SEE ALSO vtkPicker is used for quick picking. If you desire to pick points or cells, use the subclass vtkPointPicker or vtkCellPicker , respectively. The third value is related to z-buffer depth. Specify tolerance for performing pick operation.
Tolerance is specified as fraction of rendering window size.
Return position in global coordinates of pick point. The assembly may be the same as the actor. If nothing was picked then NULL is returned. Perform pick operation with selection point provided. Return non-zero if something was successfully picked.