Objective

Windows as Entities

Solution

What solution would you like?

• WindowId is now Entity
• Extend Commands with a window method returns WindowCommands similar to how the entity method returns EntityCommands,
• WindowCommandQueued will implement Command and on write send itself as an event that window backends like bevy_winit will process.
• Window should be separated into different components:
  • WindowsCommandQueue
  • WindowCursor
  • WindowCursorPosition
  • WindowHandle
  • WindowPosition
  • WindowResizeConstraints
  • WindowResolution
  • WindowTitle
  • WindowPresentation
  • WindowModeComponent
  • WindowCurrentlyFocused (marker) (WindowFocused is taken by a window event)
  • WindowDecorated (marker)
  • WindowResizable (marker)
  • A world query struct containing all these components and markers should be publicly exposed
• Windows should be spawned like an entity in Commands with a WindowDescriptor component
• Window backends should query Added and create the windows for them
• while also applying a Window marker confirming they have been created, query Added<Window> or use a WindowCreated event to get newly created windows.
• Despawning windows should be done just as entities (as they are now entities), window backends should close/destroy windows their internal component has been dropped, e.g. WinitWindow (wrapper around winit's Window that destroys itself on drop)
• A resource called PrimaryWindow contains the entity id of initial window created by WindowPlugin, this replaces Windows::primary
• Insert PrimaryWindow resource when primary window has been created
• PrimaryWindow when add_primary_window is false?
• WindowPlugin should change exit_on_close into a enum called ExitCondition with the values OnPrimaryClosed (when primary window is closed), OnAllClosed (when all windows are closed), DontExit (keep app headless)

Changelog

• WindowId has been replaced by Entity
• Window has been split into multiple components:
  • Window (marker)
  • WindowCursor
  • WindowCursorPosition
  • WindowHandle
  • WindowPresentation
  • WindowModeComponent
  • WindowPosition
  • WindowResolution
  • WindowTitle
  • WindowCanvas
  • WindowDecoraded (marker)
  • WindowCurrentlyFocused (marker)
  • WindowResizable (marker)
  • WindowTransparent (marker)
  • WindowMinimized (marker)
  • WindowMaximized (marker)
• Created WindowCommandsExtensions so that we can commands.window(entity) to get WindowCommands
  • Similar to how ÈntityCommands work
• Split enum WindowCommand into separate structs that all impl Command
• Most methods previously existing on Window is now ei
• Removed Windows as this should now be accomplished by querying for entities with the Window marker component: Query<Entity, With<Window>>

Migration Guide

• bevy_render
• bevy_window
• bevy_text
• bevy_ui
• bevy_winit
• examples