Commit Graph

11 Commits

Author SHA1 Message Date
Carter Anderson
21f1e3045c
Relationships (non-fragmenting, one-to-many) (#17398)
This adds support for one-to-many non-fragmenting relationships (with
planned paths for fragmenting and non-fragmenting many-to-many
relationships). "Non-fragmenting" means that entities with the same
relationship type, but different relationship targets, are not forced
into separate tables (which would cause "table fragmentation").

Functionally, this fills a similar niche as the current Parent/Children
system. The biggest differences are:

1. Relationships have simpler internals and significantly improved
performance and UX. Commands and specialized APIs are no longer
necessary to keep everything in sync. Just spawn entities with the
relationship components you want and everything "just works".
2. Relationships are generalized. Bevy can provide additional built in
relationships, and users can define their own.

**REQUEST TO REVIEWERS**: _please don't leave top level comments and
instead comment on specific lines of code. That way we can take
advantage of threaded discussions. Also dont leave comments simply
pointing out CI failures as I can read those just fine._

## Built on top of what we have

Relationships are implemented on top of the Bevy ECS features we already
have: components, immutability, and hooks. This makes them immediately
compatible with all of our existing (and future) APIs for querying,
spawning, removing, scenes, reflection, etc. The fewer specialized APIs
we need to build, maintain, and teach, the better.

## Why focus on one-to-many non-fragmenting first?

1. This allows us to improve Parent/Children relationships immediately,
in a way that is reasonably uncontroversial. Switching our hierarchy to
fragmenting relationships would have significant performance
implications. ~~Flecs is heavily considering a switch to non-fragmenting
relations after careful considerations of the performance tradeoffs.~~
_(Correction from @SanderMertens: Flecs is implementing non-fragmenting
storage specialized for asset hierarchies, where asset hierarchies are
many instances of small trees that have a well defined structure)_
2. Adding generalized one-to-many relationships is currently a priority
for the [Next Generation Scene / UI
effort](https://github.com/bevyengine/bevy/discussions/14437).
Specifically, we're interested in building reactions and observers on
top.

## The changes

This PR does the following:

1. Adds a generic one-to-many Relationship system
3. Ports the existing Parent/Children system to Relationships, which now
lives in `bevy_ecs::hierarchy`. The old `bevy_hierarchy` crate has been
removed.
4. Adds on_despawn component hooks
5. Relationships can opt-in to "despawn descendants" behavior, meaning
that the entire relationship hierarchy is despawned when
`entity.despawn()` is called. The built in Parent/Children hierarchies
enable this behavior, and `entity.despawn_recursive()` has been removed.
6. `world.spawn` now applies commands after spawning. This ensures that
relationship bookkeeping happens immediately and removes the need to
manually flush. This is in line with the equivalent behaviors recently
added to the other APIs (ex: insert).
7. Removes the ValidParentCheckPlugin (system-driven / poll based) in
favor of a `validate_parent_has_component` hook.

## Using Relationships

The `Relationship` trait looks like this:

```rust
pub trait Relationship: Component + Sized {
    type RelationshipSources: RelationshipSources<Relationship = Self>;
    fn get(&self) -> Entity;
    fn from(entity: Entity) -> Self;
}
```

A relationship is a component that:

1. Is a simple wrapper over a "target" Entity.
2. Has a corresponding `RelationshipSources` component, which is a
simple wrapper over a collection of entities. Every "target entity"
targeted by a "source entity" with a `Relationship` has a
`RelationshipSources` component, which contains every "source entity"
that targets it.

For example, the `Parent` component (as it currently exists in Bevy) is
the `Relationship` component and the entity containing the Parent is the
"source entity". The entity _inside_ the `Parent(Entity)` component is
the "target entity". And that target entity has a `Children` component
(which implements `RelationshipSources`).

In practice, the Parent/Children relationship looks like this:

```rust
#[derive(Relationship)]
#[relationship(relationship_sources = Children)]
pub struct Parent(pub Entity);

#[derive(RelationshipSources)]
#[relationship_sources(relationship = Parent)]
pub struct Children(Vec<Entity>);
```

The Relationship and RelationshipSources derives automatically implement
Component with the relevant configuration (namely, the hooks necessary
to keep everything in sync).

