From f44455c3778e0b7e451360e68c7e47fc3b5c689b Mon Sep 17 00:00:00 2001
From: lawnjelly <lawnjelly@gmail.com>
Date: Tue, 7 Jan 2025 11:14:15 +0000
Subject: [PATCH] Physics Interpolation - Auto-reset on
 `set_physics_interpolation_mode()`

Fixes historical bug where auto-reset wasn't working correctly.
Also fixes process modes on Cameras when mode is changed.
---
 scene/2d/camera_2d.cpp    | 1 +
 scene/3d/camera.cpp       | 1 +
 scene/main/node.cpp       | 9 ++++-----
 scene/main/scene_tree.cpp | 5 +++++
 4 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/scene/2d/camera_2d.cpp b/scene/2d/camera_2d.cpp
index 146f87d4a..c1564ae19 100644
--- a/scene/2d/camera_2d.cpp
+++ b/scene/2d/camera_2d.cpp
@@ -297,6 +297,7 @@ void Camera2D::_notification(int p_what) {
 			// Force the limits etc to update.
 			_interpolation_data.xform_curr = get_camera_transform();
 			_interpolation_data.xform_prev = _interpolation_data.xform_curr;
+			_update_process_mode();
 		} break;
 		case NOTIFICATION_TRANSFORM_CHANGED: {
 			if (!smoothing_active && !is_physics_interpolated_and_enabled()) {
diff --git a/scene/3d/camera.cpp b/scene/3d/camera.cpp
index fa1ebebd5..54bfe2108 100644
--- a/scene/3d/camera.cpp
+++ b/scene/3d/camera.cpp
@@ -229,6 +229,7 @@ void Camera::_notification(int p_what) {
 			if (is_inside_tree()) {
 				_interpolation_data.xform_curr = get_global_transform();
 				_interpolation_data.xform_prev = _interpolation_data.xform_curr;
+				_update_process_mode();
 			}
 		} break;
 		case NOTIFICATION_EXIT_WORLD: {
diff --git a/scene/main/node.cpp b/scene/main/node.cpp
index bae4f7755..0358690ed 100644
--- a/scene/main/node.cpp
+++ b/scene/main/node.cpp
@@ -1200,13 +1200,12 @@ void Node::set_physics_interpolation_mode(PhysicsInterpolationMode p_mode) {
 		} break;
 	}
 
-	// if swapping from interpolated to non-interpolated, use this as
-	// an extra means to cause a reset
-	if (is_physics_interpolated() && !interpolate && is_inside_tree()) {
+	_propagate_physics_interpolated(interpolate);
+
+	// Auto-reset on changing interpolation mode.
+	if (is_physics_interpolated() && is_inside_tree()) {
 		propagate_notification(NOTIFICATION_RESET_PHYSICS_INTERPOLATION);
 	}
-
-	_propagate_physics_interpolated(interpolate);
 }
 
 void Node::reset_physics_interpolation() {
diff --git a/scene/main/scene_tree.cpp b/scene/main/scene_tree.cpp
index 96029dc60..3e90a5f12 100644
--- a/scene/main/scene_tree.cpp
+++ b/scene/main/scene_tree.cpp
@@ -591,6 +591,11 @@ void SceneTree::set_physics_interpolation_enabled(bool p_enabled) {
 	_physics_interpolation_enabled = p_enabled;
 
 	RenderingServer::get_singleton()->set_physics_interpolation_enabled(p_enabled);
+
+	// Perform an auto reset on the root node for convenience for the user.
+	if (root) {
+		root->reset_physics_interpolation();
+	}
 }
 
 bool SceneTree::is_physics_interpolation_enabled() const {