From e1abb02cb8189670cee9b1578d295c1035da99ae Mon Sep 17 00:00:00 2001
From: PROMETHIA-27 <42193387+PROMETHIA-27@users.noreply.github.com>
Date: Thu, 19 Jun 2025 03:27:59 -0400
Subject: [PATCH] Fix character controller jitter (#43)

* fix jitter while moving character controller

* added transform interpolation to character controller
---
 src/camera.rs                    |  6 +++--
 src/control/controller_common.rs | 46 +++++++++++++++++---------------
 2 files changed, 28 insertions(+), 24 deletions(-)

diff --git a/src/camera.rs b/src/camera.rs
index 9862928..1983dab 100644
--- a/src/camera.rs
+++ b/src/camera.rs
@@ -48,8 +48,10 @@ pub fn plugin(app: &mut App) {
     app.init_resource::<CameraState>();
     app.add_systems(OnEnter(GameState::Playing), startup);
     app.add_systems(
-        PreUpdate,
-        (update, update_ui, update_look_around, rotate_view).run_if(in_state(GameState::Playing)),
+        RunFixedMainLoop,
+        (update, update_ui, update_look_around, rotate_view)
+            .after(RunFixedMainLoopSystem::AfterFixedMainLoop)
+            .run_if(in_state(GameState::Playing)),
     );
 }
 
diff --git a/src/control/controller_common.rs b/src/control/controller_common.rs
index 84b9c8f..def5210 100644
--- a/src/control/controller_common.rs
+++ b/src/control/controller_common.rs
@@ -125,6 +125,30 @@ pub struct CharacterControllerBundle {
     movement_factor: MovementSpeedFactor,
     collision_events: CollisionEventsEnabled,
     movement_config: MovementConfig,
+    interpolation: TransformInterpolation,
+}
+
+impl CharacterControllerBundle {
+    pub fn new(collider: Collider, controls: HeadControls) -> Self {
+        // Create shape caster as a slightly smaller version of collider
+        let mut caster_shape = collider.clone();
+        caster_shape.set_scale(Vector::ONE * 0.98, 10);
+
+        let config = match controls {
+            HeadControls::Plane => FLYING_MOVEMENT_CONFIG,
+            HeadControls::Walk => RUNNING_MOVEMENT_CONFIG,
+        };
+
+        Self {
+            character_controller: Character { up: Dir3::Y },
+            collider,
+            move_input: MoveInput::default(),
+            movement_factor: MovementSpeedFactor(1.0),
+            collision_events: CollisionEventsEnabled,
+            movement_config: config,
+            interpolation: TransformInterpolation,
+        }
+    }
 }
 
 #[derive(Bundle)]
@@ -183,25 +207,3 @@ const FLYING_MOVEMENT_CONFIG: MovementConfig = MovementConfig {
         deceleration_factor: 0.0,
     },
 };
-
-impl CharacterControllerBundle {
-    pub fn new(collider: Collider, controls: HeadControls) -> Self {
-        // Create shape caster as a slightly smaller version of collider
-        let mut caster_shape = collider.clone();
-        caster_shape.set_scale(Vector::ONE * 0.98, 10);
-
-        let config = match controls {
-            HeadControls::Plane => FLYING_MOVEMENT_CONFIG,
-            HeadControls::Walk => RUNNING_MOVEMENT_CONFIG,
-        };
-
-        Self {
-            character_controller: Character { up: Dir3::Y },
-            collider,
-            move_input: MoveInput::default(),
-            movement_factor: MovementSpeedFactor(1.0),
-            collision_events: CollisionEventsEnabled,
-            movement_config: config,
-        }
-    }
-}