PyQt OpenGL: drawing simple scenes

Here's a simple working example for a python QGLWidget with a button:

from OpenGL.GL import *
from OpenGL.GLU import *
from PyQt4 import QtGui
from PyQt4.QtOpenGL import *

class MainWindow(QtGui.QWidget):
    def __init__(self):
        super(MainWindow, self).__init__()
        self.widget = glWidget(self)
        self.button = QtGui.QPushButton('Test', self)
        mainLayout = QtGui.QHBoxLayout()
        mainLayout.addWidget(self.widget)
        mainLayout.addWidget(self.button)
        self.setLayout(mainLayout)

class glWidget(QGLWidget):

    def __init__(self, parent):
        QGLWidget.__init__(self, parent)
        self.setMinimumSize(640, 480)

    def paintGL(self):
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        glLoadIdentity()
        glTranslatef(-2.5, 0.5, -6.0)
        glColor3f( 1.0, 1.5, 0.0 )
        glPolygonMode(GL_FRONT, GL_FILL)
        glBegin(GL_TRIANGLES)
        glVertex3f(2.0,-1.2,0.0)
        glVertex3f(2.6,0.0,0.0)
        glVertex3f(2.9,-1.2,0.0)
        glEnd()
        glFlush()

    def initializeGL(self):
        glClearDepth(1.0)              
        glDepthFunc(GL_LESS)
        glEnable(GL_DEPTH_TEST)
        glShadeModel(GL_SMOOTH)
        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()                    
        gluPerspective(45.0,1.33,0.1, 100.0) 
        glMatrixMode(GL_MODELVIEW)

if __name__ == '__main__':
    app = QtGui.QApplication(['Yo'])
    window = MainWindow()
    window.show()
    app.exec_()

I modify Ivan's answer for Pyqt version 5.

import sys
from OpenGL.GL import *
from OpenGL.GLU import *
from PyQt5 import QtGui
from PyQt5.QtOpenGL import *
from PyQt5 import QtCore, QtWidgets, QtOpenGL


class Ui_MainWindow(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(Ui_MainWindow, self).__init__()
        self.widget = glWidget()
        self.button = QtWidgets.QPushButton('Test', self)
        mainLayout = QtWidgets.QHBoxLayout()
        mainLayout.addWidget(self.widget)
        mainLayout.addWidget(self.button)
        self.setLayout(mainLayout)


class glWidget(QGLWidget):
    def __init__(self, parent=None):
        QGLWidget.__init__(self, parent)
        self.setMinimumSize(640, 480)

    def paintGL(self):
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
        glLoadIdentity()
        glTranslatef(-2.5, 0.5, -6.0)
        glColor3f( 1.0, 1.5, 0.0 );
        glPolygonMode(GL_FRONT, GL_FILL);
        glBegin(GL_TRIANGLES)
        glVertex3f(2.0,-1.2,0.0)
        glVertex3f(2.6,0.0,0.0)
        glVertex3f(2.9,-1.2,0.0)
        glEnd()
        glFlush()

    def initializeGL(self):
        glClearDepth(1.0)              
        glDepthFunc(GL_LESS)
        glEnable(GL_DEPTH_TEST)
        glShadeModel(GL_SMOOTH)
        glMatrixMode(GL_PROJECTION)
        glLoadIdentity()                    
        gluPerspective(45.0,1.33,0.1, 100.0) 
        glMatrixMode(GL_MODELVIEW)


if __name__ == '__main__':    
    app = QtWidgets.QApplication(sys.argv)    
    Form = QtWidgets.QMainWindow()
    ui = Ui_MainWindow(Form)    
    ui.show()    
    sys.exit(app.exec_())