bevy/examples/window/low_power.rs
Alice Cecile 206c7ce219 Migrate engine to Schedule v3 (#7267)
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.
2023-02-06 02:04:50 +00:00

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7.8 KiB
Rust

//! This example illustrates how to run a winit window in a reactive, low power mode.
//!
//! This is useful for making desktop applications, or any other program that doesn't need to be
//! running the event loop non-stop.
use bevy::{
prelude::*,
utils::Duration,
window::{PresentMode, RequestRedraw, WindowPlugin},
winit::WinitSettings,
};
fn main() {
App::new()
// Continuous rendering for games - bevy's default.
.insert_resource(WinitSettings::game())
// Power-saving reactive rendering for applications.
.insert_resource(WinitSettings::desktop_app())
// You can also customize update behavior with the fields of [`WinitConfig`]
.insert_resource(WinitSettings {
focused_mode: bevy::winit::UpdateMode::Continuous,
unfocused_mode: bevy::winit::UpdateMode::ReactiveLowPower {
max_wait: Duration::from_millis(10),
},
..default()
})
.insert_resource(ExampleMode::Game)
.add_plugins(DefaultPlugins.set(WindowPlugin {
primary_window: Some(Window {
// Turn off vsync to maximize CPU/GPU usage
present_mode: PresentMode::AutoNoVsync,
..default()
}),
..default()
}))
.add_startup_system(test_setup::setup)
.add_system(test_setup::cycle_modes.in_set(CoreSet::Update))
.add_system(test_setup::rotate_cube.in_set(CoreSet::Update))
.add_system(test_setup::update_text.in_set(CoreSet::Update))
.add_system(update_winit)
.run();
}
#[derive(Resource, Debug)]
enum ExampleMode {
Game,
Application,
ApplicationWithRedraw,
}
/// Update winit based on the current `ExampleMode`
fn update_winit(
mode: Res<ExampleMode>,
mut event: EventWriter<RequestRedraw>,
mut winit_config: ResMut<WinitSettings>,
) {
use ExampleMode::*;
*winit_config = match *mode {
Game => {
// In the default `WinitConfig::game()` mode:
// * When focused: the event loop runs as fast as possible
// * When not focused: the event loop runs as fast as possible
WinitSettings::game()
}
Application => {
// While in `WinitConfig::desktop_app()` mode:
// * When focused: the app will update any time a winit event (e.g. the window is
// moved/resized, the mouse moves, a button is pressed, etc.), a [`RequestRedraw`]
// event is received, or after 5 seconds if the app has not updated.
// * When not focused: the app will update when the window is directly interacted with
// (e.g. the mouse hovers over a visible part of the out of focus window), a
// [`RequestRedraw`] event is received, or one minute has passed without the app
// updating.
WinitSettings::desktop_app()
}
ApplicationWithRedraw => {
// Sending a `RequestRedraw` event is useful when you want the app to update the next
// frame regardless of any user input. For example, your application might use
// `WinitConfig::desktop_app()` to reduce power use, but UI animations need to play even
// when there are no inputs, so you send redraw requests while the animation is playing.
event.send(RequestRedraw);
WinitSettings::desktop_app()
}
};
}
/// Everything in this module is for setting up and animating the scene, and is not important to the
/// demonstrated features.
pub(crate) mod test_setup {
use crate::ExampleMode;
use bevy::{prelude::*, window::RequestRedraw};
/// Switch between update modes when the mouse is clicked.
pub(crate) fn cycle_modes(
mut mode: ResMut<ExampleMode>,
mouse_button_input: Res<Input<KeyCode>>,
) {
if mouse_button_input.just_pressed(KeyCode::Space) {
*mode = match *mode {
ExampleMode::Game => ExampleMode::Application,
ExampleMode::Application => ExampleMode::ApplicationWithRedraw,
ExampleMode::ApplicationWithRedraw => ExampleMode::Game,
};
}
}
#[derive(Component)]
pub(crate) struct Rotator;
/// Rotate the cube to make it clear when the app is updating
pub(crate) fn rotate_cube(
time: Res<Time>,
mut cube_transform: Query<&mut Transform, With<Rotator>>,
) {
for mut transform in &mut cube_transform {
transform.rotate_x(time.delta_seconds());
transform.rotate_local_y(time.delta_seconds());
}
}
#[derive(Component)]
pub struct ModeText;
pub(crate) fn update_text(
mut frame: Local<usize>,
mode: Res<ExampleMode>,
mut query: Query<&mut Text, With<ModeText>>,
) {
*frame += 1;
let mode = match *mode {
ExampleMode::Game => "game(), continuous, default",
ExampleMode::Application => "desktop_app(), reactive",
ExampleMode::ApplicationWithRedraw => "desktop_app(), reactive, RequestRedraw sent",
};
let mut text = query.single_mut();
text.sections[1].value = mode.to_string();
text.sections[3].value = frame.to_string();
}
/// Set up a scene with a cube and some text
pub fn setup(
mut commands: Commands,
mut meshes: ResMut<Assets<Mesh>>,
mut materials: ResMut<Assets<StandardMaterial>>,
mut event: EventWriter<RequestRedraw>,
asset_server: Res<AssetServer>,
) {
commands.spawn((
PbrBundle {
mesh: meshes.add(Mesh::from(shape::Cube { size: 0.5 })),
material: materials.add(Color::rgb(0.8, 0.7, 0.6).into()),
..default()
},
Rotator,
));
commands.spawn(PointLightBundle {
point_light: PointLight {
intensity: 1500.0,
shadows_enabled: true,
..default()
},
transform: Transform::from_xyz(4.0, 8.0, 4.0),
..default()
});
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(-2.0, 2.0, 2.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
event.send(RequestRedraw);
commands.spawn((
TextBundle::from_sections([
TextSection::new(
"Press spacebar to cycle modes\n",
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 50.0,
color: Color::WHITE,
},
),
TextSection::from_style(TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 50.0,
color: Color::GREEN,
}),
TextSection::new(
"\nFrame: ",
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 50.0,
color: Color::YELLOW,
},
),
TextSection::from_style(TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 50.0,
color: Color::YELLOW,
}),
])
.with_style(Style {
align_self: AlignSelf::FlexStart,
position_type: PositionType::Absolute,
position: UiRect {
top: Val::Px(5.0),
left: Val::Px(5.0),
..default()
},
..default()
}),
ModeText,
));
}
}