void GLWidget::saveGLState()
{
  glPushAttrib(GL_ALL_ATTRIB_BITS);
  glMatrixMode(GL_PROJECTION);
  glPushMatrix();
  glMatrixMode(GL_MODELVIEW);
  glPushMatrix();
}

void GLWidget::restoreGLState()
{
  glMatrixMode(GL_PROJECTION);
  glPopMatrix();
  glMatrixMode(GL_MODELVIEW);
  glPopMatrix();
  glPopAttrib();
}

void GLWidget::initializeGL()
{
    makeCurrent ();
    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
    glClearDepth(1.0f);
    glEnable (GL_NORMALIZE);
    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LEQUAL);    

    glShadeModel(GL_SMOOTH);

    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_FASTEST);

    // Enable light and set up 2 light sources (GL_LIGHT0 and GL_LIGHT1)
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    
    float ambientLight0[] = { 0.25f, 0.25f, 0.25f, 0.6f };
    float diffuseLight0[] = { 0.2f, 0.2f, 0.2f, 0.1f };
    float specularLight0[] = { 1.0f, 1.0f, 1.0f, 1.0f };
    float position0[] = { 0, 0, -40.0f, 1.0f };

    // Assign created components to GL_LIGHT0
    glLightfv(GL_LIGHT0, GL_AMBIENT, ambientLight0);
    glLightfv(GL_LIGHT0, GL_DIFFUSE, diffuseLight0);
    glLightfv(GL_LIGHT0, GL_SPECULAR, specularLight0);
    glLightfv(GL_LIGHT0, GL_POSITION, position0);

      //
  //light model properties
  //
  float model_ambient[] = {0.4f, 0.4f, 0.4f, 1.0f};

  glLightModelfv(GL_LIGHT_MODEL_AMBIENT, model_ambient);     //small white ambient light


  //
  // meterial properties
  //
  float no_mat[] = {0.0f, 0.0f, 0.0f, 1.0f};
  float mat_ambient[] = {0.7f, 0.7f, 0.7f, 0.1f};
  float mat_diffuse[] = {0.1f, 0.5f, 0.8f, 0.1f};
  float mat_specular[] = {1.0f, 1.0f, 1.0f, 1.0f};
  float high_shininess = 0.1f;

  glMaterialfv(GL_FRONT, GL_AMBIENT, mat_ambient);
  glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_diffuse);
  glMaterialfv(GL_FRONT, GL_SPECULAR, mat_specular);
  glMaterialf(GL_FRONT, GL_SHININESS, high_shininess);
  glMaterialfv(GL_FRONT, GL_EMISSION, no_mat);

void GLWidget::paintGL()
{  
  makeCurrent();

  glClearColor(.0, 0.0, .0, 1);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  glColor4f (1.0, 1.0, 1.0, 1.0);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glFrustum(-1, 1, -1, 1, 10, 100);
  glTranslatef(0.0f, 0.0f, -15.0f);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glViewport(0, 0, width(), height());
  

  const int w = logo.width();
  const int h = logo.height();
  
  glRotatef(rot_x, 1.0f, 0.0f, 0.0f);
  glRotatef(rot_y, 0.0f, 1.0f, 0.0f);
  glRotatef(rot_z, 0.0f, 0.0f, 1.0f);
  glScalef(scale/w, scale/w, scale/w); 
 
  glTranslatef(-w+1, 0, 0.0f);

  for(int j=0; j < h-1; ++j)
  {

    glBegin(GL_TRIANGLE_STRIP);
    for(int i=0; i < w-1; ++i)
    {
      double x = i;
      double y = j;
      GLfloat v1[] = {0,0,0};
      GLfloat v2[] = {0,0,0};
      {
        GLfloat xx = x*2;
        GLfloat zz = y*2;
        int wi = y*w + x;
        GLfloat yy = wave[wi];
        glVertex3f(xx, yy, zz);
        v1[0] -= xx;
        v1[1] -= yy;
        v1[2] -= zz;
      }

      x = i+1;
      y = j;
      {
        GLfloat xx = x*2;
        GLfloat zz = y*2;
        int wi = y*w + x;
        GLfloat yy = wave[wi];
        glVertex3f(xx, yy, zz);
        v1[0] += xx;
        v1[1] += yy;
        v1[2] += zz;
        v2[0] -= xx;
        v2[1] -= yy;
        v2[2] -= zz;
      }

      x = i;
      y = j+1;
      {
        GLfloat xx = x*2;
        GLfloat zz = y*2;
        int wi = y*w + x;
        GLfloat yy = wave[wi];
        glVertex3f(xx, yy, zz);
        v2[0] += xx;
        v2[1] += yy;
        v2[2] += zz;
      }
      GLfloat normal[] = {v1[1]*v2[2] - v2[2]*v1[1], v1[2]*v2[0] - v1[0]*v2[2], v1[0]*v2[1]- v1[1]*v2[0]};
      glNormal3fv (normal);
      x = i+1;
      y = j+1;
      {
        GLfloat xx = x*2;
        GLfloat zz = y*2;
        int wi = y*w + x;
        GLfloat yy = wave[wi];
        glVertex3f(xx, yy, zz);
      }
    }
    glEnd();

  }  
  //restoreGLState();
}