Ported: Include the follow-viewport-transform into CanvasLayer transform calculations

The follow-viewport-transform was missing from several calculations
3.x version of #59682
- Sauermann
608cbd8296

doc/classes/CanvasItem.xml

@@ -289,7 +289,7 @@
 		<method name="get_canvas_transform" qualifiers="const">
 			<return type="Transform2D" />
 			<description>
-				Returns the transform matrix of this item's canvas.
+				Returns the transform from the coordinate system of the canvas, this item is in, to the [Viewport]s coordinate system.
 			</description>
 		</method>
 		<method name="get_global_mouse_position" qualifiers="const">
@@ -307,7 +307,7 @@
 		<method name="get_global_transform_with_canvas" qualifiers="const">
 			<return type="Transform2D" />
 			<description>
-				Returns the global transform matrix of this item in relation to the canvas.
+				Returns the transform from the local coordinate system of this [CanvasItem] to the [Viewport]s coordinate system.
 			</description>
 		</method>
 		<method name="get_local_mouse_position" qualifiers="const">
@@ -331,7 +331,7 @@
 		<method name="get_viewport_transform" qualifiers="const">
 			<return type="Transform2D" />
 			<description>
-				Returns this item's transform in relation to the viewport.
+				Returns the transform from the coordinate system of the canvas, this item is in, to the [Viewport]s embedders coordinate system.
 			</description>
 		</method>
 		<method name="get_world_2d" qualifiers="const">

doc/classes/CanvasLayer.xml

@@ -18,6 +18,12 @@
 				Returns the RID of the canvas used by this layer.
 			</description>
 		</method>
+		<method name="get_final_transform" qualifiers="const">
+			<return type="Transform2D" />
+			<description>
+				Returns the transform from the [CanvasLayer]s coordinate system to the [Viewport]s coordinate system.
+			</description>
+		</method>
 		<method name="hide">
 			<return type="void" />
 			<description>

scene/2d/canvas_item.cpp

@@ -473,7 +473,7 @@ void CanvasItem::_update_callback() {
 
 Transform2D CanvasItem::get_global_transform_with_canvas() const {
 	if (canvas_layer) {
-		return canvas_layer->get_transform() * get_global_transform();
+		return canvas_layer->get_final_transform() * get_global_transform();
 	} else if (is_inside_tree()) {
 		return get_world()->get_canvas_transform() * get_global_transform();
 	} else {
@@ -1230,9 +1230,9 @@ Transform2D CanvasItem::get_viewport_transform() const {
 
 	if (canvas_layer) {
 		if (get_world()) {
-			return get_world()->get_final_transform() * canvas_layer->get_transform();
+			return get_world()->get_final_transform() * canvas_layer->get_final_transform();
 		} else {
-			return canvas_layer->get_transform();
+			return canvas_layer->get_final_transform();
 		}
 
 	} else {

scene/main/canvas_layer.cpp

@@ -80,6 +80,18 @@ void CanvasLayer::set_transform(const Transform2D &p_xform) {
 	}
 }
 
+Transform2D CanvasLayer::get_final_transform() const {
+	if (is_following_viewport()) {
+		Transform2D follow;
+		follow.scale(Vector2(get_follow_viewport_scale(), get_follow_viewport_scale()));
+		if (vp) {
+			follow = vp->get_canvas_transform() * follow;
+		}
+		return follow * transform;
+	}
+	return transform;
+}
+
 Transform2D CanvasLayer::get_transform() const {
 	return transform;
 }
@@ -302,6 +314,7 @@ void CanvasLayer::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("set_transform", "transform"), &CanvasLayer::set_transform);
 	ClassDB::bind_method(D_METHOD("get_transform"), &CanvasLayer::get_transform);
+	ClassDB::bind_method(D_METHOD("get_final_transform"), &CanvasLayer::get_final_transform);
 
 	ClassDB::bind_method(D_METHOD("set_offset", "offset"), &CanvasLayer::set_offset);
 	ClassDB::bind_method(D_METHOD("get_offset"), &CanvasLayer::get_offset);

scene/main/canvas_layer.h

@@ -76,6 +76,7 @@ public:
 
 	void set_transform(const Transform2D &p_xform);
 	Transform2D get_transform() const;
+	Transform2D get_final_transform() const;
 
 	void set_offset(const Vector2 &p_offset);
 	Vector2 get_offset() const;

scene/main/viewport.cpp

@@ -537,7 +537,7 @@ void Viewport::_process_picking(bool p_ignore_paused) {
 				ObjectID canvas_layer_id;
 				if (E->get()) {
 					// A descendant CanvasLayer
-					canvas_transform = E->get()->get_transform();
+					canvas_transform = E->get()->get_final_transform();
 					canvas_layer_id = E->get()->get_instance_id();
 				} else {
 					// This Viewport's builtin canvas