PyQt4 OpenGL: GL core profile error

Question

Good afternoon, I'm studying OpenGL - the "red book". I'm trying to make the first example (draw two triangles):

# PyQT4 imports
from PyQt4 import QtGui, QtCore, QtOpenGL
from PyQt4.QtOpenGL import QGLWidget
# PyOpenGL imports
from OpenGL.GL import *
from OpenGL.GL.shaders import *

class GLPlotWidget(QGLWidget):
# default window size
width, height = 600, 600

def __init__(self, format = None):
    super(GLPlotWidget, self).__init__(format, None)

def set_data(self, data):
    self.data = data
    self.count = data.shape[0]
    self.numVAOs = 2
    self.VAOs = [0] * self.numVAOs
    self.numVBOs = 2
    self.VBOs = [0] * self.numVBOs
    self.shader = None
    self.vPositionLocation = 0

def initializeGL(self):
    glGenVertexArrays(self.numVAOs, self.VAOs)
    glBindVertexArray(self.VAOs[0])

    glGenBuffers(self.numVBOs, self.VBOs)
    glBindBuffer(GL_ARRAY_BUFFER, self.VBOs[0])
    glBufferData(GL_ARRAY_BUFFER, self.count, self.data, GL_STATIC_DRAW)

    VERTEX_SHADER = compileShader("""
        #version 410 core
        layout(location = 0) in vec4 vPosition;
        void main() {
            gl_Position = vPosition;
        }
    """, GL_VERTEX_SHADER)

    FRAGMENT_SHADER = compileShader("""
        #version 410 core
        out vec4 fColor;
        void main() {
            fColor = vec4(0.0, 0.0, 1.0, 1.0);
        }
    """, GL_FRAGMENT_SHADER)

    self.shader = compileProgram(VERTEX_SHADER, FRAGMENT_SHADER)
    glUseProgram(self.shader)

    glVertexAttribPointer(self.vPositionLocation, 2, GL_FLOAT, GL_FALSE, 0, 0)
    glEnableVertexAttribArray(self.vPositionLocation)

def paintGL(self):
    glClear(GL_COLOR_BUFFER_BIT)

    glBindVertexArray(self.VAOs[0])
    glDrawArrays(GL_TRIANGLES, 0, self.count)

    glFlush()

def resizeGL(self, width, height):
    # update the window size
    self.width, self.height = width, height

    # paint within the whole window
    glViewport(0, 0, width, height)

    # set orthographic projection (2D only)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()

    # the window corner OpenGL coordinates are (-+1, -+1)
    glOrtho(-1, 1, -1, 1, -1, 1)

if __name__ == '__main__':
    # import numpy for generating random data points
    import sys
    import numpy as np
    import numpy.random as rnd

    # define a QT window with an OpenGL widget inside it
    class TestWindow(QtGui.QMainWindow):
        def __init__(self, parent = None):
            super(TestWindow, self).__init__(parent)

            # generate random data points
            self.data = np.array([
                [ -0.90, -0.90 ], [ 0.85, -0.90 ], [ -0.90, 0.85 ],
                [  0.90, -0.85 ], [ 0.90,  0.90 ], [ -0.85, 0.90 ]
            ], dtype = np.float32)

            # initialize the GL widget
            glformat = QtOpenGL.QGLFormat()
            glformat.setVersion(4, 1)
            glformat.setProfile(QtOpenGL.QGLFormat.CoreProfile)
            glformat.setSampleBuffers( True )
            QtOpenGL.QGLFormat.setDefaultFormat(glformat)
            self.widget = GLPlotWidget(glformat)
            self.widget.set_data(self.data)

            # put the window at the screen position (100, 100)
            self.setGeometry(100, 100, self.widget.width, self.widget.height)
            self.setCentralWidget(self.widget)
            self.show()

    # create the QT App and window
    app = QtGui.QApplication(sys.argv)
    glutInitDisplayMode(GLUT_RGBA or GLUT_3_2_CORE_PROFILE)
    window = TestWindow()
    window.show()
    app.exec_()

And I get this errors:

OpenGL.error.NullFunctionError: Attempt to call an undefined function glGenVertexArrays, check for bool(glGenVertexArrays) before calling
OpenGL.error.NullFunctionError: Attempt to call an undefined function glBindVertexArray, check for bool(glBindVertexArray) before calling
OpenGL.error.NullFunctionError: Attempt to call an undefined function glBindVertexArray, check for bool(glBindVertexArray) before calling

I found out that I have to enable GL core profile, but even after I enabled it, it's not working...