The most direct way to add relationships is to spawn entities with
relationship components:

```rust
let a = world.spawn_empty().id();
let b = world.spawn(Parent(a)).id();

assert_eq!(world.entity(a).get::<Children>().unwrap(), &[b]);
```

There are also convenience APIs for spawning more than one entity with
the same relationship:

```rust
world.spawn_empty().with_related::<Children>(|s| {
    s.spawn_empty();
    s.spawn_empty();
})
```

The existing `with_children` API is now a simpler wrapper over
`with_related`. This makes this change largely non-breaking for existing
spawn patterns.

```rust
world.spawn_empty().with_children(|s| {
    s.spawn_empty();
    s.spawn_empty();
})
```

There are also other relationship APIs, such as `add_related` and
`despawn_related`.

## Automatic recursive despawn via the new on_despawn hook

`RelationshipSources` can opt-in to "despawn descendants" behavior,
which will despawn all related entities in the relationship hierarchy:

```rust
#[derive(RelationshipSources)]
#[relationship_sources(relationship = Parent, despawn_descendants)]
pub struct Children(Vec<Entity>);
```

This means that `entity.despawn_recursive()` is no longer required.
Instead, just use `entity.despawn()` and the relevant related entities
will also be despawned.

To despawn an entity _without_ despawning its parent/child descendants,
you should remove the `Children` component first, which will also remove
the related `Parent` components:

```rust
entity
    .remove::<Children>()
    .despawn()
```

This builds on the on_despawn hook introduced in this PR, which is fired
when an entity is despawned (before other hooks).

## Relationships are the source of truth

`Relationship` is the _single_ source of truth component.
`RelationshipSources` is merely a reflection of what all the
`Relationship` components say. By embracing this, we are able to
significantly improve the performance of the system as a whole. We can
rely on component lifecycles to protect us against duplicates, rather
than needing to scan at runtime to ensure entities don't already exist
(which results in quadratic runtime). A single source of truth gives us
constant-time inserts. This does mean that we cannot directly spawn
populated `Children` components (or directly add or remove entities from
those components). I personally think this is a worthwhile tradeoff,
both because it makes the performance much better _and_ because it means
theres exactly one way to do things (which is a philosophy we try to
employ for Bevy APIs).

As an aside: treating both sides of the relationship as "equivalent
source of truth relations" does enable building simple and flexible
many-to-many relationships. But this introduces an _inherent_ need to
scan (or hash) to protect against duplicates.
[`evergreen_relations`](https://github.com/EvergreenNest/evergreen_relations)
has a very nice implementation of the "symmetrical many-to-many"
approach. Unfortunately I think the performance issues inherent to that
approach make it a poor choice for Bevy's default relationship system.

## Followup Work

* Discuss renaming `Parent` to `ChildOf`. I refrained from doing that in
this PR to keep the diff reasonable, but I'm personally biased toward
this change (and using that naming pattern generally for relationships).
* [Improved spawning
ergonomics](https://github.com/bevyengine/bevy/discussions/16920)
* Consider adding relationship observers/triggers for "relationship
targets" whenever a source is added or removed. This would replace the
current "hierarchy events" system, which is unused upstream but may have
existing users downstream. I think triggers are the better fit for this
than a buffered event queue, and would prefer not to add that back.
* Fragmenting relations: My current idea hinges on the introduction of
"value components" (aka: components whose type _and_ value determines
their ComponentId, via something like Hashing / PartialEq). By labeling
a Relationship component such as `ChildOf(Entity)` as a "value
component", `ChildOf(e1)` and `ChildOf(e2)` would be considered
"different components". This makes the transition between fragmenting
and non-fragmenting a single flag, and everything else continues to work
as expected.
* Many-to-many support
* Non-fragmenting: We can expand Relationship to be a list of entities
instead of a single entity. I have largely already written the code for
this.
* Fragmenting: With the "value component" impl mentioned above, we get
many-to-many support "for free", as it would allow inserting multiple
copies of a Relationship component with different target entities.

