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<STRONG>NAME</STRONG>
<STRONG>gluNurbsSurface</STRONG> - define the shape of a NURBS surface
<STRONG>C</STRONG> <STRONG>SPECIFICATION</STRONG>
void <STRONG>gluNurbsSurface</STRONG>( GLUnurbs* <EM>nurb</EM>,
GLint <EM>sKnotCount</EM>,
GLfloat* <EM>sKnots</EM>,
GLint <EM>tKnotCount</EM>,
GLfloat* <EM>tKnots</EM>,
GLint <EM>sStride</EM>,
GLint <EM>tStride</EM>,
GLfloat* <EM>control</EM>,
GLint <EM>sOrder</EM>,
GLint <EM>tOrder</EM>,
GLenum <EM>type</EM> )
<STRONG>PARAMETERS</STRONG>
<EM>nurb</EM> Specifies the NURBS object (created with
<STRONG>gluNewNurbsRenderer</STRONG>).
<EM>sKnotCount</EM> Specifies the number of knots in the parametric
<EM>u</EM> direction.
<EM>sKnots</EM> Specifies an array of <EM>sKnotCount</EM> nondecreasing
knot values in the parametric <EM>u</EM> direction.
<EM>tKnotCount</EM> Specifies the number of knots in the parametric
<EM>v</EM> direction.
<EM>tKnots</EM> Specifies an array of <EM>tKnotCount</EM> nondecreasing
knot values in the parametric <EM>v</EM> direction.
<EM>sStride</EM> Specifies the offset (as a number of single-
precision floating point values) between
successive control points in the parametric <EM>u</EM>
direction in <EM>control</EM>.
<EM>tStride</EM> Specifies the offset (in single-precision
floating-point values) between successive
control points in the parametric <EM>v</EM> direction in
<EM>control</EM>.
<EM>control</EM> Specifies an array containing control points for
the NURBS surface. The offsets between
successive control points in the parametric <EM>u</EM>
and <EM>v</EM> directions are given by <EM>sStride</EM> and
<EM>tStride</EM>.
<EM>sOrder</EM> Specifies the order of the NURBS surface in the
parametric <EM>u</EM> direction. The order is one more
than the degree, hence a surface that is cubic
in <EM>u</EM> has a <EM>u</EM> order of 4.
<EM>tOrder</EM> Specifies the order of the NURBS surface in the
parametric <EM>v</EM> direction. The order is one more
than the degree, hence a surface that is cubic
in <EM>v</EM> has a <EM>v</EM> order of 4.
<EM>type</EM> Specifies type of the surface. <EM>type</EM> can be any
of the valid two-dimensional evaluator types
(such as <STRONG>GL_MAP2_VERTEX_3</STRONG> or <STRONG>GL_MAP2_COLOR_4</STRONG>).
<STRONG>DESCRIPTION</STRONG>
Use <STRONG>gluNurbsSurface</STRONG> 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 <STRONG>gluBeginSurface</STRONG> command.
To mark the end of a NURBS surface definition, use the
<STRONG>gluEndSurface</STRONG> command. Call <STRONG>gluNurbsSurface</STRONG> within a NURBS
surface definition only.
Positional, texture, and color coordinates are associated
with a surface by presenting each as a separate
<STRONG>gluNurbsSurface</STRONG> between a <STRONG>gluBeginSurface</STRONG>/<STRONG>gluEndSurface</STRONG>
pair. No more than one call to <STRONG>gluNurbsSurface</STRONG> for each of
color, position, and texture data can be made within a
single <STRONG>gluBeginSurface</STRONG>/<STRONG>gluEndSurface</STRONG> pair. Exactly one call
must be made to describe the position of the surface (a <EM>type</EM>
of <STRONG>GL_MAP2_VERTEX_3</STRONG> or <STRONG>GL_MAP2_VERTEX_4</STRONG>).
A NURBS surface can be trimmed by using the commands
<STRONG>gluNurbsCurve</STRONG> and <STRONG>gluPwlCurve</STRONG> between calls to <STRONG>gluBeginTrim</STRONG>
and <STRONG>gluEndTrim</STRONG>.
Note that a <STRONG>gluNurbsSurface</STRONG> with <EM>sKnotCount</EM> knots in the <EM>u</EM>
direction and <EM>tKnotCount</EM> knots in the <EM>v</EM> direction with
orders <EM>sOrder</EM> and <EM>tOrder</EM> must have (<EM>sKnotCount</EM> - <EM>sOrder</EM>) x
(<EM>tKnotCount</EM> - <EM>tOrder</EM>) control points.
<STRONG>EXAMPLE</STRONG>
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);
<STRONG>SEE</STRONG> <STRONG>ALSO</STRONG>
<STRONG>gluBeginSurface</STRONG>, <STRONG>gluBeginTrim</STRONG>, <STRONG>gluNewNurbsRenderer</STRONG>,
<STRONG>gluNurbsCurve</STRONG>, <STRONG>gluPwlCurve</STRONG>
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