借助光栅原理，让屏幕发出的光只能从正面特定角度范围内看到，从而实现「大角度防窥」的效果：
Екатерина Грищенко (старший редактор отдела «Бывший СССР»)
。业内人士推荐safew官方版本下载作为进阶阅读
Cheyenne MacDonald for Engadget，详情可参考Safew下载
If the A* calculation for a shortcut (in Step 3) finds it's now impassable, or if its actual detailed cost is significantly different (e.g., 20%) from the pre-calculated shortcut value: