Imported from thedivergentai/game-dev-agentic-skills (
skills/bevy-platform-desktop/SKILL.md). Install upstream withnpx skills add thedivergentai/game-dev-agentic-skills --skill bevy-platform-desktop. Copyright stays with the author.
Bevy desktop platform
When to use
Load this when configuring the desktop window, mode, or close behavior. Web and mobile constraints stay on their skills.
ECS shape
- Module:
bevy::windowis a platform-agnostic window interface.WindowPluginis part ofDefaultPlugins. - Components:
Windowis the defining component for window entities.PrimaryWindowmarks the primary window. - Mode:
WindowMode,PresentMode,WindowResolution,WindowPositionare enums or structs on that page. - Backend feature:
bevy_winitis the winit window and input backend.x11andwaylandare features. - Close:
exit_on_primary_closedandexit_on_all_closedare named functions.WindowCloseRequestedis the event.
Coming from Godot
| Godot idea | Bevy idiom |
|---|---|
| Window size | WindowResolution on the primary Window |
| Fullscreen | WindowMode::BorderlessFullscreen |
| Quit on close | ExitCondition::OnPrimaryClosed on WindowPlugin |
Scope
x11 and wayland are bevy features. The primary window is configured on WindowPlugin before the app runs. Runtime mode changes write the Window component marked PrimaryWindow.
Examples
[package]
name = "desktop"
version = "0.1.0"
edition = "2021"
[dependencies]
bevy = "0.20"
The primary window is 1280 by 720, vsync, and closes the app when that window closes.
use bevy::window::ExitCondition;
use bevy::window::PresentMode;
use bevy::window::WindowMode;
use bevy::window::WindowResolution;
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(WindowPlugin {
primary_window: Some(Window {
title: "Desktop".into(),
resolution: WindowResolution::new(1280, 720),
present_mode: PresentMode::AutoVsync,
mode: WindowMode::Windowed,
..default()
}),
exit_condition: ExitCondition::OnPrimaryClosed,
close_when_requested: true,
..default()
}))
.run();
}
F11 flips the primary window between windowed and borderless fullscreen on the current monitor.
use bevy::window::MonitorSelection;
use bevy::window::PrimaryWindow;
use bevy::window::WindowMode;
fn toggle_fullscreen(
keys: Res<ButtonInput<KeyCode>>,
mut windows: Query<&mut Window, With<PrimaryWindow>>,
) {
if !keys.just_pressed(KeyCode::F11) {
return;
}
let Ok(mut window) = windows.single_mut() else {
return;
};
window.mode = if window.mode == WindowMode::Windowed {
WindowMode::BorderlessFullscreen(MonitorSelection::Current)
} else {
WindowMode::Windowed
};
}
A second system reads the live resolution. It does not write Window, so it can run beside the toggle without .chain().
use bevy::window::PrimaryWindow;
fn log_resolution(windows: Query<&Window, With<PrimaryWindow>>) {
let Ok(window) = windows.single() else {
return;
};
let width = window.resolution.width();
let height = window.resolution.height();
let _ = (width, height);
}
Expert Knowledge Delta
Target: Bevy 0.20+.
Core ECS types: Component, Resource, Query, Commands, Startup, Update, Fixed / FixedMain (bevy::time), .chain(), Plugin, DefaultPlugins, MinimalPlugins. Messages and observers are an ownership slot. See bevy-events-messaging for their APIs. Systems run in parallel unless .chain() orders the ones that conflict.
Who owns state
| Piece | Owner | Who may mutate | Schedule |
|---|---|---|---|
| Data on one entity | Component |
One system via Query |
Update or FixedMain |
| One value for the whole app | Resource |
One system | Startup to insert, then the schedule that reads it |
| Spawn | Commands |
The spawning system | Startup for the initial world; later schedules for runtime spawn |
| Order that must not race | .chain() |
The chained systems only | Same schedule |
| Plugin boundary | Plugin |
build registers systems and resources |
Before the app runs |
Borrow rule: two systems that both mutably query the same component must be ordered (.chain()) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API.
Decision
| If you need | Do this | Do not |
|---|---|---|
| Per-entity data | Component + Query |
A Godot node script |
| App-wide config or clock | Resource |
Copy the value onto every entity |
| Stable simulation step | FixedMain and the Fixed clock |
Tie simulation to raw frame Update |
| Startup spawn | Commands in Startup |
Spawn from a render system |
| Cross-system notice that is not shared state | Message or observer slot in bevy-events-messaging |
A new event type invented in this file |
| An API outside the documented set | Check the official docs first | A made-up crate or API |
Load references/ecs-ownership.md for the ownership table.
NEVER
-
Do not pin
/0.20.0/in docs URLs. WHY: links stay onlatest; the 0.20 target is stated once in prose. -
Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless
.chain()orders them. -
Do not invent a physics, navigation, networking, or XR crate here. WHY: this skill only names documented Bevy crates and modules.
-
No Godot DisplayServer or window project-setting names. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
-
No Godot types in Bevy code. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
-
No invented APIs or unnamed third-party crates as the chosen solver. WHY: Bevy code stays idiomatic ECS and uses only documented Bevy APIs.
Reference
Official Documentation
bevy crate- API reference and Cargo feature list.- Assets - Official asset catalog. No third-party crate was selected.
- Examples - Example tree on the
latestbranch. - ECS -
Component, systems,Query,Startup,Update, and.chain(). - Plugins -
Plugin,DefaultPlugins,MinimalPlugins, andadd_plugins. bevy::window-Window,WindowPlugin,PrimaryWindow,WindowMode.
Related Skills
Prerequisites
- bevy-master - Hub and schedules.
- bevy-ecs-composition - Components and systems.
Complements
- bevy-platform-web - Wasm limits.
- bevy-input-handling - Pointer and keyboard.
- godot-platform-desktop - Equivalent Godot skill.
Downstream / consumers
- None yet.
Master
- bevy-master - Bevy router.
