egui support

- New Resource, EguiQueue: Utility to queue egui ui builders
- New Rendering System, EguiRenderer: Utilizes a modified egui_glium
  library to render egui UI
- Adjusted RenderingSystem trait and RenderingContext structure to
  provide event_loop and egui_queue.
- Various minor adjusments

glium_platform/src/system.rs

@@ -6,16 +6,19 @@ use indexmap::IndexMap;
 use glium::{Display, Frame};
 use glium::glutin::surface::WindowSurface;
 use raidillon_assets::ModelManagerRef;
-use raidillon_core::{define_typemap, DebugUIBuffer};
+use raidillon_core::{define_typemap, DebugUIBuffer, EguiQueue};
 use raidillon_core::scene::Scene;
 use glam::Vec3;
+use winit::event_loop::EventLoop;
 
 pub struct RenderingContext<'a> {
     pub scene: &'a Scene,
     pub target: &'a mut Frame,
     pub window: Arc<Mutex<glium::winit::window::Window>>,
+    pub display: &'a Display<WindowSurface>,
     pub asset_manager: ModelManagerRef,
     pub debug_ui_buffer: &'a DebugUIBuffer,
+    pub egui_queue: Rc<RefCell<EguiQueue>>,
     pub env_light_dir: Vec3,
 }
 
@@ -30,7 +33,7 @@ pub trait RenderingSystem {
     }
     fn prepare_frame(&mut self, _window: Arc<Mutex<glium::winit::window::Window>>) {}
     fn render(&mut self, ctx: &mut RenderingContext);
-    fn initialize(display: &Display<WindowSurface>, window: Arc<Mutex<glium::winit::window::Window>>) -> Self
+    fn initialize(display: &Display<WindowSurface>, window: Arc<Mutex<glium::winit::window::Window>>, event_loop: &EventLoop<()>) -> Self
     where
         Self: Sized;
 }
@@ -48,11 +51,11 @@ impl RenderingSystemManager {
         }
     }
 
-    pub fn add<R>(&mut self, display: &Display<WindowSurface>, window: Arc<Mutex<glium::winit::window::Window>>)
+    pub fn add<R>(&mut self, display: &Display<WindowSurface>, window: Arc<Mutex<glium::winit::window::Window>>, event_loop: &EventLoop<()>)
     where
         R: RenderingSystem + 'static,
     {
-        let system = R::initialize(display, window);
+        let system = R::initialize(display, window, event_loop);
         self.systems.insert(TypeId::of::<R>(), Box::new(system));
     }