glShadeModel - select	flat or	smooth shading

	  void glShadeModel( GLenum mode )

	  mode	Specifies a symbolic value representing	a shading
		technique.  Accepted values are	GL_FLAT	and GL_SMOOTH.
		The initial value is GL_SMOOTH.

	  GL primitives	can have either	flat or	smooth shading.
	  Smooth shading, the default, causes the computed colors of
	  vertices to be interpolated as the primitive is rasterized,
	  typically assigning different	colors to each resulting pixel
	  fragment.  Flat shading selects the computed color of	just
	  one vertex and assigns it to all the pixel fragments
	  generated by rasterizing a single primitive.	In either
	  case,	the computed color of a	vertex is the result of
	  lighting if lighting is enabled, or it is the	current	color
	  at the time the vertex was specified if lighting is

	  Flat and smooth shading are indistinguishable	for points.
	  Starting when	glBegin	is issued and counting vertices	and
	  primitives from 1, the GL gives each flat-shaded line
	  segment i the	computed color of vertex i+1, its second
	  vertex.  Counting similarly from 1, the GL gives each	flat-
	  shaded polygon the computed color of the vertex listed in
	  the following	table.	This is	the last vertex	to specify the
	  polygon in all cases except single polygons, where the first
	  vertex specifies the flat-shaded color.

		     |primitive	type of	polygon	i | vertex |
		     |Single polygon (i=1)	  |   1	   |
		     |Triangle strip		  |  i+2   |
		     |Triangle fan		  |  i+2   |
		     |Independent triangle	  |   3i   |
		     |Quad strip		  |  2i+2  |
		     |Independent quad		  |   4i   |

	  Flat and smooth shading are specified	by glShadeModel	with
	  mode set to GL_FLAT and GL_SMOOTH, respectively.

	  GL_INVALID_ENUM is generated if mode is any value other than

	  GL_INVALID_OPERATION is generated if glShadeModel is
	  executed between the execution of glBegin and	the
	  corresponding	execution of glEnd.

	  glGet	with argument GL_SHADE_MODEL

	  glBegin, glColor, glLight, glLightModel