Background and objectives: Cutting and bleeding are often independent of each other in the traditional virtual surgery system because of the differences in the calculation of physical models and the lack of internal structure. In order to improve the fidelity of virtual surgery scene and the training value for surgeons, a new geometric combination of cutting and bleeding modules is introduced.

Methods: In this paper, we introduce a cutting model based on volume rendering and meshless method. The multidimensional parameters derived from the gray values are presented to participate in the calculation of both physical and geometric models, which distinguishes between different adjacent soft tissues. The bleeding simulation with improved physical properties and rendering algorithms of geometric model is proposed to meet several different bleeding states. After cutting procedures, the tearing parts can be judged through the vision and the tactile sensation. The initial velocity and rendering algorithm of bleeding particles are determined by the multidimensional parameters of the cutting position, which realizes the geometric combination of cutting and bleeding modules.

Results and conclusions: Simulation results show that tearing different tissue structures will produce corresponding bleeding states. When the skin and flesh are torn, the blood is slowly generated at the incision, and then diffuses to the surface of soft tissue. When the important blood vessels are ruptured, the blood gushes from the laceration. Compared with the conventional virtual surgery system, both visual effect and interactivity of the cutting and bleeding modules are improved in the proposed geometric combination.

背景与目的：由于物理模型计算上的差异以及缺乏内部结构，在传统的虚拟手术系统中切割和出血通常是彼此独立的。为了提高虚拟手术场景的保真度和对外科医生的培训价值，引入了切割和出血模块的新几何组合。

方法：在本文中，我们介绍了一种基于体绘制和无网格方法的切削模型。提出了从灰度值得出的多维参数，以参与物理模型和几何模型的计算，从而区分不同的相邻软组织。提出了具有改善的物理性能的渗流模拟和几何模型的渲染算法，以满足几种不同的渗流状态。切割程序完成后，可以通过视觉和触觉判断撕裂的部分。切削位置的多维参数决定了渗出颗粒的初始速度和渲染算法，实现了切入和渗出模块的几何组合。

结果与结论：仿真结果表明，撕裂不同的组织结构会产生相应的出血状态。当皮肤和肉体被撕裂时，血液在切口处缓慢生成，然后扩散到软组织的表面。当重要血管破裂时，血液会从裂伤处涌出。与传统的虚拟手术系统相比，在所提出的几何组合中，切割和出血模块的视觉效果和交互性都得到了改善。