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https://github.com/bevyengine/bevy
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79b4f26158
# Objective Fixes #11411 ## Solution - Added a simple example how to create and configure custom schedules that are run by the `Main` schedule. - Spot checked some of the API docs used, fixed `App::add_schedule` docs that referred to a function argument that was removed by #9600. ## Open Questions - While spot checking the docs, I noticed that the `Schedule` label is stored in a field called `name` instead of `label`. This seems unintuitive since the term label is used everywhere else. Should we change that field name? It was introduced in #9600. If so, I do think this change would be out of scope for this PR that mainly adds the example.
82 lines
3 KiB
Rust
82 lines
3 KiB
Rust
//! Demonstrates how to add custom schedules that run in Bevy's `Main` schedule, ordered relative to Bevy's built-in
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//! schedules such as `Update` or `Last`.
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use bevy::app::MainScheduleOrder;
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use bevy::ecs::schedule::{ExecutorKind, ScheduleLabel};
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use bevy::prelude::*;
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#[derive(ScheduleLabel, Debug, Hash, PartialEq, Eq, Clone)]
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struct SingleThreadedUpdate;
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#[derive(ScheduleLabel, Debug, Hash, PartialEq, Eq, Clone)]
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struct CustomStartup;
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fn main() {
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let mut app = App::new();
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// Create a new [`Schedule`]. For demonstration purposes, we configure it to use a single threaded executor so that
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// systems in this schedule are never run in parallel. However, this is not a requirement for custom schedules in
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// general.
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let mut custom_update_schedule = Schedule::new(SingleThreadedUpdate);
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custom_update_schedule.set_executor_kind(ExecutorKind::SingleThreaded);
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// Adding the schedule to the app does not automatically run the schedule. This merely registers the schedule so
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// that systems can look it up using the `Schedules` resource.
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app.add_schedule(custom_update_schedule);
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// Bevy `App`s have a `main_schedule_label` field that configures which schedule is run by the App's `runner`.
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// By default, this is `Main`. The `Main` schedule is responsible for running Bevy's main schedules such as
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// `Update`, `Startup` or `Last`.
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//
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// We can configure the `Main` schedule to run our custom update schedule relative to the existing ones by modifying
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// the `MainScheduleOrder` resource.
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//
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// Note that we modify `MainScheduleOrder` directly in `main` and not in a startup system. The reason for this is
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// that the `MainScheduleOrder` cannot be modified from systems that are run as part of the `Main` schedule.
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let mut main_schedule_order = app.world.resource_mut::<MainScheduleOrder>();
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main_schedule_order.insert_after(Update, SingleThreadedUpdate);
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// Adding a custom startup schedule works similarly, but needs to use `insert_startup_after`
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// instead of `insert_after`.
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app.add_schedule(Schedule::new(CustomStartup));
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let mut main_schedule_order = app.world.resource_mut::<MainScheduleOrder>();
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main_schedule_order.insert_startup_after(PreStartup, CustomStartup);
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app.add_systems(SingleThreadedUpdate, single_threaded_update_system)
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.add_systems(CustomStartup, custom_startup_system)
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.add_systems(PreStartup, pre_startup_system)
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.add_systems(Startup, startup_system)
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.add_systems(First, first_system)
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.add_systems(Update, update_system)
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.add_systems(Last, last_system)
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.run();
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}
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fn pre_startup_system() {
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println!("Pre Startup");
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}
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fn startup_system() {
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println!("Startup");
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}
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fn custom_startup_system() {
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println!("Custom Startup");
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}
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fn first_system() {
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println!("First");
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}
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fn update_system() {
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println!("Update");
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}
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fn single_threaded_update_system() {
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println!("Single Threaded Update");
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}
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fn last_system() {
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println!("Last");
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}
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