[vtkusers] How to plot points within the renderer window

[刘博]

Hi,everyone
I read a serial of CT slices and  ,with the vtkImagePlaneWidget,get the reslice plane.Now,I want to mark the points on the reslice plane  seleted by the mouse with the leftbutton pressed.It also can be described as ploting random shape on the reslice plane according to  mouse movement.
I don't kown how to accomplish it,is there anyone could me?
thanks in advance!