docs/bevy/examples/3d/atmospheric_fog.rs 3.5 K · 108 lines · raw · history

1 //! This example showcases atmospheric fog
2 //!
3 //! ## Controls
4 //!
5 //! | Key Binding | Action |
6 //! |:-------------------|:---------------------------------------|
7 //! | `Spacebar` | Toggle Atmospheric Fog |
8 //! | `S` | Toggle Directional Light Fog Influence |
9
10 use bevy::{
11 light::{CascadeShadowConfigBuilder, NotShadowCaster},
12 prelude::*,
13 };
14
15 fn main() {
16 App::new()
17 .add_plugins(DefaultPlugins)
18 .add_systems(
19 Startup,
20 (setup_camera_fog, setup_terrain_scene, setup_instructions),
21 )
22 .add_systems(Update, toggle_system)
23 .run();
24 }
25
26 fn setup_camera_fog(mut commands: Commands) {
27 commands.spawn((
28 Camera3d::default(),
29 Transform::from_xyz(-1.0, 0.1, 1.0).looking_at(Vec3::new(0.0, 0.0, 0.0), Vec3::Y),
30 DistanceFog {
31 color: Color::srgba(0.35, 0.48, 0.66, 1.0),
32 directional_light_color: Color::srgba(1.0, 0.95, 0.85, 0.5),
33 directional_light_exponent: 30.0,
34 falloff: FogFalloff::from_visibility_colors(
35 15.0, // distance in world units up to which objects retain visibility (>= 5% contrast)
36 Color::srgb(0.35, 0.5, 0.66), // atmospheric extinction color (after light is lost due to absorption by atmospheric particles)
37 Color::srgb(0.8, 0.844, 1.0), // atmospheric inscattering color (light gained due to scattering from the sun)
38 ),
39 },
40 ));
41 }
42
43 fn setup_terrain_scene(
44 mut commands: Commands,
45 mut meshes: ResMut<Assets<Mesh>>,
46 mut materials: ResMut<Assets<StandardMaterial>>,
47 asset_server: Res<AssetServer>,
48 ) {
49 // Configure a properly scaled cascade shadow map for this scene (defaults are too large, mesh units are in km)
50 let cascade_shadow_config = CascadeShadowConfigBuilder {
51 first_cascade_far_bound: 0.3,
52 maximum_distance: 3.0,
53 ..default()
54 }
55 .build();
56
57 // Sun
58 commands.spawn((
59 DirectionalLight {
60 color: Color::srgb(0.98, 0.95, 0.82),
61 shadow_maps_enabled: true,
62 ..default()
63 },
64 Transform::from_xyz(0.0, 0.0, 0.0).looking_at(Vec3::new(-0.15, -0.05, 0.25), Vec3::Y),
65 cascade_shadow_config,
66 ));
67
68 // Terrain
69 commands.spawn(WorldAssetRoot(asset_server.load(
70 GltfAssetLabel::Scene(0).from_asset("models/terrain/Mountains.gltf"),
71 )));
72
73 // Sky
74 commands.spawn((
75 Mesh3d(meshes.add(Cuboid::new(2.0, 1.0, 1.0))),
76 MeshMaterial3d(materials.add(StandardMaterial {
77 base_color: Srgba::hex("888888").unwrap().into(),
78 unlit: true,
79 cull_mode: None,
80 ..default()
81 })),
82 Transform::from_scale(Vec3::splat(20.0)),
83 NotShadowCaster,
84 ));
85 }
86
87 fn setup_instructions(mut commands: Commands) {
88 commands.spawn((Text::new("Press Spacebar to Toggle Atmospheric Fog.\nPress S to Toggle Directional Light Fog Influence."),
89 Node {
90 position_type: PositionType::Absolute,
91 bottom: px(12),
92 left: px(12),
93 ..default()
94 })
95 );
96 }
97
98 fn toggle_system(keycode: Res<ButtonInput<KeyCode>>, mut fog: Single<&mut DistanceFog>) {
99 if keycode.just_pressed(KeyCode::Space) {
100 let a = fog.color.alpha();
101 fog.color.set_alpha(1.0 - a);
102 }
103
104 if keycode.just_pressed(KeyCode::KeyS) {
105 let a = fog.directional_light_color.alpha();
106 fog.directional_light_color.set_alpha(0.5 - a);
107 }
108 }