Fixes #3742 (If this PR is merged, I think we should open more targeted
followup issues for the work above, with a fresh tracking issue free of
the large amount of less-directed historical context)
Fixes #17301
Fixes #12235 
Fixes #15299
Fixes #15308 

## Migration Guide

* Replace `ChildBuilder` with `ChildSpawnerCommands`.
* Replace calls to `.set_parent(parent_id)` with
`.insert(Parent(parent_id))`.
* Replace calls to `.replace_children()` with `.remove::<Children>()`
followed by `.add_children()`. Note that you'll need to manually despawn
any children that are not carried over.
* Replace calls to `.despawn_recursive()` with `.despawn()`.
* Replace calls to `.despawn_descendants()` with
`.despawn_related::<Children>()`.
* If you have any calls to `.despawn()` which depend on the children
being preserved, you'll need to remove the `Children` component first.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2025-01-18 22:20:30 +00:00
Carter Anderson
af10aa38aa
AnimatedField and Rework Evaluators (#16484)
# Objective

Animating component fields requires too much boilerplate at the moment:

```rust
#[derive(Reflect)]
struct FontSizeProperty;

impl AnimatableProperty for FontSizeProperty {
    type Component = TextFont;

    type Property = f32;

    fn get_mut(component: &mut Self::Component) -> Option<&mut Self::Property> {
        Some(&mut component.font_size)
    }
}

animation_clip.add_curve_to_target(
    animation_target_id,
    AnimatableKeyframeCurve::new(
        [0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0]
            .into_iter()
            .zip([24.0, 80.0, 24.0, 80.0, 24.0, 80.0, 24.0]),
    )
    .map(AnimatableCurve::<FontSizeProperty, _>::from_curve)
    .expect("should be able to build translation curve because we pass in valid samples"),
);
```

## Solution

This adds `AnimatedField` and an `animated_field!` macro, enabling the
following:

```rust
animation_clip.add_curve_to_target(
    animation_target_id,
    AnimatableCurve::new(
        animated_field!(TextFont::font_size),
        AnimatableKeyframeCurve::new(
            [0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0]
                .into_iter()
                .zip([24.0, 80.0, 24.0, 80.0, 24.0, 80.0, 24.0]),
        )
        .expect(
            "should be able to build translation curve because we pass in valid samples",
        ),
    ),
);
```

This required reworking the internals a bit, namely stripping out a lot
of the `Reflect` usage, as that implementation was fundamentally
incompatible with the `AnimatedField` pattern. `Reflect` was being used
in this context just to downcast traits. But we can get downcasting
behavior without the `Reflect` requirement by implementing `Downcast`
for `AnimationCurveEvaluator`.

This also reworks "evaluator identity" to support either a (Component /
Field) pair, or a TypeId. This allows properties to reuse evaluators,
even if they have different accessor methods. The "contract" here is
that for a given (Component / Field) pair, the accessor will return the
same value. Fields are identified by their Reflect-ed field index. The
(TypeId, usize) is prehashed and cached to optimize for lookup speed.

This removes the built-in hard-coded TranslationCurve / RotationCurve /
ScaleCurve in favor of AnimatableField.

---------

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
2024-11-27 22:19:55 +00:00
Carter Anderson
015f2c69ca
Merge Style properties into Node. Use ComputedNode for computed properties. (#15975)
# Objective

Continue improving the user experience of our UI Node API in the
direction specified by [Bevy's Next Generation Scene / UI
System](https://github.com/bevyengine/bevy/discussions/14437)

## Solution

As specified in the document above, merge `Style` fields into `Node`,
and move "computed Node fields" into `ComputedNode` (I chose this name
over something like `ComputedNodeLayout` because it currently contains
more than just layout info. If we want to break this up / rename these
concepts, lets do that in a separate PR). `Style` has been removed.

