Use picking system for cursor grabbing

client/src/input/cursor_grab.rs

@@ -1,63 +1,60 @@
 use bevy::prelude::*;
 
+use bevy::input::common_conditions::input_just_pressed;
 use bevy::window::{CursorGrabMode, CursorOptions};
 
 use crate::Screen;
 
 pub fn plugin(app: &mut App) {
+    app.add_systems(OnEnter(Screen::Gameplay), add_window_click_observer);
+    app.add_systems(PreUpdate, center_cursor.run_if(is_cursor_grabbed));
     app.add_systems(
-        PreUpdate,
-        update_cursor_grab.run_if(in_state(Screen::Gameplay)),
+        Update,
+        ungrab_cursor.run_if(
+            is_cursor_grabbed.and(input_just_pressed(KeyCode::Escape).or(not(is_window_focused))),
+        ),
     );
 }
 
-fn update_cursor_grab(
-    mut mouse_button_input: ResMut<ButtonInput<MouseButton>>,
-    key_input: Res<ButtonInput<KeyCode>>,
-    window: Single<(&mut Window, &mut CursorOptions)>,
-) {
-    let (mut window, mut cursor) = window.into_inner();
-
-    let is_grabbed = cursor.grab_mode != CursorGrabMode::None;
-    let request_grab = mouse_button_input.any_just_pressed([MouseButton::Left, MouseButton::Right]);
-    let request_ungrab = !window.focused || key_input.just_pressed(KeyCode::Escape);
-
-    if !is_grabbed && request_grab && !request_ungrab {
-        cursor.grab_mode = CursorGrabMode::Locked;
-
-        // To prevent other systems (such as `place_break_blocks`)
-        // from seeing the mouse button inputs, clear the state here.
-        mouse_button_input.clear();
-    }
-
-    if is_grabbed && request_ungrab && !request_grab {
-        cursor.grab_mode = CursorGrabMode::None;
-    }
-
-    if is_grabbed && !request_ungrab {
-        // Set the cursor position to the center of the window, so that when
-        // it is ungrabbed, it will reappear there. Because `is_grabbed` is
-        // not updated on grab, this block is delayed by one frame.
-        //
-        // On Wayland, since the cursor is locked into place, this only needs
-        // to be done once. Unfortunately, for some reason this doesn't work
-        // in the same frame as setting `grab_mode`, and would log an error.
-        //
-        // On X11, the cursor can't be locked into place, only confined to the
-        // window bounds, so we repeatedly move the cursor back to the center
-        // while it's grabbed.
-        //
-        // On the web, the cursor can be locked, but setting its position is
-        // not supported at all, so this would instead log a bunch of errors.
-        let center = window.resolution.size() / 2.;
-        #[cfg(not(target_family = "wasm"))] // skip on web
-        window.set_cursor_position(Some(center));
-    }
-
-    // Keep cursor visbility in sync with `grab_mode`.
-    cursor.visible = cursor.grab_mode == CursorGrabMode::None;
+fn add_window_click_observer(window: Single<Entity, With<Window>>, mut commands: Commands) {
+    commands.entity(*window).observe(
+        |mut event: On<Pointer<Click>>, mut cursor: Single<&mut CursorOptions>| {
+            cursor.grab_mode = CursorGrabMode::Locked;
+            cursor.visible = false;
+            event.propagate(false);
+        },
+    );
+}
+
+fn ungrab_cursor(mut cursor: Single<&mut CursorOptions>) {
+    cursor.grab_mode = CursorGrabMode::None;
+    cursor.visible = true;
+}
+
+/// Sets the cursor position to the center of the window,
+/// so that once it is ungrabbed, it will reappear there.
+fn center_cursor(mut window: Single<&mut Window>) {
+    let center = window.resolution.size() / 2.;
+
+    // On Wayland, since the cursor is locked into place, this only needs to be
+    // done once. Unfortunately, for some reason, this doesn't work in the same
+    // frame as setting `grab_mode`, logging an error. This system is scheduled
+    // on `PreUpdate`, so it runs with one frame delay.
+    //
+    // On X11, the cursor can't be locked into place, only confined to the
+    // window bounds, so we repeatedly move the cursor back to the center
+    // while it's grabbed.
+    //
+    // On the web, the cursor can be locked, but setting its position isn't
+    // supported at all, so this would instead log a bunch of errors.
+    #[cfg(not(target_family = "wasm"))]
+    window.set_cursor_position(Some(center));
 }
 
 pub fn is_cursor_grabbed(cursor: Single<&CursorOptions>) -> bool {
     cursor.grab_mode != CursorGrabMode::None
 }
+
+pub fn is_window_focused(window: Single<&Window>) -> bool {
+    window.focused
+}

client/src/main.rs

@@ -26,7 +26,7 @@ fn main() -> Result {
     let mut app = App::new();
     app.insert_resource(args);
 
-    app.add_plugins(
+    app.add_plugins((
         DefaultPlugins
             .set(WindowPlugin {
                 primary_window: Some(Window {
@@ -47,10 +47,16 @@ fn main() -> Result {
                 meta_check: AssetMetaCheck::Never,
                 ..default()
             }),
-    );
+        bevy_fix_cursor_unlock_web::FixPointerUnlockPlugin,
+    ));
+
+    // Make entities require the `Pickable` component if
+    // they should be considered for the picking system.
+    app.insert_resource(UiPickingSettings {
+        require_markers: true,
+    });
 
     app.add_plugins((
-        bevy_fix_cursor_unlock_web::FixPointerUnlockPlugin,
         common::assets::plugin,
         common::network::plugin,
         assets::plugin,