mirror of
https://github.com/bevyengine/bevy
synced 2024-11-13 00:17:27 +00:00
07ed1d053e
This implements the most minimal variant of #1843 - a derive for marker trait. This is a prerequisite to more complicated features like statically defined storage type or opt-out component reflection. In order to make component struct's purpose explicit and avoid misuse, it must be annotated with `#[derive(Component)]` (manual impl is discouraged for compatibility). Right now this is just a marker trait, but in the future it might be expanded. Making this change early allows us to make further changes later without breaking backward compatibility for derive macro users. This already prevents a lot of issues, like using bundles in `insert` calls. Primitive types are no longer valid components as well. This can be easily worked around by adding newtype wrappers and deriving `Component` for them. One funny example of prevented bad code (from our own tests) is when an newtype struct or enum variant is used. Previously, it was possible to write `insert(Newtype)` instead of `insert(Newtype(value))`. That code compiled, because function pointers (in this case newtype struct constructor) implement `Send + Sync + 'static`, so we allowed them to be used as components. This is no longer the case and such invalid code will trigger a compile error. Co-authored-by: = <=> Co-authored-by: TheRawMeatball <therawmeatball@gmail.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
93 lines
2.9 KiB
Rust
93 lines
2.9 KiB
Rust
use bevy::{prelude::*, scene::InstanceId};
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fn main() {
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App::new()
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.insert_resource(Msaa { samples: 4 })
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.add_plugins(DefaultPlugins)
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.init_resource::<SceneInstance>()
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.add_startup_system(setup)
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.add_system(scene_update)
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.add_system(move_scene_entities)
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.run();
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}
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// Resource to hold the scene `instance_id` until it is loaded
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#[derive(Default)]
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struct SceneInstance(Option<InstanceId>);
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// Component that will be used to tag entities in the scene
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#[derive(Component)]
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struct EntityInMyScene;
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fn setup(
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mut commands: Commands,
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asset_server: Res<AssetServer>,
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mut scene_spawner: ResMut<SceneSpawner>,
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mut scene_instance: ResMut<SceneInstance>,
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) {
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commands.spawn_bundle(PointLightBundle {
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transform: Transform::from_xyz(4.0, 5.0, 4.0),
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..Default::default()
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});
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commands.spawn_bundle(PerspectiveCameraBundle {
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transform: Transform::from_xyz(1.05, 0.9, 1.5)
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.looking_at(Vec3::new(0.0, 0.3, 0.0), Vec3::Y),
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..Default::default()
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});
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// Spawn the scene as a child of another entity. This first scene will be translated backward
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// with its parent
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commands
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.spawn_bundle((
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Transform::from_xyz(0.0, 0.0, -1.0),
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GlobalTransform::identity(),
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))
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.with_children(|parent| {
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parent.spawn_scene(asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0"));
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});
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// Spawn a second scene, and keep its `instance_id`
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let instance_id =
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scene_spawner.spawn(asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0"));
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scene_instance.0 = Some(instance_id);
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}
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// This system will wait for the scene to be ready, and then tag entities from
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// the scene with `EntityInMyScene`. All entities from the second scene will be
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// tagged
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fn scene_update(
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mut commands: Commands,
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scene_spawner: Res<SceneSpawner>,
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scene_instance: Res<SceneInstance>,
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mut done: Local<bool>,
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) {
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if !*done {
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if let Some(instance_id) = scene_instance.0 {
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if let Some(entity_iter) = scene_spawner.iter_instance_entities(instance_id) {
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entity_iter.for_each(|entity| {
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commands.entity(entity).insert(EntityInMyScene);
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});
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*done = true;
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}
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}
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}
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}
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// This system will move all entities with component `EntityInMyScene`, so all
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// entities from the second scene
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fn move_scene_entities(
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time: Res<Time>,
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mut scene_entities: Query<&mut Transform, With<EntityInMyScene>>,
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) {
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let mut direction = 1.;
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let mut scale = 1.;
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for mut transform in scene_entities.iter_mut() {
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transform.translation = Vec3::new(
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scale * direction * time.seconds_since_startup().sin() as f32 / 20.,
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0.,
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time.seconds_since_startup().cos() as f32 / 20.,
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);
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direction *= -1.;
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scale += 0.5;
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}
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}
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