bevy/examples/3d/atmospheric_fog.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

108 lines
3.5 KiB
Rust

//! This example showcases atmospheric fog
//!
//! ## Controls
//!
//! | Key Binding | Action |
//! |:-------------------|:---------------------------------------|
//! | `Spacebar` | Toggle Atmospheric Fog |
//! | `S` | Toggle Directional Light Fog Influence |
use bevy::{
pbr::{CascadeShadowConfigBuilder, NotShadowCaster},
prelude::*,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(
Startup,
(setup_camera_fog, setup_terrain_scene, setup_instructions),
)
.add_systems(Update, toggle_system)
.run();
}
fn setup_camera_fog(mut commands: Commands) {
commands.spawn((
Camera3d::default(),
Transform::from_xyz(-1.0, 0.1, 1.0).looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
DistanceFog {
color: Color::srgba(0.35, 0.48, 0.66, 1.0),
directional_light_color: Color::srgba(1.0, 0.95, 0.85, 0.5),
directional_light_exponent: 30.0,
falloff: FogFalloff::from_visibility_colors(
15.0, // distance in world units up to which objects retain visibility (>= 5% contrast)
Color::srgb(0.35, 0.5, 0.66), // atmospheric extinction color (after light is lost due to absorption by atmospheric particles)
Color::srgb(0.8, 0.844, 1.0), // atmospheric inscattering color (light gained due to scattering from the sun)
),
},
));
}
fn setup_terrain_scene(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
asset_server: Res<AssetServer>,
) {
// Configure a properly scaled cascade shadow map for this scene (defaults are too large, mesh units are in km)
let cascade_shadow_config = CascadeShadowConfigBuilder {
first_cascade_far_bound: 0.3,
maximum_distance: 3.0,
..default()
}
.build();
// Sun
commands.spawn((
DirectionalLight {
color: Color::srgb(0.98, 0.95, 0.82),
shadows_enabled: true,
..default()
},
Transform::from_xyz(0.0, 0.0, 0.0).looking_at(Vec3::new(-0.15, -0.05, 0.25), Vec3::Y),
cascade_shadow_config,
));
// Terrain
commands.spawn(SceneRoot(asset_server.load(
GltfAssetLabel::Scene(0).from_asset("models/terrain/Mountains.gltf"),
)));
// Sky
commands.spawn((
Mesh3d(meshes.add(Cuboid::new(2.0, 1.0, 1.0))),
MeshMaterial3d(materials.add(StandardMaterial {
base_color: Srgba::hex("888888").unwrap().into(),
unlit: true,
cull_mode: None,
..default()
})),
Transform::from_scale(Vec3::splat(20.0)),
NotShadowCaster,
));
}
fn setup_instructions(mut commands: Commands) {
commands.spawn((Text::new("Press Spacebar to Toggle Atmospheric Fog.\nPress S to Toggle Directional Light Fog Influence."),
Node {
position_type: PositionType::Absolute,
bottom: Val::Px(12.0),
left: Val::Px(12.0),
..default()
})
);
}
fn toggle_system(keycode: Res<ButtonInput<KeyCode>>, mut fog: Single<&mut DistanceFog>) {
if keycode.just_pressed(KeyCode::Space) {
let a = fog.color.alpha();
fog.color.set_alpha(1.0 - a);
}
if keycode.just_pressed(KeyCode::KeyS) {
let a = fog.directional_light_color.alpha();
fog.directional_light_color.set_alpha(0.5 - a);
}
}