Triangulation
=============
Remember how we discussed polygon rendering and
the limitations OpenGL places on rendering polygons
i.e. non - complex and convex polygons can be 
rendered.  Here are some pointers to developing good
skills at rendering complex surfaces.  We will also
later in this section touch on triangulation and provide
examples on how to achieve this.

Pointers to Polygon rendering 
=============================

  o  Keep polygon orientations consistent.  Make sure,
     that when viewed from the outside, all polygons on 
     the surface are oriented in the same direction i.e.
     (all clockwise or all counterclockwise).  Consistency
     in orientation is necessary for two sided lighting.

  o  When subdividing a surface watch out for any non
     triangular polygons.  The three vertices of a triangle 
     are guaranteed to lie on a plane; any polygon with
     four or more vertices might not.  

  o  There is a tradeoff between how fine you want to subdivide
     and the rendering speed. i.e. the more the triangles used
     the slower the rendering.  A geneal rule of thumb is that
     objects whicha are further away in a screen can be 
     rendered with fewer polygons than objects closer to the
     viewpoint.

  
  o
					     
			  /\			 
			 /  \		
			/    \	       
		     A /__B___\C            
		       \  |   /            
			\ |  /             
			 \| /              
			  \/               
    
     Try to avoid T-intersections in your models.  The one shown above
     is undesirable since there is no guarantee that the line segments
     AB and BC lie on exactly the same pixels as segment AC.


Some notes on triangulations
============================