This accomplishes a number of goals:

## Ergonomics wins

Specifying both `Node` and `Style` is now no longer required for
non-default styles

Before:
```rust
commands.spawn((
    Node::default(),
    Style {
        width:  Val::Px(100.),
        ..default()
    },
));
```

After:

```rust
commands.spawn(Node {
    width:  Val::Px(100.),
    ..default()
});
```

## Conceptual clarity

`Style` was never a comprehensive "style sheet". It only defined "core"
style properties that all `Nodes` shared. Any "styled property" that
couldn't fit that mold had to be in a separate component. A "real" style
system would style properties _across_ components (`Node`, `Button`,
etc). We have plans to build a true style system (see the doc linked
above).

By moving the `Style` fields to `Node`, we fully embrace `Node` as the
driving concept and remove the "style system" confusion.

## Next Steps

* Consider identifying and splitting out "style properties that aren't
core to Node". This should not happen for Bevy 0.15.

---

## Migration Guide

Move any fields set on `Style` into `Node` and replace all `Style`
component usage with `Node`.

Before:
```rust
commands.spawn((
    Node::default(),
    Style {
        width:  Val::Px(100.),
        ..default()
    },
));
```

After:

```rust
commands.spawn(Node {
    width:  Val::Px(100.),
    ..default()
});
```

For any usage of the "computed node properties" that used to live on
`Node`, use `ComputedNode` instead:

Before:
```rust
fn system(nodes: Query<&Node>) {
    for node in &nodes {
        let computed_size = node.size();
    }
}
```

After:
```rust
fn system(computed_nodes: Query<&ComputedNode>) {
    for computed_node in &computed_nodes {
        let computed_size = computed_node.size();
    }
}
```
2024-10-18 22:25:33 +00:00
VitalyR
eb19a9ea0b
Migrate UI bundles to required components (#15898)
# Objective

- Migrate UI bundles to required components, fixes #15889

## Solution

- deprecate `NodeBundle` in favor of `Node`
- deprecate `ImageBundle` in favor of `UiImage`
- deprecate `ButtonBundle` in favor of `Button`

## Testing

CI.

## Migration Guide

- Replace all uses of `NodeBundle` with `Node`. e.g.
```diff
     commands
-        .spawn(NodeBundle {
-            style: Style {
+        .spawn((
+            Node::default(),
+            Style {
                 width: Val::Percent(100.),
                 align_items: AlignItems::Center,
                 justify_content: JustifyContent::Center,
                 ..default()
             },
-            ..default()
-        })
+        ))
``` 
- Replace all uses of `ButtonBundle` with `Button`. e.g.
```diff
                     .spawn((
-                        ButtonBundle {
-                            style: Style {
-                                width: Val::Px(w),
-                                height: Val::Px(h),
-                                // horizontally center child text
-                                justify_content: JustifyContent::Center,
-                                // vertically center child text
-                                align_items: AlignItems::Center,
-                                margin: UiRect::all(Val::Px(20.0)),
-                                ..default()
-                            },
-                            image: image.clone().into(),
+                        Button,
+                        Style {
+                            width: Val::Px(w),
+                            height: Val::Px(h),
+                            // horizontally center child text
+                            justify_content: JustifyContent::Center,
+                            // vertically center child text
+                            align_items: AlignItems::Center,
+                            margin: UiRect::all(Val::Px(20.0)),
                             ..default()
                         },
+                        UiImage::from(image.clone()),
                         ImageScaleMode::Sliced(slicer.clone()),
                     ))
```
- Replace all uses of `ImageBundle` with `UiImage`. e.g.
```diff
-    commands.spawn(ImageBundle {
-        image: UiImage {
+    commands.spawn((
+        UiImage {
             texture: metering_mask,
             ..default()
         },
-        style: Style {
+        Style {
             width: Val::Percent(100.0),
             height: Val::Percent(100.0),
             ..default()
         },
-        ..default()
-    });
+    ));
 ```

---------

Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2024-10-17 21:11:02 +00:00
ickshonpe
6f7d0e5725
split up TextStyle (#15857)
# Objective

Currently text is recomputed unnecessarily on any changes to its color,
which is extremely expensive.

