Add ECSRenderer for improved integration of rendering and ECS

- Introduced ECSRenderer struct to manage the connection between the renderer and the ECS.
- Implemented methods for spawning and despawning meshes within the ECS.
- Updated main function to utilize ECSRenderer for rendering and object management.
- Added a new Time module to handle frame timing and updates.

src/ecs.rs

@@ -1,13 +1,48 @@
 use glam::{Mat4, Quat, Vec3};
-use hecs::World;
+use hecs::{Entity, World};
+use crate::{render::{GliumRenderer, Renderer}, model};
+
+/// This system joins the renderer and ECS,
+/// and provides tools to use them together
+/// effectively.
+pub struct ECSRenderer {
+    pub renderer: GliumRenderer,
+    pub world: World,
+}
+
+impl ECSRenderer {
+    pub fn new(renderer: GliumRenderer, world: World) -> Self {
+        Self { renderer, world }
+    }
+
+    pub fn spawn_mesh(&mut self, mesh: model::Mesh, transform: Transform) -> Entity {
+        let mesh_id = self.renderer.meshes.len();
+        self.renderer.meshes.push(mesh);
+        self.world.spawn((transform, MeshHandle(mesh_id)))
+    }
+
+    pub fn despawn_mesh(&mut self, entity: Entity) {
+        if let Ok(mesh_handle) = self.world.get::<&MeshHandle>(entity) {
+            if mesh_handle.0 < self.renderer.meshes.len() {
+                self.renderer.meshes.remove(mesh_handle.0);
+            }
+        }
+        let _ = self.world.despawn(entity);
+    }
+
+    /// Render a single frame using the internal renderer & world.
+    pub fn render(&mut self) {
+        self.renderer.render(&self.world);
+    }
+}
 
-/// ------------ components ------------
 #[derive(Copy, Clone)]
 pub struct Transform {
     pub translation: Vec3,
     pub rotation:    Quat,
     pub scale:       Vec3,
 }
+
 impl Transform {
     pub fn matrix(&self) -> Mat4 {
         Mat4::from_scale_rotation_translation(self.scale, self.rotation, self.translation)
@@ -16,4 +51,3 @@ impl Transform {
 
 #[derive(Clone)]
 pub struct MeshHandle(pub usize);
-

src/main.rs

@@ -2,6 +2,7 @@ mod camera;
 mod ecs;
 mod model;
 mod render;
+mod time;
 
 use anyhow::Result;
 use camera::Camera;
@@ -9,9 +10,10 @@ use ecs::{MeshHandle, Transform};
 use glam::{Quat, Vec3};
 use glium::backend::glutin::SimpleWindowBuilder;
 use render::{Renderer, GliumRenderer};
-use std::time::Instant;
 
 fn main() -> Result<()> {
+    const ROTATION_SPEED: f32 = 1.0;
+
     let event_loop = glium::winit::event_loop::EventLoop::builder()
         .build()
         .expect("create event-loop");
@@ -21,27 +23,28 @@ fn main() -> Result<()> {
         .with_inner_size(1280, 720)
         .build(&event_loop);
 
-    let mut world = hecs::World::new();
+    // Create ECS renderer which internally owns both the world and the renderer
+    let mut ecsr = {
+        let world = hecs::World::new();
+        let renderer = GliumRenderer::new(display.clone())?;
+        ecs::ECSRenderer::new(renderer, world)
+    };
 
+    let mut time = time::Time::new();
+
+    let object_ent = {
         let mesh = model::load_gltf("resources/monkey-smooth.gltf", &display)?;
-    // let mesh         = model::cube(&display)?;
+        ecsr.spawn_mesh(mesh, Transform {
-    let mut renderer = GliumRenderer::new(display)?;
-    let mesh_id      = renderer.meshes.len();
-    renderer.meshes.push(mesh);
-
-    let object_ent = world.spawn((
-        Transform {
                 translation: Vec3::ZERO,
                 rotation:    Quat::IDENTITY,
                 scale:       Vec3::ONE,
-        },
+        })
-        MeshHandle(mesh_id),
+    };
-    ));
 
 
     let camera_ent = {
         let (w, h): (u32, u32) = window.inner_size().into();
-        world.spawn((Camera {
+        ecsr.world.spawn((Camera {
             eye:    Vec3::new(3.0, 2.0, 3.0),
             center: Vec3::ZERO,
             up:     Vec3::Y,
@@ -60,27 +63,27 @@ fn main() -> Result<()> {
                 Event::WindowEvent { event, .. } => match event {
                     WindowEvent::CloseRequested => el.exit(),
                     WindowEvent::Resized(sz) => {
-                        world.query_one_mut::<&mut crate::camera::Camera>(camera_ent).map(|mut cam| {
+                        ecsr.world.query_one_mut::<&mut crate::camera::Camera>(camera_ent).map(|mut cam| {
                             cam.aspect = sz.width as f32 / sz.height as f32;
                         });
                     }
                     WindowEvent::RedrawRequested => {
-                        renderer.render(&world);
+                        ecsr.render();
                     }
                     _ => {}
                 },
                 Event::AboutToWait => {
-                    // -- update logic --
+                    time.tick();
-                    let now = Instant::now();
+                    let dt = time.delta_seconds();
-                    static mut LAST: Option<Instant> = None;
+                    ecsr.world.query_one_mut::<&mut Transform>(object_ent).map(|mut object| {
-                    let dt = unsafe { // FIXME
+                        object.rotation *= Quat::from_rotation_y(ROTATION_SPEED * dt);
-                        let last = LAST.replace(now).unwrap_or(now);
-                        (now - last).as_secs_f32()
-                    };
-                    world.query_one_mut::<&mut Transform>(object_ent).map(|mut object| {
-                        object.rotation *= Quat::from_rotation_y(dt);
                     });
 
+                    // despawn the object after 3 seconds
+                    if time.total_seconds() > 3.0 {
+                        ecsr.despawn_mesh(object_ent);
+                    }
+
                     // ask for next frame
                     window.request_redraw();
                 }

src/time.rs

@@ -0,0 +1,34 @@
+use std::time::{Duration, Instant};
+
+#[derive(Clone, Debug)]
+pub struct Time {
+    last:   Instant,
+    delta:  Duration,
+    total:  Duration,
+}
+
+impl Time {
+    pub fn new() -> Self {
+        let now = Instant::now();
+        Self {
+            last:  now,
+            delta: Duration::ZERO,
+            total: Duration::ZERO,
+        }
+    }
+
+    pub fn tick(&mut self) {
+        let now = Instant::now();
+        self.delta = now - self.last;
+        self.total += self.delta;
+        self.last = now;
+    }
+
+    pub fn delta_seconds(&self) -> f32 {
+        self.delta.as_secs_f32()
+    }
+
+    pub fn total_seconds(&self) -> f32 {
+        self.total.as_secs_f32()
+    }
+}