## 7 Conclusions  
Software components, introduced and evaluated in this paper, solved certain limitations of contemporary A-Frame and Networked-Aframe-based web XR applications. The proposed 6-DoF SMC and HoloGOM components are more universal ones and, after some modifications, can be used without A-Frame. The 6-DoF SMC component provides six degrees of freedom (DoF) inside-out motion tracking for smartphones and smartphone-based VR headsets. The HoloGOM component allows web XR users to manipulate objects in virtual scenes using hand gestures. To our knowledge, there are no other implementations providing corresponding functionality for A-Frame, and this functionality is also lacking on other platforms, for example the Mozilla Hubs. Of course, as the evaluation (RQ.1) revealed, the components are not flawless: 6-DoF SMC requires a special version of web browser (Chrome Canary) and has a significant impact on both the frame rate and network response time. This performance decrease can be attributed to the motion tracking, which has to analyze the phone camera input. It seems that HoloGOM suffers from overall performance of WebXR on MS HoloLens in our experiments. Both components rely on features considered experimental. These issues are expected to be solved in future versions of the underlying software platforms and corresponding devices. The proposed ECA component is closely tied to A-Frame as it enriches the functionality of its Networked-Aframe (NAF) extension. Thanks to ECA, user positions in a shared virtual scene can be easily accessed. It also allows removing users from the scene. The evaluation confirmed minimal impact of the ECA (RQ.1) on the performance (about 5%). The only disadvantage is that ECA needs an upgrade to work with the newest version of NAF. Fortunately, the upgrade has already been developed. An interesting result of the experimental evaluation is an answer to the question how the shared XR, utilizing A-Frame and NAF, performs on MS HoloLens and mid-range hardware (RQ.2). The mid-range hardware representatives were the devices used in the experiments, namely PC with Intel Core i5 CPU, 4 GB RAM and integrated graphics and a Xiaomi Redmi Note 7 smartphone. The answer can be formulated as follows: when using relatively simple virtual scene and avatar models, one can enjoy shared XR with A-Frame and NAF even on mid-range hardware, except MS HoloLens. To be more precise, the smartphone handled the shared scene with 20 users without any problems. PC handled the scene with 15 users equally well, while the average frame rate dropped to 23.88 fps with 20 users. MS HoloLens was able to handle the scene with no other users connected. With five users in the scene, the average frame rate dropped below 20 fps. The components and scenes, developed as parts of the LIRKIS G-CVE platform, offer promising application and experimentation areas for future research and development. For example, virtual industrial installations, such as the one presented in [35], and distant education, in particular aiming at the current efforts to develop so-called digital intelligence [36] or supporting people with special needs, such as autism spectrum disorder [37]. It is also planned to utilize LIRKIS G-CVE for future versions of the experiments described in [38; 39], which focus on an assessment of VR influence on visuospatial cognitive functions [40]. Other applications, already under development, are training of civil engineering personnel, safety training and visualization of data from physical experiments in virtual environments. Such applications can also be extended by undergoing developments regarding authentication utilizing keyboard dynamics [41], additional EMG sensing and face recognition, together with emotion recognition [42] and EEG sensing. The experimental setup, introduced in this article, will be reused for other evaluations. For now, the evaluation of 6-DoF SMC with multiple mobile devices is planned.