# initialize the GL widget
glformat = QtOpenGL.QGLFormat()
glformat.setVersion(4, 1)
glformat.setProfile(QtOpenGL.QGLFormat.CoreProfile)
glformat.setSampleBuffers( True )
QtOpenGL.QGLFormat.setDefaultFormat(glformat)

At the same time if I use VBO from OpenGL.arrays.vbo it works fine.

How can I solve this problem? Where am I wrong?

Addition: I'm using Mac OS X 10.9.4, iMac with NVIDIA GeForce GTX 660M 512 MB (OpenGL 4.1 support and GLSL 4.1.0)

This sounds very much like you don't have a proper OpenGL driver installed on your system. In Windows the default drivers and those installed through the Windows Update mechanism are stripped of their OpenGL support and there's only a software fallback for OpenGL-1.4. The first thing you should do is visit your GPU vendors website, download the latest drivers for your GPU from there and install those. — datenwolf

Eugene Kolesnikov Eugene Kolesnikov · Accepted Answer · 2014-09-07T12:55:48

Moving from PyQt4 to PyQt5 solves the problem

Full source code:

# PyQT5 imports
from PyQt5 import QtGui, QtCore, QtOpenGL, QtWidgets
from PyQt5.QtOpenGL import QGLWidget
from ctypes import *
# PyOpenGL imports
from OpenGL.GL import *
from OpenGL.GL.shaders import *
from OpenGL.GLUT import *

class GLPlotWidget(QGLWidget):
    # default window size
    width, height = 600, 600

    def __init__(self, format = None):
        super(GLPlotWidget, self).__init__(format, None)

    def set_data(self, data):
        self.data = data
        self.count = self.data.nbytes
        self.numVAOs = 2
        self.VAOs = [0] * self.numVAOs
        self.numVBOs = 2
        self.VBOs = [0] * self.numVBOs
        self.shader = None
        self.vPositionLocation = 0

    def initializeGL(self):

        glClearColor(0.0, 0.0, 0.0, 1.0)

        self.VAOs = glGenVertexArrays(self.numVAOs)
        glBindVertexArray(self.VAOs[0])

        self.VBOs = glGenBuffers(self.numVBOs)
        glBindBuffer(GL_ARRAY_BUFFER, self.VBOs[0])
        glBufferData(GL_ARRAY_BUFFER, self.count, self.data, GL_STATIC_DRAW)

        VERTEX_SHADER = compileShader("""
            #version 410 core
            layout(location = 0) in vec4 vPosition;
            void main() {
                gl_Position = vPosition;
            }
        """, GL_VERTEX_SHADER)

        FRAGMENT_SHADER = compileShader("""
            #version 410 core
            out vec4 fColor;
            void main() {
                fColor = vec4(1.0, 1.0, 0.0, 1.0);
            }
        """, GL_FRAGMENT_SHADER)

        self.shader = compileProgram(VERTEX_SHADER, FRAGMENT_SHADER)
        glUseProgram(self.shader)

        glVertexAttribPointer(self.vPositionLocation, 2, GL_FLOAT, GL_FALSE, 0, c_void_p(0))
        glEnableVertexAttribArray(self.vPositionLocation)

    def paintGL(self):
        glClear(GL_COLOR_BUFFER_BIT)

        glBindVertexArray(self.VAOs[0])
        glDrawArrays(GL_TRIANGLES, 0, self.count)

        glFlush()

if __name__ == '__main__':
    # import numpy for generating random data points
    import sys
    import numpy as np
    import numpy.random as rnd

    # define a QT window with an OpenGL widget inside it
    class TestWindow(QtWidgets.QMainWindow):
        def __init__(self, parent = None):
            super(TestWindow, self).__init__(parent)
            self.data = np.array([
                [ -0.90, -0.90 ],
                [  0.85, -0.90 ],
                [ -0.90,  0.85 ],
                [  0.90, -0.85 ],
                [  0.90,  0.90 ],
                [ -0.85,  0.90 ]
            ], dtype = np.float32)
            # initialize the GL widget
            glformat = QtOpenGL.QGLFormat()
            glformat.setVersion(4, 1)
            glformat.setProfile(QtOpenGL.QGLFormat.CoreProfile)
            glformat.setSampleBuffers( True )
            self.widget = GLPlotWidget(glformat)
            self.widget.set_data(self.data)
            # put the window at the screen position (100, 100)
            self.setGeometry(100, 100, self.widget.width, self.widget.height)
            self.setCentralWidget(self.widget)
            self.show()

    # create the QT App and window
    app = QtWidgets.QApplication(sys.argv)
    window = TestWindow()
    window.show()
    app.exec_()

PyQt4 OpenGL: GL core profile error

1 Answers