结构力学计算，计算节点位移，轴力，弯矩，剪力-Structural mechanics compute nodes displacement, axial force, bending moment, shear

使用setMouseCallback,获得图像的坐标，并且保存下坐标，然后通过坐标得到剪切到的小图片-Use setMouseCallback, obtain the image coordinates, and save the coordinates, then shear is obtained by the coordinate to the small pictures