7d69d3195f
# Objective
It would be convenient to be able to call functions with `Commands` as a
parameter without having to move your own instance of `Commands`. Since
this struct is composed entirely of references, we can easily get an
owned instance of `Commands` by shortening the lifetime.
## Solution
Add `Commands::reborrow`, `EntiyCommands::reborrow`, and
`Deferred::reborrow`, which returns an owned version of themselves with
a shorter lifetime.
Remove unnecessary lifetimes from `EntityCommands`. The `'w` and `'s`
lifetimes only have to be separate for `Commands` because it's used as a
`SystemParam` -- this is not the case for `EntityCommands`.
---
## Changelog
Added `Commands::reborrow`. This is useful if you have `&mut Commands`
but need `Commands`. Also added `EntityCommands::reborrow` and
`Deferred:reborrow` which serve the same purpose.
## Migration Guide
The lifetimes for `EntityCommands` have been simplified.
```rust
// Before (Bevy 0.12)
struct MyStruct<'w, 's, 'a> {
commands: EntityCommands<'w, 's, 'a>,
}
// After (Bevy 0.13)
struct MyStruct<'a> {
commands: EntityCommands<'a>,
}
```
The method `EntityCommands::commands` now returns `Commands` rather than
`&mut Commands`.
```rust
// Before (Bevy 0.12)
let commands = entity_commands.commands();
commands.spawn(...);
// After (Bevy 0.13)
let mut commands = entity_commands.commands();
commands.spawn(...);
```
101 lines
4.2 KiB
Rust
101 lines
4.2 KiB
Rust
//! Extension to [`EntityCommands`] to modify `bevy_hierarchy` hierarchies
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//! while preserving [`GlobalTransform`].
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use bevy_ecs::{prelude::Entity, system::Command, system::EntityCommands, world::World};
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use bevy_hierarchy::{PushChild, RemoveParent};
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use crate::{GlobalTransform, Transform};
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/// Command similar to [`PushChild`], but updating the child transform to keep
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/// it at the same [`GlobalTransform`].
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///
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/// You most likely want to use [`BuildChildrenTransformExt::set_parent_in_place`]
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/// method on [`EntityCommands`] instead.
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pub struct PushChildInPlace {
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/// Parent entity to add the child to.
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pub parent: Entity,
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/// Child entity to add.
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pub child: Entity,
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}
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impl Command for PushChildInPlace {
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fn apply(self, world: &mut World) {
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let hierarchy_command = PushChild {
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child: self.child,
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parent: self.parent,
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};
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hierarchy_command.apply(world);
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// FIXME: Replace this closure with a `try` block. See: https://github.com/rust-lang/rust/issues/31436.
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let mut update_transform = || {
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let parent = *world.get_entity(self.parent)?.get::<GlobalTransform>()?;
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let child_global = *world.get_entity(self.child)?.get::<GlobalTransform>()?;
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let mut child_entity = world.get_entity_mut(self.child)?;
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let mut child = child_entity.get_mut::<Transform>()?;
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*child = child_global.reparented_to(&parent);
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Some(())
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};
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update_transform();
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}
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}
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/// Command similar to [`RemoveParent`], but updating the child transform to keep
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/// it at the same [`GlobalTransform`].
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///
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/// You most likely want to use [`BuildChildrenTransformExt::remove_parent_in_place`]
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/// method on [`EntityCommands`] instead.
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pub struct RemoveParentInPlace {
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/// [`Entity`] whose parent must be removed.
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pub child: Entity,
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}
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impl Command for RemoveParentInPlace {
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fn apply(self, world: &mut World) {
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let hierarchy_command = RemoveParent { child: self.child };
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hierarchy_command.apply(world);
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// FIXME: Replace this closure with a `try` block. See: https://github.com/rust-lang/rust/issues/31436.
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let mut update_transform = || {
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let child_global = *world.get_entity(self.child)?.get::<GlobalTransform>()?;
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let mut child_entity = world.get_entity_mut(self.child)?;
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let mut child = child_entity.get_mut::<Transform>()?;
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*child = child_global.compute_transform();
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Some(())
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};
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update_transform();
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}
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}
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/// Collection of methods similar to [`BuildChildren`](bevy_hierarchy::BuildChildren), but preserving each
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/// entity's [`GlobalTransform`].
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pub trait BuildChildrenTransformExt {
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/// Change this entity's parent while preserving this entity's [`GlobalTransform`]
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/// by updating its [`Transform`].
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///
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/// See [`BuildChildren::set_parent`](bevy_hierarchy::BuildChildren::set_parent) for a method that doesn't update the
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/// [`Transform`].
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///
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/// Note that both the hierarchy and transform updates will only execute
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/// the next time commands are applied
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/// (during [`apply_deferred`](bevy_ecs::schedule::apply_deferred)).
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fn set_parent_in_place(&mut self, parent: Entity) -> &mut Self;
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/// Make this entity parentless while preserving this entity's [`GlobalTransform`]
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/// by updating its [`Transform`] to be equal to its current [`GlobalTransform`].
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///
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/// See [`BuildChildren::remove_parent`](bevy_hierarchy::BuildChildren::remove_parent) for a method that doesn't update the
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/// [`Transform`].
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///
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/// Note that both the hierarchy and transform updates will only execute
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/// the next time commands are applied
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/// (during [`apply_deferred`](bevy_ecs::schedule::apply_deferred)).
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fn remove_parent_in_place(&mut self) -> &mut Self;
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}
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impl BuildChildrenTransformExt for EntityCommands<'_> {
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fn set_parent_in_place(&mut self, parent: Entity) -> &mut Self {
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let child = self.id();
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self.commands().add(PushChildInPlace { child, parent });
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self
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}
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fn remove_parent_in_place(&mut self) -> &mut Self {
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let child = self.id();
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self.commands().add(RemoveParentInPlace { child });
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self
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}
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}
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