Add support for handling bevy_egui focus interaction. Fixes #17

Author: ptsd

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "bevy_spectator"
 description = "A spectator camera plugin for Bevy"
-version = "0.7.0"
+version = "0.7.1"
 edition = "2021"
 authors = ["JonahPlusPlus <[email protected]>"]
 license = "MIT OR Apache-2.0"
@@ -14,6 +14,7 @@ include = ["/src", "/examples", "/LICENSE*"]
 bevy = { version = "0.15", default-features = false, features = [
   "bevy_window",
 ] }
+bevy_egui = { version = "0.31", optional = true, default-features = false }
 
 [dev-dependencies]
 bevy = { version = "0.15", default-features = false, features = [
@@ -28,7 +29,18 @@ bevy = { version = "0.15", default-features = false, features = [
   "zstd",
   "tonemapping_luts",
 ] }
+bevy_egui = { version = "0.31", default-features = false, features = [
+  "render",
+  "default_fonts",
+] }
 
 [features]
 default = ["init"]
-init = []          # Enables automatically choosing a camera
+init = []                     # Enables automatically choosing a camera
+bevy_egui = ["dep:bevy_egui"] # Enables skipping enabling spectator if egui wants focus
+
+
+[[example]]
+name = "egui"
+path = "examples/egui.rs"
+required-features = ["bevy_egui"]

