三维螺旋楼梯的自动建模

Automatic Creation of Three Dimensional Model of Spiral Stair Cases

螺旋楼梯由于其结构比较复杂,所以手工建模难度大,方法不易掌握。本文介绍一种采用化整为零的方法,将复杂的螺旋楼梯分解成梯段和栏杆,而梯段又可分解成阶梯形踏步、梯段底面、梯段侧面;栏杆的圆螺旋管扶手可分解成两半圆螺旋管,使得能够用AutoLISP编程绘制确定楼梯底面和侧面范围的螺旋线和锯齿线,从而用"边界曲面"和"直纹曲面"创建梯段底面、侧面和扶手的三维表面模型,通过阵列和移动创建梯段的踏步和栏杆。

Because the construction of spiral stair is complicated ,the manual creation of its three dimensional model is difficult. By breaking up spiral stair cases into steps, spiral surface under steps, cylinder surfaces inside steps and outside steps, handrail, and railing, and breaking up circular spiral tube handrail into inside half and outside half circular spiral tube, we make it possible to use the program of AutoLISP to draw out the spiral lines and sawtooth lines which define the boundary of spiral surface and cylinder surface and surface of half handrail which are circular spiral tubes. And then, we create the spiral surface and cylinder surface and handrail by command 'edgesurf' and 'rulesurf',and draw all the steps and all the railings by arraying a step and railings on a step and then moving them.