# Objective
Fixes#4697. Hierarchical propagation of properties, currently only Transform -> GlobalTransform, can be a very expensive operation. Transform propagation is a strict dependency for anything positioned in world-space. In large worlds, this can take quite a bit of time, so limiting it to a single thread can result in poor CPU utilization as it bottlenecks the rest of the frame's systems.
## Solution
- Move transforms without a parent or a child (free-floating (Global)Transform) entities into a separate parallel system.
- Chunk the hierarchy based on the root entities and process it in parallel with `Query::par_for_each_mut`.
- Utilize the hierarchy's specific properties introduced in #4717 to allow for safe use of `Query::get_unchecked` on multiple threads. Assuming each child is unique in the hierarchy, it is impossible to have an aliased `&mut GlobalTransform` so long as we verify that the parent for a child is the same one propagated from.
---
## Changelog
Removed: `transform_propagate_system` is no longer `pub`.
# Objective
Fixes#6378
`bevy_transform` is missing a feature corresponding to the `serialize` feature on the `bevy` crate.
## Solution
Adds a `serialize` feature to `bevy_transform`.
Derives `serde::Serialize` and `Deserialize` when feature is enabled.
# Objective
- in #3851, a feature for tracing was added to bevy_transform
- usage of that feature was moved to bevy_hierarchy, but the feature was not updated
## Solution
- add the feature to bevy_hierarchy, remove it from bevy_transform
# Objective
- Provide more information when despawning an entity
## Solution
- Add a debug log when despawning an entity
- Add spans to the recursive ways of despawning an entity
```sh
RUST_LOG=debug cargo run --example panic --features trace
# RUST_LOG=debug needed to show debug logs from bevy_ecs
# --features trace needed to have the extra spans
...
DEBUG bevy_app:frame:stage{name=Update}:system_commands{name="panic::despawn_parent"}:command{name="DespawnRecursive" entity=0v0}: bevy_ecs::world: Despawning entity 1v0
DEBUG bevy_app:frame:stage{name=Update}:system_commands{name="panic::despawn_parent"}:command{name="DespawnRecursive" entity=0v0}: bevy_ecs::world: Despawning entity 0v0
```
# 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>
# Objective
- `bevy_ecs` exposes as an optional feature `bevy_reflect`. Disabling it doesn't compile.
- `bevy_asset` exposes as an optional feature `filesystem_watcher`. Disabling it doesn't compile. It is also not possible to disable this feature from Bevy
## Solution
- Fix compilation errors when disabling the default features. Make it possible to disable the feature `filesystem_watcher` from Bevy
Objective
During work on #3009 I've found that not all jobs use actions-rs, and therefore, an previous version of Rust is used for them. So while compilation and other stuff can pass, checking markup and Android build may fail with compilation errors.
Solution
This PR adds `action-rs` for any job running cargo, and updates the edition to 2021.
This relicenses Bevy under the dual MIT or Apache-2.0 license. For rationale, see #2373.
* Changes the LICENSE file to describe the dual license. Moved the MIT license to docs/LICENSE-MIT. Added the Apache-2.0 license to docs/LICENSE-APACHE. I opted for this approach over dumping both license files at the root (the more common approach) for a number of reasons:
* Github links to the "first" license file (LICENSE-APACHE) in its license links (you can see this in the wgpu and rust-analyzer repos). People clicking these links might erroneously think that the apache license is the only option. Rust and Amethyst both use COPYRIGHT or COPYING files to solve this problem, but this creates more file noise (if you do everything at the root) and the naming feels way less intuitive.
* People have a reflex to look for a LICENSE file. By providing a single license file at the root, we make it easy for them to understand our licensing approach.
* I like keeping the root clean and noise free
* There is precedent for putting the apache and mit license text in sub folders (amethyst)
* Removed the `Copyright (c) 2020 Carter Anderson` copyright notice from the MIT license. I don't care about this attribution, it might make license compliance more difficult in some cases, and it didn't properly attribute other contributors. We shoudn't replace it with something like "Copyright (c) 2021 Bevy Contributors" because "Bevy Contributors" is not a legal entity. Instead, we just won't include the copyright line (which has precedent ... Rust also uses this approach).
* Updates crates to use the new "MIT OR Apache-2.0" license value
* Removes the old legion-transform license file from bevy_transform. bevy_transform has been its own, fully custom implementation for a long time and that license no longer applies.
* Added a License section to the main readme
* Updated our Bevy Plugin licensing guidelines.
As a follow-up we should update the website to properly describe the new license.
Closes#2373
