QGLWidget + QOpenGLVertexArrayObject = no output

I'm using Qt 5.2 and a QGLWidget.

I'm simply attempting to create a white square using two triangles, but something is going wrong -- no output appears and, of course, there's no feedback as to why.

I'm sure I've screwed up something with either the vertex buffer and/or the shader language. And, I'm hoping it's pretty obvious...

Can someone point me in the right direction to get this working?

Cheers

Code:

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QOpenGLBuffer            m_vertexBuffer;
QOpenGLBuffer            m_colorBuffer;
QOpenGLVertexArrayObject m_vao;
QOpenGLShaderProgram    *m_program;

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Code:

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void GLSurfaceWidget::initializeGL()
{
    // Initialize OpenGL Backend
    initializeOpenGLFunctions();
//    printVersionInformation();
 
    qglClearColor(QColor(125,125,140));
 
    glEnable(GL_DEPTH_TEST);
    glEnable(GL_CULL_FACE);
    glShadeModel(GL_SMOOTH);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
 
    static GLfloat lightPosition[4] = { 0, 0, 10, 1.0 };
    glLightfv(GL_LIGHT0, GL_POSITION, lightPosition);
 
    GLfloat xMax, yMax, zMax;
    xMax = 2;
    yMax = 2;
    zMax = 2;
 
    std::vector<QVector3D> boxTriangles;
    std::vector<QVector3D> boxColors;
 
    boxTriangles.push_back(QVector3D(0,       0, zMax)); boxColors.push_back(QVector3D(1,1,1));
    boxTriangles.push_back(QVector3D(xMax,    0, zMax)); boxColors.push_back(QVector3D(1,1,1));
    boxTriangles.push_back(QVector3D(0,    yMax, zMax)); boxColors.push_back(QVector3D(1,1,1));
    boxTriangles.push_back(QVector3D(0,    yMax, zMax)); boxColors.push_back(QVector3D(1,1,1));
    boxTriangles.push_back(QVector3D(xMax,    0, zMax)); boxColors.push_back(QVector3D(1,1,1));
    boxTriangles.push_back(QVector3D(xMax, yMax, zMax)); boxColors.push_back(QVector3D(1,1,1));
 
    int positionSize = boxTriangles.size() * sizeof(QVector3D);
    int colorSize    = boxColors.size() * sizeof(QVector3D);
 
    // Create Shader (Do not release until VAO is created)
    m_program = new QOpenGLShaderProgram();
 
    m_program->addShaderFromSourceCode(QOpenGLShader::Vertex,
            "#version 120\n" //330\n"
            "void main(void)\n"
            "{\n"
            "gl_FrontColor = gl_Color;\n"
            "gl_Position = ftransform();\n"
            "}");
 
    m_program->addShaderFromSourceCode(QOpenGLShader::Fragment,
            "#version 120\n"
            "void main()\n"
            "{\n"
            "gl_FragColor = gl_Color;\n"
            "}\n");
 
    m_program->link();
    m_program->bind();
    int positionAttr = m_program->attributeLocation("position");
    int colorAttr = m_program->attributeLocation("color");
//    int matrixAttr = m_program->attributeLocation("matrix");
 
    // Create Vertex Buffer (Do not release until VAO is created)
    m_vertexBuffer = QOpenGLBuffer(QOpenGLBuffer::VertexBuffer);
    m_vertexBuffer.create();
    m_vertexBuffer.bind();
    m_vertexBuffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
    m_vertexBuffer.allocate(&(boxTriangles.front()), positionSize + colorSize);
 
    // Create Vertex Array Object
    m_vao.create();
    m_vao.bind();
    m_program->enableAttributeArray(positionAttr);
    m_program->enableAttributeArray(colorAttr);
                     //    (int location, GLenum type, int offset, int tupleSize, int stride = 0);
    m_program->setAttributeBuffer(positionAttr, GL_FLOAT, 0, sizeof(QVector3D), 0);
    m_program->setAttributeBuffer(colorAttr, GL_FLOAT, 0, sizeof(QVector3D), 0);
 
    // Release (unbind) all
    m_vao.release();
    m_vertexBuffer.release();
    m_program->release();
 
}

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Code:

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void GLSurfaceWidget::paintGL()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(45 + m_zoomOffset, m_aspect, 0.1, 100);
 
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
 
    glTranslatef(0.0, 0.0, -10.0);
    glRotatef(m_xRot / 16.0, 1.0, 0.0, 0.0);
    glRotatef(m_yRot / 16.0, 0.0, 1.0, 0.0);
    glRotatef(m_zRot / 16.0, 0.0, 0.0, 1.0);
 
    draw();
 
    // Render using our shader
    m_program->bind();
    {
      m_vao.bind();
      glDrawArrays(GL_TRIANGLES, 0, 6);//sizeof(sg_vertexes) / sizeof(sg_vertexes[0]));
      m_vao.release();
    }
    m_program->release();
}

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