[vtkusers] How to Snap lines' end point, intersection points while moving mouse?

[扬帆]

I have many lines added to the scene.And I want to draw a snap rectangle when the mouse moving around any lines' end point and intersection point.Do I have to calculate these points and draw the rectangle myself.Or vtk has some support for me ?
 Any suggestions are appreciated.Thanks.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20090523/f4b884b0/attachment.htm>