PyVista Passes in the rendering

edl.py

# https://github.com/pyvista/pyvista/issues/137
import vtk

sphere = vtk.vtkSphereSource()
sphere.SetCenter(0, 0, 0)
sphere.SetRadius(1)
sphere.Update()

elevation = vtk.vtkElevationFilter()
elevation.SetInputData(sphere.GetOutput())
elevation.SetLowPoint(0, 0, -1)
elevation.SetHighPoint(0, 0, 1)
elevation.Update()
elevationMapper = vtk.vtkPolyDataMapper()
elevationMapper.SetInputData(elevation.GetOutput())
elevationActor = vtk.vtkActor()
elevationActor.SetMapper(elevationMapper)

scalarActor = vtk.vtkScalarBarActor()
scalarActor.SetLookupTable(elevationMapper.GetLookupTable())

basicPasses = vtk.vtkRenderStepsPass()
basicPasses.SetOverlayPass(None)

edl = vtk.vtkEDLShading()
edl.SetDelegatePass(basicPasses)

overlay = vtk.vtkOverlayPass()

passes = vtk.vtkRenderPassCollection()
passes.AddItem(edl)
passes.AddItem(overlay)

sequencePass = vtk.vtkSequencePass()
sequencePass.SetPasses(passes)

renderer1 = vtk.vtkRenderer()
renderer1.SetPass(sequencePass)
renderer1.SetBackground(0.3, 0.4, 0.6)
renderer1.AddActor(elevationActor)
renderer1.AddActor(scalarActor)

renderWindow = vtk.vtkRenderWindow()
renderWindow.SetSize(600, 600)
renderWindow.AddRenderer(renderer1)

iren = vtk.vtkRenderWindowInteractor()
iren.SetRenderWindow(renderWindow)
iren.Start()