from __future__ import unicode_literals
from PyQt4 import QtCore, QtGui, QtOpenGL
from vtk.qt4.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor
import sys
import vtk

class MainWindow(QtGui.QMainWindow):

    def __init__(self, parent=None):
        QtGui.QMainWindow.__init__(self, parent)

        self.frame = QtGui.QFrame()

        self.vl = QtGui.QVBoxLayout()
        self.vtkWidget = QVTKRenderWindowInteractor2(self.frame)
        self.vl.addWidget(self.vtkWidget)

        self.ren = vtk.vtkRenderer()
        self.vtkWidget.GetRenderWindow().AddRenderer(self.ren)
        self.iren = self.vtkWidget.GetRenderWindow().GetInteractor()
        self.iren.DebugOn()

        # Create source
        source = vtk.vtkSphereSource()
        source.SetCenter(0, 0, 0)
        source.SetRadius(5.0)

        # Create a mapper
        mapper = vtk.vtkPolyDataMapper()
        mapper.SetInputConnection(source.GetOutputPort())

        # Create an actor
        actor = vtk.vtkActor()
        actor.SetMapper(mapper)

        self.ren.AddActor(actor)

        self.ren.ResetCamera()

        self.frame.setLayout(self.vl)
        self.setCentralWidget(self.frame)

        self.show()
        self.vtkWidget.GetRenderWindow().Render()

        self.vtkWidget.GetRenderWindow().SetOffScreenRendering(True)
        self.vtkWidget.GetRenderWindow().Render()


        self.vtkWidget.GetRenderWindow().SetOffScreenRendering(False)
        self.vtkWidget.GetRenderWindow().Render()

        self.iren.Initialize()


if __name__ == "__main__":

    app = QtGui.QApplication(sys.argv)

    window = MainWindow()

    sys.exit(app.exec_())