bevy/examples/3d/load_gltf_extras.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

91 lines
2.4 KiB
Rust

//! Loads and renders a glTF file as a scene, and list all the different `gltf_extras`.
use bevy::{
gltf::{GltfExtras, GltfMaterialExtras, GltfMeshExtras, GltfSceneExtras},
prelude::*,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.add_systems(Update, check_for_gltf_extras)
.run();
}
#[derive(Component)]
struct ExampleDisplay;
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
commands.spawn((
Camera3d::default(),
Transform::from_xyz(2.0, 2.0, 2.0).looking_at(Vec3::ZERO, Vec3::Y),
));
commands.spawn(DirectionalLight {
shadows_enabled: true,
..default()
});
// a barebones scene containing one of each gltf_extra type
commands.spawn(SceneRoot(asset_server.load(
GltfAssetLabel::Scene(0).from_asset("models/extras/gltf_extras.glb"),
)));
// a place to display the extras on screen
commands.spawn((
Text::default(),
TextFont {
font_size: 15.,
..default()
},
Node {
position_type: PositionType::Absolute,
top: Val::Px(12.0),
left: Val::Px(12.0),
..default()
},
ExampleDisplay,
));
}
fn check_for_gltf_extras(
gltf_extras_per_entity: Query<(
Entity,
Option<&Name>,
Option<&GltfSceneExtras>,
Option<&GltfExtras>,
Option<&GltfMeshExtras>,
Option<&GltfMaterialExtras>,
)>,
mut display: Single<&mut Text, With<ExampleDisplay>>,
) {
let mut gltf_extra_infos_lines: Vec<String> = vec![];
for (id, name, scene_extras, extras, mesh_extras, material_extras) in
gltf_extras_per_entity.iter()
{
if scene_extras.is_some()
|| extras.is_some()
|| mesh_extras.is_some()
|| material_extras.is_some()
{
let formatted_extras = format!(
"Extras per entity {} ('Name: {}'):
- scene extras: {:?}
- primitive extras: {:?}
- mesh extras: {:?}
- material extras: {:?}
",
id,
name.unwrap_or(&Name::default()),
scene_extras,
extras,
mesh_extras,
material_extras
);
gltf_extra_infos_lines.push(formatted_extras);
}
display.0 = gltf_extra_infos_lines.join("\n");
}
}