## Solution
Split up `TextStyle` into two separate components `TextFont` and
`TextColor`.

## Testing

I added this system to `many_buttons`:
```rust
fn set_text_colors_changed(mut colors: Query<&mut TextColor>) {
    for mut text_color in colors.iter_mut() {
        text_color.set_changed();
    }
}
```

reports ~4fps on main, ~50fps with this PR.

## Migration Guide
`TextStyle` has been renamed to `TextFont` and its `color` field has
been moved to a separate component named `TextColor` which newtypes
`Color`.
2024-10-13 17:06:22 +00:00
UkoeHB
a6be9b4ccd
Rename TextBlock to TextLayout (#15797)
# Objective

- Improve clarity when spawning a text block. See [this
discussion](https://github.com/bevyengine/bevy/pull/15591/#discussion_r1787083571).

## Solution

- Rename `TextBlock` to `TextLayout`.
2024-10-09 20:58:27 +00:00
UkoeHB
c2c19e5ae4
Text rework (#15591)
**Ready for review. Examples migration progress: 100%.**

# Objective

- Implement https://github.com/bevyengine/bevy/discussions/15014

## Solution

This implements [cart's
proposal](https://github.com/bevyengine/bevy/discussions/15014#discussioncomment-10574459)
faithfully except for one change. I separated `TextSpan` from
`TextSpan2d` because `TextSpan` needs to require the `GhostNode`
component, which is a `bevy_ui` component only usable by UI.

Extra changes:
- Added `EntityCommands::commands_mut` that returns a mutable reference.
This is a blocker for extension methods that return something other than
`self`. Note that `sickle_ui`'s `UiBuilder::commands` returns a mutable
reference for this reason.

## Testing

- [x] Text examples all work.

---

## Showcase

TODO: showcase-worthy

## Migration Guide

TODO: very breaking

### Accessing text spans by index

Text sections are now text sections on different entities in a
hierarchy, Use the new `TextReader` and `TextWriter` system parameters
to access spans by index.

Before:
```rust
fn refresh_text(mut query: Query<&mut Text, With<TimeText>>, time: Res<Time>) {
    let text = query.single_mut();
    text.sections[1].value = format_time(time.elapsed());
}
```

After:
```rust
fn refresh_text(
    query: Query<Entity, With<TimeText>>,
    mut writer: UiTextWriter,
    time: Res<Time>
) {
    let entity = query.single();
    *writer.text(entity, 1) = format_time(time.elapsed());
}
```

### Iterating text spans

Text spans are now entities in a hierarchy, so the new `UiTextReader`
and `UiTextWriter` system parameters provide ways to iterate that
hierarchy. The `UiTextReader::iter` method will give you a normal
iterator over spans, and `UiTextWriter::for_each` lets you visit each of
the spans.

---------

Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2024-10-09 18:35:36 +00:00
Tim
700123ec64
Replace Handle<AnimationGraph> component with a wrapper (#15742)
# Objective

- Closes #15717 

## Solution

- Wrap the handle in a new wrapper component: `AnimationGraphHandle`.

## Testing

Searched for all instances of `AnimationGraph` in the examples and
updated and tested those

## Migration Guide

`Handle<AnimationGraph>` is no longer a component. Instead, use the
`AnimationGraphHandle` component which contains a
`Handle<AnimationGraph>`.
2024-10-08 22:41:24 +00:00
Joona Aalto
25bfa80e60
Migrate cameras to required components (#15641)
# Objective

Yet another PR for migrating stuff to required components. This time,
cameras!

## Solution

As per the [selected
proposal](https://hackmd.io/tsYID4CGRiWxzsgawzxG_g#Combined-Proposal-1-Selected),
deprecate `Camera2dBundle` and `Camera3dBundle` in favor of `Camera2d`
and `Camera3d`.

Adding a `Camera` without `Camera2d` or `Camera3d` now logs a warning,
as suggested by Cart [on
Discord](https://discord.com/channels/691052431525675048/1264881140007702558/1291506402832945273).
I would personally like cameras to work a bit differently and be split
into a few more components, to avoid some footguns and confusing
semantics, but that is more controversial, and shouldn't block this core
migration.

