vtkCellPicker - select a cell by shooting a ray into graphics window
Super Class: vtkPicker
vtkCellPicker is used to select a cell by shooting a ray into graphics window and intersecting with actor's defining geometry - specifically its cells. Beside returning coordinates, actor and mapper, vtkCellPicker returns the id of the closest cell within the tolerance along the pick ray, and the dataset that was picked.
Detailed Method Descriptions:
Get the id of the picked cell. If CellId = -1, nothing was picked.
Get the subId of the picked cell. If SubId = -1, nothing was picked.
Get the parametric coordinates of the picked cell. Only valid if pick was made.