from_components`, enabling us to implement
`Bundle` for types that cannot be "taken" from the ECS (such as the new
`SpawnRelatedBundle`).
* The `NoBundleEffect` trait (which implements `BundleEffect`) is
implemented for empty tuples (and tuples of empty tuples), which allows
us to constrain APIs to only accept bundles that do not have effects.
This is critical because the current batch spawn APIs cannot efficiently
apply BundleEffects in their current form (as doing so in-place could
invalidate the cached raw pointers). We could consider allocating a
buffer of the effects to be applied later, but that does have
performance implications that could offset the balance and value of the
batched APIs (and would likely require some refactors to the underlying
code). I've decided to be conservative here. We can consider relaxing
that requirement on those APIs later, but that should be done in a
followup imo.
* I've ported a few examples to illustrate real-world usage. I think in
a followup we should port all examples to the `children!` form whenever
possible (and for cases that require things like SpawnIter, use the raw
APIs).
* Some may ask "why not use the `Relationship` to spawn (ex:
`ChildOf::spawn(Foo)`) instead of the `RelationshipTarget` (ex:
`Children::spawn(Spawn(Foo))`)?". That _would_ allow us to remove the
`Spawn` wrapper. I've explicitly chosen to disallow this pattern.
`Bundle::Effect` has the ability to create _significant_ weirdness.
Things in `Bundle` position look like components. For example
`world.spawn((Foo, ChildOf::spawn(Bar)))` _looks and reads_ like Foo is
a child of Bar. `ChildOf` is in Foo's "component position" but it is not
a component on Foo. This is a huge problem. Now that `Bundle::Effect`
exists, we should be _very_ principled about keeping the "weird and
unintuitive behavior" to a minimum. Things that read like components
_should be the components they appear to be".
## Remaining Work
* The macros are currently trivially implemented using macro_rules and
are currently limited to the max tuple length. They will require a
proc_macro implementation to work around the tuple length limit.
## Next Steps
* Port the remaining examples to use `children!` where possible and raw
`Spawn` / `SpawnIter` / `SpawnWith` where the flexibility of the raw API
is required.
## Migration Guide
Existing spawn patterns will continue to work as expected.
Manual Bundle implementations now require a `BundleEffect` associated
type. Exisiting bundles would have no bundle effect, so use `()`.
Additionally `Bundle::from_components` has been moved to the new
`BundleFromComponents` trait.
```rust
// Before
unsafe impl Bundle for X {
unsafe fn from_components<T, F>(ctx: &mut T, func: &mut F) -> Self {
}
/* remaining bundle impl here */
}
// After
unsafe impl Bundle for X {
type Effect = ();
/* remaining bundle impl here */
}
unsafe impl BundleFromComponents for X {
unsafe fn from_components<T, F>(ctx: &mut T, func: &mut F) -> Self {
}
}
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
Co-authored-by: Emerson Coskey <emerson@coskey.dev>
# Objective
Basic `TextShadow` support.
## Solution
New `TextShadow` component with `offset` and `color` fields. Just insert
it on a `Text` node to add a shadow.
New system `extract_text_shadows` handles rendering.
It's not "real" shadows just the text redrawn with an offset and a
different colour. Blur-radius support will need changes to the shaders
and be a lot more complicated, whereas this still looks okay and took a
couple of minutes to implement.
I added the `TextShadow` component to `bevy_ui` rather than `bevy_text`
because it only supports the UI atm.
We can add a `Text2d` version in a followup but getting the same effect
in `Text2d` is trivial even without official support.
---
## Showcase
<img width="122" alt="text_shadow"
src="https://github.com/user-attachments/assets/0333d167-c507-4262-b93b-b6d39e2cf3a4"
/>
<img width="136" alt="g"
src="https://github.com/user-attachments/assets/9b01d5d9-55c9-4af7-9360-a7b04f55944d"
/>
# Objective
The feature gates for the `UiChildren` and `UiRootNodes` system params
make the unconstructable `GhostNode` `PhantomData` trick redundant.
## Solution
Remove the `GhostNode::new` method and change `GhostNode` into a unit
struct.
## Testing
```cargo run --example ghost_nodes```
still works
# Objective
I wrote a box shadow UI material naively thinking I could use the border
widths attribute to hold the border radius but it
doesn't work as the border widths are automatically set in the
extraction function. Need to send border radius to the shader seperately
for it to be viable.
## Solution
Add a `border_radius` vertex attribute to the ui material.
This PR also removes the normalization of border widths for custom UI
materials. The regular UI shader doesn't do this so it's a bit confusing
and means you can't use the logic from `ui.wgsl` in your custom UI
materials.
## Testing / Showcase
Made a change to the `ui_material` example to display border radius:
```cargo run --example ui_material```
<img width="569" alt="corners" src="https://github.com/user-attachments/assets/36412736-a9ee-4042-aadd-68b9cafb17cb" />
