# Objective
Adoption of #2104 and #11843. The `Option<usize>` wastes 3-7 bytes of
memory per potential entry, and represents a scaling memory overhead as
the ID space grows.
The goal of this PR is to reduce memory usage without significantly
impacting common use cases.
Co-Authored By: @NathanSWard
Co-Authored By: @tygyh
## Solution
Replace `usize` in `SparseSet`'s sparse array with
`nonmax::NonMaxUsize`. NonMaxUsize wraps a NonZeroUsize, and applies a
bitwise NOT to the value when accessing it. This allows the compiler to
niche the value and eliminate the extra padding used for the `Option`
inside the sparse array, while moving the niche value from 0 to
usize::MAX instead.
Checking the [diff in x86 generated
assembly](6e4da653cc),
this change actually results in fewer instructions generated. One
potential downside is that it seems to have moved a load before a
branch, which means we may be incurring a cache miss even if the element
is not there.
Note: unlike #2104 and #11843, this PR only targets the metadata stores
for the ECS and not the component storage itself. Due to #9907 targeting
`Entity::generation` instead of `Entity::index`, `ComponentSparseSet`
storing only up to `u32::MAX` elements would become a correctness issue.
This will come with a cost when inserting items into the SparseSet, as
now there is a potential for a panic. These cost are really only
incurred when constructing a new Table, Archetype, or Resource that has
never been seen before by the World. All operations that are fairly cold
and not on any particular hotpath, even for command application.
---
## Changelog
Changed: `SparseSet` now can only store up to `usize::MAX - 1` elements
instead of `usize::MAX`.
Changed: `SparseSet` now uses 33-50% less memory overhead per stored
item.
# Objective
- Provide a reliable and performant mechanism to allows users to keep
components synchronized with external sources: closing/opening sockets,
updating indexes, debugging etc.
- Implement a generic mechanism to provide mutable access to the world
without allowing structural changes; this will not only be used here but
is a foundational piece for observers, which are key for a performant
implementation of relations.
## Solution
- Implement a new type `DeferredWorld` (naming is not important,
`StaticWorld` is also suitable) that wraps a world pointer and prevents
user code from making any structural changes to the ECS; spawning
entities, creating components, initializing resources etc.
- Add component lifecycle hooks `on_add`, `on_insert` and `on_remove`
that can be assigned callbacks in user code.
---
## Changelog
- Add new `DeferredWorld` type.
- Add new world methods: `register_component::<T>` and
`register_component_with_descriptor`. These differ from `init_component`
in that they provide mutable access to the created `ComponentInfo` but
will panic if the component is already in any archetypes. These
restrictions serve two purposes:
1. Prevent users from defining hooks for components that may already
have associated hooks provided in another plugin. (a use case better
served by observers)
2. Ensure that when an `Archetype` is created it gets the appropriate
flags to early-out when triggering hooks.
- Add methods to `ComponentInfo`: `on_add`, `on_insert` and `on_remove`
to be used to register hooks of the form `fn(DeferredWorld, Entity,
ComponentId)`
- Modify `BundleInserter`, `BundleSpawner` and `EntityWorldMut` to
trigger component hooks when appropriate.
- Add bit flags to `Archetype` indicating whether or not any contained
components have each type of hook, this can be expanded for other flags
as needed.
- Add `component_hooks` example to illustrate usage. Try it out! It's
fun to mash keys.
## Safety
The changes to component insertion, removal and deletion involve a large
amount of unsafe code and it's fair for that to raise some concern. I
have attempted to document it as clearly as possible and have confirmed
that all the hooks examples are accepted by `cargo miri` as not causing
any undefined behavior. The largest issue is in ensuring there are no
outstanding references when passing a `DeferredWorld` to the hooks which
requires some use of raw pointers (as was already happening to some
degree in those places) and I have taken some time to ensure that is the
case but feel free to let me know if I've missed anything.
## Performance
These changes come with a small but measurable performance cost of
between 1-5% on `add_remove` benchmarks and between 1-3% on `insert`
benchmarks. One consideration to be made is the existence of the current
`RemovedComponents` which is on average more costly than the addition of
`on_remove` hooks due to the early-out, however hooks doesn't completely
remove the need for `RemovedComponents` as there is a chance you want to
respond to the removal of a component that already has an `on_remove`
hook defined in another plugin, so I have not removed it here. I do
intend to deprecate it with the introduction of observers in a follow up
PR.
## Discussion Questions
- Currently `DeferredWorld` implements `Deref` to `&World` which makes
sense conceptually, however it does cause some issues with rust-analyzer
providing autocomplete for `&mut World` references which is annoying.
There are alternative implementations that may address this but involve
more code churn so I have attempted them here. The other alternative is
to not implement `Deref` at all but that leads to a large amount of API
duplication.
- `DeferredWorld`, `StaticWorld`, something else?
