GLUNURBSSURFACE(3G)GLUNURBSSURFACE(3G)NAMEgluNurbsSurface - 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 )
delim $$
PARAMETERS
nurb Specifies the NURBS object (created with gluNewNurbsRenderer).
sKnotCount
Specifies the number of knots in the parametric u direction.
sKnots Specifies an array of sKnotCount nondecreasing knot values in
the parametric u direction.
tKnotCount
Specifies the number of knots in the parametric v direction.
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 parametric 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
surface 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) $times$ (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 ALSOgluBeginSurface(3G), gluBeginTrim(3G), gluNewNurbsRenderer(3G),
gluNurbsCurve(3G), gluPwlCurve(3G)
March 1, 2011
