bevy/examples/ui/box_shadow.rs
ickshonpe 56d5591028
Multiple box shadow support (#16502)
# 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>
2024-12-01 21:30:08 +00:00

267 lines
8.4 KiB
Rust

//! This example shows how to create a node with a shadow
use argh::FromArgs;
use bevy::color::palettes::css::BLUE;
use bevy::color::palettes::css::DEEP_SKY_BLUE;
use bevy::color::palettes::css::GREEN;
use bevy::color::palettes::css::LIGHT_SKY_BLUE;
use bevy::color::palettes::css::RED;
use bevy::color::palettes::css::YELLOW;
use bevy::prelude::*;
use bevy::winit::WinitSettings;
#[derive(FromArgs, Resource)]
/// `box_shadow` example
struct Args {
/// number of samples
#[argh(option, default = "4")]
samples: u32,
}
fn main() {
App::new()
.add_plugins(DefaultPlugins)
// Only run the app when there is user input. This will significantly reduce CPU/GPU use.
.insert_resource(WinitSettings::desktop_app())
.add_systems(Startup, setup)
.run();
}
fn setup(mut commands: Commands) {
// `from_env` panics on the web
#[cfg(not(target_arch = "wasm32"))]
let args: Args = argh::from_env();
#[cfg(target_arch = "wasm32")]
let args = Args::from_args(&[], &[]).unwrap();
// ui camera
commands.spawn((Camera2d, UiBoxShadowSamples(args.samples)));
commands
.spawn((
Node {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
padding: UiRect::all(Val::Px(30.)),
column_gap: Val::Px(30.),
flex_wrap: FlexWrap::Wrap,
..default()
},
BackgroundColor(DEEP_SKY_BLUE.into()),
))
.with_children(|commands| {
let example_nodes = [
(
Vec2::splat(50.),
Vec2::ZERO,
10.,
0.,
BorderRadius::bottom_right(Val::Px(10.)),
),
(Vec2::new(50., 25.), Vec2::ZERO, 10., 0., BorderRadius::ZERO),
(Vec2::splat(50.), Vec2::ZERO, 10., 0., BorderRadius::MAX),
(Vec2::new(100., 25.), Vec2::ZERO, 10., 0., BorderRadius::MAX),
(
Vec2::splat(50.),
Vec2::ZERO,
10.,
0.,
BorderRadius::bottom_right(Val::Px(10.)),
),
(Vec2::new(50., 25.), Vec2::ZERO, 0., 10., BorderRadius::ZERO),
(
Vec2::splat(50.),
Vec2::ZERO,
0.,
10.,
BorderRadius::bottom_right(Val::Px(10.)),
),
(Vec2::new(100., 25.), Vec2::ZERO, 0., 10., BorderRadius::MAX),
(
Vec2::splat(50.),
Vec2::splat(25.),
0.,
0.,
BorderRadius::ZERO,
),
(
Vec2::new(50., 25.),
Vec2::splat(25.),
0.,
0.,
BorderRadius::ZERO,
),
(
Vec2::splat(50.),
Vec2::splat(10.),
0.,
0.,
BorderRadius::bottom_right(Val::Px(10.)),
),
(
Vec2::splat(50.),
Vec2::splat(25.),
0.,
10.,
BorderRadius::ZERO,
),
(
Vec2::new(50., 25.),
Vec2::splat(25.),
0.,
10.,
BorderRadius::ZERO,
),
(
Vec2::splat(50.),
Vec2::splat(10.),
0.,
10.,
BorderRadius::bottom_right(Val::Px(10.)),
),
(
Vec2::splat(50.),
Vec2::splat(10.),
0.,
3.,
BorderRadius::ZERO,
),
(
Vec2::new(50., 25.),
Vec2::splat(10.),
0.,
3.,
BorderRadius::ZERO,
),
(
Vec2::splat(50.),
Vec2::splat(10.),
0.,
3.,
BorderRadius::bottom_right(Val::Px(10.)),
),
(
Vec2::splat(50.),
Vec2::splat(10.),
0.,
3.,
BorderRadius::all(Val::Px(20.)),
),
(
Vec2::new(50., 25.),
Vec2::splat(10.),
0.,
3.,
BorderRadius::all(Val::Px(20.)),
),
(
Vec2::new(25., 50.),
Vec2::splat(10.),
0.,
3.,
BorderRadius::MAX,
),
(
Vec2::splat(50.),
Vec2::splat(10.),
0.,
10.,
BorderRadius::all(Val::Px(20.)),
),
(
Vec2::new(50., 25.),
Vec2::splat(10.),
0.,
10.,
BorderRadius::all(Val::Px(20.)),
),
(
Vec2::new(25., 50.),
Vec2::splat(10.),
0.,
10.,
BorderRadius::MAX,
),
];
for (size, offset, spread, blur, border_radius) in example_nodes {
commands.spawn(box_shadow_node_bundle(
size,
offset,
spread,
blur,
border_radius,
));
}
// Demonstrate multiple shadows on one node
commands.spawn((
Node {
width: Val::Px(40.),
height: Val::Px(40.),
border: UiRect::all(Val::Px(4.)),
..default()
},
BorderColor(LIGHT_SKY_BLUE.into()),
BorderRadius::all(Val::Px(20.)),
BackgroundColor(DEEP_SKY_BLUE.into()),
BoxShadow(vec![
ShadowStyle {
color: RED.with_alpha(0.7).into(),
x_offset: Val::Px(-20.),
y_offset: Val::Px(-5.),
spread_radius: Val::Percent(10.),
blur_radius: Val::Px(3.),
},
ShadowStyle {
color: BLUE.with_alpha(0.7).into(),
x_offset: Val::Px(-5.),
y_offset: Val::Px(-20.),
spread_radius: Val::Percent(10.),
blur_radius: Val::Px(3.),
},
ShadowStyle {
color: YELLOW.with_alpha(0.7).into(),
x_offset: Val::Px(20.),
y_offset: Val::Px(5.),
spread_radius: Val::Percent(10.),
blur_radius: Val::Px(3.),
},
ShadowStyle {
color: GREEN.with_alpha(0.7).into(),
x_offset: Val::Px(5.),
y_offset: Val::Px(20.),
spread_radius: Val::Percent(10.),
blur_radius: Val::Px(3.),
},
]),
));
});
}
fn box_shadow_node_bundle(
size: Vec2,
offset: Vec2,
spread: f32,
blur: f32,
border_radius: BorderRadius,
) -> impl Bundle {
(
Node {
width: Val::Px(size.x),
height: Val::Px(size.y),
border: UiRect::all(Val::Px(4.)),
..default()
},
BorderColor(LIGHT_SKY_BLUE.into()),
border_radius,
BackgroundColor(DEEP_SKY_BLUE.into()),
BoxShadow::new(
Color::BLACK.with_alpha(0.8),
Val::Percent(offset.x),
Val::Percent(offset.y),
Val::Percent(spread),
Val::Px(blur),
),
)
}