- In adding support for hooks to `EntityWorldMut` I encountered some
unfortunate difficulties with my desired API. If commands are flushed
after each call i.e. `world.spawn() // flush commands .insert(A) //
flush commands` the entity may be despawned while `EntityWorldMut` still
exists which is invalid. An alternative was then to add
`self.world.flush_commands()` to the drop implementation for
`EntityWorldMut` but that runs into other problems for implementing
functions like `into_unsafe_entity_cell`. For now I have implemented a
`.flush()` which will flush the commands and consume `EntityWorldMut` or
users can manually run `world.flush_commands()` after using
`EntityWorldMut`.
- In order to allowing querying on a deferred world we need
implementations of `WorldQuery` to not break our guarantees of no
structural changes through their `UnsafeWorldCell`. All our
implementations do this, but there isn't currently any safety
documentation specifying what is or isn't allowed for an implementation,
just for the caller, (they also shouldn't be aliasing components they
didn't specify access for etc.) is that something we should start doing?
(see 10752)
Please check out the example `component_hooks` or the tests in
`bundle.rs` for usage examples. I will continue to expand this
description as I go.
See #10839 for a more ergonomic API built on top of this one that isn't
subject to the same restrictions and supports `SystemParam` dependency
injection.
# Objective
`downcast-rs` is not used within bevy_ecs. This is probably a remnant
from before Schedule v3 landed, since stages needed the downcasting.
## Solution
Remove it.
# Objective
The multi-threaded executor currently runs in a dedicated task on a
single thread. When a system finishes running, it needs to notify that
task and wait for the thread to be available and running before the
executor can process the completion.
See #8304
## Solution
Run the multi-threaded executor at the end of each system task. This
allows it to run immediately instead of needing to wait for the main
thread to wake up. Move the mutable executor state into a separate
struct and wrap it in a mutex so it can be shared among the worker
threads.
While this should be faster in theory, I don't actually know how to
measure the performance impact myself.
---------
Co-authored-by: James Liu <contact@jamessliu.com>
Co-authored-by: Mike <mike.hsu@gmail.com>
Fixes#12016.
Bump version after release
This PR has been auto-generated
Co-authored-by: Bevy Auto Releaser <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: François <mockersf@gmail.com>
# Objective
There's a repeating pattern of `ThreadLocal<Cell<Vec<T>>>` which is very
useful for low overhead, low contention multithreaded queues that have
cropped up in a few places in the engine. This pattern is surprisingly
useful when building deferred mutation across multiple threads, as noted
by it's use in `ParallelCommands`.
However, `ThreadLocal<Cell<Vec<T>>>` is not only a mouthful, it's also
hard to ensure the thread-local queue is replaced after it's been
temporarily removed from the `Cell`.
## Solution
Wrap the pattern into `bevy_utils::Parallel<T>` which codifies the
entire pattern and ensures the user follows the contract. Instead of
fetching indivdual cells, removing the value, mutating it, and replacing
it, `Parallel::get` returns a `ParRef<'a, T>` which contains the
temporarily removed value and a reference back to the cell, and will
write the mutated value back to the cell upon being dropped.
I would like to use this to simplify the remaining part of #4899 that
has not been adopted/merged.
---
## Changelog
TODO
---------
Co-authored-by: Joseph <21144246+JoJoJet@users.noreply.github.com>
# Objective
Reduce the size of `bevy_utils`
(https://github.com/bevyengine/bevy/issues/11478)
## Solution
Move `EntityHash` related types into `bevy_ecs`. This also allows us
access to `Entity`, which means we no longer need `EntityHashMap`'s
first generic argument.
---
## Changelog
- Moved `bevy::utils::{EntityHash, EntityHasher, EntityHashMap,
EntityHashSet}` into `bevy::ecs::entity::hash` .
- Removed `EntityHashMap`'s first generic argument. It is now hardcoded
to always be `Entity`.
## Migration Guide
- Uses of `bevy::utils::{EntityHash, EntityHasher, EntityHashMap,
EntityHashSet}` now have to be imported from `bevy::ecs::entity::hash`.
- Uses of `EntityHashMap` no longer have to specify the first generic
parameter. It is now hardcoded to always be `Entity`.
# Objective
Add interactive system debugging capabilities to bevy, providing
step/break/continue style capabilities to running system schedules.
