Implement workaround for egui issue with panels

src/egui.rs

@@ -1,6 +1,7 @@
 use bevy::prelude::*;
 
-/// A resource that tracks whether egui wants focus on the current and previous frames.
+/// A resource that tracks whether egui wants focus on the current and previous frames,
+/// in order to determine whether PanOrbitCamera should react to input events.
 ///
 /// The reason the previous frame's value is saved is because when you click inside an
 /// egui window, Context::wants_pointer_input() still returns false once before returning
@@ -17,9 +18,20 @@ pub struct EguiWantsFocus {
     pub curr: bool,
 }
 
+/// When true, just hovering over an egui panel/window will prevent PanOrbitCamera
+/// from reacting to input events. This is an optional, and hopefully temporary,
+/// workaround to this issue: https://github.com/Plonq/bevy_panorbit_camera/issues/75.
+/// Note that this will prevent PanOrbitCamera using reacting to input whenever the cursor
+/// is over an egui area, even if you're in the middle of dragging to rotate, so only use
+/// this if you use egui Panels (as opposed to Windows). If you use Windows exclusively
+/// then no workaround is required.
+#[derive(Resource, PartialEq, Eq, Default)]
+pub struct EguiFocusIncludesHover(pub bool);
+
 pub fn check_egui_wants_focus(
     mut contexts: bevy_egui::EguiContexts,
     mut wants_focus: ResMut<EguiWantsFocus>,
+    include_hover: Res<EguiFocusIncludesHover>,
     windows: Query<Entity, With<Window>>,
 ) {
     // The window that the user is interacting with and the window that contains the egui context
@@ -28,7 +40,11 @@ pub fn check_egui_wants_focus(
     // interacting with.
     let new_wants_focus = windows.iter().any(|window| {
         let ctx = contexts.ctx_for_window_mut(window);
-        ctx.wants_pointer_input() || ctx.wants_keyboard_input()
+        let mut value = ctx.wants_pointer_input() || ctx.wants_keyboard_input();
+        if include_hover.0 {
+            value |= ctx.is_pointer_over_area()
+        }
+        value
     });
     let new_res = EguiWantsFocus {
         prev: wants_focus.curr,

src/lib.rs

@@ -6,12 +6,13 @@ use std::f32::consts::{PI, TAU};
 use bevy::input::mouse::MouseWheel;
 use bevy::prelude::*;
 use bevy::render::camera::RenderTarget;
+use bevy::transform::TransformSystem;
 use bevy::window::{PrimaryWindow, WindowRef};
 #[cfg(feature = "bevy_egui")]
 use bevy_egui::EguiSet;
 
 #[cfg(feature = "bevy_egui")]
-pub use crate::egui::EguiWantsFocus;
+pub use crate::egui::{EguiFocusIncludesHover, EguiWantsFocus};
 use crate::input::{mouse_key_tracker, MouseKeyTracker};
 pub use crate::touch::TouchControls;
 use crate::touch::{touch_tracker, TouchGestures, TouchTracker};
@@ -44,7 +45,7 @@ impl Plugin for PanOrbitCameraPlugin {
             .init_resource::<MouseKeyTracker>()
             .init_resource::<TouchTracker>()
             .add_systems(
-                Update,
+                PostUpdate,
                 (
                     (
                         active_viewport_data
@@ -55,17 +56,20 @@ impl Plugin for PanOrbitCameraPlugin {
                     pan_orbit_camera,
                 )
                     .chain()
-                    .in_set(PanOrbitCameraSystemSet),
+                    .in_set(PanOrbitCameraSystemSet)
+                    .before(TransformSystem::TransformPropagate),
             );
 
         #[cfg(feature = "bevy_egui")]
         {
-            app.init_resource::<EguiWantsFocus>().add_systems(
-                Update,
-                egui::check_egui_wants_focus
-                    .after(EguiSet::InitContexts)
-                    .before(PanOrbitCameraSystemSet),
-            );
+            app.init_resource::<EguiWantsFocus>()
+                .init_resource::<EguiFocusIncludesHover>()
+                .add_systems(
+                    PostUpdate,
+                    egui::check_egui_wants_focus
+                        .after(EguiSet::InitContexts)
+                        .before(PanOrbitCameraSystemSet),
+                );
         }
     }
 }