How to set a parent `instance` for `instance` in `RenderingServer`?

[aawwaaa]

Godot Version

4.2.1

Question

I’m using RenderingServer and I’m having trouble setting a parent instance for an instance to inherit its transform.
In canvas_item related methods, RenderingServer provides canvas_item_set_parent method to set canvas_item’s parent canvas_item, but I didn’t find similar method in instance related methods.
My question is, how to set parent instance for instance to inherit transform from parent instance?

[zdrmlpzdrmlp]

can you just throw the created instance RID to the canvas_item_set_parent method to set ones instance as parent of other instance?

nevermind, it’s 2 different things, instance is for 3d, not for 2d canvasitem

[aawwaaa]

I looked at the source code of the Godot engine and found that in the 4.2 version of the source code the engine directly uses global_transform.
This means that the RenderingServer may not provide a set_parent class method for the instance or I can’t use it directly in gdscript.
Therefore, the workaround for this problem is to use global_transform directly in the code and notify the child node when the transform is updated.

void VisualInstance3D::_notification(int p_what) {
	switch (p_what) {
		case NOTIFICATION_ENTER_WORLD: {
			ERR_FAIL_COND(get_world_3d().is_null());
			RenderingServer::get_singleton()->instance_set_scenario(instance, get_world_3d()->get_scenario());
			_update_visibility();
		} break;

case NOTIFICATION_TRANSFORM_CHANGED: {
            // (edit) Here is it.
			Transform3D gt = get_global_transform();
			RenderingServer::get_singleton()->instance_set_transform(instance, gt);
		} break;

case NOTIFICATION_EXIT_WORLD: {
			RenderingServer::get_singleton()->instance_set_scenario(instance, RID());
			RenderingServer::get_singleton()->instance_attach_skeleton(instance, RID());
		} break;

case NOTIFICATION_VISIBILITY_CHANGED: {
			_update_visibility();
		} break;
	}
}

Referenced from /scene/3d/visual_instance_3d.cpp in the https://github.com/godotengine/godot 4.2 branch