* Original implementation: #8063
- `ignore_stepping()` everywhere was too much complexity
* Schedule-config & Resource discussion: #8168
- Decided on selective adding of Schedules & Resource-based control
## Solution
Created `Stepping` Resource. This resource can be used to enable
stepping on a per-schedule basis. Systems within schedules can be
individually configured to:
* AlwaysRun: Ignore any stepping state and run every frame
* NeverRun: Never run while stepping is enabled
- this allows for disabling of systems while debugging
* Break: If we're running the full frame, stop before this system is run
Stepping provides two modes of execution that reflect traditional
debuggers:
* Step-based: Only execute one system at a time
* Continue/Break: Run all systems, but stop before running a system
marked as Break
### Demo
https://user-images.githubusercontent.com/857742/233630981-99f3bbda-9ca6-4cc4-a00f-171c4946dc47.mov
Breakout has been modified to use Stepping. The game runs normally for a
couple of seconds, then stepping is enabled and the game appears to
pause. A list of Schedules & Systems appears with a cursor at the first
System in the list. The demo then steps forward full frames using the
spacebar until the ball is about to hit a brick. Then we step system by
system as the ball impacts a brick, showing the cursor moving through
the individual systems. Finally the demo switches back to frame stepping
as the ball changes course.
### Limitations
Due to architectural constraints in bevy, there are some cases systems
stepping will not function as a user would expect.
#### Event-driven systems
Stepping does not support systems that are driven by `Event`s as events
are flushed after 1-2 frames. Although game systems are not running
while stepping, ignored systems are still running every frame, so events
will be flushed.
This presents to the user as stepping the event-driven system never
executes the system. It does execute, but the events have already been
flushed.
This can be resolved by changing event handling to use a buffer for
events, and only dropping an event once all readers have read it.
The work-around to allow these systems to properly execute during
stepping is to have them ignore stepping:
`app.add_systems(event_driven_system.ignore_stepping())`. This was done
in the breakout example to ensure sound played even while stepping.
#### Conditional Systems
When a system is stepped, it is given an opportunity to run. If the
conditions of the system say it should not run, it will not.
Similar to Event-driven systems, if a system is conditional, and that
condition is only true for a very small time window, then stepping the
system may not execute the system. This includes depending on any sort
of external clock.
This exhibits to the user as the system not always running when it is
stepped.
A solution to this limitation is to ensure any conditions are consistent
while stepping is enabled. For example, all systems that modify any
state the condition uses should also enable stepping.
#### State-transition Systems
Stepping is configured on the per-`Schedule` level, requiring the user
to have a `ScheduleLabel`.
To support state-transition systems, bevy generates needed schedules
dynamically. Currently it’s very difficult (if not impossible, I haven’t
verified) for the user to get the labels for these schedules.
Without ready access to the dynamically generated schedules, and a
resolution for the `Event` lifetime, **stepping of the state-transition
systems is not supported**
---
## Changelog
- `Schedule::run()` updated to consult `Stepping` Resource to determine
which Systems to run each frame
- Added `Schedule.label` as a `BoxedSystemLabel`, along with supporting
`Schedule::set_label()` and `Schedule::label()` methods
- `Stepping` needed to know which `Schedule` was running, and prior to
this PR, `Schedule` didn't track its own label
- Would have preferred to add `Schedule::with_label()` and remove
`Schedule::new()`, but this PR touches enough already
- Added calls to `Schedule.set_label()` to `App` and `World` as needed
- Added `Stepping` resource
- Added `Stepping::begin_frame()` system to `MainSchedulePlugin`
- Run before `Main::run_main()`
- Notifies any `Stepping` Resource a new render frame is starting
## Migration Guide
- Add a call to `Schedule::set_label()` for any custom `Schedule`
- This is only required if the `Schedule` will be stepped
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Update async channel to v2.
## Solution
- async channel doesn't support `send_blocking` on wasm anymore. So
don't compile the pipelined rendering plugin on wasm anymore.
- Replaces https://github.com/bevyengine/bevy/pull/10405
## Migration Guide
- The `PipelinedRendering` plugin is no longer exported on wasm. If you
are including it in your wasm builds you should remove it.
```rust
#[cfg(all(not(target_arch = "wasm32"))]
app.add_plugins(bevy_render::pipelined_rendering::PipelinedRenderingPlugin);
```
---------
Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
# Objective
This dependency is seemingly no longer used directly after #7267.
Unfortunately, this doesn't fix us having versions of `event-listener`
in our tree.
Closes#10654
## Solution
Remove it, see if anything breaks.
# Objective
- Fix adding `#![allow(clippy::type_complexity)]` everywhere. like #9796
## Solution
- Use the new [lints] table that will land in 1.74
(https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#lints)
- inherit lint to the workspace, crates and examples.
```
[lints]
workspace = true
```
## Changelog
- Bump rust version to 1.74
- Enable lints table for the workspace
```toml
[workspace.lints.clippy]
type_complexity = "allow"
```
- Allow type complexity for all crates and examples
```toml
[lints]
workspace = true
```
---------
Co-authored-by: Martín Maita <47983254+mnmaita@users.noreply.github.com>
Preparing next release
This PR has been auto-generated
---------
Co-authored-by: Bevy Auto Releaser <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: François <mockersf@gmail.com>
# Objective
Fixes#9113
## Solution
disable `multi-threaded` default feature
## Migration Guide
The `multi-threaded` feature in `bevy_ecs` and `bevy_tasks` is no longer
enabled by default. However, this remains a default feature for the
umbrella `bevy` crate. If you depend on `bevy_ecs` or `bevy_tasks`
directly, you should consider enabling this to allow systems to run in
parallel.
