Enable eye dome lighting (EDL)

def enable_eye_dome_lighting(self):
        """Enable eye dome lighting (EDL)"""
        if hasattr(self, 'edl_pass'):
            return self
        # create the basic VTK render steps
        basic_passes = vtk.vtkRenderStepsPass()
        # blur the resulting image
        # The blur delegates rendering the unblured image to the basic_passes
        self.edl_pass = vtk.vtkEDLShading()
        self.edl_pass.SetDelegatePass(basic_passes)

        # tell the renderer to use our render pass pipeline
        self.glrenderer = vtk.vtkOpenGLRenderer.SafeDownCast(self)
        self.glrenderer.SetPass(self.edl_pass)
        return self.glrenderer