Abstract: Soft body with internal volume can’t be simulated realistically by existing methods.Aiming at this phenomenon，this paper adds virtual gas to the improved mass-spring model，and simulates the soft body by using restrictions which include internal gas pressure and the improved mass-spring limits.It is shown from the experiments that the soft body with internal volume is simulated vividly，and the method is real-time.

Key words: soft body, pressure model, mass-spring model, collision detection

摘要： 现有的方法都不能很好地模拟具有内在体积的柔性物体。针对这种现状，将虚拟气体添加到改进的质点弹簧模型之上。通过内部的气体压力约束及改进的质点弹簧模型的约束实现了对这种柔性物体的模拟。实验表明，该方法真实地模拟了有内在体积的柔性物体，并且具有较强的实时性。

关键词: 柔性物体, 压力模型, 质点-弹簧模型, 碰撞检测