CI-capable version of #9086
---------
Co-authored-by: Bevy Auto Releaser <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: François <mockersf@gmail.com>
I created this manually as Github didn't want to run CI for the
workflow-generated PR. I'm guessing we didn't hit this in previous
releases because we used bors.
Co-authored-by: Bevy Auto Releaser <41898282+github-actions[bot]@users.noreply.github.com>
# Objective
Fixes#6689.
## Solution
Add `single-threaded` as an optional non-default feature to `bevy_ecs`
and `bevy_tasks` that:
- disable the `ParallelExecutor` as a default runner
- disables the multi-threaded `TaskPool`
- internally replace `QueryParIter::for_each` calls with
`Query::for_each`.
Removed the `Mutex` and `Arc` usage in the single-threaded task pool.
## Future Work/TODO
Create type aliases for `Mutex`, `Arc` that change to single-threaaded
equivalents where possible.
---
## Changelog
Added: Optional default feature `multi-theaded` to that enables
multithreaded parallelism in the engine. Disabling it disables all
multithreading in exchange for higher single threaded performance. Does
nothing on WASM targets.
---------
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
# Objective
- Handle dangling entity references inside scenes
- Handle references to entities with generation > 0 inside scenes
- Fix a latent bug in `Parent`'s `MapEntities` implementation, which
would, if the parent was outside the scene, cause the scene to be loaded
into the new world with a parent reference potentially pointing to some
random entity in that new world.
- Fixes#4793 and addresses #7235
## Solution
- DynamicScenes now identify entities with a `Entity` instead of a u32,
therefore including generation
- `World` exposes a new `reserve_generations` function that despawns an
entity and advances its generation by some extra amount.
- `MapEntities` implementations have a new `get_or_reserve` function
available that will always return an `Entity`, establishing a new
mapping to a dead entity when the entity they are called with is not in
the `EntityMap`. Subsequent calls with that same `Entity` will return
the same newly created dead entity reference, preserving equality
semantics.
- As a result, after loading a scene containing references to dead
entities (or entities otherwise outside the scene), those references
will all point to different generations on a single entity id in the new
world.
---
## Changelog
### Changed
- In serialized scenes, entities are now identified by a u64 instead of
a u32.
- In serialized scenes, components with entity references now have those
references serialize as u64s instead of structs.
### Fixed
- Scenes containing components with entity references will now
deserialize and add to a world reliably.
## Migration Guide
- `MapEntities` implementations must change from a `&EntityMap`
parameter to a `&mut EntityMapper` parameter and can no longer return a
`Result`. Finally, they should switch from calling `EntityMap::get` to
calling `EntityMapper::get_or_reserve`.
---------
Co-authored-by: Nicola Papale <nicopap@users.noreply.github.com>
…u64, so hash safety is not a concern
# Objective
- While reading the code, just noticed the BundleInfo's HashMap is std::collections::HashMap, which uses a slow but safe hasher.
## Solution
- Use bevy_utils::HashMap instead
benchmark diff (I run several times in a linux box, the perf improvement is consistent, though numbers varies from time to time, I paste my last run result here):
``` bash
cargo bench -- spawn
Compiling bevy_ecs v0.9.0 (/home/lishuo/developer/pr/bevy/crates/bevy_ecs)
Compiling bevy_app v0.9.0 (/home/lishuo/developer/pr/bevy/crates/bevy_app)
Compiling benches v0.1.0 (/home/lishuo/developer/pr/bevy/benches)
Finished bench [optimized] target(s) in 1m 17s
Running benches/bevy_ecs/change_detection.rs (/home/lishuo/developer/pr/bevy/benches/target/release/deps/change_detection-86c5445d0dc34529)
Gnuplot not found, using plotters backend
Running benches/bevy_ecs/benches.rs (/home/lishuo/developer/pr/bevy/benches/target/release/deps/ecs-e49b3abe80bfd8c0)
Gnuplot not found, using plotters backend
spawn_commands/2000_entities
time: [153.94 µs 159.19 µs 164.37 µs]
change: [-14.706% -11.050% -6.9633%] (p = 0.00 < 0.05)
Performance has improved.
spawn_commands/4000_entities
time: [328.77 µs 339.11 µs 349.11 µs]
change: [-7.6331% -3.9932% +0.0487%] (p = 0.06 > 0.05)
No change in performance detected.
spawn_commands/6000_entities
time: [445.01 µs 461.29 µs 477.36 µs]
change: [-16.639% -13.358% -10.006%] (p = 0.00 < 0.05)
Performance has improved.
