用计算机仿真布的真实感图形

采用与布的物理结构相似的粒子网格作为布的模型，在此基础上，将布受到外力作用时的形变归纳为弹性伸缩、弯曲和剪切3类，并推导出相应的能量函数来描述这3种形变。由于布的的拉伸形变相对于弯曲和剪切形变而言具有很强的刚性，这样在数值积分时就造成了“病态系统”。选用预条件共轭梯度法，采用解线性方程组的方法，对衣服的运动方程进行数值积分，从而较好地解决了这个问题，并提高了仿真的速度。

A Practical Method forImplementing Realistic Textile Image

Breen′s algorithm required about one week′s computer time on IBM RS6000 work-station to give a realistic textile image［3］. We propose an al gorithm that can give a realistic textile image but requires only about 12 minutes of AMD K6-Ⅱ266. Like Breen, we model textile as a collection of particles that conceptually represent the crossing points of warp and weft threads in a plain weave. Unlike Breen, we decompose the deformation of textile into elastic de formation, bend and shear, and deduce simple energy functions of the three kinds of deformation in accordance with the principles of strength of materials. But unfortunately, textile strongly resists elongation or shortening while permitting easy bending or shearing, thus causing an “ill” system in numerical integration. To overcome this difficulty, we adopt preconditioned conjugate gradient method, and integrate the motion equation of textile by solving a set of linear equations.