gluBeginSurface(3G)	       OpenGL Reference		   gluBeginSurface(3G)



NAME
     gluBeginSurface, gluEndSurface - delimit a	NURBS surface definition


C SPECIFICATION
     void gluBeginSurface( GLUnurbs* nurb )

     void gluEndSurface( GLUnurbs* nurb	)


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


DESCRIPTION
     Use gluBeginSurface to mark the beginning of a NURBS surface definition.
     After calling gluBeginSurface, make one or	more calls to gluNurbsSurface
     to	define the attributes of the surface.  Exactly one of these calls to
     gluNurbsSurface must have a surface type of GL_MAP2_VERTEX_3 or
     GL_MAP2_VERTEX_4.	To mark	the end	of the NURBS surface definition, call
     gluEndSurface.

     Trimming of NURBS surfaces	is supported with gluBeginTrim,	gluPwlCurve,
     gluNurbsCurve, and	gluEndTrim.  Refer to the gluBeginTrim reference page
     for details.

     OpenGL evaluators are used	to render the NURBS surface as a set of
     polygons.	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 surface with normals; the
     texture coordinates and normals are also described	as NURBS surfaces:


	  gluBeginSurface(nobj);
	     gluNurbsSurface(nobj, ...,	GL_MAP2_TEXTURE_COORD_2);
	     gluNurbsSurface(nobj, ...,	GL_MAP2_NORMAL);
	     gluNurbsSurface(nobj, ...,	GL_MAP2_VERTEX_4);
	  gluEndSurface(nobj);



SEE ALSO
     gluBeginCurve, gluBeginTrim, gluNewNurbsRenderer, gluNurbsCurve,
     gluNurbsSurface, gluPwlCurve







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