spawn_commands/8000_entities
time: [657.94 µs 677.71 µs 696.95 µs]
change: [-8.8708% -5.2591% -1.6847%] (p = 0.01 < 0.05)
Performance has improved.
get_or_spawn/individual time: [452.02 µs 466.70 µs 482.07 µs]
change: [-17.218% -14.041% -10.728%] (p = 0.00 < 0.05)
Performance has improved.
get_or_spawn/batched time: [291.12 µs 301.12 µs 311.31 µs]
change: [-12.281% -8.9163% -5.3660%] (p = 0.00 < 0.05)
Performance has improved.
spawn_world/1_entities time: [81.668 ns 84.284 ns 86.860 ns]
change: [-12.251% -6.7872% -1.5402%] (p = 0.02 < 0.05)
Performance has improved.
spawn_world/10_entities time: [789.78 ns 821.96 ns 851.95 ns]
change: [-19.738% -14.186% -8.0733%] (p = 0.00 < 0.05)
Performance has improved.
spawn_world/100_entities
time: [7.9906 µs 8.2449 µs 8.5013 µs]
change: [-12.417% -6.6837% -0.8766%] (p = 0.02 < 0.05)
Change within noise threshold.
spawn_world/1000_entities
time: [81.602 µs 84.161 µs 86.833 µs]
change: [-13.656% -8.6520% -3.0491%] (p = 0.00 < 0.05)
Performance has improved.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high mild
Benchmarking spawn_world/10000_entities: Warming up for 500.00 ms
Warning: Unable to complete 100 samples in 4.0s. You may wish to increase target time to 4.0s, enable flat sampling, or reduce sample count to 70.
spawn_world/10000_entities
time: [813.02 µs 839.76 µs 865.41 µs]
change: [-12.133% -6.1970% -0.2302%] (p = 0.05 < 0.05)
Change within noise threshold.
```
---
## Changelog
> This section is optional. If this was a trivial fix, or has no externally-visible impact, you can delete this section.
- use bevy_utils::HashMap for Bundles::bundle_ids
## Migration Guide
> This section is optional. If there are no breaking changes, you can delete this section.
- Not a breaking change, hashmap is internal impl.
Huge thanks to @maniwani, @devil-ira, @hymm, @cart, @superdump and @jakobhellermann for the help with this PR.
# Objective
- Followup #6587.
- Minimal integration for the Stageless Scheduling RFC: https://github.com/bevyengine/rfcs/pull/45
## Solution
- [x] Remove old scheduling module
- [x] Migrate new methods to no longer use extension methods
- [x] Fix compiler errors
- [x] Fix benchmarks
- [x] Fix examples
- [x] Fix docs
- [x] Fix tests
## Changelog
### Added
- a large number of methods on `App` to work with schedules ergonomically
- the `CoreSchedule` enum
- `App::add_extract_system` via the `RenderingAppExtension` trait extension method
- the private `prepare_view_uniforms` system now has a public system set for scheduling purposes, called `ViewSet::PrepareUniforms`
### Removed
- stages, and all code that mentions stages
- states have been dramatically simplified, and no longer use a stack
- `RunCriteriaLabel`
- `AsSystemLabel` trait
- `on_hierarchy_reports_enabled` run criteria (now just uses an ad hoc resource checking run condition)
- systems in `RenderSet/Stage::Extract` no longer warn when they do not read data from the main world
- `RunCriteriaLabel`
- `transform_propagate_system_set`: this was a nonstandard pattern that didn't actually provide enough control. The systems are already `pub`: the docs have been updated to ensure that the third-party usage is clear.
### Changed
- `System::default_labels` is now `System::default_system_sets`.
- `App::add_default_labels` is now `App::add_default_sets`
- `CoreStage` and `StartupStage` enums are now `CoreSet` and `StartupSet`
- `App::add_system_set` was renamed to `App::add_systems`
- The `StartupSchedule` label is now defined as part of the `CoreSchedules` enum
- `.label(SystemLabel)` is now referred to as `.in_set(SystemSet)`
- `SystemLabel` trait was replaced by `SystemSet`
- `SystemTypeIdLabel<T>` was replaced by `SystemSetType<T>`
- The `ReportHierarchyIssue` resource now has a public constructor (`new`), and implements `PartialEq`
- Fixed time steps now use a schedule (`CoreSchedule::FixedTimeStep`) rather than a run criteria.
- Adding rendering extraction systems now panics rather than silently failing if no subapp with the `RenderApp` label is found.
- the `calculate_bounds` system, with the `CalculateBounds` label, is now in `CoreSet::Update`, rather than in `CoreSet::PostUpdate` before commands are applied.
- `SceneSpawnerSystem` now runs under `CoreSet::Update`, rather than `CoreStage::PreUpdate.at_end()`.
