docs/bevy/examples/asset/asset_loading.rs 3.5 K · 100 lines · raw · history

1 //! This example illustrates various ways to load assets.
2
3 use bevy::{asset::LoadedFolder, prelude::*};
4
5 fn main() {
6 App::new()
7 .add_plugins(DefaultPlugins)
8 .add_systems(Startup, setup)
9 .run();
10 }
11
12 fn setup(
13 mut commands: Commands,
14 asset_server: Res<AssetServer>,
15 meshes: Res<Assets<Mesh>>,
16 mut materials: ResMut<Assets<StandardMaterial>>,
17 ) {
18 // By default AssetServer will load assets from inside the "assets" folder.
19 // For example, the next line will load GltfAssetLabel::Primitive{mesh:0,primitive:0}.from_asset("ROOT/assets/models/cube/cube.gltf"),
20 // where "ROOT" is the directory of the Application.
21 //
22 // This can be overridden by setting [`AssetPlugin.file_path`].
23 let cube_handle = asset_server.load(
24 GltfAssetLabel::Primitive {
25 mesh: 0,
26 primitive: 0,
27 }
28 .from_asset("models/cube/cube.gltf"),
29 );
30 let sphere_handle = asset_server.load(
31 GltfAssetLabel::Primitive {
32 mesh: 0,
33 primitive: 0,
34 }
35 .from_asset("models/sphere/sphere.gltf"),
36 );
37
38 // All assets end up in their Assets<T> collection once they are done loading:
39 if let Some(sphere) = meshes.get(&sphere_handle) {
40 // You might notice that this doesn't run! This is because assets load in parallel without
41 // blocking. When an asset has loaded, it will appear in relevant Assets<T>
42 // collection.
43 info!("{:?}", sphere.primitive_topology());
44 } else {
45 info!("sphere hasn't loaded yet");
46 }
47
48 // You can load all assets in a folder like this. They will be loaded in parallel without
49 // blocking. The LoadedFolder asset holds handles to each asset in the folder. These are all
50 // dependencies of the LoadedFolder asset, meaning you can wait for the LoadedFolder asset to
51 // fire AssetEvent::LoadedWithDependencies if you want to wait for all assets in the folder
52 // to load.
53 // If you want to keep the assets in the folder alive, make sure you store the returned handle
54 // somewhere.
55 let _loaded_folder: Handle<LoadedFolder> = asset_server.load_folder("models/torus");
56
57 // If you want a handle to a specific asset in a loaded folder, the easiest way to get one is to call load.
58 // It will _not_ be loaded a second time.
59 // The LoadedFolder asset will ultimately also hold handles to the assets, but waiting for it to load
60 // and finding the right handle is more work!
61 let torus_handle = asset_server.load(
62 GltfAssetLabel::Primitive {
63 mesh: 0,
64 primitive: 0,
65 }
66 .from_asset("models/torus/torus.gltf"),
67 );
68
69 // You can also add assets directly to their Assets<T> storage:
70 let material_handle = materials.add(StandardMaterial {
71 base_color: Color::srgb(0.8, 0.7, 0.6),
72 ..default()
73 });
74
75 // torus
76 commands.spawn((
77 Mesh3d(torus_handle),
78 MeshMaterial3d(material_handle.clone()),
79 Transform::from_xyz(-3.0, 0.0, 0.0),
80 ));
81 // cube
82 commands.spawn((
83 Mesh3d(cube_handle),
84 MeshMaterial3d(material_handle.clone()),
85 Transform::from_xyz(0.0, 0.0, 0.0),
86 ));
87 // sphere
88 commands.spawn((
89 Mesh3d(sphere_handle),
90 MeshMaterial3d(material_handle),
91 Transform::from_xyz(3.0, 0.0, 0.0),
92 ));
93 // light
94 commands.spawn((PointLight::default(), Transform::from_xyz(4.0, 5.0, 4.0)));
95 // camera
96 commands.spawn((
97 Camera3d::default(),
98 Transform::from_xyz(0.0, 3.0, 10.0).looking_at(Vec3::ZERO, Vec3::Y),
99 ));
100 }