Dear all:
1.I wonder how to realize some selection function except for the one already existed in API，such as， picking.So Is there
any way to implement cross selection,frame selection ,and so on,
which we usually see in CAD or 3D games.
2.Where can I get some articles about boolean operation or any
open source code implementing that function existed in web？
I hope you can get the meaning of my poor English.
Thanks
here Chinese as follows:
1.我想知道如何实现除了API提供的点选外的，其它的选择，如框选，交叉选择等，这些在CAD或者3D游 戏中经常看到的
2.关于布尔运算的，哪里有这方面的资料，有已经实现这方面功能的
源码么