- `bevy_pbr::add_clusters` is no longer an exclusive system
- the top level `bevy_ecs::schedule` module was replaced with `bevy_ecs::scheduling`
- `tick_global_task_pools_on_main_thread` is no longer run as an exclusive system. Instead, it has been replaced by `tick_global_task_pools`, which uses a `NonSend` resource to force running on the main thread.
## Migration Guide
- Calls to `.label(MyLabel)` should be replaced with `.in_set(MySet)`
- Stages have been removed. Replace these with system sets, and then add command flushes using the `apply_system_buffers` exclusive system where needed.
- The `CoreStage`, `StartupStage, `RenderStage` and `AssetStage` enums have been replaced with `CoreSet`, `StartupSet, `RenderSet` and `AssetSet`. The same scheduling guarantees have been preserved.
- Systems are no longer added to `CoreSet::Update` by default. Add systems manually if this behavior is needed, although you should consider adding your game logic systems to `CoreSchedule::FixedTimestep` instead for more reliable framerate-independent behavior.
- Similarly, startup systems are no longer part of `StartupSet::Startup` by default. In most cases, this won't matter to you.
- For example, `add_system_to_stage(CoreStage::PostUpdate, my_system)` should be replaced with
- `add_system(my_system.in_set(CoreSet::PostUpdate)`
- When testing systems or otherwise running them in a headless fashion, simply construct and run a schedule using `Schedule::new()` and `World::run_schedule` rather than constructing stages
- Run criteria have been renamed to run conditions. These can now be combined with each other and with states.
- Looping run criteria and state stacks have been removed. Use an exclusive system that runs a schedule if you need this level of control over system control flow.
- For app-level control flow over which schedules get run when (such as for rollback networking), create your own schedule and insert it under the `CoreSchedule::Outer` label.
- Fixed timesteps are now evaluated in a schedule, rather than controlled via run criteria. The `run_fixed_timestep` system runs this schedule between `CoreSet::First` and `CoreSet::PreUpdate` by default.
- Command flush points introduced by `AssetStage` have been removed. If you were relying on these, add them back manually.
- Adding extract systems is now typically done directly on the main app. Make sure the `RenderingAppExtension` trait is in scope, then call `app.add_extract_system(my_system)`.
- the `calculate_bounds` system, with the `CalculateBounds` label, is now in `CoreSet::Update`, rather than in `CoreSet::PostUpdate` before commands are applied. You may need to order your movement systems to occur before this system in order to avoid system order ambiguities in culling behavior.
- the `RenderLabel` `AppLabel` was renamed to `RenderApp` for clarity
- `App::add_state` now takes 0 arguments: the starting state is set based on the `Default` impl.
- Instead of creating `SystemSet` containers for systems that run in stages, simply use `.on_enter::<State::Variant>()` or its `on_exit` or `on_update` siblings.
- `SystemLabel` derives should be replaced with `SystemSet`. You will also need to add the `Debug`, `PartialEq`, `Eq`, and `Hash` traits to satisfy the new trait bounds.
- `with_run_criteria` has been renamed to `run_if`. Run criteria have been renamed to run conditions for clarity, and should now simply return a bool.
- States have been dramatically simplified: there is no longer a "state stack". To queue a transition to the next state, call `NextState::set`
## TODO
- [x] remove dead methods on App and World
- [x] add `App::add_system_to_schedule` and `App::add_systems_to_schedule`
- [x] avoid adding the default system set at inappropriate times
- [x] remove any accidental cycles in the default plugins schedule
- [x] migrate benchmarks
- [x] expose explicit labels for the built-in command flush points
- [x] migrate engine code
- [x] remove all mentions of stages from the docs
- [x] verify docs for States
- [x] fix uses of exclusive systems that use .end / .at_start / .before_commands
- [x] migrate RenderStage and AssetStage
- [x] migrate examples
- [x] ensure that transform propagation is exported in a sufficiently public way (the systems are already pub)
- [x] ensure that on_enter schedules are run at least once before the main app
- [x] re-enable opt-in to execution order ambiguities
- [x] revert change to `update_bounds` to ensure it runs in `PostUpdate`
- [x] test all examples
- [x] unbreak directional lights
- [x] unbreak shadows (see 3d_scene, 3d_shape, lighting, transparaency_3d examples)
- [x] game menu example shows loading screen and menu simultaneously
- [x] display settings menu is a blank screen
- [x] `without_winit` example panics
- [x] ensure all tests pass
- [x] SubApp doc test fails
- [x] runs_spawn_local tasks fails
- [x] [Fix panic_when_hierachy_cycle test hanging](https://github.com/alice-i-cecile/bevy/pull/120)
## Points of Difficulty and Controversy
**Reviewers, please give feedback on these and look closely**
1. Default sets, from the RFC, have been removed. These added a tremendous amount of implicit complexity and result in hard to debug scheduling errors. They're going to be tackled in the form of "base sets" by @cart in a followup.
