title: How is one NURBS surface rendered?
body: <p>I know that GPU is efficient for rendering triangles. GPU can't render NURBS surface directly.  From the link <a href="https://stackoverflow.com/questions/14907454/nurbs-in-the-opengl-graphics-pipeline">NURBS in the OpenGL Graphics Pipeline</a>,  we know that. To render NURBS, triangulation is required. I don't know where  triangulation operation occurs. Is it performed by CAD modeling software or GPU? I guess this is done by CAD modeling software.  So the triangulation functionality of NURBS surface is one core task for any CAD modeling software?  Is this task very complex or is solved almost completely by academic researchers?</p>
  
  <p>Why do I have this question? I find that NURBS surfaces are smooth in CAD modeling software? However  if I convert the NURBS surface to triangle mesh first and open it by MeshLab. In MeshLab, some  regions are not smooth. I hope to know which part in the pipeline causes the problem.</p>