## Testing

I ran a few 2D and 3D examples, and tried cameras with and without
render graphs.

---

## Migration Guide

`Camera2dBundle` and `Camera3dBundle` have been deprecated in favor of
`Camera2d` and `Camera3d`. Inserting them will now also insert the other
components required by them automatically.
2024-10-05 01:59:52 +00:00
Matty
429987ebf8
Curve-based animation (#15434)
# Objective

This PR extends and reworks the material from #15282 by allowing
arbitrary curves to be used by the animation system to animate arbitrary
properties. The goals of this work are to:
- Allow far greater flexibility in how animations are allowed to be
defined in order to be used with `bevy_animation`.
- Delegate responsibility over keyframe interpolation to `bevy_math` and
the `Curve` libraries and reduce reliance on keyframes in animation
definitions generally.
- Move away from allowing the glTF spec to completely define animations
on a mechanical level.

## Solution

### Overview

At a high level, curves have been incorporated into the animation system
using the `AnimationCurve` trait (closely related to what was
`Keyframes`). From the top down:

1. In `animate_targets`, animations are driven by `VariableCurve`, which
is now a thin wrapper around a `Box<dyn AnimationCurve>`.
2. `AnimationCurve` is something built out of a `Curve`, and it tells
the animation system how to use the curve's output to actually mutate
component properties. The trait looks like this:
```rust
/// A low-level trait that provides control over how curves are actually applied to entities
/// by the animation system.
///
/// Typically, this will not need to be implemented manually, since it is automatically
/// implemented by [`AnimatableCurve`] and other curves used by the animation system
/// (e.g. those that animate parts of transforms or morph weights). However, this can be
/// implemented manually when `AnimatableCurve` is not sufficiently expressive.
///
/// In many respects, this behaves like a type-erased form of [`Curve`], where the output
/// type of the curve is remembered only in the components that are mutated in the
/// implementation of [`apply`].
///
/// [`apply`]: AnimationCurve::apply
pub trait AnimationCurve: Reflect + Debug + Send + Sync {
    /// Returns a boxed clone of this value.
    fn clone_value(&self) -> Box<dyn AnimationCurve>;

    /// The range of times for which this animation is defined.
    fn domain(&self) -> Interval;

    /// Write the value of sampling this curve at time `t` into `transform` or `entity`,
    /// as appropriate, interpolating between the existing value and the sampled value
    /// using the given `weight`.
    fn apply<'a>(
        &self,
        t: f32,
        transform: Option<Mut<'a, Transform>>,
        entity: EntityMutExcept<'a, (Transform, AnimationPlayer, Handle<AnimationGraph>)>,
        weight: f32,
    ) -> Result<(), AnimationEvaluationError>;
}
```
3. The conversion process from a `Curve` to an `AnimationCurve` involves
using wrappers which communicate the intent to animate a particular
property. For example, here is `TranslationCurve`, which wraps a
`Curve<Vec3>` and uses it to animate `Transform::translation`:
```rust
/// This type allows a curve valued in `Vec3` to become an [`AnimationCurve`] that animates
/// the translation component of a transform.
pub struct TranslationCurve<C>(pub C);
```

### Animatable Properties

The `AnimatableProperty` trait survives in the transition, and it can be
used to allow curves to animate arbitrary component properties. The
updated documentation for `AnimatableProperty` explains this process:
<details>
  <summary>Expand AnimatableProperty example</summary

An `AnimatableProperty` is a value on a component that Bevy can animate.

