converting GLUT/OpenGL to Qt/OpenGL

I am working on converting a pure GLUT/OpenGL/OpenCL code into Qt/OpenGL/OpenCL. For this, I use QGLWidget subclass named "GLWidget" for displaying the animation. My issue is that I would like to keep the GLUT displayfunc working of the first code : in main GLUT loop, I used `glutDisplayFunc(displayfunc);`

So, in the Qt/OpenGL, I tried to do this :

Code:

void GLWidget::initializeGL()
    {
        LoadGLTextures();  // load the textures.
        glClearColor(0.0 ,0.0, 0.0, 0.0);
        glMatrixMode(GL_PROJECTION);	
        glLoadIdentity();
 
        m_program = _compileProgram(vertexShader);
 
        glClampColor(GL_CLAMP_VERTEX_COLOR, GL_FALSE);
 
        // memsize of GPU data 
        unsigned int memSize = sizeof(cl_double4) * 4 * Galaxy->getNumParticles();
 
        createVBO(memSize);
 
        m_timer = new QTimer(this);
        connect(m_timer, SIGNAL(timeout()), this, SLOT(displayfunc()));
        m_timer->start(30); 
    }

with displayfunc :

Code:

void GLWidget::displayfunc()
    {
     if (Galaxy->isFirstLaunch)
        {
        gluLookAt (0.0, 0.0, 3.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
        glScalef(0.03f, 0.03f, 0.03f);
        drawPoints();
        //Calling kernel for calculatig subsequent positions
        Galaxy->runCLKernels();
        Galaxy->isFirstLaunch = false;
        glFlush(); 
        swapBuffers();	 
        return;
        }
       else {
              clWaitForEvents(1, &Galaxy->glEvent);
              drawPoints();
    	  //Calling kernel for calculatig subsequent positions
              Galaxy->runCLKernels();
              glFlush(); 
              swapBuffers();	 	  
             }
    	 update();
    }

and drawPoints :

Code:

void GLWidget::drawPoints()
    {
        glClear(GL_COLOR_BUFFER_BIT);
        glClear(GL_DEPTH_BUFFER_BIT);
        glEnable(GL_POINT_SPRITE);
        glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE);
        glEnable(GL_VERTEX_PROGRAM_POINT_SIZE_NV);
 
        glEnable(GL_BLEND);
        glBlendFunc (GL_SRC_ALPHA, GL_ONE);    
 
            glUseProgram(m_program);
            glUniform1f( glGetUniformLocation(m_program, "pointRadius"), m_particleRadius );
            glUniform1f( glGetUniformLocation(m_program, "pointScale"),m_pointScale);  
 
            GLuint vbo_disk;
 
            glBindBuffer(GL_ARRAY_BUFFER, vbo_disk);
            glVertexPointer(4, GL_DOUBLE, 4*sizeof(double), Galaxy->pos);
            glEnableClientState(GL_VERTEX_ARRAY);
 
            glColor4f(1.0f, 1.0f, 1.0f, 0.1f);
            glDrawArrays(GL_POINTS, 0, Galaxy->getNumParticles_disk());
 
            glBindBuffer(GL_ARRAY_BUFFER, 0);
            glDisableClientState(GL_VERTEX_ARRAY);
 
    	GLuint vbo_halo;
 
            glBindBuffer(GL_ARRAY_BUFFER, vbo_halo);
            glVertexPointer(4, GL_DOUBLE, 4*sizeof(double), &Galaxy->pos[Galaxy->getNumParticles_disk()]);
            glEnableClientState(GL_VERTEX_ARRAY);
 
            glColor4f(0.0f, 0.0f, 1.0f, 0.1f);
            glDrawArrays(GL_POINTS, 0, Galaxy->getNumParticles_halo());
 
            glBindBuffer(GL_ARRAY_BUFFER, 0);
            glDisableClientState(GL_VERTEX_ARRAY); 
 
            glDisable(GL_BLEND);		
    	glDisable(GL_POINT_SPRITE);
    }

Can I do without paintGL() function ?

I tried to add makeCurrent() into all the functions containing OpenGL functions but nothing displays in GLWidget, just black screen because of `glClearColor(0.0 ,0.0, 0.0, 0.0)`

Could you see what's wrong ?

converting GLUT/OpenGL to Qt/OpenGL - displaying issue