2. The outer schedule controls which schedule is run when `App::update` is called.
3. I implemented `Label for `Box<dyn Label>` for our label types. This enables us to store schedule labels in concrete form, and then later run them. I ran into the same set of problems when working with one-shot systems. We've previously investigated this pattern in depth, and it does not appear to lead to extra indirection with nested boxes.
4. `SubApp::update` simply runs the default schedule once. This sucks, but this whole API is incomplete and this was the minimal changeset.
5. `time_system` and `tick_global_task_pools_on_main_thread` no longer use exclusive systems to attempt to force scheduling order
6. Implemetnation strategy for fixed timesteps
7. `AssetStage` was migrated to `AssetSet` without reintroducing command flush points. These did not appear to be used, and it's nice to remove these bottlenecks.
8. Migration of `bevy_render/lib.rs` and pipelined rendering. The logic here is unusually tricky, as we have complex scheduling requirements.
## Future Work (ideally before 0.10)
- Rename schedule_v3 module to schedule or scheduling
- Add a derive macro to states, and likely a `EnumIter` trait of some form
- Figure out what exactly to do with the "systems added should basically work by default" problem
- Improve ergonomics for working with fixed timesteps and states
- Polish FixedTime API to match Time
- Rebase and merge #7415
- Resolve all internal ambiguities (blocked on better tools, especially #7442)
- Add "base sets" to replace the removed default sets.
# Objective
Currently for entities we serialize only `id`. But this is not very expected behavior. For example, in networking, when the server sends its state, it contains entities and components. On the client, I create new objects and map them (using `EntityMap`) to those received from the server (to know which one matches which). And if `generation` field is missing, this mapping can be broken. Example:
1. Server sends an entity `Entity{ id: 2, generation: 1}` with components.
2. Client puts the received entity in a map and create a new entity that maps to this received entity. The new entity have different `id` and `generation`. Let's call it `Entity{ id: 12, generation: 4}`.
3. Client sends a command for `Entity{ id: 12, generation: 4}`. To do so, it maps local entity to the one from server. But `generation` field is 0 because it was omitted for serialization on the server. So it maps to `Entity{ id: 2, generation: 0}`.
4. Server receives `Entity{ id: 2, generation: 0}` which is invalid.
In my game I worked around it by [writing custom serialization](https://github.com/dollisgame/dollis/blob/master/src/core/network/entity_serde.rs) and using `serde(with = "...")`. But it feels like a bad default to me.
Using `Entity` over a custom `NetworkId` also have the following advantages:
1. Re-use `MapEntities` trait to map `Entity`s in replicated components.
2. Instead of server `Entity <-> NetworkId ` and `Entity <-> NetworkId`, we map entities only on client.
3. No need to handling uniqueness. It's a rare case, but makes things simpler. For example, I don't need to query for a resource to create an unique ID.
Closes#6143.
## Solution
Use default serde impls. If anyone want to avoid wasting memory on `generation`, they can create a new type that holds `u32`. This is what Bevy do for [DynamicEntity](https://docs.rs/bevy/latest/bevy/scene/struct.DynamicEntity.html) to serialize scenes. And I don't see any use case to serialize an entity id expect this one.
---
## Changelog
### Changed
- Entity now serializes / deserializes `generation` field.
## Migration Guide
- Entity now fully serialized. If you want to serialze only `id`, as it was before, you can create a new type that wraps `u32`.
# Objective
While using the ParallelExecutor, systems do not actually start until `prepare_systems` completes. In stages where there are large numbers of "empty" systems with very little work to do, this delay adds significant overhead, which can add up over many stages.
## Solution
Immediately and synchronously signal the start of systems that can run without dependencies inside `prepare_systems` instead of waiting for the first executor iteration after `prepare_systems` completes. Any system that is dependent on them still cannot run until after `prepare_systems` completes, but there are a large number of unconstrained systems in the base engine where this is a general benefit in almost every case.
## Performance
This change was tested against `many_foxes` in the default configuration. As this change is sensitive to the overhead around scheduling systems, the spans for measuring system timing, system overhead, and system commands were all commented out for these measurements.
The median stage timings between `main` and this PR are as follows:
|stage|main|this PR|
|:--|:--|:--|
|First|75.54 us|61.61 us|
|LoadAssets|51.05 us|42.32 us|
|PreUpdate|54.6 us|55.56 us|
|Update|61.89 us|51.5 us|
|PostUpdate|7.27 ms|6.71 ms|
|AssetEvents|47.82 us|35.95 us|
|Last|39.19 us|37.71 us|
|reserve_and_flush|57.83 us|48.2 us|
|Extract|1.41 ms|1.28 ms|
|Prepare|554.49 us|502.53 us|
|Queue|216.29 us|207.51 us|
|Sort|67.03 us|60.99 us|
|Render|1.73 ms|1.58 ms|
|Cleanup|33.55 us|30.76 us|
|Clear Entities|18.56 us|17.05 us|
|**full frame**|**11.9 ms**|**10.91 ms**|
For the first few stages, the benefit is small but cumulative over each. For PostUpdate in particular, this allows `parent_update` to run while prepare_systems is running, which is required for the animation and transform propagation systems, which dominate the time spent in the stage, but also frontloads the contention as the other "empty" systems are also running while `parent_update` is running. For Render, where there is just a single large exclusive system, the benefit comes from not waiting on a spuriously scheduled task on the task pool to kick off the system: it's immediately scheduled to run.
