From 927566ca3d260a7f6d7444a7ee4093e6d074e595 Mon Sep 17 00:00:00 2001
From: SeanOMik <seanomik@gmail.com>
Date: Thu, 26 Oct 2023 22:26:13 -0400
Subject: [PATCH] Add delta time, use it in the free fly camera

---
 examples/testbed/src/free_fly_camera.rs | 17 +++++-----
 src/ecs/components/delta_time.rs        | 41 +++++++++++++++++++++++++
 src/ecs/components/mod.rs               | 14 ++++++++-
 src/plugin.rs                           |  3 +-
 4 files changed, 65 insertions(+), 10 deletions(-)
 create mode 100644 src/ecs/components/delta_time.rs

diff --git a/examples/testbed/src/free_fly_camera.rs b/examples/testbed/src/free_fly_camera.rs
index 10cdb45..fb0bce7 100644
--- a/examples/testbed/src/free_fly_camera.rs
+++ b/examples/testbed/src/free_fly_camera.rs
@@ -2,13 +2,12 @@ use std::ops::Deref;
 
 use edict::{Component, World};
 use lyra_engine::{
-    ecs::{components::camera::CameraComponent, EventQueue, SimpleSystem},
+    ecs::{components::{camera::CameraComponent, DeltaTime}, EventQueue, SimpleSystem},
     game::Game,
     input::{InputButtons, KeyCode, MouseMotion},
-    math::{Angle, Quat, Vec3, EulerRot},
+    math::{Quat, Vec3, EulerRot},
     plugin::Plugin,
 };
-use tracing::debug;
 
 #[derive(Clone, Component)]
 pub struct FreeFlyCamera {
@@ -21,9 +20,9 @@ pub struct FreeFlyCamera {
 impl Default for FreeFlyCamera {
     fn default() -> Self {
         Self {
-            speed: 0.07,
-            look_speed: 0.01,
-            mouse_sensitivity: 0.04,
+            speed: 3.0,
+            look_speed: 0.09,
+            mouse_sensitivity: 0.4,
             look_with_keys: false,
         }
     }
@@ -46,6 +45,8 @@ impl SimpleSystem for FreeFlyCameraController {
     fn execute_mut(&mut self, world: &mut World) -> anyhow::Result<()> {
         let mut camera_rot = Vec3::default();
 
+        let delta_time = **world.get_resource::<DeltaTime>().unwrap();
+
         let events = world
             .get_resource_mut::<EventQueue>()
             .and_then(|q| q.read_events::<MouseMotion>());
@@ -116,7 +117,7 @@ impl SimpleSystem for FreeFlyCameraController {
                 }
 
                 if velocity != Vec3::ZERO {
-                    cam.transform.translation += velocity.normalize() * fly.speed;
+                    cam.transform.translation += velocity.normalize() * fly.speed * delta_time;
                 }
             }
 
@@ -129,7 +130,7 @@ impl SimpleSystem for FreeFlyCameraController {
             }
 
             if camera_rot != Vec3::ZERO {
-                let look_velocity = camera_rot * fly.look_speed;
+                let look_velocity = camera_rot * fly.look_speed * delta_time;
 
                 let (mut y, mut x, _) = cam.transform.rotation.to_euler(EulerRot::YXZ);
                 x += look_velocity.x;
diff --git a/src/ecs/components/delta_time.rs b/src/ecs/components/delta_time.rs
new file mode 100644
index 0000000..92b6d71
--- /dev/null
+++ b/src/ecs/components/delta_time.rs
@@ -0,0 +1,41 @@
+use std::borrow::BorrowMut;
+
+use edict::{Component, World};
+use instant::Instant;
+
+use crate::plugin::Plugin;
+
+#[derive(Clone, Component)]
+pub struct DeltaTime(f32, Instant);
+
+impl std::ops::Deref for DeltaTime {
+    type Target = f32;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl std::ops::DerefMut for DeltaTime {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+fn delta_time_system(world: &mut World) -> anyhow::Result<()> {
+    let now = Instant::now();
+    let mut delta = world.get_resource_mut::<DeltaTime>().unwrap();
+    delta.0 = delta.1.elapsed().as_secs_f32();
+    delta.1 = now;
+
+    Ok(())
+}
+
+pub struct DeltaTimePlugin;
+
+impl Plugin for DeltaTimePlugin {
+    fn setup(&self, game: &mut crate::game::Game) {
+        game.world().insert_resource(DeltaTime(0.0, Instant::now()));
+        game.with_system("delta_time", delta_time_system, &[]);
+    }
+}
\ No newline at end of file
diff --git a/src/ecs/components/mod.rs b/src/ecs/components/mod.rs
index 6976828..aeb9278 100755
--- a/src/ecs/components/mod.rs
+++ b/src/ecs/components/mod.rs
@@ -1,5 +1,17 @@
 pub mod mesh;
+pub use mesh::*;
+
 pub mod model;
+pub use model::*;
+
 pub mod transform;
+pub use transform::*;
+
 pub mod camera;
-pub mod free_fly_camera;
\ No newline at end of file
+pub use camera::*;
+
+pub mod free_fly_camera;
+pub use free_fly_camera::*;
+
+pub mod delta_time;
+pub use delta_time::*;
\ No newline at end of file
diff --git a/src/plugin.rs b/src/plugin.rs
index 07ef5b0..1b78b32 100644
--- a/src/plugin.rs
+++ b/src/plugin.rs
@@ -1,6 +1,7 @@
 use lyra_resource::ResourceManager;
 
 use crate::ecs::EventsPlugin;
+use crate::ecs::components::DeltaTimePlugin;
 use crate::game::Game;
 use crate::input::InputPlugin;
 use crate::render::window::WindowPlugin;
@@ -107,10 +108,10 @@ pub struct DefaultPlugins;
 
 impl Plugin for DefaultPlugins {
     fn setup(&self, game: &mut Game) {
-        // setup input
         EventsPlugin.setup(game);
         InputPlugin.setup(game);
         ResourceManagerPlugin.setup(game);
         WindowPlugin::default().setup(game);
+        DeltaTimePlugin.setup(game);
     }
 }
\ No newline at end of file