thank you David. and do you have any example for draw a ploygon through mouse event? i mean use mouse drag to draw a Ploygon! thank you! Yinghua. -- View this message in context: http://vtk.1045678.n5.nabble.com/How-to-draw-a-ploygon-on-3D-object-tp3235000p3236419.html Sent from the VTK - Users mailing list archive at Nabble.com.