NAME
	  gluBeginCurve, gluEndCurve - delimit a NURBS curve
	  definition


     C SPECIFICATION
	  void gluBeginCurve( GLUnurbs*	nurb )

	  void gluEndCurve( GLUnurbs* nurb )


     PARAMETERS
	  nurb	Specifies the NURBS object (created with
		gluNewNurbsRenderer).

     DESCRIPTION
	  Use gluBeginCurve to mark the	beginning of a NURBS curve
	  definition.  After calling gluBeginCurve, make one or	more
	  calls	to gluNurbsCurve to define the attributes of the
	  curve.  Exactly one of the calls to gluNurbsCurve must have
	  a curve type of GL_MAP1_VERTEX_3 or GL_MAP1_VERTEX_4.	 To
	  mark the end of the NURBS curve definition, call
	  gluEndCurve.

	  GL evaluators	are used to render the NURBS curve as a	series
	  of line segments.  Evaluator state is	preserved during
	  rendering with glPushAttrib(GL_EVAL_BIT) and glPopAttrib().
	  See the glPushAttrib reference page for details on exactly
	  what state these calls preserve.

     EXAMPLE
	  The following	commands render	a textured NURBS curve with
	  normals; texture coordinates and normals are also specified
	  as NURBS curves:

	  gluBeginCurve(nobj);
	     gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2);
	     gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
	     gluNurbsCurve(nobj, ..., GL_MAP1_VERTEX_4);
	  gluEndCurve(nobj);

     SEE ALSO
	  gluBeginSurface, gluBeginTrim, gluNewNurbsRenderer,
	  gluNurbsCurve, glPopAttrib, glPushAttrib