bevy/examples/ui/ui_material.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

97 lines
3.2 KiB
Rust

//! Demonstrates the use of [`UiMaterials`](UiMaterial) and how to change material values
use bevy::{color::palettes::css::RED, prelude::*, reflect::TypePath, render::render_resource::*};
/// This example uses a shader source file from the assets subdirectory
const SHADER_ASSET_PATH: &str = "shaders/custom_ui_material.wgsl";
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_plugins(UiMaterialPlugin::<CustomUiMaterial>::default())
.add_systems(Startup, setup)
.add_systems(Update, animate)
.run();
}
fn setup(
mut commands: Commands,
mut ui_materials: ResMut<Assets<CustomUiMaterial>>,
asset_server: Res<AssetServer>,
) {
// Camera so we can see UI
commands.spawn(Camera2d);
commands
.spawn(Node {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
align_items: AlignItems::Center,
justify_content: JustifyContent::Center,
..default()
})
.with_children(|parent| {
let banner_scale_factor = 0.5;
parent.spawn((
MaterialNode(ui_materials.add(CustomUiMaterial {
color: LinearRgba::WHITE.to_f32_array().into(),
slider: 0.5,
color_texture: asset_server.load("branding/banner.png"),
border_color: LinearRgba::WHITE.to_f32_array().into(),
})),
Node {
position_type: PositionType::Absolute,
width: Val::Px(905.0 * banner_scale_factor),
height: Val::Px(363.0 * banner_scale_factor),
border: UiRect::all(Val::Px(10.)),
..default()
},
BackgroundColor(RED.into()),
));
});
}
#[derive(AsBindGroup, Asset, TypePath, Debug, Clone)]
struct CustomUiMaterial {
/// Color multiplied with the image
#[uniform(0)]
color: Vec4,
/// Represents how much of the image is visible
/// Goes from 0 to 1
#[uniform(1)]
slider: f32,
/// Image used to represent the slider
#[texture(2)]
#[sampler(3)]
color_texture: Handle<Image>,
/// Color of the image's border
#[uniform(4)]
border_color: Vec4,
}
impl UiMaterial for CustomUiMaterial {
fn fragment_shader() -> ShaderRef {
SHADER_ASSET_PATH.into()
}
}
// Fills the slider slowly over 2 seconds and resets it
// Also updates the color of the image to a rainbow color
fn animate(
mut materials: ResMut<Assets<CustomUiMaterial>>,
q: Query<&MaterialNode<CustomUiMaterial>>,
time: Res<Time>,
) {
let duration = 2.0;
for handle in &q {
if let Some(material) = materials.get_mut(handle) {
// rainbow color effect
let new_color = Color::hsl((time.elapsed_secs() * 60.0) % 360.0, 1., 0.5);
let border_color = Color::hsl((time.elapsed_secs() * 60.0) % 360.0, 0.75, 0.75);
material.color = new_color.to_linear().to_vec4();
material.slider =
((time.elapsed_secs() % (duration * 2.0)) - duration).abs() / duration;
material.border_color = border_color.to_linear().to_vec4();
}
}
}