ex21: Geodesic Sphere

Willem A. (Vlakkies) Schreuder
CSCI4229/5229 Fall 2014

This program requires OpenGL 4.0 or above
Demonstrate a tesselation shader by drawing a sphere
from an icosahedron.
Based on The Little Grashopper tutorial
http://prideout.net/blog/?p=48

Key bindings
  +/-        Increase/decrease inner and outer
  i/I        Increase/decrease inner
  o/O        Increase/decrease outer
  r          Reset inner/outer levels
  arrows     Change view angle
  PgDn/PgUp  Zoom in and out
  0          Reset view angle
  ESC        Exit
