title: How to make a OpenGl (GLUT) rotate-Animation?
body: <p>I have made a playing field and it would rotate 180 degrees.
  Unfortunately you can not see how it turns more and more slowly.
  I only see the final "twist".</p>
  
  <pre><code>/**
  @brief Rotates the Gamefield 180° with an turn animaion
  */
  void flipGamefield180degree (){
          for (int i = 0; i &lt; 180; i++){
              glRotatef(1, 0, 1, 0);
              glutPostRedisplay();
              Sleep(20);
          }
  }
  
  
  void display(void)
  {
  
      // Löscht den Bildschirm
     glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  
     // Zeichenfarbe setzen  
     glColor3f (1.0, 1.0, 1.0);
     glLoadIdentity ();             
  
     // _,_,_ wo steht die Kamera, _,_,_ wo hin, wo ist oben?
     gluLookAt (0.0, 0.0, 10, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
  
  
     // Rotation X-Achse
     rotating(0);
     // Rotation Y-Achse
     rotating(1);
     // Rotation Z-Achse
     rotating(2);
  
     if (flip180degree){
         flipGamefield180degree();
     }
  
     /*glRotatef(15,0,1,0);
     glRotatef(-15,1,0,0);
     */
  
     glTranslatef(-5.5, -6 ,0);
     glPushMatrix();
     drawGameField(false, 10);
     glPopMatrix();
  
     glPushMatrix();
     glTranslatef(11, 0 ,0);
     glPushMatrix();
     drawGameField(true, 10);
     glPopMatrix();
     glPopMatrix();
  
     //drawShipOnField(s1, feldSpieler);
     drawShipOnField(s1, feldSpieler);
  
     //glDisable(GL_LIGHTING);
     /*glColor3f(0, 0, 1); 
     glutSolidCube(1);
     glEnable(GL_LIGHTING);*/
    /* glTranslatef(5, 0, 0);
     drawGameField(true, 10);*/
     //glutSolidTeapot(1.0);
  
  
     //glRotatef(30,1.0,0.0,0.0);
  
  
  
  
  
  
     glFlush ();
  }
  </code></pre>