gluNurbsSurface

GLUNURBSSURFACE(3G)					  GLUNURBSSURFACE(3G)



NAME
       gluNurbsSurface - define the shape of a NURBS surface


C SPECIFICATION
       void gluNurbsSurface( GLUnurbs* nurb,
			     GLint sKnotCount,
			     GLfloat* sKnots,
			     GLint tKnotCount,
			     GLfloat* tKnots,
			     GLint sStride,
			     GLint tStride,
			     GLfloat* control,
			     GLint sOrder,
			     GLint tOrder,
			     GLenum type )


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

       sKnotCount  Specifies the number of knots in the parametric  u  direc-
		   tion.

       sKnots	   Specifies an array of sKnotCount nondecreasing knot values
		   in the parametric u direction.

       tKnotCount  Specifies the number of knots in the parametric  v  direc-
		   tion.

       tKnots	   Specifies an array of tKnotCount nondecreasing knot values
		   in the parametric v direction.

       sStride	   Specifies the offset	 (as  a	 number	 of  single-precision
		   floating  point  values) between successive control points
		   in the parametric u direction in control.

       tStride	   Specifies the offset (in  single-precision  floating-point
		   values)  between successive control points in the paramet-
		   ric v direction in control.

       control	   Specifies an array containing control points for the NURBS
		   surface.  The offsets between successive control points in
		   the parametric u and v directions are given by sStride and
		   tStride.

       sOrder	   Specifies the order of the NURBS surface in the parametric
		   u direction. The order is one more than the degree,	hence
		   a surface that is cubic in u has a u order of 4.

       tOrder	   Specifies the order of the NURBS surface in the parametric
		   v direction. The order is one more than the degree,	hence
		   a surface that is cubic in v has a v order of 4.

       type	   Specifies  type  of	the  surface.  type can be any of the
		   valid   two-dimensional   evaluator	 types	  (such	   as
		   GL_MAP2_VERTEX_3 or GL_MAP2_COLOR_4).

DESCRIPTION
       Use  gluNurbsSurface  within  a	NURBS (Non-Uniform Rational B-Spline)
       surface definition to describe the shape of a  NURBS  surface  (before
       any  trimming).	To  mark the beginning of a NURBS surface definition,
       use the gluBeginSurface command.	 To mark the end of a  NURBS  surface
       definition, use the gluEndSurface command. Call gluNurbsSurface within
       a NURBS surface definition only.

       Positional, texture, and color coordinates are associated with a	 sur-
       face  by	 presenting  each  as  a  separate  gluNurbsSurface between a
       gluBeginSurface/gluEndSurface  pair.  No	 more  than   one   call   to
       gluNurbsSurface	for  each of color, position, and texture data can be
       made within a single gluBeginSurface/gluEndSurface pair.	 Exactly  one
       call  must  be made to describe the position of the surface (a type of
       GL_MAP2_VERTEX_3 or GL_MAP2_VERTEX_4).

       A NURBS surface can be trimmed by using the commands gluNurbsCurve and
       gluPwlCurve between calls to gluBeginTrim and gluEndTrim.

       Note  that  a gluNurbsSurface with sKnotCount knots in the u direction
       and tKnotCount knots in the v direction with orders sOrder and  tOrder
       must  have  (sKnotCount	-  sOrder)  ×  (tKnotCount  - tOrder) control
       points.

EXAMPLE
       The following commands render a textured NURBS surface  with  normals;
       the texture coordinates and normals are also 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
       gluBeginSurface(3G),	gluBeginTrim(3G),    gluNewNurbsRenderer(3G),
       gluNurbsCurve(3G), gluPwlCurve(3G)




							  GLUNURBSSURFACE(3G)