title: Per vertex shading vs per fragment shading on large models
body: <p>I am new to GLSL and writing a small application that will show a 3d model and has some user input to rotate, zoom etc. The models are rather big  ( e.g. 6 million vertices, 15million faces). Right now, I am using per vertex shading and performance is ok on my personal pc. But I might need to use larger models ( with 10-15 million vertices).</p>
  
  <p>The question I have is related to the performance comparison between per-vertex and per-fragment shading. From severeal resources, as well as searching the net, I have come to the conclusion that per-fragment is shading has better output especially for specular highlights however its performance is lower since it makes calculations for each pixel of the polygons instead of each vertex ( as in per vertex shading). </p>
  
  <p>Maybe I am thinking completely wrong, but if the vertex count is large , should I expect per fragment shading to run faster for example in my case ( 6-10 million vertex) ? Isthe perforamnce of per fragment shading dependent on the number of pixels that is being drawn to the screen whereas per vertex shading is not?</p>