# Objective
The `UiBoxShadowSamples` resource should be renamed to
`BoxShadowSamples` so it matches the `BoxShadow` component.
## Migration Guide
`UiBoxShadowSamples` has been renamed to `BoxShadowSamples`
# Objective
Add support for multiple box shadows on a single `Node`.
## Solution
* Rename `BoxShadow` to `ShadowStyle` and remove its `Component` derive.
* Create a new `BoxShadow` component that newtypes a `Vec<ShadowStyle>`.
* Add a `new` constructor method to `BoxShadow` for single shadows.
* Change `extract_shadows` to iterate through a list of shadows per
node.
Render order is determined implicitly from the order of the shadows
stored in the `BoxShadow` component, back-to-front.
Might be more efficient to use a `SmallVec<[ShadowStyle; 1]>` for the
list of shadows but not sure if the extra friction is worth it.
## Testing
Added a node with four differently coloured shadows to the `box_shadow`
example.
---
## Showcase
```
cargo run --example box_shadow
```
<img width="460" alt="four-shadow"
src="https://github.com/user-attachments/assets/2f728c47-33b4-42e1-96ba-28a774b94b24">
## Migration Guide
Bevy UI now supports multiple shadows per node. A new struct
`ShadowStyle` is used to set the style for each shadow. And the
`BoxShadow` component is changed to a tuple struct wrapping a vector
containing a list of `ShadowStyle`s. To spawn a node with a single
shadow you can use the `new` constructor function:
```rust
commands.spawn((
Node::default(),
BoxShadow::new(
Color::BLACK.with_alpha(0.8),
Val::Percent(offset.x),
Val::Percent(offset.y),
Val::Percent(spread),
Val::Px(blur),
)
));
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# 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();
}
}
```
# Objective
UI box shadow support
Adds a new component `BoxShadow`:
```rust
pub struct BoxShadow {
/// The shadow's color
pub color: Color,
/// Horizontal offset
pub x_offset: Val,
/// Vertical offset
pub y_offset: Val,
/// Horizontal difference in size from the occluding uninode
pub spread_radius: Val,
/// Blurriness of the shadow
pub blur_radius: Val,
}
```
To use `BoxShadow`, add the component to any Bevy UI node and a shadow
will be drawn beneath that node.
Also adds a resource `BoxShadowSamples` that can be used to adjust the
shadow quality.
#### Notes
* I'm not super happy with the field names. Maybe we need a `struct Size
{ width: Val, height: Val }` type or something.
* The shader isn't very optimised but I don't see that it's too
important for now as the number of shadows being rendered is not going
to be massive most of the time. I think it's more important to get the
API and geometry correct with this PR.
* I didn't implement an inset property, it's not essential and can
easily be added in a follow up.
* Shadows are only rendered for uinodes, not for images or text.
* Batching isn't supported, it would need out-of-the-scope-of-this-pr
changes to the way the UI handles z-ordering for it to be effective.
# Showcase
```cargo run --example box_shadow -- --samples 4```
<img width="391" alt="br" src="https://github.com/user-attachments/assets/4e8add96-dc93-46e0-9e35-d995eb0943ad">
```cargo run --example box_shadow -- --samples 10```
<img width="391" alt="s10"
src="https://github.com/user-attachments/assets/ecb384c9-4012-4cd6-9dea-5180904bf28e">
