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 :

Qt Code: 
  1. void GLWidget::initializeGL()
  2.     {
  3.         LoadGLTextures();  // load the textures.
  4.         glClearColor(0.0 ,0.0, 0.0, 0.0);
  5.         glMatrixMode(GL_PROJECTION);	
  6.         glLoadIdentity();
  7.  
  8.         m_program = _compileProgram(vertexShader);
  9.  
  10.         glClampColor(GL_CLAMP_VERTEX_COLOR, GL_FALSE);
  11.  
  12.         // memsize of GPU data 
  13.         unsigned int memSize = sizeof(cl_double4) * 4 * Galaxy->getNumParticles();
  14.  
  15.         createVBO(memSize);
  16.  
  17.         m_timer = new QTimer(this);
  18.         connect(m_timer, SIGNAL(timeout()), this, SLOT(displayfunc()));
  19.         m_timer->start(30); 
  20.     }
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with displayfunc :



Qt Code: 
  1. void GLWidget::displayfunc()
  2.     {
  3.      if (Galaxy->isFirstLaunch)
  4.         {
  5.         gluLookAt (0.0, 0.0, 3.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
  6.         glScalef(0.03f, 0.03f, 0.03f);
  7.         drawPoints();
  8.         //Calling kernel for calculatig subsequent positions
  9.         Galaxy->runCLKernels();
  10.         Galaxy->isFirstLaunch = false;
  11.         glFlush(); 
  12.         swapBuffers();	 
  13.         return;
  14.         }
  15.        else {
  16.               clWaitForEvents(1, &Galaxy->glEvent);
  17.               drawPoints();
  18.     	  //Calling kernel for calculatig subsequent positions
  19.               Galaxy->runCLKernels();
  20.               glFlush(); 
  21.               swapBuffers();	 	  
  22.              }
  23.     	 update();
  24.     }
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and drawPoints :

Qt Code: 
  1. void GLWidget::drawPoints()
  2.     {
  3.         glClear(GL_COLOR_BUFFER_BIT);
  4.         glClear(GL_DEPTH_BUFFER_BIT);
  5.         glEnable(GL_POINT_SPRITE);
  6.         glTexEnvi(GL_POINT_SPRITE, GL_COORD_REPLACE, GL_TRUE);
  7.         glEnable(GL_VERTEX_PROGRAM_POINT_SIZE_NV);
  8.  
  9.         glEnable(GL_BLEND);
  10.         glBlendFunc (GL_SRC_ALPHA, GL_ONE);    
  11.  
  12.             glUseProgram(m_program);
  13.             glUniform1f( glGetUniformLocation(m_program, "pointRadius"), m_particleRadius );
  14.             glUniform1f( glGetUniformLocation(m_program, "pointScale"),m_pointScale);  
  15.  
  16.             GLuint vbo_disk;
  17.  
  18.             glBindBuffer(GL_ARRAY_BUFFER, vbo_disk);
  19.             glVertexPointer(4, GL_DOUBLE, 4*sizeof(double), Galaxy->pos);
  20.             glEnableClientState(GL_VERTEX_ARRAY);
  21.  
  22.             glColor4f(1.0f, 1.0f, 1.0f, 0.1f);
  23.             glDrawArrays(GL_POINTS, 0, Galaxy->getNumParticles_disk());
  24.  
  25.             glBindBuffer(GL_ARRAY_BUFFER, 0);
  26.             glDisableClientState(GL_VERTEX_ARRAY);
  27.  
  28.     	GLuint vbo_halo;
  29.  
  30.             glBindBuffer(GL_ARRAY_BUFFER, vbo_halo);
  31.             glVertexPointer(4, GL_DOUBLE, 4*sizeof(double), &Galaxy->pos[Galaxy->getNumParticles_disk()]);
  32.             glEnableClientState(GL_VERTEX_ARRAY);
  33.  
  34.             glColor4f(0.0f, 0.0f, 1.0f, 0.1f);
  35.             glDrawArrays(GL_POINTS, 0, Galaxy->getNumParticles_halo());
  36.  
  37.             glBindBuffer(GL_ARRAY_BUFFER, 0);
  38.             glDisableClientState(GL_VERTEX_ARRAY); 
  39.  
  40.             glDisable(GL_BLEND);		
  41.     	glDisable(GL_POINT_SPRITE);
  42.     }
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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 ?