README.md

@@ -43,6 +43,20 @@ fn setup(mut commands: Commands) {
 }
 ```
 
+## Features
+
+### `init`
+
+Handles automatically setting `active_spectator` when there is exactly one camera with the `Spectator` component present.
+
+Enabled by default.
+
+### `bevy_egui`
+
+Handles selectively disabling spectator mode entry when [bevy_egui](https://docs.rs/bevy_egui/latest/bevy_egui/) wants focus.
+
+See [egui](crate::egui) for details.
+
 ## Bevy compatibility
 
 | bevy | bevy_spectator |

examples/egui.rs

@@ -0,0 +1,76 @@
+//! The same as 3d_scene but showing the `bevy_egui` integration.
+
+use bevy::prelude::*;
+use bevy_egui::{egui, EguiContexts, EguiPlugin};
+use bevy_spectator::*;
+
+fn main() {
+    App::new()
+        .insert_resource(SpectatorSettings {
+            base_speed: 5.0,
+            alt_speed: 15.0,
+            sensitivity: 0.0015,
+            ..default()
+        })
+        .add_plugins((DefaultPlugins, EguiPlugin, SpectatorPlugin))
+        .add_systems(Startup, setup)
+        .add_systems(Update, ui_example)
+        .run();
+}
+
+fn setup(
+    mut commands: Commands,
+    mut meshes: ResMut<Assets<Mesh>>,
+    mut materials: ResMut<Assets<StandardMaterial>>,
+) {
+    commands.spawn((
+        Camera3d::default(),
+        Transform::from_xyz(-3.0, 1.5, 3.0).looking_at(Vec3::ZERO, Vec3::Y),
+        Spectator,
+    ));
+    commands.spawn((
+        PointLight {
+            shadows_enabled: true,
+            ..default()
+        },
+        Transform::from_xyz(4.0, 8.0, 4.0),
+    ));
+
+    commands.spawn((
+        Mesh3d(meshes.add(Plane3d::default().mesh().size(5.0, 5.0))),
+        MeshMaterial3d(materials.add(Color::srgb(0.3, 0.5, 0.3))),
+    ));
+    commands.spawn((
+        Mesh3d(meshes.add(Cuboid::default())),
+        MeshMaterial3d(materials.add(Color::srgb(0.8, 0.7, 0.6))),
+        Transform::from_xyz(0.0, 0.5, 0.0),
+    ));
+}
+
+fn ui_example(
+    mut contexts: EguiContexts,
+) {
+    egui::SidePanel::left("left")
+        .resizable(false)
+        .show(contexts.ctx_mut(), |ui| {
+            ui.label("Left fixed panel");
+        });
+
+    egui::SidePanel::right("right")
+        .resizable(true)
+        .show(contexts.ctx_mut(), |ui| {
+            ui.label("Right resizeable panel");
+
+            ui.allocate_rect(ui.available_rect_before_wrap(), egui::Sense::hover());
+        });
+
+    egui::Window::new("Movable Window").show(contexts.ctx_mut(), |ui| {
+        ui.label("Move me!");
+    });
+
+    egui::Window::new("Immovable Window")
+        .movable(false)
+        .show(contexts.ctx_mut(), |ui| {
+            ui.label("I can't be moved :(");
+        });
+}

src/egui.rs

@@ -0,0 +1,70 @@
+//! Handles focus / input conflicts between `bevy_egui` and this crate.
+//!
+//! ## Usage
+//!
+//! Enable the `bevy_egui` feature of this crate.
+//!
+//! Ensure [`bevy_egui::EguiPlugin`] is added to your app.
+//!
+//! *Note: this may be automatically done by `bevy_inspector_egui` plugins for example.*
+
+use bevy::prelude::*;
+use bevy_egui::{EguiContexts, EguiPlugin, EguiSet};
+
+/// A `Resource` for determining whether [`crate::Spectator`]s should handle input.
+///
+/// To check focus state it is recommended to call
+///
+/// [`EguiFocusState::wants_focus`]
+///
+/// which only returns true if egui wanted focus in both this frame and the previous frame.
+///
+#[derive(Resource, PartialEq, Eq, Default)]
+pub struct EguiFocusState {
+    /// Whether egui wants focus this frame
+    pub current_frame_wants_focus: bool,
+    /// Whether egui wanted focus in the previous frame
+    pub previous_frame_wanted_focus: bool,
+}
+
+impl EguiFocusState {
+    /// The default method for checking focus.
+    pub fn wants_focus(&self) -> bool {
+        self.previous_frame_wanted_focus && self.current_frame_wants_focus
+    }
+}
+
+pub(crate) struct EguiFocusPlugin;
+
+impl Plugin for EguiFocusPlugin {
+    fn build(&self, app: &mut App) {
+        app.init_resource::<EguiFocusState>();
+    }
+
+    fn finish(&self, app: &mut App) {
+        if app.is_plugin_added::<EguiPlugin>() {
+            app.add_systems(
+                PostUpdate,
+                check_egui_wants_focus.after(EguiSet::InitContexts),
+            );
+        } else {
+            warn!("EguiPlugin not added, no focus checking will occur.");
+        }
+    }
+}
+
+fn check_egui_wants_focus(
+    mut contexts: EguiContexts,
+    mut focus_state: ResMut<EguiFocusState>,
+    windows: Query<Entity, With<Window>>,
+) {
+    let egui_wants_focus_this_frame = windows.iter().any(|window| {
+        let ctx = contexts.ctx_for_entity_mut(window);
+        ctx.wants_pointer_input() || ctx.wants_keyboard_input() || ctx.is_pointer_over_area()
+    });
+
+    focus_state.set_if_neq(EguiFocusState {
+        previous_frame_wanted_focus: focus_state.current_frame_wants_focus,
+        current_frame_wants_focus: egui_wants_focus_this_frame,
+    });
+}

src/lib.rs

@@ -6,6 +6,12 @@ use bevy::{
     window::{CursorGrabMode, PrimaryWindow},
 };
 
+#[cfg(feature = "bevy_egui")]
+use crate::egui::{EguiFocusPlugin, EguiFocusState};
+
+#[cfg(feature = "bevy_egui")]
+pub mod egui;
+
 /// A marker `Component` for spectating cameras.
 ///
 /// ## Usage
@@ -32,6 +38,9 @@ impl Plugin for SpectatorPlugin {
         app.add_systems(PostStartup, spectator_init);
 
         app.add_systems(Update, spectator_update);
+
+        #[cfg(feature = "bevy_egui")]
+        app.add_plugins(EguiFocusPlugin);
     }
 }
 
@@ -67,6 +76,7 @@ fn spectator_update(
     mut windows: Query<(&mut Window, Option<&PrimaryWindow>)>,
     mut camera_transforms: Query<&mut Transform, With<Spectator>>,
     mut focus: Local<bool>,
+    #[cfg(feature = "bevy_egui")] egui_focus: Res<EguiFocusState>,
 ) {
     let Some(camera_id) = settings.active_spectator else {
         motion.clear();
@@ -116,6 +126,10 @@ fn spectator_update(
     if keys.just_pressed(KeyCode::Escape) {
         set_focus(false);
     } else if buttons.just_pressed(MouseButton::Left) {
+        #[cfg(feature = "bevy_egui")]
+        set_focus(!egui_focus.wants_focus());
+
+        #[cfg(not(feature = "bevy_egui"))]
         set_focus(true);
     }