gluDisk - draw a disk

	  void gluDisk(	GLUquadric* quad,
			GLdouble inner,
			GLdouble outer,
			GLint slices,
			GLint loops )

	  quad	  Specifies the	quadrics object	(created with

	  inner	  Specifies the	inner radius of	the disk (may be 0).

	  outer	  Specifies the	outer radius of	the disk.

	  slices  Specifies the	number of subdivisions around the z

	  loops	  Specifies the	number of concentric rings about the
		  origin into which the	disk is	subdivided.

	  gluDisk renders a disk on the	z = 0 plane. The disk has a
	  radius of outer, and contains	a concentric circular hole
	  with a radius	of inner. If inner is 0, then no hole is
	  generated. The disk is subdivided around the z axis into
	  slices (like pizza slices), and also about the z axis	into
	  rings	(as specified by slices	and loops, respectively).

	  With respect to orientation, the +z side of the disk is
	  considered to	be "outside" (see gluQuadricOrientation).
	  This means that if the orientation is	set to GLU_OUTSIDE,
	  then any normals generated point along the +z	axis.
	  Otherwise, they point	along the -z axis.

	  If texturing has been	turned on (with	gluQuadricTexture),
	  texture coordinates are generated linearly such that where
	  r=outer, the value at	(r, 0, 0) is (1, 0.5), at (0, r, 0) it
	  is (0.5, 1), at (-r, 0, 0) it	is (0, 0.5), and at (0,	-r, 0)
	  it is	(0.5, 0).

	  gluCylinder, gluNewQuadric, gluPartialDisk,
	  gluQuadricOrientation, gluQuadricTexture, gluSphere