Can't reset root node type to Node3D in advanced import settings

[mbrlabs]

Godot version

4.0.3 and latest 4.1 (2d6b880)

System information

Manjaro Linux

Issue description

When you change the root type of an imported scene (in my case it's a glb file) you can't change it back to a Node3D. Changing it to any other 3D node works though.

Steps to reproduce

1. Import a glb file
2. Double click it to open the advanced import settings and change the root type to StaticBody3D or any other type that inherits from Node3D. Click reimport.
3. Now try to change it from StaticBody3D to Node3D. This will fail silently.

Minimal reproduction project

RootTypeBug.zip

[AThousandShips]

Might have found the cause of this, will try investigate when I have the time, it checks for the root type and doesn't do anything if it is Node3D, I think that check needs to be different

[mbrlabs]

Yeah, i guess you found this:

godot/editor/import/resource_importer_scene.cpp

Lines 2430 to 2439 in 7b1387f

	if (root_type != "Node3D") {
	Node *base_node = Object::cast_to<Node>(ClassDB::instantiate(root_type));
	if (base_node) {
	scene->replace_by(base_node);
	scene->set_owner(nullptr);
	memdelete(scene);
	scene = base_node;
	}
	}

Not sure why Node3D is excluded here. I removed the check but it didn't seem to do anything. Didn't dig too deep into this though, so feel free to investigate further :)

[kdiduk]

I've found something interesting.

godot/editor/import/scene_import_settings.cpp

Lines 927 to 930 in c3b0a92

	void SceneImportSettings::_re_import() {
	HashMap<StringName, Variant> main_settings;
	main_settings = defaults;

When any node, apart from Node3D is selected in the dialog, the dictionary defaults contains an entry with the key nodes/root_type and the string value with the name of selected node type.

However, for some reason, when we select Node3D, the dictionary defaults doesn't have an entry with the key nodes/root_type.

[capnm]

The workaround is to use the "non-advanced" import settings, the 🐛 seems to be somewhere in the flawed logic of the new one ...

[kdiduk]

I've found the problem and made a pull-request 😌 It turned out that it affected literally any import setting, not only Root Type. That is, when we change any setting to non-default value and reimported the scene, afterwards it was not possible to set it back to a default value.

Although it was tricky to find it, the fix for it is just one line.

[mikest]

I have run into this issue while Reimporting gltf models after changing the root node type from Node3D to RigidBody3D. I can no longer change back to Node3D. The changes don't stick on re-import.

This would be on 4.1.2