117 lines
4.7 KiB
Rust
117 lines
4.7 KiB
Rust
use bevy::{prelude::*, reflect::TypeRegistry, utils::Duration};
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/// This example illustrates loading and saving scenes from files
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fn main() {
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App::build()
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.add_plugins(DefaultPlugins)
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.register_type::<ComponentA>()
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.register_type::<ComponentB>()
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.add_startup_system(save_scene_system.system())
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.add_startup_system(load_scene_system.system())
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.add_startup_system(infotext_system.system())
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.add_system(print_system.system())
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.run();
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}
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// Registered components must implement the `Reflect` and `FromResources` traits.
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// The `Reflect` trait enables serialization, deserialization, and dynamic property access.
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// `Reflect` enable a bunch of cool behaviors, so its worth checking out the dedicated `reflect.rs` example.
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// The `FromResources` trait determines how your component is constructed when it loads. For simple use cases you can just
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// implement the `Default` trait (which automatically implements FromResources). The simplest registered component just needs
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// these two derives:
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#[derive(Reflect, Default)]
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#[reflect(Component)] // this tells the reflect derive to also reflect component behaviors
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struct ComponentA {
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pub x: f32,
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pub y: f32,
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}
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// Some components have fields that cannot (or should not) be written to scene files. These can be ignored with
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// the #[reflect(ignore)] attribute. This is also generally where the `FromResources` trait comes into play.
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// `FromResources` gives you access to your App's current ECS `Resources` when you construct your component.
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#[derive(Reflect)]
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#[reflect(Component)]
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struct ComponentB {
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pub value: String,
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#[reflect(ignore)]
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pub time_since_startup: Duration,
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}
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impl FromResources for ComponentB {
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fn from_resources(resources: &Resources) -> Self {
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let time = resources.get::<Time>().unwrap();
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ComponentB {
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time_since_startup: time.time_since_startup(),
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value: "Default Value".to_string(),
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}
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}
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}
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fn load_scene_system(asset_server: Res<AssetServer>, mut scene_spawner: ResMut<SceneSpawner>) {
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// Scenes are loaded just like any other asset.
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let scene_handle: Handle<DynamicScene> = asset_server.load("scenes/load_scene_example.scn");
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// SceneSpawner can "spawn" scenes. "Spawning" a scene creates a new instance of the scene in the World with new entity ids.
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// This guarantees that it will not overwrite existing entities.
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scene_spawner.spawn_dynamic(scene_handle);
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// This tells the AssetServer to watch for changes to assets.
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// It enables our scenes to automatically reload in game when we modify their files
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asset_server.watch_for_changes().unwrap();
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}
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// This system prints all ComponentA components in our world. Try making a change to a ComponentA in load_scene_example.scn.
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// You should immediately see the changes appear in the console.
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fn print_system(query: Query<(Entity, &ComponentA), Changed<ComponentA>>) {
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for (entity, component_a) in query.iter() {
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println!(" Entity({})", entity.id());
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println!(
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" ComponentA: {{ x: {} y: {} }}\n",
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component_a.x, component_a.y
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);
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}
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}
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fn save_scene_system(_world: &mut World, resources: &mut Resources) {
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// Scenes can be created from any ECS World. You can either create a new one for the scene or use the current World.
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let mut world = World::new();
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world.spawn((
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ComponentA { x: 1.0, y: 2.0 },
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ComponentB {
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value: "hello".to_string(),
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..ComponentB::from_resources(resources)
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},
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Transform::default(),
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));
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world.spawn((ComponentA { x: 3.0, y: 4.0 },));
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// The TypeRegistry resource contains information about all registered types (including components). This is used to construct scenes.
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let type_registry = resources.get::<TypeRegistry>().unwrap();
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let scene = DynamicScene::from_world(&world, &type_registry);
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// Scenes can be serialized like this:
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println!("{}", scene.serialize_ron(&type_registry).unwrap());
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// TODO: save scene
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}
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// This is only necessary for the info message in the UI. See examples/ui/text.rs for a standalone text example.
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fn infotext_system(commands: &mut Commands, asset_server: Res<AssetServer>) {
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commands.spawn(CameraUiBundle::default()).spawn(TextBundle {
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style: Style {
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align_self: AlignSelf::FlexEnd,
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..Default::default()
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},
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text: Text::with_section(
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"Nothing to see in this window! Check the console output!",
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TextStyle {
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 50.0,
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color: Color::WHITE,
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},
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Default::default(),
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),
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..Default::default()
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});
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}
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