gluBeginCurve, gluEndCurve - delimit a NURBS curve defini-
       tion



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  speci-
       fied as NURBS curves:

       gluBeginCurve(nobj);
          gluNurbsCurve(nobj, ..., GL_MAP1_TEXTURE_COORD_2);
          gluNurbsCurve(nobj, ..., GL_MAP1_NORMAL);
          gluNurbsCurve(nobj,   ...,  GL_MAP1_VERTEX_4);  gluEnd-
       Curve(nobj);


SEE ALSO

       gluBeginSurface,    gluBeginTrim,     gluNewNurbsRenderer,
       gluNurbsCurve, glPopAttrib, glPushAttrib




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