# Objective
Fixes#5362
## Solution
Add the attribute `#[label(ignore_fields)]` for `*Label` types.
```rust
#[derive(SystemLabel)]
pub enum MyLabel {
One,
// Previously this was not allowed since labels cannot contain data.
#[system_label(ignore_fields)]
Two(PhantomData<usize>),
}
```
## Notes
This label makes it possible for equality to behave differently depending on whether or not you are treating the type as a label. For example:
```rust
#[derive(SystemLabel, PartialEq, Eq)]
#[system_label(ignore_fields)]
pub struct Foo(usize);
```
If you compare it as a label, it will ignore the wrapped fields as the user requested. But if you compare it as a `Foo`, the derive will incorrectly compare the inner fields. I see a few solutions
1. Do nothing. This is technically intended behavior, but I think we should do our best to prevent footguns.
2. Generate impls of `PartialEq` and `Eq` along with the `#[derive(Label)]` macros. This is a breaking change as it requires all users to remove these derives from their types.
3. Only allow `PhantomData` to be used with `ignore_fields` -- seems needlessly prescriptive.
---
## Changelog
* Added the `ignore_fields` attribute to the derive macros for `*Label` types.
* Added an example showing off different forms of the derive macro.
<!--
## Migration Guide
> This section is optional. If there are no breaking changes, you can delete this section.
- If this PR is a breaking change (relative to the last release of Bevy), describe how a user might need to migrate their code to support these changes
- Simply adding new functionality is not a breaking change.
- Fixing behavior that was definitely a bug, rather than a questionable design choice is not a breaking change.
-->
(follow-up to #4423)
# Objective
Currently, it isn't possible to easily fire commands from within par_for_each blocks. This PR allows for issuing commands from within parallel scopes.
# Objective
The pointer types introduced in #3001 are useful not just in `bevy_ecs`, but also in crates like `bevy_reflect` (#4475) or even outside of bevy.
## Solution
Extract `Ptr<'a>`, `PtrMut<'a>`, `OwnedPtr<'a>`, `ThinSlicePtr<'a, T>` and `UnsafeCellDeref` from `bevy_ecs::ptr` into `bevy_ptr`.
**Note:** `bevy_ecs` still reexports the `bevy_ptr` as `bevy_ecs::ptr` so that crates like `bevy_transform` can use the `Bundle` derive without needing to depend on `bevy_ptr` themselves.
# Objective
Reduce from scratch build time.
## Solution
Reduce the size of the critical path by removing dependencies between crates where not necessary. For `cargo check --no-default-features` this reduced build time from ~51s to ~45s. For some commits I am not completely sure if the tradeoff between build time reduction and convenience caused by the commit is acceptable. If not, I can drop them.
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 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>
# Objective
Fixes these issues:
- `WorldId`s currently aren't necessarily unique
- I want to guarantee that they're unique to safeguard my librarified version of https://github.com/bevyengine/bevy/discussions/2805
- There probably hasn't been a collision yet, but they could technically collide
- `SystemId` isn't used for anything
- It's no longer used now that `Locals` are stored within the `System`.
- `bevy_ecs` depends on rand
## Solution
- Instead of randomly generating `WorldId`s, just use an incrementing atomic counter, panicing on overflow.
- Remove `SystemId`
- We do need to allow Locals for exclusive systems at some point, but exclusive systems couldn't access their own `SystemId` anyway.
- Now that these don't depend on rand, move it to a dev-dependency
## Todo
Determine if `WorldId` should be `u32` based instead
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
# Objective
Reduce compilation time
# Solution
Remove unused dependencies. While this PR doesn't remove any crates from `Cargo.lock`, it may unlock more build parallelism.
[RENDERED](https://github.com/NiklasEi/bevy/blob/ecs_readme/crates/bevy_ecs/README.md)
Since I am trying to learn more about Bevy ECS at the moment, I thought this issue is a perfect fit.
This PR adds a readme to the `bevy_ecs` crate containing a minimal running example of stand alone `bevy_ecs`. Unique features like customizable component storage, Resources or change detection are introduced. For each of these features the readme links to an example in a newly created examples directory inside the `bevy_esc` crate.
Resolves#2008
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
Updates the requirements on [fixedbitset](https://github.com/bluss/fixedbitset) to permit the latest version.
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