[Erro em interface gráfica com Pyqt5 e OpenGL]

Esse código deveria mostrar uma janela e desenhar um triângulo.

import sys
from PyQt5 import QtOpenGL
from PyQt5.QtWidgets import *
from OpenGL.GL import *

class MyCanvas(QtOpenGL.QGLWidget):

    def __init__(self):
        super(MyCanvas, self).__init__()
        self.setGeometry(100, 100, 600, 400)
        self.setWindowTitle('MyGLDrawer')
        self.m_w = 0
        self.m_h = 0

    def initializeGL(self):
        glClearColor(1.0, 1.0, 1.0, 1.0)
        glClear(GL_COLOR_BUFFER_BIT)

    def resizeGL(self, _width, _height):
        self.m_w = _width
        self.m_h = _height

        glViewport(0, 0, self.m_w, self.m_h)
        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()
        glOrtho(0.0, self.m_w, 0.0, self.m_h, -1.0, 1.0)
        glMatrixMode(GL_MODELVIEW)
        glLoadIdentity()

    def paintGL(self):
        glClear(GL_COLOR_BUFFER_BIT)

        xA = self.m_w / 3.0
        yA = self.m_h / 3.0
        xB = self.m_w * (2.0 / 3.0)
        yB = self.m_h / 3.0
        xC = self.m_w / 2.0
        yC = self.m_h * (2.0 / 3.0)
        glShadeModel(GL_SMOOTH)
        glBegin(GL_TRIANGLES)
        glColor3f(1.0, 0.0, 0.0) # red
        glVertex2f(xA, yA)
        glColor3f(0.0, 1.0, 0.0)  # green
        glVertex2f(xB, yB)
        glColor3f(0.0, 0.0, 1.0)  # blue
        glVertex2f(xC, yc)
        glEnd()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    widget = MyCanvas()
    widget.show()
    sys.exit(app.exec_())

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Executando esse código está aparecendo o seguinte erro:

  File "C:\Users\BuscapÚ\PycharmProjects\Rafael_Vieira\main3.py", line 19, in initializeGL
    glClearColor(1.0, 1.0, 1.0, 1.0)
  File "C:\Users\BuscapÚ\AppData\Local\Programs\Python\Python36\lib\site-packages\OpenGL\platform\baseplatform.py", line 415, in __call__
    return self( *args, **named )
  File "C:\Users\BuscapÚ\AppData\Local\Programs\Python\Python36\lib\site-packages\OpenGL\error.py", line 234, in glCheckError
    baseOperation = baseOperation,
OpenGL.error.GLError: GLError(
        err = 1282,
        description = b'opera\xe7\xe3o inv\xe1lida',
        baseOperation = glClearColor,
        cArguments = (1.0, 1.0, 1.0, 1.0)
)

 

Alguém tem ideia do que pode ser?