bevy/examples/window/multiple_windows.rs
Aceeri ddfafab971 Windows as Entities (#5589)
# Objective

Fix https://github.com/bevyengine/bevy/issues/4530

- Make it easier to open/close/modify windows by setting them up as `Entity`s with a `Window` component.
- Make multiple windows very simple to set up. (just add a `Window` component to an entity and it should open)

## Solution

- Move all properties of window descriptor to ~components~ a component.
- Replace `WindowId` with `Entity`.
- ~Use change detection for components to update backend rather than events/commands. (The `CursorMoved`/`WindowResized`/... events are kept for user convenience.~
  Check each field individually to see what we need to update, events are still kept for user convenience.

---

## Changelog

- `WindowDescriptor` renamed to `Window`.
    - Width/height consolidated into a `WindowResolution` component.
    - Requesting maximization/minimization is done on the [`Window::state`] field.
- `WindowId` is now `Entity`.

## Migration Guide

- Replace `WindowDescriptor` with `Window`.
    - Change `width` and `height` fields in a `WindowResolution`, either by doing
      ```rust
      WindowResolution::new(width, height) // Explicitly
      // or using From<_> for tuples for convenience
      (1920., 1080.).into()
      ```
- Replace any `WindowCommand` code to just modify the `Window`'s fields directly  and creating/closing windows is now by spawning/despawning an entity with a `Window` component like so:
  ```rust
  let window = commands.spawn(Window { ... }).id(); // open window
  commands.entity(window).despawn(); // close window
  ```

## Unresolved
- ~How do we tell when a window is minimized by a user?~
  ~Currently using the `Resize(0, 0)` as an indicator of minimization.~
  No longer attempting to tell given how finnicky this was across platforms, now the user can only request that a window be maximized/minimized.
  
 ## Future work
 - Move `exit_on_close` functionality out from windowing and into app(?)
 - https://github.com/bevyengine/bevy/issues/5621
 - https://github.com/bevyengine/bevy/issues/7099
 - https://github.com/bevyengine/bevy/issues/7098


Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2023-01-19 00:38:28 +00:00

49 lines
1.5 KiB
Rust

//! Uses two windows to visualize a 3D model from different angles.
use bevy::{prelude::*, render::camera::RenderTarget, window::WindowRef};
fn main() {
App::new()
// By default, a primary window gets spawned by `WindowPlugin`, contained in `DefaultPlugins`
.add_plugins(DefaultPlugins)
.add_startup_system(setup_scene)
.add_system(bevy::window::close_on_esc)
.run();
}
fn setup_scene(mut commands: Commands, asset_server: Res<AssetServer>) {
// add entities to the world
commands.spawn(SceneBundle {
scene: asset_server.load("models/monkey/Monkey.gltf#Scene0"),
..default()
});
// light
commands.spawn(PointLightBundle {
transform: Transform::from_xyz(4.0, 5.0, 4.0),
..default()
});
// main camera, cameras default to the primary window
// so we don't need to specify that.
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(0.0, 0.0, 6.0).looking_at(Vec3::ZERO, Vec3::Y),
..default()
});
// Spawn a second window
let second_window = commands
.spawn(Window {
title: "Second window".to_owned(),
..default()
})
.id();
// second window camera
commands.spawn(Camera3dBundle {
transform: Transform::from_xyz(6.0, 0.0, 0.0).looking_at(Vec3::ZERO, Vec3::Y),
camera: Camera {
target: RenderTarget::Window(WindowRef::Entity(second_window)),
..default()
},
..default()
});
}