title: Partial drawing with OpenGL
body: <p>Can we partially redraw the frame in OpenGl?</p>
  
  <p>For Example: If I have both Lines and Polygons in my frame, Polygons does not change ( same dimensions, colour etc) but there is some slight change in Lines. So I want to render only lines again and not polygons. </p>
  
  <p>Is there a way to achieve this?  There will a drastic change in the performance of my application if this is possible.</p>