## 1 Introduction  
In Extended Reality (XR) environments, realistic interaction with virtual objects is a key element that provides an immersive experience [1]. In particular, the simulation of flexible objects such as clothing, curtains, and flags plays an important role in building realistic virtual environments. However, implementing high-quality cloth simulation with interactive responsiveness is computationally expensive and presents significant technical challenges due to the limited computing resources of XR devices [2]. The built-in Cloth component of the widely used Unity engine provides a simple interface and stable simulation, but there are performance constraints in complex environmental interactions and high-resolution mesh processing. These constraints are particularly pronounced in standalone XR headsets such as the Meta Quest. Recent advances in soft-body simulation research for XR environments have made significant progress in addressing these computational challenges. [PERSON] et al. [3] conducted a comprehensive survey on improvements to Position-Based Dynamics (PBD), highlighting its growing adoption in XR applications. Their study emphasized the strengths of PBD in terms of efficiency, stability, and controllability--characteristics particularly well-suited for real-time simulation in resource-constrained XR systems. These developments collectively reinforce PBD as a promising approach for achieving high-performance, physically plausible simulations in XR environments. This study proposes a GPU-accelerated Position-Based Dynamics (PBD) cloth simulation system and compares it with Unity's default Cloth component. PBD is a method that utilizes position-based constraints for stable and controllable physics simulation, making it suitable for real-time applications [4]. The system developed in this research maximizes parallel processing capabilities by utilizing Unity's Compute Shader, efficiently processing high-resolution cloth simulation and enhancing interactivity in XR environments [5]. One of the characteristics of XR environments is the integration of physical space and virtual objects. This research implements interactions between environmental meshes and cloth by leveraging this characteristic. Through the spatial awareness capabilities of the Meta Quest, meshes of real environmental objects, such as desks, chairs, and walls, are extracted and utilized in collision processing, allowing virtual cloth to naturally respond to the XR space [6]. Unlike the existing Unity Cloth component, which can only interact with simplified colliders, the proposed system enables accurate collision processing with complex meshes, allowing for realistic behaviors such as virtual cloth being placed on a desk or naturally draping along the edges of real objects. Additionally, this research focuses on natural interaction between the user's hands and cloth in XR environments. Using the Meta Quest's hand tracking system, hand movements are detected in real time, and collision processing between hands and cloth is implemented [7]. Through GPU-based parallel processing algorithms, collision detection and response are efficiently calculated, enabling complex interactions, such as picking up or pressing cloth with fingers. This combination of hand interaction and environmental mesh collision processing provides an immersive experience where virtual cloth responds to users and the environment as if it were a real object. This paper explains the design and implementation method of the proposed GPU-based simulation system and analyzes the differences in performance, visual quality, and interaction aspects through comparative experiments with the Unity Cloth component. The characteristics of both systems are comprehensively evaluated by measuring computational efficiency, memory usage, scalability according to mesh resolution, and precision of environmental mesh and hand interaction in key benchmark scenarios.