I’ve been experimenting with picking/selection in vtk and started with picking points and cells from a vtkUnstructuredGrid using the frustum from a vtkInteractorStyleRubberBandPick style in a vtkExtractGeometry filter.
When I extend this code to use a vtkMultiBlockDataSet consisting of a hierarchy of vtkUnstructuredGrids as input, the vtkExtractGeometry filter fails to return any cells. The code fragment below works just fine when “target” is a vtkUnstructuredGrid - extract contains the cells inside the frustum. But when mesh is a vtkMultiBlockDataSet, extracted is “None”
frustum = self.GetInteractor().GetPicker().GetFrustum() extract_geometry = vtk.vtkExtractGeometry() extract_geometry.SetImplicitFunction(frustum) extract_geometry.SetInputData(target) extract_geometry.Update() extracted = extract_geometry.GetOutput()
Any guidance on how to rubber band pick from a vtkMultiBlockDataSet will be gratefully received.