## 2 Related Work
### User Interactions with Digital Learning Systems
Most people are used to interacting with computers through standard 2D interfaces using a mouse and keyboard, with the screen being the output device. However, with the advancement of technology, especially in virtual environments, conventional input is not always practical [26]. This still raises the question of what is the most natural way to interact with these virtual systems and which devices are best suited for this. In contrast, 3D interaction is a type of interaction between humans and computers in which users can move and interact freely in a 3D space. The interaction itself involves information processing by both humans and machines, where the physical position of elements within the environment is critical to achieving the desired results. The space in such a system can be defined as a real physical environment, a virtual environment created by computer simulation, or a hybrid combination of both environments. If the real physical space is used for data input, the user interacts with the machine via an input device that recognizes the user's gestures. If, on the other hand, it is used for data output, the simulated virtual 3D scene is projected into the real world using a suitable output device (hologram, VR glasses, etc.). It is important to note that interactive systems that display 3D graphics do not necessarily require 3D interaction. For example, if a user views a building model on their desktop computer by selecting different views from a classic menu, this is not a form of 3D interaction. If the user clicks on a target object within the same application to navigate to it, then the 2D input is converted directly into a virtual 3D location. This type of interaction is called 3D interaction [27]. Most 3D interactions are usually more complex than 2D interactions because they require new interface components, which are usually realized with special devices. These types of devices offer many opportunities for designing new user experience-based interactions [28]. The main categories of these devices are standard input devices, tracking, control, navigation and gesture interfaces, 3D mice, and brain-computer interfaces. Two different methods of interaction in the XR environment are direct and indirect. When considering their impact on user experience, engagement, and learning outcomes, both offer different benefits that can complement each other in a learning context. Direct interaction in XR environments mimics real-life activities, increasing physical involvement and potentially boosting intrinsic motivation. Indirect interactions with classic UI elements provide greater precision through an interface, although they usually require more cognitive effort and affect usability and motivation in different ways. A combination of both interaction methods can create a balanced and effective learning environment, as this approach supports hands-on learning in the initial phase and facilitates precision tasks in more advanced phases [29]. Various approaches have been developed to overcome the limitations of mapping 2D inputs to 3D spaces. One of the earliest methods is the triad cursor, which allows the manipulation of objects using a mouse relative to their projected axes [30], while another method uses two cursors to perform translation, rotation, and scaling simultaneously [31]. Alternatives include a handle box [32] and virtual handles [33] for applying transformations to virtual objects, while [PERSON] presented a technique that allows object rotation by drawing arcs on a virtual sphere with the mouse [34]. Although these techniques are more than 30 years old, they are still used in the form of widgets in modern tools such as Unity3D. Other tools, such as AutoCAD, 3D Studio Max, and Blender, use orthogonal views instead of widgets for more precise manipulation of 3D objects [35]. Numerous studies have investigated different approaches for the selection and manipulation of objects in virtual 3D spaces.