## 5 Results and Conclusions  
This study proposed a GPU-accelerated Position-Based Dynamics (PBD) cloth simulation system for real-time use in XR environments and conducted a comprehensive comparison with Unity's built-in Cloth component in terms of performance and functional capabilities. Performance evaluations across various resolutions (\(8\times 8\) to \(128\times 128\)) showed that Unity Cloth maintained a consistent 72 FPS in all scenarios, demonstrating its strong internal optimization. This stable frame rate makes Unity Cloth highly suitable for lightweight XR applications or rapid prototyping scenarios where simple interactions and consistent runtime behavior are prioritized. In comparison, the GPU-PBD system sustained equivalent 72 FPS performance up to a 32 \(\times\) 32 resolution. At \(64\times 64\), it maintained 65 FPS for the single-sided setup and 40 FPS for the double-sided version. At \(128\times 128\), performance dropped to 42 FPS (single-sided) and 16 FPS (double-sided). Despite the decline at higher resolutions, the GPU-PBD system preserved real-time interactivity up to \(64\times 64\) in double-sided mode, which is generally sufficient for interactive XR tasks. Figure 14: Quantitative user evaluation comparing Unity Cloth and GPU-PBD systems. Scores are averaged from 10 participants across 5 criteria, using a 5-point Likert scale. Functionally, Unity Cloth is limited to single-sided rendering and supports only simple primitive colliders. The GPU-PBD system, by contrast, supports two-sided cloth behavior, collision with scanned RoomMesh surfaces, and real-time interaction with OVRMesh-based hand models. It offers fine-grained control of distance and bending constraints and is highly extensible due to its modular Compute Shader architecture. In physical interaction tests, GPU-PBD cloth objects realistically draped and responded to real-world structures such as desks, while Unity Cloth often displayed unnatural behavior such as mesh penetration or inaccurate folding. Similarly, in hand interaction experiments using both OVRMesh and OVRSkeleton capsule colliders, the GPU-PBD system provided stable and physically plausible responses, whereas Unity Cloth frequently produced popping artifacts or failed to detect complex hand geometry. Quantitative user evaluation further supported these findings. In a 10-participant study using 5 evaluation metrics--Visual Realism, Interaction Naturalness, Responsiveness, Spatial Alignment, and Immersive Experience--the GPU-PBD system received higher ratings in all categories. Participants especially noted its realistic response to folding, wrinkling, and surface sliding during hand interactions, in contrast to Unity Cloth, which was perceived as physically limited under similar conditions. In conclusion, while Unity Cloth remains a viable solution for simple, low-complexity XR scenarios due to its consistent frame rate and ease of integration, the GPU-PBD system demonstrates clear advantages in handling complex environments, realistic interactions, and immersive simulation experiences. Designed with portability in mind, the framework is suitable for adaptation to other XR devices such as Apple Vision Pro and Microsoft HoloLens 2. Future research will explore the expansion of the system beyond cloth to include general deformable and cutting simulations based on the PBD framework, enabling advanced applications in medical training, anatomical education, and emergency response simulations. Conceptualization, M.H. ; Methodology, T.K. ; Software, T.K. ; Formal analysis, J.M. and T.K. ; Writing--original draft preparation, T.K. ; Writing--review and editing, T.K., M.H. and J.M. ; Project administration, M.H. All authors have read and agreed to the published version of the manuscript. This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Education (NRF-2022R1 IIA3069371), funded by BK21 FOUR (Fostering Outstanding Universities for Research) (No.