问如何去掉毛边？

EN

import sys
import vtk

from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *

from vtk.qt.QVTKRenderWindowInteractor import QVTKRenderWindowInteractor

class MainWindow(QWidget):

    def __init__(self, parent=None):
        super().__init__()
        self.setStyleSheet('background-color: rgb(255,0,0)')
        self.setContentsMargins(0, 0, 0, 0)
        self.frame = QFrame()

        self.vl = QVBoxLayout()
        self.setLayout(self.vl)
        self.vtkWidget = QVTKRenderWindowInteractor(self.frame)
        self.vtkWidget.setContentsMargins(0, 0, 0, 0)
        self.vl.addWidget(self.vtkWidget)

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

        # 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.show()
        self.iren.Initialize()


if __name__ == "__main__":
    app = QApplication(sys.argv)

    window = MainWindow()

    sys.exit(app.exec_())