Fix debug UI not working at all

src/debug_tools.rs

@@ -3,11 +3,9 @@
 use std::{collections::HashMap, time::Duration};
 
 use bevy::{
-    input::InputSystems,
-    prelude::*,
-    settings::{ReflectSettingsGroup, SaveSettingsDeferred, SettingsGroup},
+    camera::{CameraOutputMode, visibility::RenderLayers}, input::InputSystems, prelude::*, render::render_resource::BlendState, settings::{ReflectSettingsGroup, SaveSettingsDeferred, SettingsGroup},
 };
-use bevy_egui::{EguiContexts, EguiPrimaryContextPass, egui};
+use bevy_egui::{EguiContexts, EguiGlobalSettings, EguiPrimaryContextPass, PrimaryEguiContext, egui};
 use bevy_ggrs::{RollbackFrameRate, RunGgrsSystems};
 use enum_cycling::EnumCycle;
 use enum_cycling_derive::EnumCycle;
@@ -397,6 +395,7 @@ impl Plugin for DebugToolsPlugin {
                     .before(RunGgrsSystems)
                     .run_if(in_state(AppState::InMatch)),
             )
+            .add_systems(Startup, spawn_egui_camera)
             .add_systems(PreUpdate, restore_frame_step_time.after(RunGgrsSystems))
             .add_systems(
                 Update,
@@ -408,6 +407,26 @@ impl Plugin for DebugToolsPlugin {
     }
 }
 
+pub fn spawn_egui_camera(mut commands: Commands, mut egui_global_settings: ResMut<EguiGlobalSettings>,) {
+    egui_global_settings.auto_create_primary_context = false;
+    commands.spawn((
+        // The `PrimaryEguiContext` component requires everything needed to render a primary context.
+        PrimaryEguiContext,
+        Camera2d,
+        // Setting RenderLayers to none makes sure we won't render anything apart from the UI.
+        RenderLayers::none(),
+        Camera {
+            order: 2,
+            output_mode: CameraOutputMode::Write {
+                blend_state: Some(BlendState::ALPHA_BLENDING),
+                clear_color: ClearColorConfig::None,
+            },
+            clear_color: ClearColorConfig::Custom(Color::NONE),
+            ..default()
+        },
+    ));
+}
+
 fn player_handles(players: &Query<&Player>) -> Vec<usize> {
     let mut handles = players
         .iter()