bevy/examples/ui/ui_texture_slice_flip_and_tile.rs
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

75 lines
2.8 KiB
Rust

//! This example illustrates how to how to flip and tile images with 9-slicing in the UI.
use bevy::{
prelude::*,
render::texture::{ImageLoaderSettings, ImageSampler},
winit::WinitSettings,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.insert_resource(UiScale(2.))
// Only run the app when there is user input. This will significantly reduce CPU/GPU use for UI-only apps.
.insert_resource(WinitSettings::desktop_app())
.add_systems(Startup, setup)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
let image = asset_server.load_with_settings(
"textures/fantasy_ui_borders/numbered_slices.png",
|settings: &mut ImageLoaderSettings| {
// Need to use nearest filtering to avoid bleeding between the slices with tiling
settings.sampler = ImageSampler::nearest();
},
);
let slicer = TextureSlicer {
// `numbered_slices.png` is 48 pixels square. `BorderRect::square(16.)` insets the slicing line from each edge by 16 pixels, resulting in nine slices that are each 16 pixels square.
border: BorderRect::square(16.),
// With `SliceScaleMode::Tile` the side and center slices are tiled to to fill the side and center sections of the target.
// And with a `stretch_value` of `1.` the tiles will have the same size as the corresponding slices in the source image.
center_scale_mode: SliceScaleMode::Tile { stretch_value: 1. },
sides_scale_mode: SliceScaleMode::Tile { stretch_value: 1. },
..default()
};
// ui camera
commands.spawn(Camera2d);
commands
.spawn(Node {
width: Val::Percent(100.),
height: Val::Percent(100.),
justify_content: JustifyContent::Center,
align_content: AlignContent::Center,
flex_wrap: FlexWrap::Wrap,
column_gap: Val::Px(10.),
row_gap: Val::Px(10.),
..default()
})
.with_children(|parent| {
for ([width, height], flip_x, flip_y) in [
([160., 160.], false, false),
([320., 160.], false, true),
([320., 160.], true, false),
([160., 160.], true, true),
] {
parent.spawn((
UiImage {
texture: image.clone(),
flip_x,
flip_y,
..default()
},
Node {
width: Val::Px(width),
height: Val::Px(height),
..default()
},
ImageScaleMode::Sliced(slicer.clone()),
));
}
});
}