OpenCASCADE绘制测试线束：图形命令之Axonometric观察器
- view, delete
- axo, pers, top, ...
- mu, md, 2dmu, 2dmd, zoom, 2dzoom
- pu, pd, pl, pr, 2dpu, 2dpd, 2dpl, 2dpr
- fit，2dfit
- u, d, l, r
- focal, fu, fd
- color
- dtext
- hardcopy, hcolor, xwd
- wclick, pick
- autodisplay
- display, donly
- erase, clear, 2dclear
- disp, don, era
- repa