You can implement this trait on a unit struct in order to support
animating
custom components other than transforms and morph weights. Use that type
in
conjunction with `AnimatableCurve` (and perhaps
`AnimatableKeyframeCurve`
to define the animation itself). For example, in order to animate font
size of a
text section from 24 pt. to 80 pt., you might use:

```rust
#[derive(Reflect)]
struct FontSizeProperty;

impl AnimatableProperty for FontSizeProperty {
    type Component = Text;
    type Property = f32;
    fn get_mut(component: &mut Self::Component) -> Option<&mut Self::Property> {
        Some(&mut component.sections.get_mut(0)?.style.font_size)
    }
}
```

You can then create an `AnimationClip` to animate this property like so:

```rust
let mut animation_clip = AnimationClip::default();
animation_clip.add_curve_to_target(
    animation_target_id,
    AnimatableKeyframeCurve::new(
        [
            (0.0, 24.0),
            (1.0, 80.0),
        ]
    )
    .map(AnimatableCurve::<FontSizeProperty, _>::from_curve)
    .expect("Failed to create font size curve")
);
```

Here, the use of `AnimatableKeyframeCurve` creates a curve out of the
given keyframe time-value
pairs, using the `Animatable` implementation of `f32` to interpolate
between them. The
invocation of `AnimatableCurve::from_curve` with `FontSizeProperty`
indicates that the `f32`
output from that curve is to be used to animate the font size of a
`Text` component (as
configured above).


</details>

### glTF Loading

glTF animations are now loaded into `Curve` types of various kinds,
depending on what is being animated and what interpolation mode is being
used. Those types get wrapped into and converted into `Box<dyn
AnimationCurve>` and shoved inside of a `VariableCurve` just like
everybody else.

### Morph Weights

There is an `IterableCurve` abstraction which allows sampling these from
a contiguous buffer without allocating. Its only reason for existing is
that Rust disallows you from naming function types, otherwise we would
just use `Curve` with an iterator output type. (The iterator involves
`Map`, and the name of the function type would have to be able to be
named, but it is not.)

A `WeightsCurve` adaptor turns an `IterableCurve` into an
`AnimationCurve`, so it behaves like everything else in that regard.

## Testing

Tested by running existing animation examples. Interpolation logic has
had additional tests added within the `Curve` API to replace the tests
in `bevy_animation`. Some kinds of out-of-bounds errors have become
impossible.

Performance testing on `many_foxes` (`animate_targets`) suggests that
performance is very similar to the existing implementation. Here are a
couple trace histograms across different runs (yellow is this branch,
red is main).
<img width="669" alt="Screenshot 2024-09-27 at 9 41 50 AM"
src="https://github.com/user-attachments/assets/5ba4e9ac-3aea-452e-aaf8-1492acc2d7fc">
<img width="673" alt="Screenshot 2024-09-27 at 9 45 18 AM"
src="https://github.com/user-attachments/assets/8982538b-04cf-46b5-97b2-164c6bc8162e">

---

## Migration Guide

Most user code that does not directly deal with `AnimationClip` and
`VariableCurve` will not need to be changed. On the other hand,
`VariableCurve` has been completely overhauled. If you were previously
defining animation curves in code using keyframes, you will need to
migrate that code to use curve constructors instead. For example, a
rotation animation defined using keyframes and added to an animation
clip like this:
```rust
animation_clip.add_curve_to_target(
    animation_target_id,
    VariableCurve {
        keyframe_timestamps: vec![0.0, 1.0, 2.0, 3.0, 4.0],
        keyframes: Keyframes::Rotation(vec![
            Quat::IDENTITY,
            Quat::from_axis_angle(Vec3::Y, PI / 2.),
            Quat::from_axis_angle(Vec3::Y, PI / 2. * 2.),
            Quat::from_axis_angle(Vec3::Y, PI / 2. * 3.),
            Quat::IDENTITY,
        ]),
        interpolation: Interpolation::Linear,
    },
);
```

would now be added like this:
```rust
animation_clip.add_curve_to_target(
    animation_target_id,
    AnimatableKeyframeCurve::new([0.0, 1.0, 2.0, 3.0, 4.0].into_iter().zip([
        Quat::IDENTITY,
        Quat::from_axis_angle(Vec3::Y, PI / 2.),
        Quat::from_axis_angle(Vec3::Y, PI / 2. * 2.),
        Quat::from_axis_angle(Vec3::Y, PI / 2. * 3.),
        Quat::IDENTITY,
    ]))
    .map(RotationCurve)
    .expect("Failed to build rotation curve"),
);
```

Note that the interface of `AnimationClip::add_curve_to_target` has also
changed (as this example shows, if subtly), and now takes its curve
input as an `impl AnimationCurve`. If you need to add a `VariableCurve`
directly, a new method `add_variable_curve_to_target` accommodates that
(and serves as a one-to-one migration in this regard).

