From 9a09fc35d8ab0314e852a00702217dac3798824f Mon Sep 17 00:00:00 2001
From: Asaduji <39374509+Asaduji@users.noreply.github.com>
Date: Mon, 5 May 2025 21:56:34 +0200
Subject: [PATCH] Physics Interpolation - Fix XR Nodes to work with
 `SceneTreeFTI`

---
 scene/3d/xr/xr_nodes.cpp | 69 +++++++++-------------------------------
 scene/3d/xr/xr_nodes.h   |  6 ++--
 2 files changed, 17 insertions(+), 58 deletions(-)

diff --git a/scene/3d/xr/xr_nodes.cpp b/scene/3d/xr/xr_nodes.cpp
index 12e01c78511..48a7cc07ac4 100644
--- a/scene/3d/xr/xr_nodes.cpp
+++ b/scene/3d/xr/xr_nodes.cpp
@@ -72,36 +72,13 @@ void XRCamera3D::_removed_tracker(const StringName &p_tracker_name, int p_tracke
 
 void XRCamera3D::_pose_changed(const Ref<XRPose> &p_pose) {
 	if (p_pose->get_name() == pose_name) {
-		Node3D *parent = Object::cast_to<Node3D>(get_parent());
-
-		if (is_inside_tree() && parent && parent->is_physics_interpolated_and_enabled() && !is_set_as_top_level() && !is_physics_interpolated()) {
-			pose_offset = p_pose->get_adjusted_transform();
-		} else {
-			set_transform(p_pose->get_adjusted_transform());
-		}
+		set_transform(p_pose->get_adjusted_transform());
 	}
 }
 
-void XRCamera3D::_notification(int p_what) {
-	switch (p_what) {
-		case NOTIFICATION_ENTER_TREE: {
-			if (!Engine::get_singleton()->is_editor_hint()) {
-				set_desired_process_modes(true, false);
-			}
-		} break;
-
-		case NOTIFICATION_INTERNAL_PROCESS: {
-			if (!is_inside_tree() || is_physics_interpolated() || Engine::get_singleton()->is_editor_hint()) {
-				break;
-			}
-
-			Node3D *parent = Object::cast_to<Node3D>(get_parent());
-
-			if (parent && parent->is_physics_interpolated_and_enabled() && !is_set_as_top_level()) {
-				set_global_transform(parent->get_global_transform_interpolated() * pose_offset);
-			}
-		} break;
-	}
+void XRCamera3D::_physics_interpolated_changed() {
+	Camera3D::_physics_interpolated_changed();
+	update_configuration_warnings();
 }
 
 PackedStringArray XRCamera3D::get_configuration_warnings() const {
@@ -114,6 +91,10 @@ PackedStringArray XRCamera3D::get_configuration_warnings() const {
 		if (parent && origin == nullptr) {
 			warnings.push_back(RTR("XRCamera3D may not function as expected without an XROrigin3D node as its parent."));
 		};
+
+		if (is_physics_interpolated()) {
+			warnings.push_back(RTR("XRCamera3D should have physics_interpolation_mode set to OFF in order to avoid jitter."));
+		}
 	}
 
 	return warnings;
@@ -431,13 +412,7 @@ void XRNode3D::_removed_tracker(const StringName &p_tracker_name, int p_tracker_
 
 void XRNode3D::_pose_changed(const Ref<XRPose> &p_pose) {
 	if (p_pose.is_valid() && p_pose->get_name() == pose_name) {
-		Node3D *parent = Object::cast_to<Node3D>(get_parent());
-
-		if (is_inside_tree() && parent && parent->is_physics_interpolated_and_enabled() && !is_set_as_top_level() && !is_physics_interpolated()) {
-			pose_offset = p_pose->get_adjusted_transform();
-		} else {
-			set_transform(p_pose->get_adjusted_transform());
-		}
+		set_transform(p_pose->get_adjusted_transform());
 		_set_has_tracking_data(p_pose->get_has_tracking_data());
 	}
 }
@@ -477,26 +452,8 @@ void XRNode3D::_update_visibility() {
 	}
 }
 
-void XRNode3D::_notification(int p_what) {
-	switch (p_what) {
-		case NOTIFICATION_ENTER_TREE: {
-			if (!Engine::get_singleton()->is_editor_hint()) {
-				set_process_internal(true);
-			}
-		} break;
-
-		case NOTIFICATION_INTERNAL_PROCESS: {
-			if (!is_inside_tree() || is_physics_interpolated() || Engine::get_singleton()->is_editor_hint()) {
-				break;
-			}
-
-			Node3D *parent = Object::cast_to<Node3D>(get_parent());
-
-			if (parent && parent->is_physics_interpolated_and_enabled() && !is_set_as_top_level()) {
-				set_global_transform(parent->get_global_transform_interpolated() * pose_offset);
-			}
-		} break;
-	}
+void XRNode3D::_physics_interpolated_changed() {
+	update_configuration_warnings();
 }
 
 XRNode3D::XRNode3D() {
@@ -540,6 +497,10 @@ PackedStringArray XRNode3D::get_configuration_warnings() const {
 		if (pose_name == "") {
 			warnings.push_back(RTR("No pose is set."));
 		}
+
+		if (is_physics_interpolated()) {
+			warnings.push_back(RTR("XRNode3D should have physics_interpolation_mode set to OFF in order to avoid jitter."));
+		}
 	}
 
 	return warnings;
diff --git a/scene/3d/xr/xr_nodes.h b/scene/3d/xr/xr_nodes.h
index 65ba86abd20..a02d5f3f2d9 100644
--- a/scene/3d/xr/xr_nodes.h
+++ b/scene/3d/xr/xr_nodes.h
@@ -46,14 +46,13 @@ protected:
 	StringName tracker_name = "head";
 	StringName pose_name = SceneStringName(default_);
 	Ref<XRPositionalTracker> tracker;
-	Transform3D pose_offset;
 
 	void _bind_tracker();
 	void _unbind_tracker();
 	void _changed_tracker(const StringName &p_tracker_name, int p_tracker_type);
 	void _removed_tracker(const StringName &p_tracker_name, int p_tracker_type);
 	void _pose_changed(const Ref<XRPose> &p_pose);
-	void _notification(int p_what);
+	virtual void _physics_interpolated_changed() override;
 
 public:
 	PackedStringArray get_configuration_warnings() const override;
@@ -81,7 +80,6 @@ private:
 	StringName pose_name = SceneStringName(default_);
 	bool has_tracking_data = false;
 	bool show_when_tracked = false;
-	Transform3D pose_offset;
 
 protected:
 	Ref<XRPositionalTracker> tracker;
@@ -98,7 +96,7 @@ protected:
 	void _set_has_tracking_data(bool p_has_tracking_data);
 
 	void _update_visibility();
-	void _notification(int p_what);
+	virtual void _physics_interpolated_changed() override;
 
 public:
 	void _validate_property(PropertyInfo &p_property) const;