a304fd9a99
# Objective - Hierarchy tools are not just used for `Transform`: they are also used for scenes. - In the future there's interest in using them for other features, such as visiibility inheritance. - The fact that these tools are found in `bevy_transform` causes a great deal of user and developer confusion - Fixes #2758. ## Solution - Split `bevy_transform` into two! - Make everything work again. Note that this is a very tightly scoped PR: I *know* there are code quality and docs issues that existed in bevy_transform that I've just moved around. We should fix those in a seperate PR and try to merge this ASAP to reduce the bitrot involved in splitting an entire crate. ## Frustrations The API around `GlobalTransform` is a mess: we have massive code and docs duplication, no link between the two types and no clear way to extend this to other forms of inheritance. In the medium-term, I feel pretty strongly that `GlobalTransform` should be replaced by something like `Inherited<Transform>`, which lives in `bevy_hierarchy`: - avoids code duplication - makes the inheritance pattern extensible - links the types at the type-level - allows us to remove all references to inheritance from `bevy_transform`, making it more useful as a standalone crate and cleaning up its docs ## Additional context - double-blessed by @cart in https://github.com/bevyengine/bevy/issues/4141#issuecomment-1063592414 and https://github.com/bevyengine/bevy/issues/2758#issuecomment-913810963 - preparation for more advanced / cleaner hierarchy tools: go read https://github.com/bevyengine/rfcs/pull/53 ! - originally attempted by @finegeometer in #2789. It was a great idea, just needed more discussion! Co-authored-by: Carter Anderson <mcanders1@gmail.com>
54 lines
1.4 KiB
Rust
54 lines
1.4 KiB
Rust
#![warn(missing_docs)]
|
|
//! `bevy_hierarchy` can be used to define hierarchies of entities.
|
|
//!
|
|
//! Most commonly, these hierarchies are used for inheriting `Transform` values
|
|
//! from the [`Parent`] to its [`Children`].
|
|
|
|
mod components;
|
|
pub use components::*;
|
|
|
|
mod hierarchy;
|
|
pub use hierarchy::*;
|
|
|
|
mod child_builder;
|
|
pub use child_builder::*;
|
|
|
|
mod systems;
|
|
pub use systems::*;
|
|
|
|
#[doc(hidden)]
|
|
pub mod prelude {
|
|
#[doc(hidden)]
|
|
pub use crate::{child_builder::*, components::*, hierarchy::*, HierarchyPlugin};
|
|
}
|
|
|
|
use bevy_app::prelude::*;
|
|
use bevy_ecs::prelude::*;
|
|
|
|
/// The base plugin for handling [`Parent`] and [`Children`] components
|
|
#[derive(Default)]
|
|
pub struct HierarchyPlugin;
|
|
|
|
/// Label enum for the systems relating to hierarchy upkeep
|
|
#[derive(Debug, Hash, PartialEq, Eq, Clone, SystemLabel)]
|
|
pub enum HierarchySystem {
|
|
/// Updates [`Parent`] when changes in the hierarchy occur
|
|
ParentUpdate,
|
|
}
|
|
|
|
impl Plugin for HierarchyPlugin {
|
|
fn build(&self, app: &mut App) {
|
|
app.register_type::<Children>()
|
|
.register_type::<Parent>()
|
|
.register_type::<PreviousParent>()
|
|
.add_startup_system_to_stage(
|
|
StartupStage::PostStartup,
|
|
parent_update_system.label(HierarchySystem::ParentUpdate),
|
|
)
|
|
.add_system_to_stage(
|
|
CoreStage::PostUpdate,
|
|
parent_update_system.label(HierarchySystem::ParentUpdate),
|
|
);
|
|
}
|
|
}
|