### For reviewers

The diff is pretty big, and the structure of some of the changes might
not be super-obvious:
- `keyframes.rs` became `animation_curves.rs`, and `AnimationCurve` is
based heavily on `Keyframes`, with the adaptors also largely following
suite.
- The Curve API adaptor structs were moved from `bevy_math::curve::mod`
into their own module `adaptors`. There are no functional changes to how
these adaptors work; this is just to make room for the specialized
reflection implementations since `mod.rs` was getting kind of cramped.
- The new module `gltf_curves` holds the additional curve constructions
that are needed by the glTF loader. Note that the loader uses a mix of
these and off-the-shelf `bevy_math` curve stuff.
- `animatable.rs` no longer holds logic related to keyframe
interpolation, which is now delegated to the existing abstractions in
`bevy_math::curve::cores`.

---------

Co-authored-by: Gino Valente <49806985+MrGVSV@users.noreply.github.com>
Co-authored-by: aecsocket <43144841+aecsocket@users.noreply.github.com>
2024-09-30 19:56:55 +00:00
Patrick Walton
8154164f1b
Allow animation clips to animate arbitrary properties. (#15282)
Currently, Bevy restricts animation clips to animating
`Transform::translation`, `Transform::rotation`, `Transform::scale`, or
`MorphWeights`, which correspond to the properties that glTF can
animate. This is insufficient for many use cases such as animating UI,
as the UI layout systems expect to have exclusive control over UI
elements' `Transform`s and therefore the `Style` properties must be
animated instead.

This commit fixes this, allowing for `AnimationClip`s to animate
arbitrary properties. The `Keyframes` structure has been turned into a
low-level trait that can be implemented to achieve arbitrary animation
behavior. Along with `Keyframes`, this patch adds a higher-level trait,
`AnimatableProperty`, that simplifies the task of animating single
interpolable properties. Built-in `Keyframes` implementations exist for
translation, rotation, scale, and morph weights. For the most part, you
can migrate by simply changing your code from
`Keyframes::Translation(...)` to `TranslationKeyframes(...)`, and
likewise for rotation, scale, and morph weights.

An example `AnimatableProperty` implementation for the font size of a
text section follows:

     #[derive(Reflect)]
     struct FontSizeProperty;

     impl AnimatableProperty for FontSizeProperty {
         type Component = Text;
         type Property = f32;
fn get_mut(component: &mut Self::Component) -> Option<&mut
Self::Property> {
             Some(&mut component.sections.get_mut(0)?.style.font_size)
         }
     }

In order to keep this patch relatively small, this patch doesn't include
an implementation of `AnimatableProperty` on top of the reflection
system. That can be a follow-up.

This patch builds on top of the new `EntityMutExcept<>` type in order to
widen the `AnimationTarget` query to include write access to all
components. Because `EntityMutExcept<>` has some performance overhead
over an explicit query, we continue to explicitly query `Transform` in
order to avoid regressing the performance of skeletal animation, such as
the `many_foxes` benchmark. I've measured the performance of that
benchmark and have found no significant regressions.

A new example, `animated_ui`, has been added. This example shows how to
use Bevy's built-in animation infrastructure to animate font size and
color, which wasn't possible before this patch.

## Showcase


https://github.com/user-attachments/assets/1fa73492-a9ce-405a-a8f2-4aacd7f6dc97

## Migration Guide

* Animation keyframes are now an extensible trait, not an enum. Replace
`Keyframes::Translation(...)`, `Keyframes::Scale(...)`,
`Keyframes::Rotation(...)`, and `Keyframes::Weights(...)` with
`Box::new(TranslationKeyframes(...))`, `Box::new(ScaleKeyframes(...))`,
`Box::new(RotationKeyframes(...))`, and
`Box::new(MorphWeightsKeyframes(...))` respectively.
2024-09-23 17:14:12 +00:00