3 unstable releases
0.2.0 | Jul 6, 2024 |
---|---|
0.1.1 | May 4, 2024 |
0.1.0 | Mar 11, 2024 |
#888 in Game dev
1MB
370 lines
bevy_descendant_collector
This crate lets you map a complex entity tree onto a single component as long as those entities (and their ancestors) are named.
This is especially useful for scenes spawned from GLTF models since you'd need complex queries to retrieve deep entities from the scene hierarchy.
Example
Running the example:
cargo run -p bevy_descendant_collector --example turret
Imagine you have a model file with the following structure in Blender:
Collection
├── Armature
│ ├── Bone.Root
│ │ └── Bone.Neck
│ │ └── Bone.Head
│ └── Bone.Head.IK_CTRL
You can define a component like this:
#[derive(Component, EntityCollectorTarget)]
#[name_path("Armature")]
pub struct MyTurretArmature {
#[name_path("Bone.Root")]
pub base: Entity,
#[name_path("Bone.Root", "Bone.Neck")]
pub neck: Entity,
#[name_path("Bone.Root", "Bone.Neck", "Bone.Head")]
pub head: Entity,
#[name_path("Bone.Head.IK_CTRL")]
pub head_ik_ctrl: Entity,
}
Then, you need to add a Plugin, this plugin will handle the insertion of this component:
Each different
EntityCollectorTarget
needs its own plugin added!
In this example this is a GLTF model, so I want the root entity to be resolved
as a scene. HierarchyRootPosition::Scene
tells the plugin to find the root
of the hierarchy based on #[name_path("Armature")]
among the grandchildren
of the entity where I want this MyTurretArmature
to be inserted into.
app.add_plugins(DescendantCollectorPlugin::<MyTurretArmature>::new(HierarchyRootPosition::Scene));
And lastly, I need to identify the entities where I want MyTurretArmature
to
be inserted into! To do this, when you spawn this scene, add the target
component to your entity.
fn spawn_turret(mut commands: Commands, turret_model_assets: Res<TurretModelAssets>) {
commands.spawn((
SceneBundle {
scene: turret_model_assets.turret_model.clone(),
..default()
},
DescendantCollectorTarget::<MyTurretArmature>::default(),
));
}
Expanding the proc macro
In case you want to inspect the output of the proc macro.
If you haven't installed cargo-expand
yet.
cargo install cargo-expand
cargo expand --example turret
Bevy Compatibility Table
Bevy | bevy_descendant_collector |
---|---|
0.13 | 0.1 |
Dependencies
~24MB
~453K SLoC